Laser pistol EverReadys
Winchell Chung
on one of the most cherished items in space opera: the Laser Sidearm.
Specifically, how ludicrous are the requirements for the
batteries powering the blasted thing.
Offhand, it would seem that it is far more efficient to use
an ancient Colt .45 chemically fueled bullet instead of a laser
pistol to drill a hole in a hapless target.
Say that the laser has ten shots worth of energy in the
battery. Say each shot is capable of doing quote significant
unquote damage to a human target. Say the laser has
an efficiency in the neighborhood of the best efficiencies
we can manage with current technology (free electron laser
or whatever).
How much energy will the battery be required to store?
Just a back of the envelope, order of magnitude estimate.
This will, of course, depend upon the definition of
"significant damage", which I have no idea of how to
quantify.
John Schilling stated the opinion that a bit over one kilojoule
will be required to reliably incapacitate a human target.
(divided into ~1 joule pulses at ~5 microsecond intervals)
Offhand I'd imagine that the power in one battery could
be used to light up a all the apartments in a city block
for a hour or so. In any event, probably five or six
orders of magnitude better than current batteries.
John Schilling suggested that 2.5 kilojoules per cubic centimeter
battery densities will be required.
Charles R Martin
>
> I would like some help in shining the harsh light of reality
> on one of the most cherished items in space opera: the Laser Sidearm.
> John Schilling suggested that 2.5 kilojoules per cubic centimeter
> battery densities will be required.
Sounds like you need some kind of explosive in a magnetic field thing, a la a
rail gun.
Well, maybe that explains why the Star Wars "blasters" go "bang" and shoot
smoke?
Timothy Little
>I would like some help in shining the harsh light of reality
>on one of the most cherished items in space opera: the Laser Sidearm.
Oh god, not again! :^)
>Specifically, how ludicrous are the requirements for the
>batteries powering the blasted thing.
[...]
>Say that the laser has ten shots worth of energy in the
>battery. Say each shot is capable of doing quote significant
>unquote damage to a human target.
[...]
>John Schilling stated the opinion that a bit over one kilojoule
>will be required to reliably incapacitate a human target.
>(divided into ~1 joule pulses at ~5 microsecond intervals)
So, that makes 10 kJ per battery if the laser is 100% efficient. The
most efficient laser I was able to find had 38% electricity ->
coherent light. With properties unsuited to a weapon, though you were
talking about the "best efficiencies we can manage with current
technology".
Make the efficiency lower (say 20%) to allow for losses in the stages
between battery and lasing device, and call the energy requirement
50 kJ.
>Offhand I'd imagine that the power in one battery could be used to
>light up a all the apartments in a city block for a hour or so.
I get enough to light up one small room for 15 minutes.
> In any event, probably five or six orders of magnitude better than
>current batteries.
Well, my camera batteries supply about 3 kJ of useful energy in about
10 cm^3 (including casing). That's just about all you need.
The basic energy requirement doesn't seem to be a huge problem. The
problem seems to be getting a high-efficiency multi-kW weapon laser
assembly into something as small and rugged as a sidearm needs to be,
with a *fast* compact energy source that won't kill you if you break
it.
- Tim
K. Key
Winchell Chung wrote:
> I would like some help in shining the harsh light of reality
> on one of the most cherished items in space opera: the Laser Sidearm.
>
> Specifically, how ludicrous are the requirements for the
> batteries powering the blasted thing.
>
> Offhand, it would seem that it is far more efficient to use
> an ancient Colt .45 chemically fueled bullet instead of a laser
> pistol to drill a hole in a hapless target.
Keep in mind, if all you want is efficiency, an arrow will cause lethal
damage with far less energy than a Colt .45.
> Say that the laser has ten shots worth of energy in the
> battery. Say each shot is capable of doing quote significant
> unquote damage to a human target. Say the laser has
> an efficiency in the neighborhood of the best efficiencies
> we can manage with current technology (free electron laser
> or whatever).
The last sentance is the easiest to answer - modern free electron lasers
can exceed 99% efficiency at turning electricity into light. This is
extraordinarily efficient, really efficient lasers of other kinds operate
at the 20 to 40% efficiency level.
Now lets turn our attention to what energy is required to do significant
damage to a human. This depends on the details of the laser beam. For
the moment, let us assume we are talking about lasers operating at one of
the windows in which the atmosphere is transparent - 15 to 8 micron IR, 4
to 3 micron IR, and 1 micron IR through the visible range through the
UV-A and UV-B bands to about 0.2 microns. Anything else is absorbed by
atmosphere, although you can play tricks to get hard x-rays to penetrate
a useful distance.
If you direct 100 kilojoules of light into a circle one meter in diameter
in a relatively short period of time (say, 1/10 of a second or less), any
exposed skin in that circle will recieve third degree burns. Skin under
relatively lightweight clothing (t-shirts, jeans, military uniforms) will
recieve second degree burns. Most clothing will ignite, causing further
burns, though white or light colored clothing may only smoulder a bit.
If the beam gets in the eyes, the target will not only be burned on the
face, but blinded. Second or third degree burns over a quarter of the
body or more are very serious, and probably lethal without medical
intervention. Most people would probably be incapacitated by these
burns, though anyone who can ignore the pain may still be able to
function for a short while (although they might be blind). This method
has the drawbacks that it will not do anything through thick clothing,
armor, or barriers, although it will ignite some armors (like spectra).
You can try using a highly focused beam rather than a wide beam. Hard
data on the damage this will cause to flesh is lacking, but we can try to
extrapolate from the available information. According to an article in
Science magazine, the MIRACL laser (a megawatt range deuterium fluoride
laser developed by the military as an experimental anti-missile laser,
probably operating at just over a megawatt for civilian research
purposes) was used to drill through sandstone at the rate of 4 cm/s. The
hole was fairly large, maybe 3 cm across (estimating from the photo with
the article, but it was a while since I saw the photo since it is not
available with the on-line version of the article). If the limiting rate
at which it could drill was due to the absorption of the beam by the
plasma from the material superheated by the beam, we might expect it
could drill through flesh at about 3 times this rate, or 12 cm/s, since
flesh is about 1/3 as dense as rock. To cause lethal damage this way,
you need to drill down deep enough to reach vital organs, at least 10
cm. therefore, you will need to keep the beam focused on the same spot
for about a second to cause lethal damage. This will be very difficult
as people tend to move around a bit when you try to drill through them.
If you can hold it on a person for a whole second, it will take one
megajoule to cause lethal damage - better go with the burning option.
Using a higher or lower power, under this assumption, will not alter the
rate at which it burns through the person, just the spot size of the beam
(any more concentrated and the beam is largely absorbed and does not
contribute to burning the target).
Now MIRACL operates at a number of wavelengths between 3 and 4 microns
IR. The shorter the wavelength of the laser, the higher the
concentration of the plasma the light can penetrate. If the laser is
operating at 0.2 micron (UV) wavelengths and the beam is limited by
absorption by the plasma it generates, it could penetrate about four
times as far in a given time, so you would only need to hold the beam
steady on target for about 1/5 of a second, or 200 kilojoules for
possibly lethal damage (but the spot size would be only half the
diameter, making holding the beam to a dispersion of less than the spot
size more difficult. To get the same diameter beam, increase the energy
required by a factor of 4).
If the limiting rate is determined by the rate at which the beam could
deliver energy to evaporate the sandstone, things look a bit better since
it takes about 10 times more energy to vaporize rock than flesh, so we
get the laser drilling through about 40 cm/s of a person. You still need
to hold the beam to less than a 3 cm deviation for 1/4 of a second on a
target who will probably be taking evasive action. Now, you need a
pretty constant 250 kilojoules to drill a 3 cm wide hole 10 cm into your
target. A narrower beam would take less energy, but would once again
make it harder to keep the beam focused onto one spot.
Okay, so continuous beam lasers are not looking like an attractive
option, other than as a long range flamethower. Lets look at pulse
lasers. Now things are starting to look a bit better. A nanosecond
pulse will deliver nearly all of its energy into a thin layer of plasma
before the plasma has a chance to expand. When it does expand, it does
so explosively and delivers most of the energy of the pulse as a shock
wave into the target. This will do damage equivalent to the energy
released by a high explosive of similar energy yeild. TNT is generally
quoted as having a yeild of 4 to 5 megajoules per kilogram (let's say 5
MJ/kg for our purposes). A 5 megajoule pulse would therefore cause about
as much damage as a kilogram of TNT - enough to blast a person apart and
then some. This is a bit of overkill, but pulse energies in the 10 to
100 kilojoule range could probably prove lethal, especially if they were
incident on the chest so they could throw rib fragments around the chest
cavity, or if they were incident on the head.
The problem with these pulses is that they have no penetration - they
blast the first thing they encounter, be it a person, a thin curtain, a
leaf or twig, a thin layer of clothing, whatever. Also, the damage is
localized to a roughly spherical region around the point of incidence, so
you need a lot of energy to penetrate down to vital organs. If there was
a way to deliver the energy deep inside a person, this would be ideal.
There is a way that might work. When a shockwave goes through tissue (or
anything else) the material the shock passes through ends up moving in
the same direction as the shock. For a spherical shock (like you would
get from a tightly focused pulse), this means that you get a rapidly
expanding cavity in the person. Flesh is highly elastic, comparing with
gunshot wounds from high velocity rifle bullets, the cavity probably
colapses back without disrupting a lot of tissue, but the flesh near the
center of the cavity gets stretched a lot and will probably tear. The
cavity will last for a few milliseconds before collapsing, if a second
pulse is incident on the back of the still expanding cavity, it will
cause a second cavity to form, causing extra ripping damage deeper inside
while the shockwave of the second pulse will overtake and merge with the
first pulse in the forward direction, enhancing the strength of the
shock. Using a train of pulses in this fashion, delivered in less time
than the few milliseconds it takes the original cavity to colapse, you
might be able to cause damage deep inside a person, deep enough to
disrupt vital organs. This is highly speculative, but if it works, you
could probably cause lethal damage with about the same energy as a modern
high powered rifle, say between 1 and 10 kilojoules.
Alternately, you could try to use a tightly focused beam of hard x-rays
to "burn" an evacuated tunnel through the atmosphere for the rest of the
hard x-ray beam to follow. X-rays will not be stopped by plasma produced
by the target, they will go right through and evaporate the target. You
could burn a 1 mm wide hole right through someone with only about 4
kilojoules delivered in a short pulse, and the scattered x-rays would
burn the surrounding tissue. The total radiation dose from one shot
would be lethal to the target, posibly within minutes from brain death,
but certainly within weeks or months from radiation sickness.
Unfortunately, the backscattered radiation from your own beam would pose
a radiation hazard to you. Probably no one would use one of these things
unless they had a lot of shielding between themselves and the laser beam
(likley restricting their use to armored fighting vehicles).
> How much energy will the battery be required to store?
> Just a back of the envelope, order of magnitude estimate.
For 99% efficiency and a ten shot magazine using the pulse train
described earlier, between 10 and 100 kilojoules. If the pulse train
idea does not work, increase this by a factor of 10.
> This will, of course, depend upon the definition of
> "significant damage", which I have no idea of how to
> quantify.
> John Schilling stated the opinion that a bit over one kilojoule
> will be required to reliably incapacitate a human target.
> (divided into ~1 joule pulses at ~5 microsecond intervals)
>
> Offhand I'd imagine that the power in one battery could
> be used to light up a all the apartments in a city block
> for a hour or so. In any event, probably five or six
> orders of magnitude better than current batteries.
A kilojoule will light a 100 Watt light bulb for 10 seconds, so you could
light that bulb for 100 to 1000 seconds.
> John Schilling suggested that 2.5 kilojoules per cubic centimeter
> battery densities will be required.
The energy storage capacity just determines the size of the batteries you
need to tote around. Modern carbon fiber materials could store about a
megajoule per kilogram if you could make a perfect flywheel out of them,
you would then need a 10 to 100 gram battery for your laser gun. In
reality, modern flywheels store far less than this theoretical maximum by
about an order of magnitude or so (and you need to account for the mass
of the motor to convert the rotational energy of the flywheel into
electricity, too. Too small a motor and you do not generate enough power
to drive your laser). Chemical batteries are even worse. You might be
able to use explosive power generators. These use an explosive wrapped
in copper inside an electromagnet - the explosion compresses the magnetic
field and delivers much of the energy of the explosive into a sudden
surge of electricity. As a rough guess, these might be an order of
magnitude more bulky than the explosive alone with an equivalent amount
of explosive energy, maybe half a megajoule per kilogram.
Hope this helps.
K. Key
Winchell Chung wrote:
> I would like some help in shining the harsh light of reality
> on one of the most cherished items in space opera: the Laser Sidearm.
>
> Specifically, how ludicrous are the requirements for the
> batteries powering the blasted thing.
>
> Offhand, it would seem that it is far more efficient to use
> an ancient Colt .45 chemically fueled bullet instead of a laser
> pistol to drill a hole in a hapless target.
Keep in mind, if all you want is efficiency, an arrow will cause lethal
damage with far less energy than a Colt .45.
> Say that the laser has ten shots worth of energy in the
> battery. Say each shot is capable of doing quote significant
> unquote damage to a human target. Say the laser has
> an efficiency in the neighborhood of the best efficiencies
> we can manage with current technology (free electron laser
> or whatever).
The last sentance is the easiest to answer - modern free electron lasers
> How much energy will the battery be required to store?
> Just a back of the envelope, order of magnitude estimate.
For 99% efficiency and a ten shot magazine using the pulse train
described earlier, between 10 and 100 kilojoules. If the pulse train
idea does not work, increase this by a factor of 10.
> This will, of course, depend upon the definition of
> "significant damage", which I have no idea of how to
> quantify.
> John Schilling stated the opinion that a bit over one kilojoule
> will be required to reliably incapacitate a human target.
> (divided into ~1 joule pulses at ~5 microsecond intervals)
>
> Offhand I'd imagine that the power in one battery could
> be used to light up a all the apartments in a city block
> for a hour or so. In any event, probably five or six
> orders of magnitude better than current batteries.
A kilojoule will light a 100 Watt light bulb for 10 seconds, so you could
light that bulb for 100 to 1000 seconds.
> John Schilling suggested that 2.5 kilojoules per cubic centimeter
> battery densities will be required.
The energy storage capacity just determines the size of the batteries you
Timothy Little
>
>I would be interested in hearing how this number was arrived at.
>A kilojoule doesn't seem like very much.
Somewhere between pistol and rifle bullet energies. I believe the
proposed method is a very rapid pulse train, each successive pulse
blasting a little deeper into the target.
> The only object I can find on hand with a rated energy storage
>capacity is (don't laugh) a can of soup. It contains 200 "calories"
>of chemical energy in a form extractable by human metabolism.
Which is actually quite a lot. If you could efficiently extract that
energy fast enough to power a laser, you'd be set. Most energy
storage methods are within the same order of magnitude of J/kg,
determined by the magnitude of energy involved in chemical bonds.
Soup, batteries, flywheels, propane, etc. are not greatly dissimilar
in the amount of energy they can produce per unit mass.
Of course, some are more suited than others to particular
applications.
- Tim
Nyrath the nearly wise
> >John Schilling stated the opinion that a bit over one kilojoule
> >will be required to reliably incapacitate a human target.
> >(divided into ~1 joule pulses at ~5 microsecond intervals)
>
> A kilojoule doesn't seem like very much.
Here's a quote for you:
John Schilling (schi...@spock.usc.edu) wrote:
>Nyr...@clark.net wrote:
>Kind sir, would it be possible for you to post a few off-the-top-of
>your-head specs for such a weapon?
Well, it beats arguing with people who think machine guns and
matchlocks are equally complex :-)
I'll assume a 50-year time frame with no particular haste in
developing directed-energy small arms and no fundamental
breakthroughs. Only technology currently on the drawing board,
in however limited a form, is allowed, but in 50 years expect
today's crude laboratory demos to be refined, mature technologies.
I'll also use a standard military or police service handgun as
the baseline - you can easily extrapolate down to a compact pistol
or up to a small submachinegun-equivilant if you like, but going
up to rifle or heavy-weapon scales is a bit trickier.
There are four basic technological approaches I would consider
based on my personal knowledge, all of which would lead to similar
end results if they worked at all.
1. Phase-locked diode laser arrays. Lots of microlasers on a
chip, all working together. Extremely efficient, if you
can atually get them to work together.
2. Diode-pumped YAG lasers. Lots of microlasers on a chip, each
working alone. They won't produce a good beam that way, but
if you tune them to the right absorbtion band and direct them
all into a YAG crystal, you can get the latter to lase quite
efficiently.
3. Pulsed linear induction accelerators. Fairly conventional
technology for producing high-energy, high-current electron
beams with external magnetic fields. This one will need to
be pushed right up to the theoretical limits to work on a
handgun scale, and it will need an unconventional electron
source such as a pseudospark discharge.
4. Wake field accelerators. Clever way of producing high-energy
electron beams using the internal electric fields of forced
plasma waves. Still in it's infancy, potential unknown but
may well be adequate in the long run.
You'll also need a power source. Three approaches come to mind,
two of which are pretty sure things. Burning a liquid propellant
in a pulsed MHD generator or flux compression generator can be
done now, and there are thermal primary (i.e. nonrechargeable)
batteries which are pretty close to what would be needed.
Unfortunately, both of these involve high operating temperatures
and expendable power sources.
Advanced bipolar designs of conventional secondary batteries
*might* be up to the task, and have the advantage of being fully
rechargeable. Besides, it is rather humorous to consider that a
21st-century laser weapon might really be powered by a lead-acid
or NiCad battery :-)
I'll assume non-rechargeable systems at an energy density of 2.5
kilojoules per cubic centimeter, which is quite plausible. You might
consider a rechargeable battery pack as an option, with half the
capacity of the non-rechargeables.
Either way, the energy will have to be stored in and dumped from
a capacitor or (if the switching problem is solved) inductor to
meed the peak power requirement. Electrochemical double-layer
capacitors ought to do the job if nothing else is available.
And you'll need some serious cooling. I'd go with liquid-metal
microchannel heat pipes etched into all the hot surfaces, and
leading to cooling fins around the "barrel". If you use the
chemical-propellant option, regenerative cooling could also work.
Whether you use lasers or particle beams, you'll need a bit over
a kilojoule of output energy to reliably incapacitate a human
target. In the case of a laser weapon, that energy would be
subdivided into ~1 joule pulses at ~5 microsecond intervals,
to achieve penetration in the face of a laser's natural tendency
to deposit energy at the target's surface. Particle beams don't
have that problem; boost the electrons up to a few hundred MeV,
and you can dump the whole kilojoule's worth at once.
