How obvious is weapons-grade laser fire?
George Herbert
>Basically, my question is pretty much what the title says. I've been
>reading some SF lately with descriptions of laser weapons (handguns,
>mostly) firing, and I've seen widely varying ideas of how such fire
>would look, sound, smell, etc. I'd like to know what folks reading this
>list think (there seem to be some pretty well informed people around
>here). If someone fired, say, a 500 kJ, 0.01 second laser through
>Earth-normal atmosphere, what sort of effects would this produce?
>Unless there's mist or smoke, the beam itself shouldn't be visible,
>right? But what about the smell of ionization, or a clap from
>superheated air expanding out? Would a laser of this sort actually
>sizzle a person who got hit, or would the person possibly not notice and
>keep going until they noticed their hand or whatever had fallen off (as
>many SF stories would have it)? I've even heard some authors say that
>weapons-grade laser fire would superheat flesh so quickly that it would
>explode due to steam pressure. Is this possible?
It depends on the laser.
Sufficiently powerful lasers will ionize the air even if there
isn't any dust or smoke or fog. That will give you a bright
line and loud bang. That's more powerful than what seems to
be proposed for weapons lasers though.
Moderately powerful lasers operating in frequencies other
than the visible still heat to incandescence some dust and
smoke particles. This will be less pronounced than the
visible line from ionized air. They won't make any sound
in passing, though the laser itself might have active components
which make sound, and the target will probably explode loudly.
Moderately powerful lasers operating in the visible frequencies
are very visible if there's any dust, smoke, or fog in the
beampath. Also won't make any sound except the laser itself
or the target.
The preferred damage mechanism is, yes, very short pulses
which hit with enough energy to vaporize the surface layer
and then effectively do contact explosion damage rather than
burn damage. Longer pulses often don't hit the same part
of the target, which difuses the damage. Over longer periods
of time the heat also can radiate away and difuse away and
reduce damage. It takes a lot of energy to continuously burn
a target enough to injure it; a fraction of that energy compressed
into short pulses will cause significant injury due to explosive
effects instead of thermal burns.
You would notice being hit; it would be like someone set off
an explosive right next to you.
>Also, what effects should lasers have on the people using the weapons?
>There's no recoil, surely (unless the technology somehow requires it)?
>Is it really possible, as in GURPS, to aim multiple shots on exactly the
>same place? In the final analysis, which is easier to detect, a
>conventional gunpowder slugthrower or a laser? Which is easier to fire?
The laser proper won't recoil. Chemical lasers have a large
flow of chemical laser fuel, which has to exhaust somewhere and will
push you around in doing so. Non-chemical lasers should be effectively
recoilless (photons technically carry momentum, so in physics terms
there is some recoil, but in engineering sense it's recoilless).
You could aim multiple shots at the same place as well as you can
aim multiple shots of other weapons at the same place. Depends on
how accurately you can aim. The pointing accuracy of the laser
weapon should be excellent (very small inherent groups) but humans
and automatic aiming systems aren't perfect. "good" is a couple
of inches (5 cm) of average dispersion per 100m of range.
Snipers or carefully aimed fire can be half that or less.
>I know all of this is highly speculative, but there may be people who've
>seen references for things like this, or who have a good idea how real
>laser weapons may eventually work.
There are some good sites with more info. Look around for MIRACL and
ABL in web searches; MIRACL is the Mid-InfraRed Advanced Chemical Laser,
a US Navy project which made a functional ship-based laser weapon for
anti-aircraft and anti-missile use in the 1980s. While the project
was successful in producing a working laser, analysis showed that
it (and other possible current lasers) weren't best for the Navy's
combat needs at the time, so it never went into production. ABL is
an Air Force project to build an airborne laser weapon plane
(big chemical laser in a 747 airframe) for shooting down Scuds
and similar medium range ballistic missiles. An ABL experimental
demonstrator aircraft laser shot down a number of flying targets
(various missiles and drones) in the early 1990s; the production
ABLs are rolling towards being ready.
-george william herbert
gher...@crl.com
Rachel Kronick
Basically, my question is pretty much what the title says. I've been
reading some SF lately with descriptions of laser weapons (handguns,
mostly) firing, and I've seen widely varying ideas of how such fire
would look, sound, smell, etc. I'd like to know what folks reading this
list think (there seem to be some pretty well informed people around
here). If someone fired, say, a 500 kJ, 0.01 second laser through
Earth-normal atmosphere, what sort of effects would this produce?
Unless there's mist or smoke, the beam itself shouldn't be visible,
right? But what about the smell of ionization, or a clap from
superheated air expanding out? Would a laser of this sort actually
sizzle a person who got hit, or would the person possibly not notice and
keep going until they noticed their hand or whatever had fallen off (as
many SF stories would have it)? I've even heard some authors say that
weapons-grade laser fire would superheat flesh so quickly that it would
explode due to steam pressure. Is this possible?
Also, what effects should lasers have on the people using the weapons?
There's no recoil, surely (unless the technology somehow requires it)?
Is it really possible, as in GURPS, to aim multiple shots on exactly the
same place? In the final analysis, which is easier to detect, a
conventional gunpowder slugthrower or a laser? Which is easier to fire?
I know all of this is highly speculative, but there may be people who've
seen references for things like this, or who have a good idea how real
laser weapons may eventually work.
Thanks in advance for any responses!
-- Rachel Kronick
<http://www.geocities.com/jiawen6>
DrFaust
>
[snip]
> The preferred damage mechanism is, yes, very short pulses
> which hit with enough energy to vaporize the surface layer
> and then effectively do contact explosion damage rather than
> burn damage. Longer pulses often don't hit the same part
> of the target, which difuses the damage. Over longer periods
> of time the heat also can radiate away and difuse away and
> reduce damage. It takes a lot of energy to continuously burn
> a target enough to injure it; a fraction of that energy compressed
> into short pulses will cause significant injury due to explosive
> effects instead of thermal burns.
>
Are you saying that a shorter pulse will do more damage? I don't think
so. A longer pulse will deliver more energy to the target (and hence do
more damage). Are you saying this is not so?
--
dRfAuSt
*******************************************************
* Due to excessive spam, a spam-blocker is in effect. *
* Eliminate '~' and 'rem' to reply *
*******************************************************
DavidR3986
>so. A longer pulse will deliver more energy to the target (and hence do
>more damage). Are you saying this is not so?
The problem here is what happens to the target as the laser burns it away.
When the laser first hits, part of the target will vaporize, forming a small
gas cloud. This gas cloud will then absorb part of the energy of the laser.
By pulsing the laser, the time between laser pulses allows the gas cloud to
dissipate, so that when the next laser pulse hits, it delivers all its energy
to the target.
You are correct that there is less laser energy in each small pulse, but more
energy is delivered to the target by pulsing the laser than by using a
continuous beam.
Keep in mind that the pulses are so rapid, the beam will look continuous to the
human eye, much as the separate frames of a movie look continuous.
-David
Maren
effect you will get cooked flesh) while the short pulse will deposit the energy in
such a short time, that the tissue gets torn apart.
Best for that would be lasers emitting in the infrared spectrum, not in the
visible. Unfortunately they have the nasty habit of getting absorbed by moisture in
the atmosphere, so their effective range (where they still do plenty damage) will
be a little limited.
Maren
DavidR3986 schrieb:
Rachel E. Taylor
>>Basically, my question is pretty much what the title says. I've been
>>reading some SF lately with descriptions of laser weapons (handguns,
>>mostly) firing, and I've seen widely varying ideas of how such fire
>>would look, sound, smell, etc. I'd like to know what folks reading this
>>list think (there seem to be some pretty well informed people around
>>here). If someone fired, say, a 500 kJ, 0.01 second laser through
>>Earth-normal atmosphere, what sort of effects would this produce?
>>Unless there's mist or smoke, the beam itself shouldn't be visible,
>>right? But what about the smell of ionization, or a clap from
>>superheated air expanding out? Would a laser of this sort actually
>>sizzle a person who got hit, or would the person possibly not notice and
>>keep going until they noticed their hand or whatever had fallen off (as
>>many SF stories would have it)? I've even heard some authors say that
>>weapons-grade laser fire would superheat flesh so quickly that it would
>>explode due to steam pressure. Is this possible?
>
Slightly off the topic....
It really doesn't matter how effective the laser would be.
All that is required in most instances is that the laser (or
any other weapon, for that matter) is sufficient to
incapacitate the target.
From a purely military standpoint it is often more desirable
to render an individual un-combat worthy, rather than dead.
A screaming, agonized soldier does more to lessen the morale
of his side than one who simply keels over dead. Further,
survivors place greater logistical demands on their side,
requiring emergency treatment, evacuation from the
battlezone, ongoing treatment etc.
Of course, a wounded soldier may live to fight another day,
whilst a dead one remains dead.
I would suggest a laser would only need be powerful enough
to effectively blind an opponent in order to be a suitable
battlefield weapon. Not being very good at physics I'm not
sure how powerful a laser would need to be to accomplish
that, but I don't think it would be that much.
Rachel Taylor
Brett Evill
>
> Are you saying that a shorter pulse will do more damage? I don't think
> so. A longer pulse will deliver more energy to the target (and hence do
> more damage). Are you saying this is not so?
Don't forget that some types of lasers are inherently pulsed. Producing
a pulsed beam is not simply a question of switching off a beam that
could be sustained continuously. So while it seems unlikely that a
shorter pulse at the same intensity would do more damage, the option
might be for the shorter pulse to be much more intense.
I'm not saying that it is so (what I know of lasers I read a long time
ago, and it may be out of date), but it seems possible in principle that
some of the pulsed types of laser might produce a higher average power
output than any of continuous-beam types. And even if that were not the
case, it certainly seems possible that half a megajoule arriving in a
millisecond might do more damage to a reflecting surface, and might tend
more to overwhelm conduction, than even a whole megajoule that arrives
spread out over a second.
Regards,
Brett Evill
Brett Evill
>
> Also a longer or continuous pulse will dissipate, heating up the area ( so in
> effect you will get cooked flesh) while the short pulse will deposit the energy in
> such a short time, that the tissue gets torn apart.
> Best for that would be lasers emitting in the infrared spectrum, not in the
> visible. Unfortunately they have the nasty habit of getting absorbed by moisture in
> the atmosphere, so their effective range (where they still do plenty damage) will
> be a little limited.