I'm assuming a weapon designed to penetrate ~30cm in soft body
tissue. This gives about 15cm in bone or plastic, 5cm in brick
or concrete, or 2.5cm in steel or most ceramics. Synthetics
won't be very good at stopping energy weapons, even tough ones
like kevlar, but you might be able to find a ceramic that could
stop a laser beam with a centimeter's thickness or so. Particle
beams are tougher to stop; it mostly comes down to sticking mass
in the way without regard to material properties.
In soft materials, vapor expansion will carve out a hole much
larger than the original one millimeter - I got four centimeters
maximum hole diameter for soft body tissue, so the effect should
be at least equal to a modern high-velocity pistol bullet, and
perhaps comparable to a small centerfire rifle. Brittle materials
are likely to shatter within a similar radius, tough stuff like
steel will show little effect beyond the original hole.
And no, mirrors will *not* work as armor. The best finish you
can reasonably expect to keep on an exterior surface, will still
absorb 10-20% of the incident energy, which will be enough to
burn throgh the outer layer on the first pulse. And the rough
and now hot interior will be even less reflective.
I also mentioned earlier that lasers would likely have to have
pulse energy and frequency tuned to the specific material being
targeted. It might be possible to do this automatically, based
on crude spectoanalysis of the material vaporized in each pulse,
but if not expect penetration to be roughly halved if a laser
weapon is fired at a target it has not been optimized for.
Target-shooting lasers won't be optimized for flesh, and certainly
not for ceramic armor, so there may be legal implications here.
Particle beams are less likely to suffer such inconveniences.
Taking into account the inefficiency of the system, the input
energy will likely be somewhere between two and five kilojoules
per shot. So you could get fifty to a hundred shots from a
pistol-sized nonrechargeable energy source, or half that with
a rechargeable battery. Automatic fire at anywhere up to 20 Hz
(1200 rpm) shouldn't be a problem in the short term, though might
cause cooling problems if you keep it up.
You also need to focus the energy on the target, with a spot size
of a millimeter or less. With a laser, that gets kind of tricky.
A 5-centimeter mirror, about the largest you can really imagine
on a pistol, gives an effective range of perhaps sixty meters,
beyond which the weapon starts losing penetration quite rapidly.
And the mirror needs to adjust for target range - adaptive optics
(flexible mirror with microactuators) coupled to a laser range
finder seems to be the way to go here - you've already got the
pulsed laser part of the rangefinder.
Pulsed, high-current electron beams tend to be self-focusing in
air, which simplifies things if you take that route. For ranges
much over a hundred meters you have to start worrying about
energy loss, which can *probably* be dealt with. For handguns,
it isn't a problem.
With penetration, range, and repeatability dealt with, it is time
to turn to accuracy. Lack of recoil, automatic fire capability,
and line-of-sight accuracy are all major assets here, but there
is one more improvement to be made. Both lasers and particle
beams can be steered at least a degree or two off-axis, in the
case of the laser via the adaptive-optic mirror, for particle
beams with a transverse magnetic field at the muzzle.
If we can throw in a chip-mounted laser or acoustic gyro set,
we can have a gyrostabilized handgun. The weapon shoots not
at where the gun is pointed at the instant of firing, but at
a weighted average of where it has *been* pointing over the
past quarter of a second or so. Smooths out a lot of the
jitter inherent in human marksmanship.
You'd probably want to integrate this feature with the weapon's
sights. A reflex-type optical sight could have an LED display
linked to the gyrostabilizer, rather than a fixed reticle. The
dot, or crosshairs, would then indicate the actual shot path
and would remain similarly stable under jitter.
In combat, I would expect such a weapon to be used in automatic
fire mode at ~10 Hz. With fifty to a hundred pulses to play with,
you won't run out of ammunition too soon as is the case with
current machine pistols. And recoilless, stabilized automatic
fire should allow a moderately capable marksman to walk a burst
on target in one or two reaction cycles (say, half a second) in
most circumstances. Imperial Stormtroopers (tm) could no doubt
still find a way to miss with such a weapon at ten meters, but
not competent soldiers. Practical combat range, if you don't
mind missing a good part of the time, would be on the order of 50
meters
Erik Max Francis
> Somewhere between pistol and rifle bullet energies. I believe the
> proposed method is a very rapid pulse train, each successive pulse
> blasting a little deeper into the target.
This discussion pops up from time to time (for good reason, it's not all
that clear). One thing that's the case is you can't directly compare
beam energies and bullet kinetic energies; they have different jobs.
Getting damage from kinetic energy is cheap when you've got a slug that
you're throwing. When all you have is the beam itself, it needs to be
powerful enough to incapacitate, which means that it's going to have to
burn some flesh, preferably a lot. I'd say that involves quite a bit
more than 1 kJ.
> > The only object I can find on hand with a rated energy storage
> > capacity is (don't laugh) a can of soup. It contains 200 "calories"
> > of chemical energy in a form extractable by human metabolism.
>
> Which is actually quite a lot.
200 food calories = 200 Cal = 200 kcal = 840 kJ. Never underestimate
the power of cheese.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ Extremes meet.
\__/ John Hall Wheelock
Product's Quake III Arena Tips / http://www.bosskey.net/
Tips and tricks from the absolute beginner to the Arena Master.
Christopher M. Jones
> I would like some help in shining the harsh light of reality
> on one of the most cherished items in space opera: the Laser Sidearm.
>
> Specifically, how ludicrous are the requirements for the
> batteries powering the blasted thing.
>
> Offhand, it would seem that it is far more efficient to use
> an ancient Colt .45 chemically fueled bullet instead of a laser
> pistol to drill a hole in a hapless target.
Yes quite. I think the main reason why energy sidearms would
be popular would be due to some stupdendous breakthrough in
energy storage (i.e. batteries) that made it a lot easier
(and cheaper) to use weapons powered by the super battery than
to use other systems.
Also, you might consider other types of energy driven weapons,
such as rail guns, coil guns, plasma weapons, etc.
Now, if you go with a visible or near-vis laser system, then
you have several significant engineering problems. First is
the laser system, which needs to be high power, reliable,
compact, and efficient. That's not impossible, but it's
difficult. Second is (of course) the power system which
needs to be compact, very high density (energy wise), and
fast (in releasing it's energy). At present regular
batteries don't fit this bill too well. Theoretically you
could go with "next generation" batteries (i.e. some factor
higher energy density or somesuch) combined with a capacitor
"quick release" mechanism (like with camera flashes). Even
with factor of 10 improvements compared to what's possible
currently you may have something that's dangerous and maybe
even lethal but it will be distinctly "not impressive".
Now, there are other energy storage systems other than
batteries that could be used. For example, a
superconducting induction coil, or you could use a
"micro-fusion" reactor to power the thing (which is really
pushing it though in terms of credibility). There's also
a possibility that you could use something strange like
excited nuclei to store the power (I think something in
the high MegaJoules per kg would be possible in that
area).
Also, there are other ways than electricity to create a
laser beam. You could use a chemical powered laser. The
energy for the laser is provided by a chemical reaction
that occurs in the lasing medium. Basically, you have a
"cartridge" that you "burn" to create the laser beam, then
you use a new cartridge. One popular chemical laser is
Hydrogen Flouride. This is probably the best way to
achieve high power laser beams in a man portable system.
--
Must replace optical switches with dancing lemurs.
John Schilling
>I would like some help in shining the harsh light of reality
>on one of the most cherished items in space opera: the Laser Sidearm.
>Specifically, how ludicrous are the requirements for the
>batteries powering the blasted thing.
>Offhand, it would seem that it is far more efficient to use
>an ancient Colt .45 chemically fueled bullet instead of a laser
>pistol to drill a hole in a hapless target.
[...]
>This will, of course, depend upon the definition of
>"significant damage", which I have no idea of how to
>quantify.
>John Schilling stated the opinion that a bit over one kilojoule
>will be required to reliably incapacitate a human target.
>(divided into ~1 joule pulses at ~5 microsecond intervals)
And for those who are wondering, the damage mechanism was mechanical
destruction by repeated steam microexplosions. If you insist on
thermal damage, using a laser as a sort of radiant flamethrower to
burn flesh, the requisite energy increases by about two orders of
magnitude.
>Offhand I'd imagine that the power in one battery could
>be used to light up a all the apartments in a city block
>for a hour or so. In any event, probably five or six
>orders of magnitude better than current batteries.
Assuming 20% efficiency, it will run a standard incandescent
light bulb for ten minutes.
If you don't believe this is enough enery to reliably incapacitate
a human target ten times over, try grabbing a lit 100-watt bulb in
your hand and holding on for a full minute :-)
>John Schilling suggested that 2.5 kilojoules per cubic centimeter
>battery densities will be required.
John Schilling will now note that the energy density in an ordinary
flashlight battery is approximately 0.5 kilojoules per cubic centimeter.
If you splurge and buy lithium cells, it goes up to 3.0 kilojoules per
cubic centimeter.
Counterintuitive as it may seem, good flashlight batteries have more than
enough energy for an SFnal laser pistol. The only problem is that they are
designed to deliver that energy over the course of many hours, and unless
you are fighting the Ice Slugs of Tedium IV you probably won't be able to
convince your enemy to stand still that long :-)
It is not out of the question that rearranging the electrode configuration
of relatively conventional batteries would allow you to extract their stored
energy fast enough to serve as the prime power source for a useful weapon.
There have been labratory experiments which demonstrated the requisite power
density and discharge time, though they are a long way from producing a
useful product.
Oh, and if they ever start selling *those* batteries at your local hardware
store, it would be Really Bad to accidentally short-circuit one.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schi...@spock.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
Charles R Martin
>
> "Winchell Chung" <nyr...@projectrho.com> wrote:
> > I would like some help in shining the harsh light of reality
> > on one of the most cherished items in space opera: the Laser Sidearm.
> >
> > Specifically, how ludicrous are the requirements for the
> > batteries powering the blasted thing.
> >
> > Offhand, it would seem that it is far more efficient to use
> > an ancient Colt .45 chemically fueled bullet instead of a laser
> > pistol to drill a hole in a hapless target.
>
> Yes quite. I think the main reason why energy sidearms would
> be popular would be due to some stupdendous breakthrough in
> energy storage (i.e. batteries) that made it a lot easier
> (and cheaper) to use weapons powered by the super battery than
> to use other systems.
Don't forget some of the other advantages laser weapons might have. One that
strikes me offhand is that (at least as a hand weapon) you just aim at what
you want to hit, no matter the range or relative motion. No "leading" the
target, no range adjustment on the sights, no "windage", and no recoil. It
strikes me that having no recoil could be very important to Tom Corbett of the
Space Patrol....
Erik Max Francis
> Don't forget some of the other advantages laser weapons might have.
> One that
> strikes me offhand is that (at least as a hand weapon) you just aim at
> what
> you want to hit, no matter the range or relative motion. No "leading"
> the
> target, no range adjustment on the sights, no "windage", and no
> recoil.
And don't forget that such systems would have severe drawbacks, as well.
A cloud of dust or steam will foil a laser; forget about trying to fight
a war with them when it's rainy.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ Blood is the god of war's rich livery.
\__/ Christopher Marlowe
Kepler's laws / http://www.alcyone.com/max/physics/kepler/
A proof of Kepler's laws.
Charles R Martin
>
> Charles R Martin wrote:
>
> > Don't forget some of the other advantages laser weapons might have.
> > One that
> > strikes me offhand is that (at least as a hand weapon) you just aim at
> > what
> > you want to hit, no matter the range or relative motion. No "leading"
> > the
> > target, no range adjustment on the sights, no "windage", and no
> > recoil.
>
> And don't forget that such systems would have severe drawbacks, as well.
> A cloud of dust or steam will foil a laser; forget about trying to fight
> a war with them when it's rainy.
Rain, dust, smoke etc are significant impediments to using the usual bullets
in combat as well. (I do think Tom Corbett of Space Patrol would often be in
a situation where rain and smoke could be discounted as issues....)
Mark Fergerson
<snip>
> Also, there are other ways than electricity to create a
> laser beam. You could use a chemical powered laser. The
> energy for the laser is provided by a chemical reaction
> that occurs in the lasing medium. Basically, you have a
> "cartridge" that you "burn" to create the laser beam, then
> you use a new cartridge. One popular chemical laser is
> Hydrogen Flouride. This is probably the best way to
> achieve high power laser beams in a man portable system.
Agreed, but HF (the exhaust) is a tad difficult to deal with.
Monatomic H-O systems give nice UV IIRC, but storing the stuff is also
awkward. Must be a usable chemical system out there somewhere.
Mark L. Fergerson
Mike Williams
>Winchell Chung <nyr...@projectrho.com> wrote:
>>I would like some help in shining the harsh light of reality
>>on one of the most cherished items in space opera: the Laser Sidearm.
>
>Oh god, not again! :^)
>
>>Specifically, how ludicrous are the requirements for the
>>batteries powering the blasted thing.
>[...]
>>Say that the laser has ten shots worth of energy in the
>>battery. Say each shot is capable of doing quote significant
>>unquote damage to a human target.
>[...]
>>John Schilling stated the opinion that a bit over one kilojoule
>>will be required to reliably incapacitate a human target.
>>(divided into ~1 joule pulses at ~5 microsecond intervals)
>
>So, that makes 10 kJ per battery if the laser is 100% efficient. The
>most efficient laser I was able to find had 38% electricity ->
>coherent light. With properties unsuited to a weapon, though you were
>talking about the "best efficiencies we can manage with current
>technology".
>
>Make the efficiency lower (say 20%) to allow for losses in the stages
>between battery and lasing device, and call the energy requirement
>50 kJ.
20% efficiency? Doesn't that cause rather extreme problems of dealing
with the waste heat? Considering that the victim is damaged by the heat
caused when the laser pulse hits him, and the fact that 80% of the
energy is lost as waste heat in the gun, that gun is going to get
seriously hot.
In particular, if you're stuck in an icy wasteland and try the trick
where you use the laser beam to heat up a rock to keep you warm, you're
going to find that the temperature rise in the gun will be considerably
more than the temperature rise in the rock.
--
Mike Williams
Gentleman of Leisure
Christopher M. Jones
Oops, I didn't mean to imply that HF was the best way to
achieve high power laser sidearms, I was speaking of chemical
lasers in general. I would assume that there would be
considerable advancement in the area before you got to the
"spaceman spiff raygun" level of reliability and usefulness.
--
And now, remain gone, illegitimate-faced bugger-folk! And, if you think you
got a nasty taunting this time, you ain't heard nothing yet, dappy English
k-nnniggets! Thpppt!
Christopher M. Jones
> Erik Max Francis wrote:
> > And don't forget that such systems would have severe drawbacks, as well.
> > A cloud of dust or steam will foil a laser; forget about trying to fight
> > a war with them when it's rainy.
>
> Rain, dust, smoke etc are significant impediments to using the usual
bullets
> in combat as well. (I do think Tom Corbett of Space Patrol would often be
in
> a situation where rain and smoke could be discounted as issues....)
To a _much_ less degree though. Dust, smoke, and rain do not
particularly serve as impediments to the bullets themselves!
As is the case with near-vis laser beams. However, they can
reduce visibility and cause as an impediment to the _use_ of
weapons of all types.
--
To beguile many, and be beguil'd by one.
Isaac Kuo
schi...@spock.usc.edu (John Schilling) wrote:
>Winchell Chung <nyr...@projectrho.com> writes:
>>John Schilling stated the opinion that a bit over one kilojoule
>>will be required to reliably incapacitate a human target.
>>(divided into ~1 joule pulses at ~5 microsecond intervals)
>And for those who are wondering, the damage mechanism was mechanical
>destruction by repeated steam microexplosions. If you insist on
>thermal damage, using a laser as a sort of radiant flamethrower to
>burn flesh, the requisite energy increases by about two orders of
>magnitude.
Ah, but the energy can be applied with a lower peak
power continuous beam chemical laser over a large area.
The weapon would look and sound a lot like a flame
thrower which its bulky fuel tanks. You don't get
a whole lot of shots, but pity the poor person on
the other end!
Also, pity the poor weapon operator if someone hits
his fuel tanks. Assuming he isn't wearing a gas mask,
that is.
--
_____ Isaac Kuo mec...@yahoo.com ICQ 29055726
__|_)o(_|__
/___________\
\=\)-----(/=/
Sent via Deja.com
http://www.deja.com/
David McKee
: >battery densities will be required.
:
: John Schilling will now note that the energy density in an ordinary
: flashlight battery is approximately 0.5 kilojoules per cubic centimeter.
: If you splurge and buy lithium cells, it goes up to 3.0 kilojoules per
: cubic centimeter.
:
: Counterintuitive as it may seem, good flashlight batteries have more than
: enough energy for an SFnal laser pistol. The only problem is that they are
: designed to deliver that energy over the course of many hours, and unless
: you are fighting the Ice Slugs of Tedium IV you probably won't be able to
: convince your enemy to stand still that long :-)
:
: It is not out of the question that rearranging the electrode configuration
: of relatively conventional batteries would allow you to extract their stored
: energy fast enough to serve as the prime power source for a useful weapon.
: There have been labratory experiments which demonstrated the requisite power
: density and discharge time, though they are a long way from producing a
: useful product.
Anyone who has made the mistake of short-circuiting a NiCd D cell knows
that these cells can deliver their entire load in a very short time.
: Oh, and if they ever start selling *those* batteries at your local hardware
: store, it would be Really Bad to accidentally short-circuit one.
Yah. That NiCd battery set a piece of balsa wood on fire for me. :-(
Thankfully it didn't short through me. I imagine that that would be a
Bad Thing (tm).
Cheers,
--
-- David McKee
-- dmc...@jlab.org
-- (757) 269-7492 (Office)
Matthew DeBell
>I would like some help in shining the harsh light of reality
>on one of the most cherished items in space opera: the Laser Sidearm.
>
>Specifically, how ludicrous are the requirements for the
>batteries powering the blasted thing.
Not particularly ludicrous. The energy density I expect you'd want exceeds
the capacity of current battery technology, but the energy density of, say,
TNT would work fine. If you settle for a low-power laser, current batteries
might work.