Sorry not to have joined in earlier, at a more logical point in the
discussion.
I expect that there will be problems providing enough power to a laser
smallarm to maintain a continuous beam that is intense enough to do real
damage.
The first solution to this problem that occurs to me is the cartridge
laser. This has permanent mirrors and collimating lens (and probably
replaceable neutral filters to protect the lens). Between the mirrors
you place a cartridge of optical glass that contains, say, hydrogen, and
is connected to a bulb containing, say, fluorine under pressure. Press
the trigger, and the firing circuit melts a partition and lets the
fluorine rush into the cartridge: the hydrogen and fluorine react
producing an invert population, and there is a brief flash of laser
light (IR for that particular reaction, if memory serves). Waste heat
probably fuses the glass and makes it all bubbly and cloudy. But you
don't care. You throw away the cartridge like and old-fashioned
flashbulb, and slip in another. Who knows? The pepperpot might make a
comeback.
Next, if we suppose some suitable solid-state laser, is that a backpack
or belt-mounted battery provides power through a superconducting cable
to an array of capacitors in the weapon itself. This should charge up in
perhaps as little as a fraction of a second. When the trigger is
pressed, a circuit is closed which causes the capacitors to discharge
through the lasing element, which will produce a very intense beam
lasting a few milliseconds (although the laser is technically a
continuous-beam one, I doubt power would be available to keep it going
for longer than that. Although UV lasers are probably possible, the
atmosphere is rather milky in the deep UV, so it probably isn't a good
idea to go much further than the visible spectrum.
Anyway: how conspicuous?
One of the possible problems with laser weapons is that absorbtion of
the laser beam by the air, even though it is only slight, causes the air
to expand and thus lowers its refractive index. The result is that the
refractive index of the air in the middle of the beam is lower than that
at the edge, which is the reverse of the pattern used in optical fibres
to keep the beam on the straight and narrow. In brief, the beam spreads
out, or blooms, as it passes through air. One way to avoid this is to
use low beam intensities, but that makes it hard to deliver killing
energy to a moving target. Another approach is to use such high beam
intensities that all the air is blown out from the path of the beam in
the first fraction of a millisecond, leaving an evacuated channel for
the main body of the beam to travel through.
So in my SF setting laser weapons at pretty conspicuous: the beams are
actually UV (at the higher tech levels), but beam intensities are high
enough that they break down the oxygen and nitrogen molecules in their
path. These recombine very rapidly, producing ozone and oxides of
nitrogen as well as molecular nitrogen and oxygen, and also producing a
blue flash like that seen in a lightning bolt or electrical spark. And
the superheated air rushing out from the beam (and then rushing back)
produces a sharp 'crack' like the sound of a big spark. Then there may
be a whining sound like that from the electronic flash on a camera as
the capacitors recharge for the next shot. So in addition to the
steam-explosion in the target, the screams, and the stench of burning
flesh there is a sharp bang, a bright flash like a flashbulb stretched
out from the muzzle to the target, a whining sound, and a whiff of
nitrous and ozone. And any survivors are likely to get sunburn from the
UV scattered from the beam as it makes its evacuated channel.
You may, of course, like to do it differently in your campaigns.
Regards,
Brett Evill
Brett Evill
> I would suggest a laser would only need be powerful enough
> to effectively blind an opponent in order to be a suitable
> battlefield weapon. Not being very good at physics I'm not
> sure how powerful a laser would need to be to accomplish
> that, but I don't think it would be that much.
You are probably right about that. But such is the horror of being
blinded that weapons designed to blind the enemy have already been
banned. And treatment of anyone captured with one by his or her captors
is likely to be nasty enough to deter a great many soldiers from using
such weapons. Remember what happened to serrated bayonets.
Regards,
Brett Evill
Rachel Kronick
Um, didn't know where to post this, so I'll put it here... I just
wanted to say thanks to everyone who's written here. I've gotten a lot
of good information from what you've said! (On the other hand, harumph,
there go the laser-based sniper weapons, right out the window.)
Anyway, thanks. Oh, also, I'm going to post this on rec.arts.sf.science
to see what else I can find out. Look for it there, if you're
interested.
Brett Evill wrote:
>
> Rachel E. Taylor wrote:
>
Cool, another person named Rachel around here! :)
As a total aside: Brett, how do you pronounce your last name? I can't
help but have (what I'm sure is) the wrong pronunciation drift through
my head when I read your name. Could you supply a fo-ne`-tik spe`-lin?
Rachel E. Taylor
<b.e...@nospam.tyndale.apana.org.au> wrote:
>Rachel E. Taylor wrote:
>
>> I would suggest a laser would only need be powerful enough
>> to effectively blind an opponent in order to be a suitable
>> battlefield weapon. Not being very good at physics I'm not
>> sure how powerful a laser would need to be to accomplish
>> that, but I don't think it would be that much.
>
>You are probably right about that. But such is the horror of being
>blinded that weapons designed to blind the enemy have already been
>banned. And treatment of anyone captured with one by his or her captors
>is likely to be nasty enough to deter a great many soldiers from using
>such weapons. Remember what happened to serrated bayonets.
>
It's true that a lot of weapons have been banned, or are
being banned - napalm, anti-personnel mines etc.