You mentioned a delivered energy of 1kJ, so for now let's say that's the
required delivered energy. If the laser is 33% efficient and you want 10
shots, then your power pack must hold 30kJ. If the weapon is to be a
practical sidearm then the power pack shouldn't mass more than about .5kg,
preferably less. If that's the mass then the energy density is 60kJ/kg. If
the power pack masses a more convenient 100g, then the energy density is
300kJ/kg. That's in the ballpark of what should be possible with current
batteries. The battery for my laptop computer holds about 45 Watt/hours
(i.e. 160kJ), and although I don't have a scale handy I'd guess it's about
.5kg, so it would work fine for this laser.
But 1kJ of delivered energy may be on the low side; see below.
>Offhand, it would seem that it is far more efficient to use
>an ancient Colt .45 chemically fueled bullet instead of a laser
>pistol to drill a hole in a hapless target.
In terms of energy efficiency it probably is. However, the laser is
recoilless and perfectly accurate.
>Say that the laser has ten shots worth of energy in the
>battery. Say each shot is capable of doing quote significant
>unquote damage to a human target. Say the laser has
>an efficiency in the neighborhood of the best efficiencies
>we can manage with current technology (free electron laser
>or whatever).
>
>How much energy will the battery be required to store?
>Just a back of the envelope, order of magnitude estimate.
>
>This will, of course, depend upon the definition of
>"significant damage", which I have no idea of how to
>quantify.
>John Schilling stated the opinion that a bit over one kilojoule
>will be required to reliably incapacitate a human target.
>(divided into ~1 joule pulses at ~5 microsecond intervals)
A laser would cause damage by burning or vaporizing tissue. There are a
couple of wound mechanisms. One is that it simply burns a hole and that it
acheives depth of penetration using a pulsed beam. The second is that when
tissue is suddenly turned to gas (or plasma), that gas expands at high
pressure and causes damage to surrounding tissue. I'm not qualified to
remark on the gas/plasma expansion, but if we consider the energy required
for hole-burning, 1kJ seems too low.
The average specific heat of the human body is 3470 J/kg per degree C.
Thus, 1000J could vaporize .0046 kg of tissue (4-5cc). As bullet wounds go
that's not particularly large. It could easily be lethal, but it's probably
not enough for reliable prompt incapacitiation.
For a ballpark estimate of the energy required for an effective weapon, we
can begin by figuring the amount of energy required to vaporize 'enough'
tissue to cause prompt incapacitation. Terminal ballistics experts suggest
that a bullet should be able to penetrate about a foot of tissue to be a
reliable defense weapon. If we want the laser to vaporize an amount of
tissue equal to that destroyed by effective bullets, then it should be able
to destroy a track about 10mm in diameter and 300mm deep, or about 30cc.
If we take the specific heat of tissue as 3.47J/cc/degree C, and tissue
starts at 37 and vaporizes at 100, then vaporizing 30cc of tissue takes at
least 6600 J. Adjust that upward by a factor of 2 to allow for energy
wasted in over-heating or dissipated in surrounding tissue, and another
factor of 3 for the weapon's inefficiency in converting electricity into
coherent light, and we have a power requirement for each shot of about 40kJ.
My computer battery would be good for 4 shots if it could deliver the energy
fast enough (which it can't).
For 10 shots we need 400kJ. In a 100g battery, that's an energy density of
4MJ/kg, which is about the same as dynamite and about one tenth as much as
gasoline. That's a fantastic battery, but it's nothing special compared to
other forms of energy storage.
(The validity of this whole example depends on the assumption that the wound
mechanism is vaporizing a deep hole in the target. This clashes with
assumptions about rapidly expanding gas/plasma, but I'll have to leave
evaluation of that mechanism to others.)
>Offhand I'd imagine that the power in one battery could
>be used to light up a all the apartments in a city block
>for a hour or so. In any event, probably five or six
>orders of magnitude better than current batteries.
For what I just made up, the power pack would run the lights in my apartment
for an hour or so. (It runs 1111 Watts for one hour.)
--
Matthew DeBell
free hard SF RPG at www.vanguardgames.com
Luke Campbell
> There are four basic technological approaches I would consider
> based on my personal knowledge, all of which would lead to similar
> end results if they worked at all.
>
> 1. Phase-locked diode laser arrays. Lots of microlasers on a
> chip, all working together. Extremely efficient, if you
> can atually get them to work together.
>
> 2. Diode-pumped YAG lasers. Lots of microlasers on a chip, each
> working alone. They won't produce a good beam that way, but
> if you tune them to the right absorbtion band and direct them
> all into a YAG crystal, you can get the latter to lase quite
> efficiently.
>
> 3. Pulsed linear induction accelerators. Fairly conventional
> technology for producing high-energy, high-current electron
> beams with external magnetic fields. This one will need to
> be pushed right up to the theoretical limits to work on a
> handgun scale, and it will need an unconventional electron
> source such as a pseudospark discharge.
>
> 4. Wake field accelerators. Clever way of producing high-energy
> electron beams using the internal electric fields of forced
> plasma waves. Still in it's infancy, potential unknown but
> may well be adequate in the long run.
The problem with particle beams is that scattered radiation from the
beam will irradiate the person firing the gun. When you are throwing
around kilojoules of ionizing radiation, this will be enough to cause
radiation burns, radiation sickness, sterility, and possibly cancer and
genetic damage.
Fortuneately, the energy in a particle beam can be turned into light
using a wiggler or undulator with very high efficiency, and you've now
got a free electron laser.
Any reason why you do not expect excimers to be compact laser handguns?
(Other than minor details like giving the firer and anyone close to the
beam sunburn). They seem to be able to make fairly high powered pulsed
excimers which are highly efficient (similar to those of YAG, diode, and
CO2 lasers).
> Whether you use lasers or particle beams, you'll need a bit over
> a kilojoule of output energy to reliably incapacitate a human
> target. In the case of a laser weapon, that energy would be
> subdivided into ~1 joule pulses at ~5 microsecond intervals,
> to achieve penetration in the face of a laser's natural tendency
> to deposit energy at the target's surface.
Do you have any sources for this? I would be interested in any
published material on this subject.
Lacking this, a kilojoule seems a bit optimistic, though not
impossible. I would worry about a couple issues. First, has the plasma
from the previous pulses diffused enough in that 5 microseconds that it
is transparent to subsequent pulses? If not, the plasma will absorb the
subsequent pulses and the target will be largely spared. Second, what
about debris from the target that previous pulses scatter into the beam
path? These could prematurely absorb pulses before they reach the
target.
> Particle beams don't
> have that problem; boost the electrons up to a few hundred MeV,
> and you can dump the whole kilojoule's worth at once.
Not to mention that if your target survives the initial pulse, it still
has to contend with radiation sickness and, for high enough doses,
possible rapid brain death.
> In soft materials, vapor expansion will carve out a hole much
> larger than the original one millimeter - I got four centimeters
> maximum hole diameter for soft body tissue, so the effect should
> be at least equal to a modern high-velocity pistol bullet, and
> perhaps comparable to a small centerfire rifle.
Keep in mind that in tissue, the cavity blasted out will collapse back
on itself in a few milliseconds (and probably re-expand and collapse
again in pulse-like oscillations for a few cycles). Comparing this to
the temporary cavity from firearms, the tissue stretched by the cavity
may still be perfectly functional, you do not neccessarily get damaged
organs out to several centimeters radius.
> I also mentioned earlier that lasers would likely have to have
> pulse energy and frequency tuned to the specific material being
> targeted. It might be possible to do this automatically, based
> on crude spectoanalysis of the material vaporized in each pulse,
> but if not expect penetration to be roughly halved if a laser
> weapon is fired at a target it has not been optimized for.
For very short pulses, the front of the pulse heats up the surface it is
incident on to a layer of plasma, which absorbs the rest of the pulse
with high efficiency. Once this has happened, the optical properties of
the material should not matter much, so I do not see that matching the
frequency to the target as being necessary.
(The exception is if you are using lasers in the vacuum UV or higher
frequency, which will go right through plasma with a density of solid
matter. These also do not have to be tuned to the target, at these
energies a single photon will break any molecular bond and they will
photo-ionize the material they are incident on quite well. The problem
is that these ionizing frequencies do not get through the air.)
> You also need to focus the energy on the target, with a spot size
> of a millimeter or less. With a laser, that gets kind of tricky.
> A 5-centimeter mirror, about the largest you can really imagine
> on a pistol, gives an effective range of perhaps sixty meters,
> beyond which the weapon starts losing penetration quite rapidly.
If you are already talking about the laser excavating cavities several
centimeters in diameter, sub-millimeter spot sizes do not seem
necessary, you just need a moderate fraction of the cavity's maximum
size.
Luke
Ash Wyllie
>Timothy Little wrote:
>> Somewhere between pistol and rifle bullet energies. I believe the
>> proposed method is a very rapid pulse train, each successive pulse
>> blasting a little deeper into the target.
>This discussion pops up from time to time (for good reason, it's not all
>that clear). One thing that's the case is you can't directly compare
>beam energies and bullet kinetic energies; they have different jobs.
>Getting damage from kinetic energy is cheap when you've got a slug that
>you're throwing. When all you have is the beam itself, it needs to be
>powerful enough to incapacitate, which means that it's going to have to
>burn some flesh, preferably a lot. I'd say that involves quite a bit
>more than 1 kJ.
>> > The only object I can find on hand with a rated energy storage
>> > capacity is (don't laugh) a can of soup. It contains 200 "calories"
>> > of chemical energy in a form extractable by human metabolism.
>>
>> Which is actually quite a lot.
>200 food calories = 200 Cal = 200 kcal = 840 kJ. Never underestimate
>the power of cheese.
But you need an oxygen source to get that energy. And a candy bar would be
more compact.
-ash
for assistance dial MYCROFTXXX
GrapeApe
the mirrors they wear?
I'm all for this discussion of making a cutting laser as a hadn weapon, at
least as far as getting the fast drain battery size down to a soup can full of
lithium batterys that would have to be loaded into the gun as ammo.
But it should still have somewhat limited use tactically don't you think, due
to reflections, absorption (not even considering the danger of the power source
misfiring), hmm?
But I think it would be great for trimming the yard, trimming brush and trees,
if you have water nearby.
--cut and paste to adopt this sig file---
Make Deja a useful Usenet Archive again!
GrapeApe
for mowing the yard, with an adjustable width beam containe by mirrors.
John Schilling
>Nyrath the nearly wise wrote:
>> There are four basic technological approaches I would consider
>> based on my personal knowledge, all of which would lead to similar
>> end results if they worked at all.
>> 1. Phase-locked diode laser arrays...
>> 2. Diode-pumped YAG lasers...
>> 3. Pulsed linear induction accelerators...
>> 4. Wake field accelerators....
>The problem with particle beams is that scattered radiation from the
>beam will irradiate the person firing the gun. When you are throwing
>around kilojoules of ionizing radiation, this will be enough to cause
>radiation burns, radiation sickness, sterility, and possibly cancer and
>genetic damage.
At kilojoule levels in air the backscatter isn't terribly bad; these
would be very high-enery electrons, which tends to collimate the
scattered radiation in the forward direction. Particle-beam artillery
would be another matter, of course.
>Any reason why you do not expect excimers to be compact laser handguns?
>They seem to be able to make fairly high powered pulsed excimers which
>are highly efficient (similar to those of YAG, diode, and CO2 lasers).
But rather more complex, and with no compelling advantage over diode
pumped crystal lasers that I can see. It's possibility, but not one
I would bet on.
>> Whether you use lasers or particle beams, you'll need a bit over
>> a kilojoule of output energy to reliably incapacitate a human
>> target. In the case of a laser weapon, that energy would be
>> subdivided into ~1 joule pulses at ~5 microsecond intervals,
>> to achieve penetration in the face of a laser's natural tendency
>> to deposit energy at the target's surface.
>Do you have any sources for this? I would be interested in any
>published material on this subject.
Very little has been published, especially regarding the sort of
"low" power systems that would be appropriate for small arms use.
I've a fair ammount of my own notes and BOTE calculations, but
nothing of publication quality.
>Lacking this, a kilojoule seems a bit optimistic, though not
>impossible. I would worry about a couple issues. First, has the plasma
>from the previous pulses diffused enough in that 5 microseconds that it
>is transparent to subsequent pulses? If not, the plasma will absorb the
>subsequent pulses and the target will be largely spared. Second, what
>about debris from the target that previous pulses scatter into the beam
>path? These could prematurely absorb pulses before they reach the
>target.
The plasma clears away easily in that time frame; debris is the real issue,
and the driving force between the 5 microsecond pulse rate. That allows
roughly 90% of the debris to clear the beam path, assuming a 1mm beam and
instantaneous 1J pulses.
[...]
>> In soft materials, vapor expansion will carve out a hole much
>> larger than the original one millimeter - I got four centimeters
>> maximum hole diameter for soft body tissue, so the effect should
>> be at least equal to a modern high-velocity pistol bullet, and
>> perhaps comparable to a small centerfire rifle.
>Keep in mind that in tissue, the cavity blasted out will collapse back
>on itself in a few milliseconds (and probably re-expand and collapse
>again in pulse-like oscillations for a few cycles).
Yes, and this is a problem if you want to push the penetration much
above the 30cm I specified. If your pulses come fast enough to gouge
out a meter-deep path before the surrounding tissue recoils back into
the cavity and blocks the beam, they come too fast for the per-shot
debris to clear the beam.
>Comparing this to the temporary cavity from firearms, the tissue stretched
>by the cavity may still be perfectly functional, you do not neccessarily
>get damaged organs out to several centimeters radius.
Yes, complete tissue destruction would be reduced proportional to the yield
strain of the tissue in question; usually a factor of two or three. OTOH,
you get a great deal of temporary disruption (massive bruising, roughly
speaking) well beyond the temporary cavity as displaced tissue piles up
on itself. Not necessarily lethal, but quite disabling.
>> I also mentioned earlier that lasers would likely have to have
>> pulse energy and frequency tuned to the specific material being
>> targeted. It might be possible to do this automatically, based
>> on crude spectoanalysis of the material vaporized in each pulse,
>> but if not expect penetration to be roughly halved if a laser
>> weapon is fired at a target it has not been optimized for.
>For very short pulses, the front of the pulse heats up the surface it is
>incident on to a layer of plasma, which absorbs the rest of the pulse
>with high efficiency. Once this has happened, the optical properties of
>the material should not matter much, so I do not see that matching the
>frequency to the target as being necessary.
Ah, we're using different definitions of "frequency" here; you're thinking
laser wavelength. I am talking about the repetition frequency of the pulses;
1 joule every 5 microseconds is optimal against soft tissue, other materials
will want different pulse trains.
>> You also need to focus the energy on the target, with a spot size
>> of a millimeter or less. With a laser, that gets kind of tricky.
>> A 5-centimeter mirror, about the largest you can really imagine
>> on a pistol, gives an effective range of perhaps sixty meters,
>> beyond which the weapon starts losing penetration quite rapidly.
>If you are already talking about the laser excavating cavities several
>centimeters in diameter, sub-millimeter spot sizes do not seem
>necessary, you just need a moderate fraction of the cavity's maximum
>size.
No, you still need to get down to a millimeter or so to flash-boil water
in a layer ~one optical depth in thickness. Once you do that, the steam
will expand and spread the damage around, but if you don't hit the threshold
for turning water into steam all you do is warm up the target.
Christopher M. Jones
> Forget about shooting the bad guys like you are John Wayne, just make one
safe
> for mowing the yard, with an adjustable width beam containe by mirrors.
Remind me of the "Amazin' laser" saturday night live commercial.
i.e.:
Mowing... (shown mowing lawn) Raking... (shown raking lawn) Pruning...
(shown pruning tree). It takes a lot of work to keep a place like this
looking so good, but the hard part is getting rid of all this mess
(stands by piles of leaves, branches, grass, etc); Unless you have the
Amazin' Laser, the amazing new gardening tool that vaporizes any and all
matter in it's path, giving your home a professionally landscaped look.
Use the amazin' laser on grass clippings (shoots at pile of grass
clippings that dissapear, caption: "WARNING: Do not fire Amazin' Laser
at Police Officers").
Get rid of brush piles and branches (shoots at branches which dissapear,
caption: "WARNING: Do not fire Amazin' Laser at Military Personnel").
And what about this 1800lb granite boulder? (Shoots at boulder which
dissapears, caption: "WARNING: Do not use Amazin' Laser when drowsy or
on medication") Gone in an instant with Amazin' Laser.
How accurate is Amazin' Laser? Accurate enough to hit a man in a moving
automobile at up to 3,000 feet away (Caption: "WARNING: Do not fire
Amazin' Laser at the President"). Is that accurate enough for you?
And Amazin' Laser won't rust or corrode like metal garden tools, because
it's made out of durable 100% lexon plastic. Just watch it go through
this metal detector! (Walks through detector holding Amazin' Laser,
alarm does not sound, caption: "WARNING: Terrorists, please do not buy
Amazin' Laser").
Make your yard look it's best, with the Amazin' Laser (caption: "WARNING:
Amazin' Laser can be used for good or evil, please use only for good",
shoots a gardener's truck with it). The Amazin' Laser, it's amazing!
(caption: "ON SECOND THOUGHT, please do not buy Amazin' Laser").
Announcer: Amazin' Laser, available at Walgreens and Rickel Home Centers,
ask for it by name.
--
Random Sig Message #17
Luke Campbell
> Luke Campbell <lwc...@u.washington.edu> writes:
>
> >> 3. Pulsed linear induction accelerators...
>
> >> 4. Wake field accelerators....
>
> >The problem with particle beams is that scattered radiation from the
> >beam will irradiate the person firing the gun. When you are throwing
> >around kilojoules of ionizing radiation, this will be enough to cause
> >radiation burns, radiation sickness, sterility, and possibly cancer and
> >genetic damage.
>
> At kilojoule levels in air the backscatter isn't terribly bad; these
> would be very high-enery electrons, which tends to collimate the
> scattered radiation in the forward direction. Particle-beam artillery
> would be another matter, of course.
It would still probably quickly put you above the current occupational safety
limits. A few shots might be safe, but your accumulated dose from time on the
firing range could get dangerous, and not practicing with your weapon could be
even more dangerous...
> >Any reason why you do not expect excimers to be compact laser handguns?
> >They seem to be able to make fairly high powered pulsed excimers which
> >are highly efficient (similar to those of YAG, diode, and CO2 lasers).
>
> But rather more complex, and with no compelling advantage over diode
> pumped crystal lasers that I can see. It's possibility, but not one
> I would bet on.