I can't help but think that banning a weapon because "it's
too nasty, or horrible" wouldn't last long in a protracted
war, particularly for the losing side.
There is a strange kind of logic at work that says it is OK
to kill someone, so long as it is quick and painless, but
not otherwise. Having your legs blown off by a mine is no
different from having them blown off by a mortar shell, or
cut off by machine gun fire.
But I guess it's weapons that are designed to maim that are
the cause of such concern. I suppose it is a sign of our
increasing maturity as a species that we are at least trying
to get rid of some weapons.
Rachel Taylor
Jim Walters
: Hi all!
: Basically, my question is pretty much what the title says. I've been
: reading some SF lately with descriptions of laser weapons (handguns,
: mostly) firing, and I've seen widely varying ideas of how such fire
: would look, sound, smell, etc. I'd like to know what folks reading this
: list think (there seem to be some pretty well informed people around
: here). If someone fired, say, a 500 kJ, 0.01 second laser through
: Earth-normal atmosphere, what sort of effects would this produce?
: Unless there's mist or smoke, the beam itself shouldn't be visible,
: right?
I'm not so sure about that. A beam that powerful should ionize the air it
is passing through, and the ionized air would glow. There might also be
some scattering from any dust in the air, although the dust probably
wouldn't last very long.
: But what about the smell of ionization, or a clap from
: superheated air expanding out?
I'm not sure that ionized air even has a smell. Ozone does, but I'm not
sure if ozone would be created by a high power laser. I would definitely
expect a thunderclap of some sort.
: Would a laser of this sort actually
: sizzle a person who got hit, or would the person possibly not notice and
: keep going until they noticed their hand or whatever had fallen off (as
: many SF stories would have it)?
I'd think that people would tend to notice when their limbs are being cut
off, regardless of what is doing the cutting.
: I've even heard some authors say that
: weapons-grade laser fire would superheat flesh so quickly that it would
: explode due to steam pressure. Is this possible?
There may be an explosion, but it wouldn't blowup the person you are
targeting. The beam would probably be no larger than a coin when it hits
the target, and the explosion would be confined to an area that small.
The problem with the explosion is that it would send shockwaves through
the target's body, and those shockwaves could damage the internal organs.
: Also, what effects should lasers have on the people using the weapons?
: There's no recoil, surely (unless the technology somehow requires it)?
Lasers have recoil, because light has momentum. In this particular case
the recoil would be negligible.
: Is it really possible, as in GURPS, to aim multiple shots on exactly the
: same place? In the final analysis, which is easier to detect, a
: conventional gunpowder slugthrower or a laser? Which is easier to fire?
I've never cared for the GURPS rule. If the target is a stationary object
and the weapon is mounted on another stationary object, then you can drop
as many shots as you want upon each other. In a more realistic situation,
you are limited by the ability of the shooter to keep the weapon pointed
at exactly the same spot on a target which is trying to prevent this from
happening. In other words, it ain't gonna happen.
--
Jim Walters jwal...@clark.net
"My race is pacifist and does not believe in war.
We kill only out of personal spite." Brain Guy - MST3K
Fitz
<rac...@hipoint.co.uk> wrote:
>There is a strange kind of logic at work that says it is OK
>to kill someone, so long as it is quick and painless, but
>not otherwise. Having your legs blown off by a mine is no
>different from having them blown off by a mortar shell, or
>cut off by machine gun fire.
In point of fact, it's not the fact that they maim which is used as a
reason for banning mines; it's the fact that unlike shells and
machinegun bullets, a mine will sit around waiting to maim for years
after the conflict in which they were laid is ended.
A lot of work is going into the development of mines which expire,
either naturally via chemical reaction, or in response to a
deactivation signal. If it becomes viable, it strikes me as a good
compromise between military necessity and post-conflict safety issues.
Moramarth
Taylor <rac...@hipoint.co.uk> writes
>On Sat, 27 Nov 1999 07:28:56 +1100, Brett Evill
><b.e...@nospam.tyndale.apana.org.au> wrote:
>
>>Rachel E. Taylor wrote:
>>
>>> I would suggest a laser would only need be powerful enough
>>> to effectively blind an opponent in order to be a suitable
>>> battlefield weapon. Not being very good at physics I'm not
>>> sure how powerful a laser would need to be to accomplish
>>> that, but I don't think it would be that much.
>>
>>You are probably right about that. But such is the horror of being
>>blinded that weapons designed to blind the enemy have already been
>>banned.
circumstances - the last couple of times I tried to do some photography
at my local bombing range I was warned off as some aircraft were self-
designating, also where helicopter-borne FACs were operating (even
though I pointed out my video camera had no direct optical path: SLR
cameras and binoculars were obviously right out). There have already
been cases of laser devices (often rangefinders) of fUSSR warships and
AGIs causing permanent visual impairment in NATO personnel: the
"Dazzlers" fitted to RN warships after the Falklands were not supposed
to cause any permanent effects (unless you count death by flying into
the deck) on enemy pilots.
>>is likely to be nasty enough to deter a great many soldiers from using
>>such weapons. Remember what happened to serrated bayonets.
were routinely hung with their own rifle slings in Normandy - strictly
against the rules, but what the hell, we won! - but sniping is still
popular.
>>
>It's true that a lot of weapons have been banned, or are
>being banned - napalm, anti-personnel mines etc.
>
>I can't help but think that banning a weapon because "it's
>too nasty, or horrible" wouldn't last long in a protracted
>war, particularly for the losing side.
One of the nastiest and most effective AP mines was (is?) produced in
the fYR, the Serbs have left a lot of them all over Kosovo.
>
>There is a strange kind of logic at work that says it is OK
>to kill someone, so long as it is quick and painless, but
>not otherwise. Having your legs blown off by a mine is no
>different from having them blown off by a mortar shell, or
>cut off by machine gun fire.
>
>But I guess it's weapons that are designed to maim that are
>the cause of such concern. I suppose it is a sign of our
>increasing maturity as a species that we are at least trying
>to get rid of some weapons.
Been trying too, from way back when. Back when the crossbow was coming
into use on a large scale in around AD1200, the Pope banned them from
use on fellow Christians, which was almost universally ignored, the
English taking to them with great enthusiasm, contrary to "Braveheart",
we weren't into longbows that early.
>
>Rachel Taylor
Cheers,
--
Moramarth
Brett Evill
>
> I can't help but think that banning a weapon because "it's
> too nasty, or horrible" wouldn't last long in a protracted
> war, particularly for the losing side.
>
> to kill someone, so long as it is quick and painless, but
> not otherwise. Having your legs blown off by a mine is no
> different from having them blown off by a mortar shell, or
> cut off by machine gun fire.
>
> But I guess it's weapons that are designed to maim that are
> the cause of such concern. I suppose it is a sign of our
> increasing maturity as a species that we are at least trying
> to get rid of some weapons.
Well, a lot of the impetus against land mines has come from the deaths
and maiming they continue to inflict (particularly against children) for
years after the war has ended.
And you could argue that the Germans in 1917 filing the serrations off
their bayonets were doing so because they realised that a serrated
bayonet wasn't more effective on a personal level, whereas they feared
that the Australians and Canadians would kill them very personally if
they were caught with them.
Perhaps if blinding weapons were very effective soldiers would risk the
summary executions that their opponents would dish out to troops caught
using them.
But on the other hand a Dum-dum bullet *is* more effective on a personal
level, and the ban on their use in war has been effective. So I guess it
could go either way.
Regards,
Brett Evill
Rachel E. Taylor
wrote:
>
>In point of fact, it's not the fact that they maim which is used as a
>reason for banning mines; it's the fact that unlike shells and
>machinegun bullets, a mine will sit around waiting to maim for years
>after the conflict in which they were laid is ended.
>
>A lot of work is going into the development of mines which expire,
>either naturally via chemical reaction, or in response to a
>deactivation signal. If it becomes viable, it strikes me as a good
>compromise between military necessity and post-conflict safety issues.
>
I suspect some kind of chemical timed-expiry is the more
logical way to go. Form the arms manufacturer's point of
view it requires the least change to their production line.
Of course, if the demand for deactivatable mines is there
then no doubt they will all jump on the bandwagon rather
than be left behind.
Personally, I never understood the mentality of producing a
weapon (of any sort) that was not totally under the users
control.
Rachel Taylor
Rachel E. Taylor
<Mora...@moramarth.demon.co.uk> wrote:
>Been trying too, from way back when. Back when the crossbow was coming
>into use on a large scale in around AD1200, the Pope banned them from
>use on fellow Christians, which was almost universally ignored, the
>English taking to them with great enthusiasm, contrary to "Braveheart",
>we weren't into longbows that early.
>
And retaliation against captured troops who used weapons
"disapproved of" by the other side is also not new.
Wasn't it the French who used to lop off the first two
fingers of captured English longbowmen? Hence the "V's"
gesture we have today.
Rachel Taylor
Shawn Wilson
"Rachel E. Taylor" <rac...@hipoint.co.uk> wrote in message
news:rlo24sobth9tssm2e...@4ax.com...
> Personally, I never understood the mentality of producing a
> weapon (of any sort) that was not totally under the users
> control.
Since when has ANY weapon ever been 'entirely under the users control'?
Ed Chauvin IV
rec.games.frp.misc, Rachel E. Taylor used a less than adequate
newsreader Forte Agent 1.7/32.534
to describe Re: How obvious is weapons-grade laser fire?
>On Sat, 27 Nov 1999 21:47:04 GMT, pj_...@hotmail.com (Fitz)
>wrote:
>>
>>In point of fact, it's not the fact that they maim which is used as a
>>reason for banning mines; it's the fact that unlike shells and
>>machinegun bullets, a mine will sit around waiting to maim for years
>>after the conflict in which they were laid is ended.
>>
>That is a very valid point.
>
>>A lot of work is going into the development of mines which expire,
>>either naturally via chemical reaction, or in response to a
>>deactivation signal. If it becomes viable, it strikes me as a good
>>compromise between military necessity and post-conflict safety issues.
>>
>I suspect some kind of chemical timed-expiry is the more
>logical way to go. Form the arms manufacturer's point of
>view it requires the least change to their production line.
Not to mention the logistical headaches of producing a mine that can
be "signaled", but not by the enemy.
Ed Chauvin IV
--
It is by caffeine alone I set my mind in motion.
It is by the Beans of Java that thoughts acquire speed,
the hands acquire shaking, the shaking becomes a warning.