Well, they could focus to a millimeter spot size at much longer ranges without
having to rely on frequency doubling or trippling techniques. (More atmospheric
scattering, though, but this probably will not be significant until you start
talking about ranges on the order of a kilometer or so).
> >> Whether you use lasers or particle beams, you'll need a bit over
> >> a kilojoule of output energy to reliably incapacitate a human
> >> target. In the case of a laser weapon, that energy would be
> >> subdivided into ~1 joule pulses at ~5 microsecond intervals,
> >> to achieve penetration in the face of a laser's natural tendency
> >> to deposit energy at the target's surface.
>
> >Do you have any sources for this? I would be interested in any
> >published material on this subject.
>
> Very little has been published, especially regarding the sort of
> "low" power systems that would be appropriate for small arms use.
> I've a fair ammount of my own notes and BOTE calculations, but
> nothing of publication quality.
What a pity. I wish I were weathy enough to buy some beamtime on a pulsed, high
powered laser and test it on slabs of meat or animal carcases.
> >> In soft materials, vapor expansion will carve out a hole much
> >> larger than the original one millimeter - I got four centimeters
> >> maximum hole diameter for soft body tissue, so the effect should
> >> be at least equal to a modern high-velocity pistol bullet, and
> >> perhaps comparable to a small centerfire rifle.
>
> >Keep in mind that in tissue, the cavity blasted out will collapse back
> >on itself in a few milliseconds (and probably re-expand and collapse
> >again in pulse-like oscillations for a few cycles).
>
> Yes, and this is a problem if you want to push the penetration much
> above the 30cm I specified. If your pulses come fast enough to gouge
> out a meter-deep path before the surrounding tissue recoils back into
> the cavity and blocks the beam, they come too fast for the per-shot
> debris to clear the beam.
Perhaps you could use the rebound oscillations to get deeper penetrations?
Seems kind of iffy, the rebounds might not be regular enough.
> >> You also need to focus the energy on the target, with a spot size
> >> of a millimeter or less. With a laser, that gets kind of tricky.
> >> A 5-centimeter mirror, about the largest you can really imagine
> >> on a pistol, gives an effective range of perhaps sixty meters,
> >> beyond which the weapon starts losing penetration quite rapidly.
>
> >If you are already talking about the laser excavating cavities several
> >centimeters in diameter, sub-millimeter spot sizes do not seem
> >necessary, you just need a moderate fraction of the cavity's maximum
> >size.
>
> No, you still need to get down to a millimeter or so to flash-boil water
> in a layer ~one optical depth in thickness. Once you do that, the steam
> will expand and spread the damage around, but if you don't hit the threshold
> for turning water into steam all you do is warm up the target.
Surely optical depth varies with the frequency of light? I would think that
visible or near UV light would give a shorter optical depth than the IR light
the diode or YAG lasers you were thinking of using give off (but I have no real
data on this, just intuition).
Alternately, use more powerful pulses with a longer interval between pulses.
Rely on the mechanical ripping of tissue from superimposed expanding cavities to
get deep penetration rather than the (assumed) direct vaporization of a 1 mm
hole through the target you seem to be considering.
Luke
Nyrath the nearly wise
> One popular chemical laser is Hydrogen Flouride.
In the novel THE SPACE EATER, the army has pillbox emplacements
armed with Hydrogen Fluoride powered lasers.
They vent their exhaust around the base of the pillbox in order
to provide a rude surprise to any enemy soldiers who have bright
ideas about sneaking up to it.
Our Hero tried it, but he was good as new after they put
the corroded remains of his body into the regeneration vat.
Charles R Martin
>
Um, it's not as easy as that ... did you see the ER episode where the guy has
gotten HF burns over a good bit of his body? The problem is that HF is also a
toxin as well as corrosive (I don't recall the exact mechanism, but it *might*
have been that the F replaces something physiologically important like
calcium) so the guy is doomed in a fairly short time even though he got quick
treatment.
Ray Drouillard
> on one of the most cherished items in space opera: the Laser Sidearm.
>
> Specifically, how ludicrous are the requirements for the
> batteries powering the blasted thing.
You really hadn't oughtta pretend that current technology will limit future
technology. We don't have the ability to store it in chemical batteries
yet, but that doesn't mean that we will never be able to store it. Here's a
few ideas:
1) Why assume lasers will always be inefficient? There is lots of room for
improvement.
2) A gas dynamic laser doesn't use electricity. It uses moving heated gas
to produce the effect. You can heat the gas with the chemical fuel of your
choice - even gunpowder :-) If you manage to design a laser that uses about
2/3 CO2 and 1/3 water vapor (molar fraction), you can simply burn acetylene
(C2H2) with pure oxygen. Other trace elements can be added to one of the
gasses if necessary.
3) Doped buckytubes are practically superconductors. Undoped buckytubes are
excellent insulators. You can therefore make a really big capacitor out of
concentric buckytubes. The plate area would be huge and the spacing would
be really small. I haven't done the math, but I'm sure that capacitors in
the thousands or millions of farads would be possible. They could be made
the size of bullets and simply be used one at a time as you fire the shots.
Actually, instead of concentric buckytubes, you can shift the structure a
bit and make it out of "rolled" pieces of buckytube - just like a modern
electrolytic capacitor - except that the plates are a whole lot closer to
each other and the area is a whole lot bigger.
With a little imagination, you can handwave lots of things, like nuclear
powered lasers (fission or fusion). In fact, someone actually made an x-ray
laser that is powered by the fissioning of a thin layer of uranium or
plutonium (I forgot which). I remember reading about it years ago.
Ray Drouillard
Erik Max Francis
> Rain, dust, smoke etc are significant impediments to using the usual
> bullets
> in combat as well.
To aiming, perhaps. The bullets go through rain, dust, and smoke just
fine. Lasers don't. Big difference.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ With such a weapon I could boil the Earth to vapor.
\__/ Chmeee
Fat Boy and Little Man / http://www.fatboyandlittleman.com/
Watch Fat Boy and Little Man go about their antics.
Timothy Little
>Timothy Little wrote:
>> Somewhere between pistol and rifle bullet energies. I believe the
>> proposed method is a very rapid pulse train, each successive pulse
>> blasting a little deeper into the target.
>
>This discussion pops up from time to time (for good reason, it's not all
>that clear). One thing that's the case is you can't directly compare
>beam energies and bullet kinetic energies; they have different jobs.
Sure, I wasn't implying that they do. I was just answering the
question.
>Getting damage from kinetic energy is cheap when you've got a slug that
>you're throwing. When all you have is the beam itself, it needs to be
>powerful enough to incapacitate, which means that it's going to have to
>burn some flesh, preferably a lot.
All it needs to do is to make something important stop working. Of
course, the more damage you do the more likely it is that such a
something is involved.
> I'd say that involves quite a bit more than 1 kJ.
How much energy does it take to make a hole through to someone's heart
or lungs? The "successive pulse" mechanism isn't proven, but doesn't
have anything obviously wrong with it. Certainly reasonable enough
for science fiction purposes.
The fact is, we don't really know what makes people drop when shot.
Certainly someone whose heart is torn up isn't long for this world,
but some people are incapacitated without anything visibly wrong.
Some people continue fighting for a short time with certainly fatal
wounds.
Until such lasers are actually tested on people, I'd be very wary of
ruling out any particular energy level. I would hope that they never
are tested.
With a beam weapon, adaptive optics, and reasonable onboard computing
power I'd bet on 'smartguns'. You point it in the direction of the
target's upper body and head, and the adaptive optics and sensors
fine-tune that to particularly vulnerable spots, e.g. eyes, putting a
hole through the spinal cord, or damaging enemy weapons or sensors.
Of course, that doesn't really match the typical science-fiction laser
pistol gunfight image, and maybe it would never work. I find it
plausible though not particularly pleasant.
- Tim
Timothy Little
>Wasn't it Timothy Little who wrote:
Why yes, it was! :)
>>Make the efficiency lower (say 20%) to allow for losses in the stages
>>between battery and lasing device, and call the energy requirement
>>50 kJ.
>
>20% efficiency? Doesn't that cause rather extreme problems of dealing
>with the waste heat?
Yes. No matter what, you want a good cooling system. As I understand
it, conventional guns leave only about 10-30% of the projectile energy
in the chamber and barrel. At high rates of fire, they get hot enough
as it is.
A laser weapon dumping 4 kJ into the weapon each time you fire it is a
significantly worse problem. Air cooling might be sufficient, with
large area of convection surfaces and probably forced airflow.
Whatever mechanism might be used, it would add extra bulk, weight,
cost and complexity to an already difficult-to-engineer system.
>In particular, if you're stuck in an icy wasteland and try the trick
>where you use the laser beam to heat up a rock to keep you warm,
>you're going to find that the temperature rise in the gun will be
>considerably more than the temperature rise in the rock.
Not if it blows a lot of hot air in the rock's direction. Or maybe
I'm the one blowing hot air :)
- Tim
Timothy Little
>A laser would cause damage by burning or vaporizing tissue.
No, I think the best mechanism proposed is tearing by explosive
expansion of vapor. If you vaporise 1 mm^3, it expands by a factor of
over 1000. Do it slowly and it just dissipates, leaving a 1 mm^3
hole.
Do it rapidly and it makes a bigger hole as the pressure required to
accelerate the vapor out of the hole exceeds the strength of the
material, causing structural failure outside that 1 mm^3 volume.
i.e. it tears or breaks.
Vaporisation is overkill -- you want to be able to vaporise a small
amount, but do it fast enough to do a lot of structural damage nearby.
The biggest question is whether it is possible for the beam to
penetrate the resulting gas/plasma well enough to do deeper damage on
subsequent pulses. It also shows why you want a narrow beam: a wide
beam has to do more vaporisation for a given depth of penetration and
hence more energy required.
- Tim
Charles R Martin
>
> Charles R Martin wrote:
>
> > Rain, dust, smoke etc are significant impediments to using the usual
> > bullets
> > in combat as well.
>
> To aiming, perhaps. The bullets go through rain, dust, and smoke just
> fine. Lasers don't. Big difference.
Why thank you, Max. I'm so glad you've cleared that up for me.
Matthew DeBell
>Charles R Martin wrote:
>
>> Rain, dust, smoke etc are significant impediments to using the usual
>> bullets
>> in combat as well.
>
>To aiming, perhaps. The bullets go through rain, dust, and smoke just
>fine. Lasers don't. Big difference.
OTOH, lasers ignore wind, and bullets don't, which can make a big difference
at long range.
--
Matthew DeBell
Erik Max Francis
> Why thank you, Max. I'm so glad you've cleared that up for me.
Then why did you bring it up? There's light-years' distance between not
being able to see your target clearly because of weather and having your
weapon not reach its target because of weather. That is not a
quantitative difference, but a qualitative one.
--
Erik Max Francis / m...@alcyone.com / http://www.alcyone.com/max/
__ San Jose, CA, US / 37 20 N 121 53 W / ICQ16063900 / &tSftDotIotE
/ \ [Western Civiliation?] It would be a good idea.
\__/ Mohandas K. Gandhi
Esperanto reference / http://mirror/alcyone/max/lang/esperanto/
An Esperanto reference for English speakers.
Matthew DeBell
>Matthew DeBell <m...@attglobal.net> wrote:
>
>>A laser would cause damage by burning or vaporizing tissue.
>
>No, I think the best mechanism proposed is tearing by explosive
>expansion of vapor. If you vaporise 1 mm^3, it expands by a factor of
>over 1000. Do it slowly and it just dissipates, leaving a 1 mm^3
>hole.
>
>Do it rapidly and it makes a bigger hole as the pressure required to
>accelerate the vapor out of the hole exceeds the strength of the
>material, causing structural failure outside that 1 mm^3 volume.
>i.e. it tears or breaks.
Maybe so. How does one figure the effects of the vapor expansion?
--
Matthew DeBell
Timothy Little
>>i.e. it tears or breaks.
>
>Maybe so. How does one figure the effects of the vapor expansion?
Come on, you already know the answer to that question!
"With difficulty" :)
More seriously, you can estimate the rate of absorption. You can
compare it with mechanisms that transport that power away from the
target site -- conduction, reradiation, convection, vaporisation, ion
dissociation etc., with associated time and distance scales (probably
in that order).
After that, you should be able to guess at a free rate of expansion
(as a function of time and distance), and work out how it changes
based on the fact that the stuff isn't actually free to expand in all
directions. If the resulting stresses exceed the maximum strength of
the material, figure that it breaks in an appropriate manner, and try
to work out useful things like a rough idea of the likely geometry of
any breaks and how far they would be expected to propogate.
Work out what should happen after the power input ceases -- e.g. how
long the cavity takes to collapse, how long it takes for various types
of products to disperse from the area of interest, how long things
stay hot and in which directions, etc.
Probably do some numerical models of more or less complexity, with
slightly different parameters including a few calibration runs where
the true outcome is known (if any) or testing outcomes against
different models of the same phenomenon.
One hassle is that human body tissues are greatly inhomogeneous and
anisotropic in many properties. This makes it really annoying to
model mathematically, and could mean that the pulse-train idea
wouldn't work in practice. This could happen if the properties differ
enough that timings and energies suitable for (e.g.) muscle have
little effective overlap with those needed for bone or fat.
- Tim
Nyrath the nearly wise
Point taken. However, the "regeneration vats" in the novel
were techno-magic anyway. They not only could bring back to
life a dead person, they could restore to normal a person who had
been sliced into one centimeter wide strips.
Charles R Martin
>
> Charles R Martin wrote:
>
> > Why thank you, Max. I'm so glad you've cleared that up for me.
>
> Then why did you bring it up? There's light-years' distance between not
> being able to see your target clearly because of weather and having your
> weapon not reach its target because of weather. That is not a
> quantitative difference, but a qualitative one.
Max. Look up "sarcasm."
Matthias Warkus
...and Charles R Martin <crma...@indra.com> wrote:
> > Yes quite. I think the main reason why energy sidearms would
> > be popular would be due to some stupdendous breakthrough in
> > energy storage (i.e. batteries) that made it a lot easier
> > (and cheaper) to use weapons powered by the super battery than
> > to use other systems.
>
> Don't forget some of the other advantages laser weapons might have. One that
> strikes me offhand is that (at least as a hand weapon) you just aim at what
> you want to hit, no matter the range or relative motion. No "leading" the
> target, no range adjustment on the sights, no "windage", and no recoil.
Diffraction and diffusion by passing through non-pure air of
non-uniform temperature and density, however.
mawa
--
We handle four billion calls a year, for everyone from presidents and
kings to the scum of the earth. So your call doesn't go through once
in a while, or you get billed for a call or two you didn't make. We
don't care. We don't have to, we're the phone company. -- Lily Tomlin
Charles R Martin
Whoo. Them's good vats.
Christian Thalmann
> With a beam weapon, adaptive optics, and reasonable onboard computing
> power I'd bet on 'smartguns'. You point it in the direction of the
> target's upper body and head, and the adaptive optics and sensors
> fine-tune that to particularly vulnerable spots, e.g. eyes, putting a
> hole through the spinal cord, or damaging enemy weapons or sensors.
What I imagine for the future of personal combat weapons is a gun
that is fixed to a backpack frame or to a similar carrying device
on the shoulders. It's got servo-motors and gyro-stabilizers and
can acquire targets and perform different attack schemes (disable,
disarm, snipe-kill, mass-kill etc.). The gunner wears a combat
visor that can 1) display tactical information, 2) show zoomed
video feed from the weapons targeting sensors, 3) display a thin
glowing line showing the current line of fire from your weapon and
4) track your eyeballs so you can use the focus of your eyes as a
3D-cursor to designate targets.
Of course, such a weapon would be impractical for use as a
personal protection gun in civilian settings. Deadly weapons
might be outlawed for civilians anyway if non-lethal stunners
like the very promising-sounding APBW project by HSV technology
reach the market. Their stunner uses UV-lasers to ionize twin
paths of oxygen plasma as a conductor for a tetanizing or stunning
electric shock.
Check out their homepage at www.hsvt.org.
> Of course, that doesn't really match the typical science-fiction laser
> pistol gunfight image, and maybe it would never work. I find it
> plausible though not particularly pleasant.
My shoulder-gun is even further from this cliché, but it would
free up the gunner's hands and eliminate most physical sources
for inaccuracy. It would be WYSIWYH -- what you see is what you
hit. ;-)
-- Christian Thalmann
Christian Thalmann
> 3) Doped buckytubes are practically superconductors. Undoped buckytubes are
> excellent insulators. You can therefore make a really big capacitor out of
> concentric buckytubes. The plate area would be huge and the spacing would
> be really small. I haven't done the math, but I'm sure that capacitors in
> the thousands or millions of farads would be possible. They could be made
> the size of bullets and simply be used one at a time as you fire the shots.
>
> Actually, instead of concentric buckytubes, you can shift the structure a
> bit and make it out of "rolled" pieces of buckytube - just like a modern
> electrolytic capacitor - except that the plates are a whole lot closer to
> each other and the area is a whole lot bigger.
Sounds very promising, and it seems to me (though I am technically
a newbie ;-) that such a capacitor would even meet the
lightning-quick discharge requirements for a pulsed laser.
Are those capacitors capable of holding a charge for extended
periods of time like a battery, or would they have to be charged
immediately before use?
What's their energy density as compared to other energy storage
media?
And just out of curiosity: Is it possible to explain the meaning
of "doped" to a third-semester physics student without delving too
deep into advanced knowledge? Does it mean "covered with a
molecular-thin metal layer" or something?
> With a little imagination, you can handwave lots of things, like nuclear
> powered lasers (fission or fusion). In fact, someone actually made an x-ray
> laser that is powered by the fissioning of a thin layer of uranium or
> plutonium (I forgot which). I remember reading about it years ago.
High-energy density batteries seem unavoidable for a high-tech
sci-fi setting, so I've made up the "matrix cell" a few years ago.
Basically, it's a crystal structure that can be forced to switch
into another crystal state with extremely low entropy. Due to the
entropic gradient between the two states, it would require large
amounts of energy to shift to the second state; energy which would
be stored as an increase in mass.
I have no idea whether this makes sense to a real physicist, and
if so, of what order of magnitude the mass increase would be. Any
ideas? Are energy densities one or two orders of magnitudes below
nuclear fuels imaginable?
-- Christian Thalmann
Marc Lombart
wrote:
>> Rain, dust, smoke etc are significant impediments to using the usual
>> bullets
>> in combat as well.
>
>To aiming, perhaps. The bullets go through rain, dust, and smoke just
>fine. Lasers don't. Big difference.