It is by caffeine alone I set my mind in motion.
Wayne Shaw
>weapon (of any sort) that was not totally under the users
>control.
There are always tradeoffs. Many Vietnam era American troops enjoyed
the pleasures of "friendly fire" when artillery rounds didn't go quite
where desired, and to some extent, no area effect weapon is ever
"totally under the user's control". Some weapons have beneficial
enough operational or tactical uses you just shrug and move on. In
the case of mines, the benefit of channelling what directions you have
to worry about ground attack coming from usually well outweigh any
worries about wandering into your own mine fields.
Moramarth
Taylor <rac...@hipoint.co.uk> writes
>And retaliation against captured troops who used weapons
>"disapproved of" by the other side is also not new.
>
>Wasn't it the French who used to lop off the first two
>fingers of captured English longbowmen? Hence the "V's"
>gesture we have today.
>
>Rachel Taylor
sexual, there again he said pretty much the same about all gestures.
OTH I think he was on the mark observing the line to which Italy was
colonised by the Ancient Greeks is still reflected in the different
gestures used today. If you ever need the miniature of a gesturing
longbowman, Foundry do one in 28mm!
Cheers,
--
Moramarth
Eric Tolle
>
> Maren wrote:
> I expect that there will be problems providing enough power to a laser
> smallarm to maintain a continuous beam that is intense enough to do real
> damage.
I recall a laser expert saying that the most damaging battlefield
use of a laser would be to fly over and drop the power supply on
the enemy. ;')
Another potential problem would be focusing elements- in addition
to needing to find the range to the target, the optics and
focusing elements would need a fair degree of precision, and would
likely be both delicate and finicky to maintain. And you
definitely wouldn't want the lens to get dusty or muddy.
And then there's the cooling problems, the fact that different
frequencies are absorbed better by different substances, and the
fact that laser beams would expend their energy on the first thing
they contact- no taking blind shots through the shrubbery...
It's likely that even if the power supply problems were to be
worked out, slug throwers would remain the robust weapon of choice
for infantry. Simple, reliable, well understood...those are major
advantages. I'd see more advances coming with associated
electronics then the basic damage dealing method.
> The first solution to this problem that occurs to me is the cartridge
> laser. This has permanent mirrors and collimating lens (and probably
This is a nice idea- it occurs to me that properly made, one could
turn the cartridge into a heat sink, and eject the thing like a
bullet. That would go a long way to dealing with cooling
requirements.
--
Eric Tolle sch...@silcom.com
Information does not want to be free. Information wants to be
folded, spindled, mutilated, and used to make funky children's
party hats.
Eric Tolle
> I can't help but think that banning a weapon because "it's
> too nasty, or horrible" wouldn't last long in a protracted
> war, particularly for the losing side.
Which is of course, why the Germans used chemical weaponry on
the advancing Allied forces in World War II.
There's a number of reasons not to use banned weapons even when
one's own side is losing a war. Fear of retaliation is one such
reason, harsh treatment after the war is another. That and angry
soldiers on the opposing side.
One other factor regarding the use of blinding lasers- counter-
measures. IIRC, goggles to prevent blinding by lasers are either
in development or production. This would mean that lasers would
have a relatively short period of use in a war.
Wayne Shaw
>worked out, slug throwers would remain the robust weapon of choice
>for infantry. Simple, reliable, well understood...those are major
>advantages. I'd see more advances coming with associated
>electronics then the basic damage dealing method.
On the other hand, slugthrower technology per se seems to have reached
pretty much the end of what you can do to it; while there's been some
fiddling around with special ammo types, most of the ammo used in 1920
is not that different in any important way from what's used today, and
the technology of the guns themselves has only improved incrementally
in the last 40 years (the last really important breakthrough was
effective lightweight fully automatic rifles). Laser weaponry is
still in it's infantcy, and there are obvious places where engineering
and technology could improve them significantly, including the areas
you mentioned. In the long run they might well outstrip slugthrowers
as weapons of choice once those problems are addressed. Or not. But
it's a bit early in the day of trying to use them as weapons to say.
Wayne Shaw
wrote:
>Rachel E. Taylor wrote:
>
>> I can't help but think that banning a weapon because "it's
>> too nasty, or horrible" wouldn't last long in a protracted
>> war, particularly for the losing side.
>
>Which is of course, why the Germans used chemical weaponry on
>the advancing Allied forces in World War II.
Well, the fact they also weren't all that effective as weapons
compared to others used in similar ways didn't hurt. Chemical weapons
are, for most purposes, not only nasty but stupid.
Eric Stevenson
: One other factor regarding the use of blinding lasers- counter-
: measures. IIRC, goggles to prevent blinding by lasers are either
: in development or production. This would mean that lasers would
: have a relatively short period of use in a war.
Ah yes, the blinding lasers thread again. I'd just like to repeat a few
of my points from last time.
Lasers have considerable limitations for infantry use: line of sight,
getting tortured by enemy soldiers, etc. So they wouldn't be used by
infantry.
Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
sweep over the battlefield like a searchlight, covering large amounts of
territory rapidly, over a long range, and has line of sight to almost
everything. It is a high dollar unit, like an AWACS plane, and is
protected appropriately. So, it does its job well, and is in little
danger of destruction by revenge motivated grunts.