>
>--
And with the new scopes being prototyped, rain, dust and smoke
are not much of an impediment to aiming.
--
Marc el Kato
mailto:master...@netzero.net
ICQ UIN: 3337155
Please, reply either to the group or via eMail, not both.
Marc Lombart
You should thank him for correcting the error you made.
Isaac Kuo
Christian Thalmann <ci...@iname.com> wrote:
>What I imagine for the future of personal combat weapons is a gun
>that is fixed to a backpack frame or to a similar carrying device
>on the shoulders. It's got servo-motors and gyro-stabilizers and
>can acquire targets and perform different attack schemes (disable,
>disarm, snipe-kill, mass-kill etc.). The gunner wears a combat
>visor that can 1) display tactical information, 2) show zoomed
>video feed from the weapons targeting sensors, 3) display a thin
>glowing line showing the current line of fire from your weapon and
>4) track your eyeballs so you can use the focus of your eyes as a
>3D-cursor to designate targets.
I used to have ideas like that, but I've since returned to
the idea of a small compact handheld weapon.
Basically, the backpack idea is pretty good--but why stop
there? If you've got a visor with all that display stuff
remotely controlling an automated gun on a backpack,
why make the operator lug around the backpack? Make it
a semi-autonomous remote control robot "soldier", that
patrols with the operator like a faithful guard dog.
If you want to go "over the top", just send the robot
and leave the operator safely cowering in the trench!
But of course, that leaves the operator vulnerable in
the case of the robot being far away from the operator
(i.e. the robot has been sent into a building while
the operator stays outside). To some extent, this
problem can be mitigated with redundant robots.
However, the operator will at least feel more secure
with a final option of last resort.
As such, this final option of last resort should be
compact and lightweight. Aiming servos and other
gizmos get in the way of these criteria.
Incidentally, this lightweight gun can also be used
as a pointer to target an enemy for robot attack.
As a panic weapon of last resort, you pull the
trigger and not only do you fire bullets at the
target, all of the nearby robot "dogs" blast away
at it as well! Your gun might be a crappy little
9mm which just bounces off the armor of the APC
you unexpectedly encountered, but the massed
fire of 40mm grenades from your faithful robot
"dogs" could rip it to pieces.
--
_____ Isaac Kuo mec...@yahoo.com ICQ 29055726
__|_)o(_|__
/___________\
\=\)-----(/=/
Sent via Deja.com
http://www.deja.com/
Christian Thalmann
> Basically, the backpack idea is pretty good--but why stop
> there? If you've got a visor with all that display stuff
> remotely controlling an automated gun on a backpack,
> why make the operator lug around the backpack? Make it
> a semi-autonomous remote control robot "soldier", that
> patrols with the operator like a faithful guard dog.
> If you want to go "over the top", just send the robot
> and leave the operator safely cowering in the trench!
Remote-controlled intelligent weapons are always a
safety hazard, since they could be jammed or even
taken control of by the enemy.
> As such, this final option of last resort should be
> compact and lightweight. Aiming servos and other
> gizmos get in the way of these criteria.
Hmmm... a lightweight recoil-less compact gun could be
built directly onto the combat helmet, so it'll always
point into the general direction that you're looking
in. I guess you'd be able to aim quite accurately with
the help of a crosshair on your visor, unless your head
is shaking from battlefield trauma. ;-)
On the other hand, I don't really have anything against
pistol-shaped weapons. =)
> Incidentally, this lightweight gun can also be used
> as a pointer to target an enemy for robot attack.
> As a panic weapon of last resort, you pull the
> trigger and not only do you fire bullets at the
> target, all of the nearby robot "dogs" blast away
> at it as well! Your gun might be a crappy little
> 9mm which just bounces off the armor of the APC
> you unexpectedly encountered, but the massed
> fire of 40mm grenades from your faithful robot
> "dogs" could rip it to pieces.
Sure, you could carry a set of transponder bullets
that adhere to the armor and radiate in all bandwidths
like a christmas tree. ;-)
Or you could use the good old laser pointer.
-- Christian Thalmann
Christopher M. Jones
> The fact is, we don't really know what makes people drop when shot.
> Certainly someone whose heart is torn up isn't long for this world,
> but some people are incapacitated without anything visibly wrong.
> Some people continue fighting for a short time with certainly fatal
> wounds.
That's not true, we know a lot about damage mechanisms of
firearms. Keep in mind though that guns and ammunition come
in many different calibers, types, powers, etc. so "shooting
someone with a gun" is not nearly a constant.
There are primarily 4 different "aspects" of a human getting
hit with a bullet. The first is the basic entry and exit
wounds, the "hole" through the person. The second is the
blood loss, which can be dramatically affected by the type
and speed of the bullet. The third is "shock" to the body
from the bullet. The fourth is the "knock down force", the
sheer momentum transfer.
Some rounds (such as a .22, 9mm, .38 special, .25 auto,
especially in the case of full metal jacketed bullets) have
low power and low weight and the predominant "result" of
"a hit" is simply a puncture through the victim's body. In
the case of a .25 auto round, it doesn't even have enough
power to break bone and in many cases doesn't fully penetrate
through the body. Firing a .25 automatic at a medium large
determined individual will most likely not stop them and the
result could very probably be them beating the ever loving
daylights out of you.
Other rounds (such as .357 magnum, .44 magnum, especiall in
the case of hollow point or soft point bullets) have a lot
more power and speed (as well as bullet weight) and will
create a large exit wound and will also "suck" blood through
the exit wound. This dramatically lowers the blood pressure
of the victim and results in rapid blood loss. Hollow point
bullets and the like will result in mushrooming of the bullet
and jacket as it penetrates the body, leading to much greater
damage through larger exit wounds et al. Additionally, the
force of the bullet smashing into the body will create a
"shock" that passes through the body (basically, this is a
"shock wave") and can do additional damage (especially to
vital organs like the lungs, heart, liver, kidneys).
Heavier rounds with more momentum (.45 Auto, for example)
have the ability to deliver that "knock down punch" even
at slower speeds and with full metal jacketed rounds. These
rounds have enough kinetic energy and momentum to actually
knock a person down, to knock the breath out of them, etc.
Additionally, due to the large amount of damage that a round
of this size can do to the human body, once a person is knocked
down, they are unlikely to get back up.
Other even higher energy rounds (.50 caliber, shotgun, .308
rifle rounds, etc.) have so much power, momentum, and produce
so much damage that they cause _enormous_ amounts of damage
to the victim and essentially kill them instantaneously. For
example, a single .50 caliber round can literaly tear a body
in half. The shot or slug from a 12 gauge shotgun hitting the
torso of a human will cause so much damage so rapidly that
death is assured and almost instantaneous. High power rifle
rounds are often (but not always) fatal depending on the exact
power of the round, the type of round (full metal jacket,
soft point, etc.), and the part of the body that was hit. For
example, getting hit in the foot with a .308 rifle round would
rarely be fatal, and getting hit in the shoulder with a high
velocity 5.56 mm round (M16) would also rarely be fatal.
Getting hit by a .50 caliber round just about anywhere is
essentially fatal.
Of course, the physiology (and psychology) of the individual
also plays an important role. Some people hit with a
"pip-squeek" round like a .25 auto may decide to fall down
simply out of shock and that "I've been shot!" panic. Other
people may recieve lethal damage from a high caliber round
penetrating their abdomen, but are not knocked down, still
have enough blood pressure to stay concious a while longer,
and can adequately handle the pain enough to continue on.
But, I can guarantee you that if you shoot someone with a
12 gauge slug, a .308 rifle, a .45 auto or magnum, or a .50
caliber rifle that the person will drop immediately after
being hit no matter how strong or determined they are.
--
Error processing request, please try again
Mark Lanett
"Charles R Martin" <crma...@indra.com> wrote in message
news:3A5F2715...@indra.com...
Also a good egg slicer.
~mark
Luke Campbell
> It was the Thu, 11 Jan 2001 13:47:41 -0700...
> ...and Charles R Martin <crma...@indra.com> wrote:
> > > Yes quite. I think the main reason why energy sidearms would
> > > be popular would be due to some stupdendous breakthrough in
> > > energy storage (i.e. batteries) that made it a lot easier
> > > (and cheaper) to use weapons powered by the super battery than
> > > to use other systems.
> >
> > Don't forget some of the other advantages laser weapons might have. One that
> > strikes me offhand is that (at least as a hand weapon) you just aim at what
> > you want to hit, no matter the range or relative motion. No "leading" the
> > target, no range adjustment on the sights, no "windage", and no recoil.
>
> Diffraction and diffusion by passing through non-pure air of
> non-uniform temperature and density, however.
It apears that the second problem can be corrected with adaptive optics, although
this requires a signifcant amount of computing power. The first problem seems to
be more fundamental.
Luke
Luke Campbell
> And just out of curiosity: Is it possible to explain the meaning
> of "doped" to a third-semester physics student without delving too
> deep into advanced knowledge? Does it mean "covered with a
> molecular-thin metal layer" or something?
If you dope with a given substance, you add a small amount of that substance as
impurities to another, nearly pure, substance.
> > With a little imagination, you can handwave lots of things, like nuclear
> > powered lasers (fission or fusion). In fact, someone actually made an x-ray
> > laser that is powered by the fissioning of a thin layer of uranium or
> > plutonium (I forgot which). I remember reading about it years ago.
>
> High-energy density batteries seem unavoidable for a high-tech
> sci-fi setting, so I've made up the "matrix cell" a few years ago.
> Basically, it's a crystal structure that can be forced to switch
> into another crystal state with extremely low entropy. Due to the
> entropic gradient between the two states, it would require large
> amounts of energy to shift to the second state; energy which would
> be stored as an increase in mass.
>
> I have no idea whether this makes sense to a real physicist, and
> if so, of what order of magnitude the mass increase would be. Any
> ideas? Are energy densities one or two orders of magnitudes below
> nuclear fuels imaginable?
The difference in entropy merely means that the low entropy crystal can (and
eventually will) spontaneously change phase to the high entropy crystal, it makes
no statement about the energy required or liberated in doing so. It may, for
example, suck heat from the surrounding environment to supply the energy needed
to change to the high entropy phase, rather than liberating energy. The actual
energy involved in the phase change depends entirely on the energy stored in the
chemical bonds that hold the crystal together, in addition to any work it does
against the surrounding environment if it changes its volume, magnetization,
polarization, or whatever. So, you still only end up with chemical energy
densities.
Luke
Charles R Martin
>
> On Thu, 11 Jan 2001 22:04:44 -0700, Charles R Martin
> <crma...@indra.com> wrote:
>
> >> Charles R Martin wrote:
> >>
> >> > Rain, dust, smoke etc are significant impediments to using the usual
> >> > bullets
> >> > in combat as well.
> >>
> >> To aiming, perhaps. The bullets go through rain, dust, and smoke just
> >> fine. Lasers don't. Big difference.
> >
> >Why thank you, Max. I'm so glad you've cleared that up for me.
>
> You should thank him for correcting the error you made.
Not till he thanks me for correcting his.
Luke Campbell
> "Timothy Little" <t...@freeman.little-possums.net> wrote:
> > The fact is, we don't really know what makes people drop when shot.
> > Certainly someone whose heart is torn up isn't long for this world,
> > but some people are incapacitated without anything visibly wrong.
> > Some people continue fighting for a short time with certainly fatal
> > wounds.
>
> That's not true, we know a lot about damage mechanisms of
> firearms. Keep in mind though that guns and ammunition come
> in many different calibers, types, powers, etc. so "shooting
> someone with a gun" is not nearly a constant.
>
> There are primarily 4 different "aspects" of a human getting
> hit with a bullet. The first is the basic entry and exit
> wounds, the "hole" through the person. The second is the
> blood loss, which can be dramatically affected by the type
> and speed of the bullet. The third is "shock" to the body
> from the bullet. The fourth is the "knock down force", the
> sheer momentum transfer.
>
> Other rounds (such as .357 magnum, .44 magnum, especiall in
> the case of hollow point or soft point bullets) have a lot
> more power and speed (as well as bullet weight) and will
> create a large exit wound and will also "suck" blood through
> the exit wound.
"Suck" blood through the exit wound? This sounds like bunk to me. Do
you have a mechanism by which it does this? Do you have any good
references?
> This dramatically lowers the blood pressure
> of the victim and results in rapid blood loss. Hollow point
> bullets and the like will result in mushrooming of the bullet
> and jacket as it penetrates the body, leading to much greater
> damage through larger exit wounds et al. Additionally, the
> force of the bullet smashing into the body will create a
> "shock" that passes through the body (basically, this is a
> "shock wave") and can do additional damage (especially to
> vital organs like the lungs, heart, liver, kidneys).
From the medical litterature which I have read, the shock wave itself
seems to be largely inconsequential except possibly to the head, where
overpressure _might_ be able to burst the skull. Shock waves in the
weak shock limit will only cause damage at interfaces of different
densities (strong shocks cause shock heating - bullets do not cook
tissue near them, so the bullet must be well outside of the strong shock
limit) . Although they may cause some tearing at muscle/bone
interfaces, the primary areas where shocks will cause damage are in
rupturing the bowels (which have pockets of gas in them) and rupturing
the lungs (which are chock full of tissue/gas interfaces). Although
these tissues can be damaged by explosive produced shocks, the more
localized effects of bullet produced shocks do not seem to be
significant. This is probably due, in large part, to the low density
and highly inhomogeneous nature of the lungs.
Also keep in mind that in order to get a shock, the bullet will have to
be moving faster than the speed of sound in tissue (not the speed of
sound in air!). The speed of sound varies with the type of tissue, but
should be larger than the speed of sound in air in most cases.
Bullets can cause damage far from the wound path by the mechanism of
creating temporary cavities. This is where the rapid passage of the
bullet through the tissue forces the tissue out of the way of the bullet
at high velocities. This causes a large cavity surrounded by highly
stretched tissue. Tissue is highly elastic, so it quickly recollapses.
The stretching of the tissue can cause some damage, but most tissue is
highly elastic and is not strongly affected. There may be bruising, but
the tissue does not die. The exception seems to be in the liver, which
is more readily disrupted by these temporary cavities than most other
tissue types. Another exception is with soft point or disintegrating
bullets from high powered rifles, which stretch large volumes of tissue
well beyond its elastic limits, helped by the passage of multiple
fragments of the bullet passing through the stretched tissue, leading to
tearing of tissue over those large volumes. These types of bullets can
cause awful wounds.
> Heavier rounds with more momentum (.45 Auto, for example)
> have the ability to deliver that "knock down punch" even
> at slower speeds and with full metal jacketed rounds.
Wait a minute, the .45 auto is about the same mass (slightly less, by my
sources) than the .44 magnum, and goes slower, yet you put it in a
category with more knock down punch that the .44 magnum?
> These
> rounds have enough kinetic energy and momentum to actually
> knock a person down, to knock the breath out of them, etc.
The momentum transfer from bullets to the target is negligible. It is,
in fact, equal to or less than the momentum transfered to the person
firing the gun, and the firer usually only falls over if they flinch
from the recoil.
Energy does not knock people over, only momentum does that, and bullets
do not have enough momentum.
> Other even higher energy rounds (.50 caliber, shotgun, .308
> rifle rounds, etc.) have so much power, momentum, and produce
> so much damage that they cause _enormous_ amounts of damage
> to the victim and essentially kill them instantaneously. For
> example, a single .50 caliber round can literaly tear a body
> in half.
And yet soldiers have been struck in the torso by multiple .50 caliber
machine gun bullets and survived.
> The shot or slug from a 12 gauge shotgun hitting the
> torso of a human will cause so much damage so rapidly that
> death is assured and almost instantaneous. High power rifle
> rounds are often (but not always) fatal depending on the exact
> power of the round, the type of round (full metal jacket,
> soft point, etc.), and the part of the body that was hit. For
> example, getting hit in the foot with a .308 rifle round would
> rarely be fatal, and getting hit in the shoulder with a high
> velocity 5.56 mm round (M16) would also rarely be fatal.
> Getting hit by a .50 caliber round just about anywhere is
> essentially fatal.
A limb hit by a .50 caliber machine gun would only be fatal through
blood loss or infection, although there is a good chance it would
amputate the limb. Since people frequently survive having limbs
violently amputated, I do not see this as being essentially fatal.
> Of course, the physiology (and psychology) of the individual
> also plays an important role. Some people hit with a
> "pip-squeek" round like a .25 auto may decide to fall down
> simply out of shock and that "I've been shot!" panic. Other
> people may recieve lethal damage from a high caliber round
> penetrating their abdomen, but are not knocked down, still
> have enough blood pressure to stay concious a while longer,
> and can adequately handle the pain enough to continue on.
> But, I can guarantee you that if you shoot someone with a
> 12 gauge slug, a .308 rifle, a .45 auto or magnum, or a .50
> caliber rifle that the person will drop immediately after
> being hit no matter how strong or determined they are.
These rounds (except for possibly the .50 cal) do not always immediately
stop deer. All the males in my family are hunters (I'm the only one who
hasn't bagged anything yet, I seem to be bad luck) and they are always
complaining about deer that they shoot through the lungs with their
favorite hunting round, and the deer doesn't have the good graces to
just fall down and die. Instead it takes off running cross country,
down steep valleys and into the most inaccessable places filled with
nearly impassable brush before finally exanguinating, and the poor
hunter has to go and lug it back out. If deer do not always
conveniently drop when hit by these rounds, people will not always
conveniently drop either. I don't know anyone who hunts with .50
caliber rounds, but I am highly sceptical that these will immediately
drop people either. There is just no good mechanism that I can find
that will reliably cause trauma to the central nervous system or inhibit
the load bearing properties of the muscular and skeletal systems for an
arbitrary shot placement.
Luke
Luke Campbell
> Luke Campbell <lwc...@u.washington.edu> writes:
>
> >Any reason why you do not expect excimers to be compact laser handguns?
> >They seem to be able to make fairly high powered pulsed excimers which
> >are highly efficient (similar to those of YAG, diode, and CO2 lasers).
>
> But rather more complex, and with no compelling advantage over diode
> pumped crystal lasers that I can see. It's possibility, but not one
> I would bet on.
Just remembered this one - a possibly compelling advantage of excimers is that
they have a 100% quantum efficiency (or close to it, anyway) - all the energy
that goes into putting the halogen and noble gas into an excited state is
returned as a UV photon. Any losses in energy are due to other mechanisms (like
inefficiency in getting the excited halogen-noble gas molecule). I can't find
my class notes, but the quantum efficiency for neodymnium lasers is somewhere
between 20 to 40%. if I recall correctly. This means that in principle you
could get very high efficiency excimers, which means a lot less heat to get rid
of and less weight to pack around in your batteries.