What about their defenses? They can either keep their eyes on the ground
100% of the time, which will reduce their combat effectiveness, or wear
protective eyewear. A big, expensive laser like this can be made to work
on variable frequencies, so goggles may have to block the entire visible
spectrum. This means the soldiers will be blind before the laser even
gets to then.
What about a camera-tv system for the soldiers? Good idea, you can put in
light amplification and IR while you're at it. Presumably, you've got
enough money and research into them that you can equip all of your
soldiers with high-tech toys that won't break down under battlefield
conditions. You have spent a lot more than the blinding laser cost,
though, so it's good that they have other uses besides eye protection.
Frank T. Sronce
>
> Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
> sweep over the battlefield like a searchlight, covering large amounts of
> territory rapidly, over a long range, and has line of sight to almost
> everything. It is a high dollar unit, like an AWACS plane, and is
> protected appropriately. So, it does its job well, and is in little
> danger of destruction by revenge motivated grunts.
>
> What about their defenses? They can either keep their eyes on the ground
> 100% of the time, which will reduce their combat effectiveness, or wear
> protective eyewear. A big, expensive laser like this can be made to work
> on variable frequencies, so goggles may have to block the entire visible
> spectrum. This means the soldiers will be blind before the laser even
> gets to then.
>
Wear hats with big brims and good sunglasses. Boots with big, jangling
spurs nice, but optional. :-)
Kiz
Luke Campbell
> Sufficiently powerful lasers will ionize the air even if there
> isn't any dust or smoke or fog. That will give you a bright
> line and loud bang. That's more powerful than what seems to
> be proposed for weapons lasers though.
Ionized air tends to absorb the laser beam, at least at lower frequencies of
light. Experiments with CO_2 lasers that tried to ionize a path through the
air (for directing lightning bolts from storm clouds) encountered just this
problem - the lasers would absorb their own beam and none of the beam would
get to where the researchers wanted it to go. The lasers had to be focused
so that they only ionized the air at the point they were focused to, and
then the focal point swept through the path that the lightning bolt would
take.
> Moderately powerful lasers operating in the visible frequencies
> are very visible if there's any dust, smoke, or fog in the
> beampath. Also won't make any sound except the laser itself
> or the target.
Don't forget Rayleigh scattering off air molecules. This will cause lasers
powerful enough to be used as weapons to be visible even in perfectly clean
air.
Luke Campbell
> Hi all!
>
> Basically, my question is pretty much what the title says. I've been
> reading some SF lately with descriptions of laser weapons (handguns,
> mostly) firing, and I've seen widely varying ideas of how such fire
> would look, sound, smell, etc. I'd like to know what folks reading this
> list think (there seem to be some pretty well informed people around
> here). If someone fired, say, a 500 kJ, 0.01 second laser through
> Earth-normal atmosphere, what sort of effects would this produce?
> Unless there's mist or smoke, the beam itself shouldn't be visible,
Light can (and does) scatter off of air molecules. This is why the sky is
blue - blue light scatters more than red light, so beams of sunlight
passing through the air overhead get blue light scattered out of them so
that we can see them. The same thing would happen to laser light - the
higher the frequency of the laser's light, the more its light will
scatter. I did a few calculations a while ago, and a multiple kilojoule
pulse from a visible light laser would be very visible even in broad
daylight, a blue beam would be much brighter than a red beam. There are
very good reasons for using blue beams, though, since higher frequencies
can be focused more tightly at long distances than lower frequencies, even
if they have more losses from scattering. Dust, pollen, mist, and smoke
will just make the beam more visible.
Laser beams outside the visible range will not be visible from this
effect. They can heat dust particles in the air to incandescence, however,
causing a sparkly effect. They can also cause ionization of the air, which
will absorb the laser beam. I doubt weapon designers would make lasers
that ionized the air because then none of the light from the laser would
reach the target. A narrow beam of near UV or IR light might thus have
very little visual effects, narrow beams would catch less dust to heat up.
However, narrow beams are also harder to focus at long ranges, this is less
of a problem with UV than IR.
One note about ionization - many other posters have mentioned the ability
of lasers to ionize the air the beam passes through. Ionization occurs
more readily at low frequencies. The lower the frequency of light, the
less the intensity of the beam that will ionize the air. At mid infrared
frequencies, ionization can be a real bother, because it limits the size of
the spot of laser light you can project onto your target (a smaller spot
means higher intensities - good for damaging effects but bad if you want to
avoid ionizing the air and having all of your beam absorbed before it
reaches the target). As you get towards mid IR and visible frequencies,
ionization becomes unimortant except at extreme intensities, and the higher
frequency light is likely to just pass through ionized air without being
absorbed, anyway. Once you get past the near UV, light again starts
ionizing the air (this time from photoemission rather than electric field
effects), and at these frequencies, the ionization is independant of
intensity, all the light is rapidly absorbed. These frequencies might make
good space weapons, but are of almost no use in an atmosphere. One
exception would be hard x-rays and gamma rays, which can be focused so
tightly that they can make a very, very narrow beam such that the front of
the laser pulse heats all the air in the beam to such high temperatures
that it is essentially a vacuum inside and the rest of the beam can
propagate without interferance from the atmosphere.