Luke
John Schilling
>Charles R Martin wrote:
>> Rain, dust, smoke etc are significant impediments to using the usual
>> bullets
>> in combat as well.
>To aiming, perhaps. The bullets go through rain, dust, and smoke just
>fine. Lasers don't. Big difference.
Lasers go through any rain, dust, or smoke that you can see through to
aim in the first place. They do of course have problems with recon by
fire and indirect fire, for those who favor such tactics.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schi...@spock.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
Christopher M. Jones
> "Christopher M. Jones" wrote:
> > Other rounds (such as .357 magnum, .44 magnum, especiall in
> > the case of hollow point or soft point bullets) have a lot
> > more power and speed (as well as bullet weight) and will
> > create a large exit wound and will also "suck" blood through
> > the exit wound.
>
> "Suck" blood through the exit wound? This sounds like bunk to me. Do
> you have a mechanism by which it does this? Do you have any good
> references?
Meaning that the pressure differentials caused by the bullet
passing through the body tends to cause more blood to flow
through a hole than if you just poked a hole.
> Wait a minute, the .45 auto is about the same mass (slightly less, by my
> sources) than the .44 magnum, and goes slower, yet you put it in a
> category with more knock down punch that the .44 magnum?
The "categories" aren't meant to be exclusive, the .44 magnum
will indeed be able to deliver that "knock down punch".
> And yet soldiers have been struck in the torso by multiple .50 caliber
> machine gun bullets and survived.
If it's a full metal jacketed round, that is possible, but you'd
need to be pretty lucky. Of course, in modern times with highly
capable battlefield medics if you are lucky enough to not die
immediately, even if you've been hit in the gut you can probably
be saved.
> A limb hit by a .50 caliber machine gun would only be fatal through
> blood loss or infection, although there is a good chance it would
> amputate the limb. Since people frequently survive having limbs
> violently amputated, I do not see this as being essentially fatal.
OK, then "excluding getting hit in the arm and possibly the lower
legs", getting hit by a .50 caliber round is essentially fatal.
If you get hit in the head, torso, or upper legs, you will almost
certainly die very quickly unless the bullet just happens to miss
vital organs and you can get medical attention _really_ soon.
> These rounds (except for possibly the .50 cal) do not always immediately
> stop deer. All the males in my family are hunters (I'm the only one who
> hasn't bagged anything yet, I seem to be bad luck) and they are always
> complaining about deer that they shoot through the lungs with their
> favorite hunting round, and the deer doesn't have the good graces to
> just fall down and die. Instead it takes off running cross country,
> down steep valleys and into the most inaccessable places filled with
> nearly impassable brush before finally exanguinating, and the poor
> hunter has to go and lug it back out. If deer do not always
> conveniently drop when hit by these rounds, people will not always
> conveniently drop either. I don't know anyone who hunts with .50
> caliber rounds, but I am highly sceptical that these will immediately
> drop people either. There is just no good mechanism that I can find
> that will reliably cause trauma to the central nervous system or inhibit
> the load bearing properties of the muscular and skeletal systems for an
> arbitrary shot placement.
Deer and humans are not identical, and in fact I think there's a
good case to be made for deer being "stronger" than humans when it
comes to getting injured or shot at (in some regards). For one, a
deer's body is a lot narrower than a human's so just about with any
bullet that's not a soft point or a hollow point, the bullet is just
going to pass right through, which is unlikely to cause immediate
fatal damage. As for humans, if you hit them with a .308 Winchester,
a 12 gauge slug, or such like, I can almost guarantee that they will
be going down really fast and not getting up.
--
Gonna paint our wagon,
Gonna paint it good,
We ain't braggin',
We're gonna coat that wood.
Timothy Little
>"Timothy Little" <t...@freeman.little-possums.net> wrote:
>> The fact is, we don't really know what makes people drop when shot.
>
>firearms. Keep in mind though that guns and ammunition come
>in many different calibers, types, powers, etc. so "shooting
>someone with a gun" is not nearly a constant.
We know a lot about about terminal ballistics and damage mechanisms,
perhaps, but still not much about how and why people are "stopped".
[...lots of discussion about physical wound mechanisms...]
> The shot or slug from a 12 gauge shotgun hitting the torso of a
>human will cause so much damage so rapidly that death is assured and
>almost instantaneous.
Oh? Then explain the recorded instances of a few people continuing to
fight after receiving *multiple* shotgun wounds to the torso, and
surviving with rapid (on the order of a few minutes) medical
attention.
>Of course, the physiology (and psychology) of the individual
>also plays an important role.
Yes, and that is what I was referring to. We know very little about
what factors connect personal attributes of the individual with
objective wounding effects to give any particular response to being
shot.
Particularly so for laser weapons. It may turn out that a particular
pulse rate induces nerve signals that interfere with heart function,
or that produces crippling pain even without doing a lot of tissue
damage. Or it may turn out that despite severe damage, the lack of
momentum transfer (knockback, as you call it) greatly reduces the
likelihood of dropping the target and removing them from the fight.
>But, I can guarantee you that if you shoot someone with a 12 gauge
>slug, a .308 rifle, a .45 auto or magnum, or a .50 caliber rifle that
>the person will drop immediately after being hit no matter how strong
>or determined they are.
I reject your guarantees. There are many recorded instances of
shooting victims continuing to fight and survive after hits from each
one of these weapons. Particularly the pistol rounds. They are more
likely to succeed than some others, but the final effect is not
"guaranteed" in anywhere near the same sense as a bullet being
guaranteed to penetrate X inches of ballistic gelatin.
- Tim
Luke Campbell
> "Luke Campbell" <lwc...@u.washington.edu> wrote:
> > "Christopher M. Jones" wrote:
> > > Other rounds (such as .357 magnum, .44 magnum, especiall in
> > > the case of hollow point or soft point bullets) have a lot
> > > more power and speed (as well as bullet weight) and will
> > > create a large exit wound and will also "suck" blood through
> > > the exit wound.
> >
> > "Suck" blood through the exit wound? This sounds like bunk to me. Do
> > you have a mechanism by which it does this? Do you have any good
> > references?
>
> Meaning that the pressure differentials caused by the bullet
> passing through the body tends to cause more blood to flow
> through a hole than if you just poked a hole.
But these pressure differences are only for a very short time. You might
get a short pulse of extra blood, but I do not see anything like this making
a significant difference to the amount of blood in your body. If you have
good references to this sort of thing, I would be interested.
> > A limb hit by a .50 caliber machine gun would only be fatal through
> > blood loss or infection, although there is a good chance it would
> > amputate the limb. Since people frequently survive having limbs
> > violently amputated, I do not see this as being essentially fatal.
>
> OK, then "excluding getting hit in the arm and possibly the lower
> legs", getting hit by a .50 caliber round is essentially fatal.
> If you get hit in the head, torso, or upper legs, you will almost
> certainly die very quickly unless the bullet just happens to miss
> vital organs and you can get medical attention _really_ soon.
Alright, I can buy that with the qualifiers. Long term survival will be
rare, death is likely to occur rapidly (but not necessarily
instantaneously). That jives with what I've heard from other sources.
> > These rounds (except for possibly the .50 cal) do not always immediately
> > stop deer. All the males in my family are hunters (I'm the only one who
> > hasn't bagged anything yet, I seem to be bad luck) and they are always
> > complaining about deer that they shoot through the lungs with their
> > favorite hunting round, and the deer doesn't have the good graces to
> > just fall down and die. Instead it takes off running cross country,
> > down steep valleys and into the most inaccessable places filled with
> > nearly impassable brush before finally exanguinating, and the poor
> > hunter has to go and lug it back out. If deer do not always
> > conveniently drop when hit by these rounds, people will not always
> > conveniently drop either. I don't know anyone who hunts with .50
> > caliber rounds, but I am highly sceptical that these will immediately
> > drop people either. There is just no good mechanism that I can find
> > that will reliably cause trauma to the central nervous system or inhibit
> > the load bearing properties of the muscular and skeletal systems for an
> > arbitrary shot placement.
>
> Deer and humans are not identical, and in fact I think there's a
> good case to be made for deer being "stronger" than humans when it
> comes to getting injured or shot at (in some regards). For one, a
> deer's body is a lot narrower than a human's so just about with any
> bullet that's not a soft point or a hollow point, the bullet is just
> going to pass right through, which is unlikely to cause immediate
> fatal damage.
All the deer hunters I know use soft points. They like quick kills - makes
it easier to drag the critter home, you don't have to track it down, and
there is a lot less suffering involved. These bullets still go out the other
side, but they make a big exit wound and they make a real mess of the tissue
around the bullet path, you get massive internal damage. The quick kill
seems more important than the bullet turning prime cuts into meat only
suitable for hamburger. And yet, even with their lungs turned into pulp, the
deer sometimes run off down steep, slippery, rocky hills and die in the
middle of a manzanita patch.
> As for humans, if you hit them with a .308 Winchester,
> a 12 gauge slug, or such like, I can almost guarantee that they will
> be going down really fast and not getting up.
But the same argument can be made for nearly any large mammal I've heard of
people hunting - deer, elk, bear, wolves, lion, mountain lion, whatever.
Sometimes they drop immediately, sometimes they live for a minute or so even
on a direct chest hit. Deer are smaller than people (well, most deer are
smaller than most people). A given amount of tissue damage or blood loss
will be a bigger deal for a deer than a human. For big deer, the distance a
bullet would traverse going in one side and out the other is about the same
as the distance a bullet would traverse going in the front side of a small
person and out the back. Elk are bigger than people, you would get more
tissue damage from the bullet because it gets to traverse a larger distance.
Either way, they both can live for an annoyingly long time after getting
shot, as can all the other large mammals I've heard of people shooting. Why
would humans be any different?
Then there are the cases of police firing at dangerous felons (often on
drugs, admittedly) who take multiple shots from 12 gauge shotguns at close
range (plus multiple pistol bullets) and still keep going for a bit before
expiring (or at least until an officer gets a lucky shot to the spinal
column). It has been a while since hearing these reports, so I do not know
if the felon was shot with slugs or buckshot.
I have no doubt that anyone hit with a soft point round from a high powered
rifle or a shotgun slug will probably die well before they will ever get to a
hospital, it is just that, given these other data points, it seems unlikely
they will reliably die immediately. Even with complete circulatory failure,
people can continue to act for several seconds, you would need some mechanism
to reliably cause trauma to the brain or spinal cord to cause instant
incapacitation.
Luke
GrapeApe
wound in the process?
--cut and paste to adopt this sig file---
Make Deja a useful Usenet Archive again!
Ray Drouillard
"Christian Thalmann" <ci...@iname.com> wrote in message
news:3A5F3D3D...@iname.com...
That depends on a few factors. I'll start with the basic formula and work
from there.
E = .5 * C * V^2
E = energy (joules)
C = capacitence (farads)
V = voltage (volts)
The maximum (practical) voltage will be some fraction of the puncture
voltage of a layer of buckytube. Since we're only talking about a single
thickness of carbon atoms. In a practical design, you would go with
multiple layers.
The actual working voltage of the capacitor would probably be designed
somewhere in the 1000 to 10,000 volt range - depending on the voltage
required by the laser.
The puncture voltage goes up linearly with the plate separation (thickness
of the dielectric).
The capacitence goes down linearly with the plate separation.
The energy stored goes up with the square of the voltage (see the above
equation)
OTOH, there will be less plate area because there will be room for less
plates as you thicken the dielectric.
If I know the dielectric constant of buckytubes, and the separation between
layers, I can calculate the capacitence and working voltage of a given
design.
>
> What's their energy density as compared to other energy storage
> media?
>
> And just out of curiosity: Is it possible to explain the meaning
> of "doped" to a third-semester physics student without delving too
> deep into advanced knowledge? Does it mean "covered with a
> molecular-thin metal layer" or something?
Doping is a technique used in semiconductors. Pure silicon is an insulator
because all of its electrons are tied up in the crystal lattice (to simplify
it). The outer shell will hold eight electrons, but there are only four
electrons. The atoms "share" four others from their neighbors.
Carbon in a diamond, buckyball, or buckytube is in the same situation. All
electrons are tightly involved in the bonds, so the whole structure is an
insulator with a high puncture voltage.
If you replace some of the atoms with atoms that have either three or five
free electrons, there will be free electrons (if it's 5) or "holes" (if it's
3) in the structure. If there are extra electrons, it's refrred to as an
"n" type substance, and if there are holes, it is referred to as a "p" type
substance.
So there you have it - a quick lesson in semiconductore (with somewhat
sloppy terminology - which I'm sure that someone will correct).
>
>
> > With a little imagination, you can handwave lots of things, like nuclear
> > powered lasers (fission or fusion). In fact, someone actually made an
x-ray
> > laser that is powered by the fissioning of a thin layer of uranium or
> > plutonium (I forgot which). I remember reading about it years ago.
>
> High-energy density batteries seem unavoidable for a high-tech
> sci-fi setting, so I've made up the "matrix cell" a few years ago.
> Basically, it's a crystal structure that can be forced to switch
> into another crystal state with extremely low entropy. Due to the
> entropic gradient between the two states, it would require large
> amounts of energy to shift to the second state; energy which would
> be stored as an increase in mass.
>
> I have no idea whether this makes sense to a real physicist, and
> if so, of what order of magnitude the mass increase would be. Any
> ideas? Are energy densities one or two orders of magnitudes below
> nuclear fuels imaginable?
I have no ides... I'm just a humble EE :-)
Ray Drouillard
>
>
> -- Christian Thalmann
>
Charles R Martin
>
> Wouldn't a laser able to poke a hole through flesh be likely to cauterize that
> wound in the process?
>
I'd imagine so, but on the other hand having a 1 cm hole burned through your
torso would still kinda spoil your whole day.
Ray Drouillard
> safety hazard, since they could be jammed or even
> taken control of by the enemy.
There are techniques that would make it EXTREMELY difficult to jam the
communications - and even more difficult (essentially impossible) to
subvert.
There are encryption schemes that are totally secure (an electronic version
of the "tear off pad" method), and spread spectrum radio is really difficult
to jam effectively.
Ray Drouillard
Matthew DeBell
>
>What I imagine for the future of personal combat weapons is a gun
>that is fixed to a backpack frame or to a similar carrying device
>on the shoulders. It's got servo-motors and gyro-stabilizers and
>can acquire targets and perform different attack schemes (disable,
>disarm, snipe-kill, mass-kill etc.). The gunner wears a combat
>visor that can 1) display tactical information, 2) show zoomed
>video feed from the weapons targeting sensors, 3) display a thin
>glowing line showing the current line of fire from your weapon and
>4) track your eyeballs so you can use the focus of your eyes as a
>3D-cursor to designate targets.
The visor sounds great. The backpack/shoulder weapon mount might be a pain.
A significant disadvantage of having the firing mechanism attached to a
backpack or the shoulders is that the soldier has to expose his or her head
to enemy fire in order to shoot. The soldier can't shoot around corners or
from behind cover without adopting an awkward posture.
If you move the gun to a hand-held device with optics attached, and with a
data feed to your smart visor, then the shooter can reach around corners or
over a wall and fire from good cover while exposing only the weapon and his
or her hand.
--
Matthew DeBell
SF RPG www.vanguardgames.com
Mark Fergerson
>
> It was the Thu, 11 Jan 2001 13:47:41 -0700...
> ...and Charles R Martin <crma...@indra.com> wrote:
> > > Yes quite. I think the main reason why energy sidearms would
> > > be popular would be due to some stupdendous breakthrough in
> > > energy storage (i.e. batteries) that made it a lot easier
> > > (and cheaper) to use weapons powered by the super battery than
> > > to use other systems.
> >
> > Don't forget some of the other advantages laser weapons might have. One that
> > strikes me offhand is that (at least as a hand weapon) you just aim at what
> > you want to hit, no matter the range or relative motion. No "leading" the
> > target, no range adjustment on the sights, no "windage", and no recoil.
Range adjustment will be needed if focusing the beam is essential to
putting "light on target" in a particular weapon design, also human
eyes like some prefocusing in the sight picture. No such thing as an
infinite field of depth scope AFAIK.
> Diffraction and diffusion by passing through non-pure air of
> non-uniform temperature and density, however.
Hmm. Might be significant if beam wavelength isn't in the visible
range. Otherwise, beam will "see" same path as sightline. Also argues
favorably for boresighting laser somehow. But, those beamsplitters
etc. better exclude _all_ the beam energy from return sight path lest
backscatter (= "optical recoil"?) blind you.
> We handle four billion calls a year, for everyone from presidents and
> kings to the scum of the earth. So your call doesn't go through once
> in a while, or you get billed for a call or two you didn't make. We
> don't care. We don't have to, we're the phone company. -- Lily Tomlin
I hope the ignorant Liberal bitch is enjoying her six-page phone
bills. I largely blame her for the Bell breakup and _my_ six-page
phone bill.
OTOH Bell kept promising vidiphones "real soon now" for thirty years
and now I've got near thirty options for use with my computer that
don't use phone lines at all.
Don't mind me: just grousing about things SF authors didn't foresee
but _should have_.
Mark L. Fergerson
Don Middendorf
What about continous beam laser weapons? Like Nivens flashlight laser. A
continous beam hot enough to cause serious burns (not instantly fatal
mind you, just awful) would be a terrific suppresion and defence weapon,
which is what small arms are for currently anway. Defending your heavy
weapons and support so they can kill the bad guys. I'm not sure what the
future holds for those sort of systems, but I expect big changes.
Don Middendorf
Mark Lanett
news:93o5t6$56k$1...@spock.usc.edu...
> Erik Max Francis <m...@alcyone.com> writes:
> >Charles R Martin wrote:
>
> >> Rain, dust, smoke etc are significant impediments to using the usual
> >> bullets
> >> in combat as well.
>
> >To aiming, perhaps. The bullets go through rain, dust, and smoke just
> >fine. Lasers don't. Big difference.
>
> Lasers go through any rain, dust, or smoke that you can see through to
> aim in the first place. They do of course have problems with recon by
> fire and indirect fire, for those who favor such tactics.
They don't go through it as well as a bullet, though. If one can see a
target, dimly, through the rain and shoot at it with a bullet, that bullet
will do about as much damage as without any interfering rain, etc (assuming
one hits the target). The laser would be attenuated.
~mark
Charles R Martin
>
> Charles R Martin wrote:
> >
> > GrapeApe wrote:
> > >
> > > Wouldn't a laser able to poke a hole through flesh be likely to cauterize that
> > > wound in the process?
> > >
> >
> > I'd imagine so, but on the other hand having a 1 cm hole burned through your
> > torso would still kinda spoil your whole day.
>
> What about continous beam laser weapons?
Truthfully, I don't think the issue of burning a hole through someone is that
big of a deal. Back along this thread somewhere, someone was talking about
pulsed lasers and hydrostatic shock, and made the point that a plausible laser
pulse could liberate a number of Joules comparable in order of magnitude to 10
to 100 grams of dynamite. This may not have seemed important and I had to go
look it up because I haven't blown a stump in years -- but a standard 8-inch
stick of dynamite is .46 pounds, or about 208 g. I can *promise* you, having
a half-stick of dynamite go off in your vest pocket would be *very* convincing
if you were trying to argue that the affected party should lie down and play
dead. You would at the very least be looking at a flail chest and a ruptured
spleen....
> ... Like Nivens flashlight laser. A
> continous beam hot enough to cause serious burns (not instantly fatal
> mind you, just awful) would be a terrific suppresion and defence weapon,
> which is what small arms are for currently anway.
Similarly, if you can keep up suppressing fire with something that simulates
100 g of dynamite going off on whatever it hits (including *behind* the black
hats if you want) I think you'd have a very convincing argument indeed.
> Defending your heavy
> weapons and support so they can kill the bad guys. I'm not sure what the
> future holds for those sort of systems, but I expect big changes.
It's kind of off the subject, but have you-all seen the stuff about the Army
Advanced Infantry Weapon (Advanced Combat Rifle, Objective Individual Combat
Weapon, it seems to go through a lot of program name changes)? Here's the
first thing I found on it, not all *that* informative, but this is one of
those areas in which real information is so thoroughly buried in @%^#@ gaming
fiction that I had very little luck with a search....
Charles R Martin
>
> Matthias Warkus wrote:
> >
> > It was the Thu, 11 Jan 2001 13:47:41 -0700...
> > ...and Charles R Martin <crma...@indra.com> wrote:
> > > > Yes quite. I think the main reason why energy sidearms would
> > > > be popular would be due to some stupdendous breakthrough in
> > > > energy storage (i.e. batteries) that made it a lot easier
> > > > (and cheaper) to use weapons powered by the super battery than
> > > > to use other systems.
> > >
> > > Don't forget some of the other advantages laser weapons might have. One that
> > > strikes me offhand is that (at least as a hand weapon) you just aim at what
> > > you want to hit, no matter the range or relative motion. No "leading" the
> > > target, no range adjustment on the sights, no "windage", and no recoil.
>
> Range adjustment will be needed if focusing the beam is essential to
> putting "light on target" in a particular weapon design, also human
> eyes like some prefocusing in the sight picture. No such thing as an
> infinite field of depth scope AFAIK.
Focus adjustment I assume would either be more or less automatic (radar, laser
ranging, something) or would be fixed with some "effective range" through
which the focus is good enough.
Your point about the sights, and wanting a prefocus, is somewhat mistaken, I
think. The eye is pretty much focussed at infinity past about 25 feet (mine
are increasingly pretty much focussed at infinity whether I like it or not!)
so past that distance naked-eye you do have more or less infinite depth of
field. And while you're absolutely right about the scope -- well, a scope is
something for a specialized sniper's weapon anyway. The usual infantry
trooper uses the iron sights if they use the sights at all, because they can't
afford the time to get set up and use the scope (including getting the eye in
the right place, getting the focus, and so forth.) My point was that you
don't have to put up the iron sight and then raise the back end up three
inches to account for the bulllet's drop over the 400 yds to the target.
Charles R Martin
On the issue of power supplies, I just found this on the National Academy
Press site:
http://books.nap.edu/books/0309059348/html/index.html
Title is "Energy Efficient Technologies for the Dismounted Soldier".
(By the way, whoever it was who pointed out another book on this site:
Thanks. I think. :-)
George William Herbert
>200 food calories = 200 Cal = 200 kcal = 840 kJ. Never underestimate
>the power of cheese.
I don't think anyone has practically gotten Cheese to release energy
at a dangerous rate. However, LOX and Bagels are in fact a lethally
dangerous combination...
-george william herbert
gher...@retro.com
George William Herbert
>"John Schilling" <schi...@spock.usc.edu> wrote:
>> Erik Max Francis <m...@alcyone.com> writes:
>> >Charles R Martin wrote:
>> >> Rain, dust, smoke etc are significant impediments to using the usual
>> >> bullets
>> >> in combat as well.
>> >To aiming, perhaps. The bullets go through rain, dust, and smoke just
>> >fine. Lasers don't. Big difference.
>> Lasers go through any rain, dust, or smoke that you can see through to
>> aim in the first place. They do of course have problems with recon by
>> fire and indirect fire, for those who favor such tactics.
>They don't go through it as well as a bullet, though. If one can see a
>target, dimly, through the rain and shoot at it with a bullet, that bullet
>will do about as much damage as without any interfering rain, etc (assuming
>one hits the target). The laser would be attenuated.
I should point out that targeting is improving rapidly.
Right now, modern western battle tanks can see in the dark,
dust, smoke etc. almost as well as in clear daytime conditions
(and for some scenarios, more clearly... i.e., tanks are warm
and stand out at night on thermal sights...). These are not
all that much better than the Gen III thermal sights available
today for rifle sized weapons.
All weather radar systems small enough to fit on a tank have
existed for some time now. Man portable radar systems are also
coming into use, mostly for shorter range applications but no doubt
the technology will improve over time.
-george william herbert
gher...@retro.com
Timothy Little
>The puncture voltage goes up linearly with the plate separation (thickness
>of the dielectric).
>
>The capacitence goes down linearly with the plate separation.
>
>The energy stored goes up with the square of the voltage (see the above
>equation)
>
>OTOH, there will be less plate area because there will be room for less
>plates as you thicken the dielectric.
If the "plates" are of negligible volume, then this is linear in
dialectric thickness too. So overall energy storage is roughly
independent of plate separation.
Not surprising if you think about it in terms of a constant breakdown
field strength rather than varying breakdown voltage. The energy is
essentially contained in the dielectric, with a maximum energy per
unit volume that depends mostly upon its properties.
(Once again, it is limited by chemical properties)
In response to the original question, an ideal capacitor could hold
its charge forever. In practice, there is always some small amount of
leakage, and you also don't want to short one out accidentally. I
don't think using any capacitor for long-term energy storage is a good
idea.
- Tim
Timothy Little
>Wouldn't a laser able to poke a hole through flesh be likely to
>cauterize that wound in the process?
A continuous beam probably would, but not a pulsed laser. Each pulse
vaporises a tiny amount of flesh, but most of the damage would be done
to surrounding tissue by the resulting "explosion".
That's why I think pulsed lasers are more likely (though still not
very likely, I must admit). It takes a lot less energy to tear flesh
than to burn it.
- Tim
Ray Drouillard
> its charge forever. In practice, there is always some small amount of
> leakage, and you also don't want to short one out accidentally. I
> don't think using any capacitor for long-term energy storage is a good
> idea.
You could probably make it at least as safe as storing energy in gunpowder
or gasoline.
Ray
John Park
>[...]
> seems to be largely inconsequential except possibly to the head, where
> overpressure _might_ be able to burst the skull. Shock waves in the
> weak shock limit will only cause damage at interfaces of different
> densities (strong shocks cause shock heating - bullets do not cook
> tissue near them, so the bullet must be well outside of the strong shock
> limit) . Although they may cause some tearing at muscle/bone
> interfaces, the primary areas where shocks will cause damage are in
> rupturing the bowels (which have pockets of gas in them) and rupturing
> the lungs (which are chock full of tissue/gas interfaces). Although
> these tissues can be damaged by explosive produced shocks, the more
> localized effects of bullet produced shocks do not seem to be
> significant. This is probably due, in large part, to the low density
> and highly inhomogeneous nature of the lungs.
>
been addressed explicitly). How wide is the gap between the strong and weak
shock limits, and what happens in it? What would be the effects of
"intermediate" shock on, say, the spinal cord?
--John Park
Christian Thalmann
> If I know the dielectric constant of buckytubes, and the separation between
> layers, I can calculate the capacitence and working voltage of a given
> design.
Any educated numeric guesses? ;-)
-- Christian Thalmann
Matthew DeBell
>Matthew DeBell <m...@attglobal.net> wrote:
>>>i.e. it tears or breaks.
>>
>>Maybe so. How does one figure the effects of the vapor expansion?
>
>Come on, you already know the answer to that question!
>"With difficulty" :)
> [helpful details cut]
Indeed!
MD
John Kensmark
>
> Isaac Kuo wrote:
>> Make it a semi-autonomous remote control robot "soldier",
>> that patrols with the operator like a faithful guard dog.
>> If you want to go "over the top", just send the robot and
>> leave the operator safely cowering in the trench!
>
> Remote-controlled intelligent weapons are always a
> safety hazard, since they could be jammed or even
> taken control of by the enemy.
I'd just like to point out that virtually every sizeable military on
the planet *currently* uses remote-controlled intelligent weapons
called "soldiers".
Further, note that machines that do the jobs of people generally do
them more reliably. They tend to be less adaptive and flexible, but
more consistent. Whether or not automated-soldier sorts of weapons
are practical or not depends in large part on how sophisticated
their AI is.
--
John Kensmark kensmark#hotmail.com
Abash'd the devil stood,
And felt how awful goodness is, and saw
Virtue in her shape how lovely.
-- John Milton
Leonard Erickson
>
> Of course, such a weapon would be impractical for use as a
> personal protection gun in civilian settings. Deadly weapons
> might be outlawed for civilians anyway if non-lethal stunners
> like the very promising-sounding APBW project by HSV technology
> reach the market. Their stunner uses UV-lasers to ionize twin
> paths of oxygen plasma as a conductor for a tetanizing or stunning
> electric shock.
>
> Check out their homepage at www.hsvt.org.
Consider what a chainmail shirt over a kevlar vest would do to this
weapon...
Also consider that those UV beams would be almost guaranteed to do
*serious* damage to the eye. And that a head shot could be fatal.
For that matter, even a *perfect* "stunner" type weapon is capable pf
major abuse. Either stun the person at an inconvenient moment (say at
the top of a flight of stairs), or just get them more or less alone,
stun them, then beat them to death.
Also, a stunner is likely to be a *lousy* choice for personal
protection. Someone who'd back down from a knife or gun (or even fists)
may just decide to take a chance on being able to close with you before
you can hit him with a shot.
--
Leonard Erickson (aka Shadow)
sha...@krypton.rain.com <--preferred
leo...@qiclab.scn.rain.com <--last resort
Leonard Erickson
>
> It is not out of the question that rearranging the electrode configuration
> of relatively conventional batteries would allow you to extract their stored
> energy fast enough to serve as the prime power source for a useful weapon.
> There have been labratory experiments which demonstrated the requisite power
> density and discharge time, though they are a long way from producing a
> useful product.
>
> Oh, and if they ever start selling *those* batteries at your local hardware
> store, it would be Really Bad to accidentally short-circuit one.
It's not particularly wise to short circuit nicads as it is. I once
accidentally shorted a 15 volt nicad pack (made up from AA cells!) and
before I had a chance to do anything the insulation *boiled* off the
leads I had attached, and the bare wires were glowing *yellow*.
I managed to use something to knock the (remains) of the leads apart.
Nicads will throw *insane* amounts of current into a dead short.
I don't want to know what the batteries you describe would do.
Leonard Erickson
> Also, there are other ways than electricity to create a
> laser beam. You could use a chemical powered laser. The
> energy for the laser is provided by a chemical reaction
> that occurs in the lasing medium. Basically, you have a
> "cartridge" that you "burn" to create the laser beam, then
> you use a new cartridge. One popular chemical laser is
> Hydrogen Flouride. This is probably the best way to
> achieve high power laser beams in a man portable system.
Not if you want your troops to survive firing them!
I suggest you look up the handling and toxicity figures for both
fluorine and hydrogen fluoride.
The "exhaust" from those cartridges would require full chemical
protection gear. And if the fluorine leaked, it'd eat a hole in *that*.
Leonard Erickson
>
> Nyrath the nearly wise wrote:
> >
> > "Christopher M. Jones" wrote:
> >
> > armed with Hydrogen Fluoride powered lasers.
> > They vent their exhaust around the base of the pillbox in order
> > to provide a rude surprise to any enemy soldiers who have bright
> > ideas about sneaking up to it.
> >
> > Our Hero tried it, but he was good as new after they put
> > the corroded remains of his body into the regeneration vat.
>
> Um, it's not as easy as that ... did you see the ER episode where the guy has
> gotten HF burns over a good bit of his body? The problem is that HF is also a
> toxin as well as corrosive (I don't recall the exact mechanism, but it *might*
> have been that the F replaces something physiologically important like
> calcium) so the guy is doomed in a fairly short time even though he got quick
> treatment.
I used to work around the stuff. The dilute HF we used wouldn't give
"prompt" chemical burns (as I recall), but you did need to get treated.
And the treatment included something to try to keep it from latching
onto the calcium in your bones.
I do know that a couple people who got minor splashes *did* return to
work after treatment.
Of course *gaseous* HF would be a real nightmare.
Leonard Erickson
>
> Winchell Chung wrote in message <3A5D160F...@projectrho.com>...
> >I would like some help in shining the harsh light of reality
> >on one of the most cherished items in space opera: the Laser Sidearm.
> >
> >Specifically, how ludicrous are the requirements for the
> >batteries powering the blasted thing.
>
> Not particularly ludicrous. The energy density I expect you'd want exceeds
> the capacity of current battery technology, but the energy density of, say,
> TNT would work fine. If you settle for a low-power laser, current batteries
> might work.
>
> You mentioned a delivered energy of 1kJ, so for now let's say that's the
> required delivered energy. If the laser is 33% efficient and you want 10
> shots, then your power pack must hold 30kJ. If the weapon is to be a
> practical sidearm then the power pack shouldn't mass more than about .5kg,
> preferably less. If that's the mass then the energy density is 60kJ/kg. If
> the power pack masses a more convenient 100g, then the energy density is
> 300kJ/kg. That's in the ballpark of what should be possible with current
> batteries. The battery for my laptop computer holds about 45 Watt/hours
> (i.e. 160kJ), and although I don't have a scale handy I'd guess it's about
> .5kg, so it would work fine for this laser.
>
> But 1kJ of delivered energy may be on the low side; see below.
>
> >Offhand, it would seem that it is far more efficient to use
> >an ancient Colt .45 chemically fueled bullet instead of a laser
> >pistol to drill a hole in a hapless target.
>
> In terms of energy efficiency it probably is. However, the laser is
> recoilless and perfectly accurate.
>
> >Say that the laser has ten shots worth of energy in the
> >battery. Say each shot is capable of doing quote significant
> >unquote damage to a human target. Say the laser has
> >an efficiency in the neighborhood of the best efficiencies
> >we can manage with current technology (free electron laser
> >or whatever).
> >
> >How much energy will the battery be required to store?
> >Just a back of the envelope, order of magnitude estimate.
> >
> >This will, of course, depend upon the definition of
> >"significant damage", which I have no idea of how to
> >quantify.
> >John Schilling stated the opinion that a bit over one kilojoule
> >will be required to reliably incapacitate a human target.
> >(divided into ~1 joule pulses at ~5 microsecond intervals)
>
> A laser would cause damage by burning or vaporizing tissue. There are a
> couple of wound mechanisms. One is that it simply burns a hole and that it
> acheives depth of penetration using a pulsed beam. The second is that when
> tissue is suddenly turned to gas (or plasma), that gas expands at high
> pressure and causes damage to surrounding tissue. I'm not qualified to
> remark on the gas/plasma expansion, but if we consider the energy required
> for hole-burning, 1kJ seems too low.
It doesn't "expand at high pressure". It vaporizes *explosively*.
Rate of energy transfer is *very* important when dealing with pulse
lasers. the 1 kJ is applied over a *nanosecond* level timescale. That
means the average power is on the order of gigawatts to terawatts.
At the sort of energy density involved, you'd better believe the energy
is applied as a high energy explosion.
> The average specific heat of the human body is 3470 J/kg per degree C.
> Thus, 1000J could vaporize .0046 kg of tissue (4-5cc). As bullet wounds go
> that's not particularly large. It could easily be lethal, but it's probably
> not enough for reliable prompt incapacitiation.
But it is actually applying the energy to a cylinder as wide as the spot
size and an mm or so deep (optical depth of the tissue). Call it 50
mm^3. That's about 50 milligrams of tissue. For an energy density of 20
MJ/kg.
That's going to be a rather impressive explosion. :-)
> For a ballpark estimate of the energy required for an effective weapon, we
> can begin by figuring the amount of energy required to vaporize 'enough'
> tissue to cause prompt incapacitation. Terminal ballistics experts suggest
> that a bullet should be able to penetrate about a foot of tissue to be a
> reliable defense weapon. If we want the laser to vaporize an amount of
> tissue equal to that destroyed by effective bullets, then it should be able
> to destroy a track about 10mm in diameter and 300mm deep, or about 30cc.
Sorry, but that's a completely inappropriate way to calculate it,
because it assumes the wrong transfer mechanism.
> If we take the specific heat of tissue as 3.47J/cc/degree C, and tissue
> starts at 37 and vaporizes at 100, then vaporizing 30cc of tissue takes at
> least 6600 J. Adjust that upward by a factor of 2 to allow for energy
> wasted in over-heating or dissipated in surrounding tissue, and another
> factor of 3 for the weapon's inefficiency in converting electricity into
> coherent light, and we have a power requirement for each shot of about 40kJ.
> My computer battery would be good for 4 shots if it could deliver the energy
> fast enough (which it can't).
And this is wrong as well. There is no dissispation in surrounding
tissue, because the time scale doesn't allow it. And what you are
considering "overheating" is in fact the main damage mechanism. You dump
so much energy into the tissue so fast that the tissue converts
*explosively* into a plasma. With a higher kJ/kg than TNT!
> (The validity of this whole example depends on the assumption that the wound
> mechanism is vaporizing a deep hole in the target. This clashes with
> assumptions about rapidly expanding gas/plasma, but I'll have to leave
> evaluation of that mechanism to others.)
Again, just examine the physics. The energy is delivers in a sub
microsecond duration (possible in the low nanosecond range) pulse of
energy. The energy is applied to the tissue across the illuminated spot
and to the depth that the light can penetrate before being absorbed (a
few mm at best). *All* of the energy goes into that small amount of
tissue.
Figure out what temperature that bit of tissue reaches. And what sort of
pressures it'll hit.
As I said above, the result is going to be like setting off a blasting
cap. It'll make a nice hole.
Charles R Martin
>
> Charles R Martin wrote:
> >
> > Nyrath the nearly wise wrote:
> > >
> > > "Christopher M. Jones" wrote:
> > > > One popular chemical laser is Hydrogen Flouride.
> > >
> > > In the novel THE SPACE EATER, the army has pillbox emplacements
> > > armed with Hydrogen Fluoride powered lasers.
> > > They vent their exhaust around the base of the pillbox in order
> > > to provide a rude surprise to any enemy soldiers who have bright
> > > ideas about sneaking up to it.
> > >
> > > Our Hero tried it, but he was good as new after they put
> > > the corroded remains of his body into the regeneration vat.
> >
> > Um, it's not as easy as that ... did you see the ER episode where the guy has
> > gotten HF burns over a good bit of his body? The problem is that HF is also a
> > toxin as well as corrosive (I don't recall the exact mechanism, but it *might*
> > have been that the F replaces something physiologically important like
> > calcium) so the guy is doomed in a fairly short time even though he got quick
> > treatment.
>
> I used to work around the stuff. The dilute HF we used wouldn't give
> "prompt" chemical burns (as I recall), but you did need to get treated.
> And the treatment included something to try to keep it from latching
> onto the calcium in your bones.
>
> I do know that a couple people who got minor splashes *did* return to
> work after treatment.
Oh, yeah, I don't mean that HF is instantly and permanently fatal in small
doses... this character in ER had like 75 percent burns.
(Dramatically it weas great -- the guy wasn't in too bad of shape, not tons of
apin, conscious ... and had something like 36 hours to live.)
Charles R Martin
>
[bank]
> Figure out what temperature that bit of tissue reaches. And what sort of
> pressures it'll hit.
>
> As I said above, the result is going to be like setting off a blasting
> cap. It'll make a nice hole.
More than a blasting cap -- it'd take a stump out real nice.
Christian Thalmann
>
> Christian Thalmann wrote:
> >
> > Check out their homepage at www.hsvt.org.
>
> Consider what a chainmail shirt over a kevlar vest would do to this
> weapon...
So what? Such armament would also stop regular weapons.
> Also consider that those UV beams would be almost guaranteed to do
> *serious* damage to the eye.
Wrong. Read the HSVT's FAQ about "Ocular Safety".
> And that a head shot could be fatal.
Wrong again. You really should have a look at that FAQ.
> For that matter, even a *perfect* "stunner" type weapon is capable pf
> major abuse. Either stun the person at an inconvenient moment (say at
> the top of a flight of stairs),
Yep, that's a problem, especially if you use the tetanizing
function rather than the stunner. It freezes your muscles, but
keeps you at full consciousness. =\
I actually sent HSVT a mail concerning this.
> or just get them more or less alone,
> stun them, then beat them to death.
You might as well shoot them. Guns and bullets are a lot
cheaper than UV lasers.
> Also, a stunner is likely to be a *lousy* choice for personal
> protection. Someone who'd back down from a knife or gun (or even fists)
> may just decide to take a chance on being able to close with you before
> you can hit him with a shot.
On the other hand, you can fire a stunner with much less scruples
and at a much lower earlier threat level due to the fact that it
doesn't do permanent damage. More effective than a pepper spray,
and with less legal consequences.
-- Christian Thalmann
Timothy Little
> As I said above, the result is going to be like setting off a blasting
> cap. It'll make a nice hole.
A very tiny blasting cap, but yes. Then at the bottom of the hole
that one makes(*), you set off another one. And then another, until
you get about 30cm deep.
(*) Well, actually while it's still in the process of making the hole,
but that's just being nitpicky.
- Tim
George William Herbert
>It's not particularly wise to short circuit nicads as it is. I once
>accidentally shorted a 15 volt nicad pack (made up from AA cells!) and
>before I had a chance to do anything the insulation *boiled* off the
>leads I had attached, and the bare wires were glowing *yellow*.
>I managed to use something to knock the (remains) of the leads apart.
>Nicads will throw *insane* amounts of current into a dead short.
>I don't want to know what the batteries you describe would do.
I accidentally arc welded with a 12-pack of D-cell Ni-Cad batteries.
If you could figure out how to keep them from overheating and blowing
up they'd make a nifty portable emergency welder.
-george william herbert
gher...@retro.com
John DiFool
>
> Then there are the cases of police firing at dangerous felons (often on
> drugs, admittedly) who take multiple shots from 12 gauge shotguns at close
> range (plus multiple pistol bullets) and still keep going for a bit before
> expiring (or at least until an officer gets a lucky shot to the spinal
> column). It has been a while since hearing these reports, so I do not know
> if the felon was shot with slugs or buckshot.
(getting back on-topic-this is a SF group after all...)...this also touches
on
those SF/horror shows where zombies/vampires wade into vicious hails of
gunfire, and just keep on lurching towards you (unless of course you get
in some head shots). Sure, perhaps perforating their livers or lungs doesn't
slow them down much, but shattering their spines or other >mechanical<
parts of their body (ligaments/bones in their legs etc.) sure as hell will...
John DiFool
Earl Colby Pottinger
Personally, I think you have all talked yourselves into tight corners by only
thinking in terms of a chemical battery to power a handheld laser. Thaere
are a number of other choices available with a little engineering.
First, think in terms of a gun that weighs more than a 750 grams, while a
heavy you gain the freedom needed to break open some ideas: Example :-
1) FlyWheel/Capacitor - In the handle is a high speed flywheel (probably two
counter-rotating ones) that when you release the safety lever charge up a
cap. good for one or two shots. While there may be a limit on rapid fire,
anyone want to work out how
many joules a one kilogram, carbon fiber (bucky tubes?) can hold?
2) HomoPolar Generator - Same idea as above, but now the flywheel is the
generator. A simpler design, but you will not be able to extract as much
energy. Still you now can pull even more power per pulse if needed.
3) Pulse MHD - First, I don't know that you can build a MHD unit this small,
but if yes, a small explosion vented out a MHD would supply the power needed
for the laser - Vent out of two MHDs facing 180 degrees from each other and
you have taken care of most of the recoil.
4) Moving Slugs - Use the explosion to move two metal slugs (magnets?) and
use thier movement to feed power into coils or pickup power from the slugs if
they are in magnetic field.
5) Fast Tickle charge generators - A small generator and engine that charges
a cap to the power needed per pulse.
Notice I am assuming liquid fuels and oxiders to make the most use of the
volume of the handle.
Earl Colby Pottinger
--
Hydrogen Peroxide Rockets, BePrint, BePrinter, RAMDISK, Cabin Raising,
Camping, BoatBuilding, Girlfriend. What happened to the time?
http://webhome.idirect.com/~earlcp
Ray Drouillard
> Rate of energy transfer is *very* important when dealing with pulse
> lasers. the 1 kJ is applied over a *nanosecond* level timescale. That
> means the average power is on the order of gigawatts to terawatts.
1 kJ / 1 nS = 10^3 J / 10^9 S = 10^12 watts
1 terawatt
Matthew DeBell
>Matthew DeBell wrote:
>> A laser would cause damage by burning or vaporizing tissue. There are a
>> couple of wound mechanisms. One is that it simply burns a hole and that
it
>> acheives depth of penetration using a pulsed beam. The second is that
when
>> tissue is suddenly turned to gas (or plasma), that gas expands at high
>> pressure and causes damage to surrounding tissue. I'm not qualified to
>> remark on the gas/plasma expansion, but if we consider the energy
required
>> for hole-burning, 1kJ seems too low.
>
>It doesn't "expand at high pressure". It vaporizes *explosively*.
Ok, but that's what an explosion is, so the difference is rhetorical.
>> The average specific heat of the human body is 3470 J/kg per degree C.
>> Thus, 1000J could vaporize .0046 kg of tissue (4-5cc). As bullet wounds
go
>> that's not particularly large. It could easily be lethal, but it's
probably
>> not enough for reliable prompt incapacitiation.
>
>But it is actually applying the energy to a cylinder as wide as the spot
>size and an mm or so deep (optical depth of the tissue). Call it 50
>mm^3. That's about 50 milligrams of tissue. For an energy density of 20
>MJ/kg.
>
>That's going to be a rather impressive explosion. :-)
I'll buy that.
--
Matthew DeBell
pervect
"David McKee" <dmc...@cebaf.gov> wrote in message
news:93lajl$mip$1...@inn.jlab.org...
> Thankfully it didn't short through me. I imagine that that would be a
> Bad Thing (tm).
Your skin is a poor enough conductor that 12 volts (for example) just won't
generate a significant current. You are not in danger of electrocuting
yourself with a 12 volt car battery, for instance. You can safely touch
both terminals at the same time. However, do NOT drop a wrench across the
terminals of a car battery - it might melt.
Isaac Kuo
>Personally, I think you have all talked yourselves
>into tight corners by only thinking in terms of a
>chemical battery to power a handheld laser. Thaere
>are a number of other choices available with a
>little engineering.
Yes, there has been relatively little variety in
the power sources proposed.
>First, think in terms of a gun that weighs more than
>a 750 grams, while a heavy you gain the freedom
>needed to break open some ideas: Example :-
>1) FlyWheel/Capacitor - In the handle is a high speed flywheel
(probably two
>counter-rotating ones) that when you release the safety lever charge
up a
>cap. good for one or two shots.
Counter-rotating flywheels induce high stresses on the shared
axle when the axle is rotated (or high stresses on whatever
is connecting the two axles if not shared). The only really
practical notion is that of a gymbal.
This gymbal need not necessarily have full freedom. For
example, the flywheels's axis of rotation could be vertical,
with a single gymbal joint to allow the gun to be pointed
up/down. This gun would aim in any direction like a turret,
but not be able to easily be "rolled".
Counterrotating flywheels are still desirable, though. If
they aren't counterrotating, then the process of drawing
energy from a flywheel will tend to rotate the gun in
the opposite direction of its rotation (affecting aim).
To minimize the effect on aim, the counterrotating
flywheels should be on a shared axis along with a freely
rotating generator (or the generator should be integral
to the flywheels).
One interesting possibility is to use the flywheels and
the gymbal to actively aim the gun. Apply a little
brake to one flywheel, and you aim the gun horizontally.
Motorize the gymbal and you aim the gun vertically.
This gun doesn't actually need someone holding it in
order to aim in any direction!
>While there may be a limit on rapid fire,
>anyone want to work out how
>many joules a one kilogram, carbon fiber (bucky tubes?) can hold?
The amount of energy storage possible depends upon its
geometry. For a given mass, you want the flywheel to
have a big radius, but you can't make the radius
unlimited because of strength limitations. Generally,
though, you want the flywheel to be big.
Intuitively, though, the flywheels would only be good
for one or maybe two shots. Thus, it's useful only
as temporary intermetiate storage of energy. There's
no point to have both flywheels and capacitors.
>2) HomoPolar Generator - Same idea as above, but now the
>flywheel is the generator. A simpler design, but you
>will not be able to extract as much energy. Still you
>now can pull even more power per pulse if needed.
If you're going to use flywheels at all, you're doing
it to use a homopolar generator, probably.
>3) Pulse MHD - First, I don't know that you can build
>a MHD unit this small, but if yes, a small explosion
>vented out a MHD would supply the power needed for the
>laser - Vent out of two MHDs facing 180 degrees from
>each other and you have taken care of most of the recoil.
Having a rearward going backblast is probably more
annoying than having a little recoil. Among current
small arms, the only recoilless rifles we use are
"bazookas" which launch really heavy projectiles
which otherwise would tear the user's shoulder off.
I don't know how well a small MHD would work, but
I suspect your moving slug idea is more practical.
A small MHD would waste a lot of energy just getting
the gas hot enough to conduct electricity.
>4) Moving Slugs - Use the explosion to move two
>metal slugs (magnets?) and use thier movement to
>feed power into coils or pickup power from the slugs if
>they are in magnetic field.
I don't know if this is the name for this, but
surely a "linear homopolar generator" can be
devised to quickly draw the energy from a gas
driven slug. If not, there are a number of ways
to use an explosive charge to drive a wheel into
rotational motion.
>5) Fast Tickle charge generators - A small generator
>and engine that charges a cap to the power needed
>per pulse.
This can be much simpler and more robust than a
flywheel system, but presumably it's also heavier.
Otherwise, proposed rail gun tank designs would
use capacitors rather than a flywheel. Capacitors
have a lot of advantages like being able to be
distributed in almost any form factor and being
useful as armor to some extent. They could be
effective as a middle layer of composite armor.
>Notice I am assuming liquid fuels and oxiders to
>make the most use of the volume of the handle.
--
_____ Isaac Kuo mec...@yahoo.com ICQ 29055726
__|_)o(_|__
/___________\
\=\)-----(/=/
Sent via Deja.com
http://www.deja.com/
Christopher M. Jones
> Re: Laser pistol Non Battery power source.
>
> Personally, I think you have all talked yourselves into tight corners by
only
> thinking in terms of a chemical battery to power a handheld laser. Thaere
> are a number of other choices available with a little engineering.
Well, I never assumed that. There are many problems with
alternatives to conventional batteries, however most of these
are mainly due to technological immaturity.
Nevertheless, many concepts have severe intrinsic problems.
For example, flywheels have problems with size and safety.
Creating a flywheel capable of holding enough energy to
power a laser that can do significant damage to a human body
is very difficult, especially since you have to factor in
laser efficiency and you probably want more than one shot.
Merely creating the material for the flywheel that is strong
enough to do that is a challenge, let alone the mounting and
the charge / discharge systems. Certainly we can expect
techological progress to increase the utility and decrease
the dangers and drawbacks of such a design but no matter how
you slice it it's still a fairly difficult proposition.
One idea I put out was storing energy in a superconducting
loop. Since there is zero resitance in a superconductor
you can send electrons around a loop essentially infinitely.
Modern devices that do this can store several megaJoules,
although they are distinctly not suitable for hand held
operation. However, assuming really super duper high
temperature super conductors (which may be too much to ask)
it might be possible to make something small enough to
power a "ray gun".
Another possibility is to store energy in excited nuclear
states. This isn't nuclear fission, basically you have
some isotope and you put the nucleus into an excited state.
The excited nucleus will then decay over a period of time
into the lower energy state and release a photon (usually
a gamma ray). You can also force the nucleus to decay by
hitting it with a lower energy photon (which "bumps" it
out of the excited state). What you want is an excited
state that has a long lifetime and that stores a lot of
energy. For example, an "isomer" of Hafnium-178 has a
lifetime of about 30 years, can be triggered by X-Rays, and
"stores" about 2.5 MeV in the excited state. That
corresponds to around 1 gigaJoule of energy per gram at
"100% saturation". Of course, it's unlikely that such
high efficiency could be achieved, but with even a
fraction of that you get some serious bang for you buck.
--
By the pricking of my thumbs,
Something wicked this way comes.
Steven Rogers
the invading aliens used weapons that launched what were essentially bolts of
super charged Ball Lightening. Is this actually feasible as a weapon inspace?
What kind of power levels in the projectile and what "muzzle velocities" would
we be practical?
Steve
Yoicks! And Away!
Luke Campbell
Unfortunately, my acoustics book is at home. Basically, shock waves are a
discontinuous boundary between unshocked matter and shocked matter, the latter
of which has a different density, pressure, temperature, and velocity than the
unshocked stuff. All shock waves heat the matter they pass through, the cutoff
between week and strong shocks (from my text, anyway) depends on how well the
shock discontinuity satisfies certain approximations. Stronger shocks loose
their energy more rapidly than the approximations would indicate, and thus heat
the matter they pass through more. For wounding mechanisms, the question
becomes is the shock strong enough to damage tissue through thermal effects? I
do not believe shocks in the weak shock limit can do this.
There may be other damage mechanisms that can operate when shocks are stronger
that the limit which ruptures lung tissue but weaker than the limit where
tissue is cooked. Some research into tenderizing meat on an industrial scale
has shown that shock waves can rupture enough muscle tissue to make a steak
much more enjoyable. These "intermediate" shocks might be able to crush
relatively homogenious tissues as well as ripping tissues at interfaces between
tissues of different densities.
> What would be the effects of
> "intermediate" shock on, say, the spinal cord?
I suspect that if crushing effects are signifcant, the forces at interfaces
will be so severe that survival is impossible anyway, but I truthfully do not
know. In any event, every interface between different tissues in the spinal
cord would experience severe stresses, tearing muscles and tendons from bone,
separating vertebrae from the cushioning cartilage disks, and separating the
nerve tissue from everything else. The bone vertebrae may spall off fragments
of bone when the release wave hits (the wave that relieves the increased
pressure caused by the shock wave), which would send these bone fragments
through the surrounding tissue. On top of this, muscle, bone, nerve tissue,
ligaments, and cartilage may be crushed. It would be pretty nasty.
Luke
Luke Campbell
energy of the excimer molecule (small effect), the repulsive energy of the
unexcited noble gas and the halogen atom (small effect) and the energy required to
break the halogen-halogen chemical bond (big effect). The efficiency of excimers
is still quite good compared to chemical and solid state lasers, but probably will
not be close to 100%.
Luke Campbell wrote:
> John Schilling wrote:
>
> > Luke Campbell <lwc...@u.washington.edu> writes:
> >
> > >Any reason why you do not expect excimers to be compact laser handguns?
> > >They seem to be able to make fairly high powered pulsed excimers which
> > >are highly efficient (similar to those of YAG, diode, and CO2 lasers).
> >
> > But rather more complex, and with no compelling advantage over diode
> > pumped crystal lasers that I can see. It's possibility, but not one
> > I would bet on.
>
> Just remembered this one - a possibly compelling advantage of excimers is that
> they have a 100% quantum efficiency (or close to it, anyway) - all the energy
> that goes into putting the halogen and noble gas into an excited state is
> returned as a UV photon. Any losses in energy are due to other mechanisms (like
> inefficiency in getting the excited halogen-noble gas molecule). I can't find
> my class notes, but the quantum efficiency for neodymnium lasers is somewhere
> between 20 to 40%. if I recall correctly. This means that in principle you
> could get very high efficiency excimers, which means a lot less heat to get rid
> of and less weight to pack around in your batteries.
>
> Luke