> right? But what about the smell of ionization, or a clap from
> superheated air expanding out? Would a laser of this sort actually
If you have ionized air, you will get a strong smell of ozone (along with
nitrogen oxides, but these are less noticeable), and a thunderclap from the
superheated air. As mentioned, however, ionization is generally bad and
most laser weapons would be designed not to ionize the air. The beam
itself would be silent and would produce no odor, but the operation of the
laser mechanism and the explosion of vaporized material from the "impact"
point of the laser would be a different matter entirely.
> sizzle a person who got hit, or would the person possibly not notice and
> keep going until they noticed their hand or whatever had fallen off (as
> many SF stories would have it)? I've even heard some authors say that
You would notice. See below.
> weapons-grade laser fire would superheat flesh so quickly that it would
> explode due to steam pressure. Is this possible?
This is basically the way it works. Vaporized material expands to at least
1500 times its volume, hot vapor would take up even more volume. You would
want very high intensity flashes from your laser that would heat the
material very rapidly to a plasma state, which then absorbs the rest of the
flash and delivers all the energy to the target through thermal conduction
from the plasma or mechanical effects of the plasma exploding outward at
supersonic speeds.
X ray and gamma ray lasers would act somewhat differently. These laser
beams would not be absorbed by their own plasma, they would burn a narrow
hole through someone. They are also beams of ionizing radiation, anyone
they hit, or even just nicked or grazed, would recieve a lethal dose of
radiation. If you are near someone or something that gets hit, you could
also get a bad case of radiation sickness.
> Also, what effects should lasers have on the people using the weapons?
> There's no recoil, surely (unless the technology somehow requires it)?
The recoil from a laser beam will be so increadibly miniscule that you will
not notice it at all. If you do have a laser weapon strong enough to
produce noticable recoil, the power of the beam will be so astronomically
high that whatever it hits would explode like a nuclear weapon (without the
radiation effects). Other than the engineering problems of designing such
a weapon and its power supply, this has obvious drawbacks if you are
shooting at something close to you.
> Is it really possible, as in GURPS, to aim multiple shots on exactly the
> same place? In the final analysis, which is easier to detect, a
If you just clamp your laser in place and turn it on so that its beam hits
a stationary target, this is what will happen. Electronic aiming systems
may well be able to achieve this kind of accuracy, it is doubtful that
unassisted humans would. However, a man portable laser rifle could very
well be equipped with image stabilization electronics, similar to those in
modern camcorders, to keep the beam steady against a moving, active target,
effectively allowing all the laser pulses to hit the same spot.
> conventional gunpowder slugthrower or a laser? Which is easier to fire?
It depends on the mechanism by which the laser operates. The beam of a
laser will likely be silent, while a rifle bullet (but not a pistol bullet)
will produce a loud crack from the sound of the bullet punching through the
air at supersonic speeds, but the laser beam will probably be more visible
than the bullet. Both will make noises when they hit something. Of
course, the conventional gunpowder weapon will make a loud bang and a
muzzle flash when it goes off due to the combusting gunpowder, who knows
what the laser mechanism itself will sound or look like - chemical lasers
might be just as bad as gunpowder weapons, electrically powered free
electron lasers might be silent and produce no light other than the beam
itself.
A projectile weapon will produce recoil, a laser will not. A laser will
thus be easier on the firer. In addition, a laser beam will not be
affected by gravity or wind conditions, a bullet will. Lasers will thus be
easier to aim, especially at long distances. While their might be some
distortion to the path of light due to the atmosphere or other effects, you
are using the light from your target to aim, the laser will follow exactly
the same path back (assuming you are using visible or near visible beams),
so you do not need to make any adjustments to where your targeting
crosshairs or the dot from your laser sight are. Other effects will depend
on the laser device itself, a chemical laser might well vent noxious fumes
to the air, requiring their users to wear gas masks. this would obviously
be hard on the user. An x ray or gamma ray laser would produce
backscattered radiation, and cause radiation poisoning to whoever was using
it unless they had a lot of shielding.
Luke
Luke Campbell
> Are you saying that a shorter pulse will do more damage? I don't think
> so. A longer pulse will deliver more energy to the target (and hence do
> more damage). Are you saying this is not so?
If the shorter pulse contains the same amount of energy as the longer
pulse, yes, it will.
Luke
Luke Campbell
> DrFaust wrote:
> >
>
> > Are you saying that a shorter pulse will do more damage? I don't think
> > so. A longer pulse will deliver more energy to the target (and hence do
> > more damage). Are you saying this is not so?
>
> Don't forget that some types of lasers are inherently pulsed. Producing
> a pulsed beam is not simply a question of switching off a beam that
> could be sustained continuously. So while it seems unlikely that a
> shorter pulse at the same intensity would do more damage, the option
> might be for the shorter pulse to be much more intense.
>
> I'm not saying that it is so (what I know of lasers I read a long time
> ago, and it may be out of date), but it seems possible in principle that
> some of the pulsed types of laser might produce a higher average power
> output than any of continuous-beam types. And even if that were not the
> case, it certainly seems possible that half a megajoule arriving in a
> millisecond might do more damage to a reflecting surface, and might tend
> more to overwhelm conduction, than even a whole megajoule that arrives
> spread out over a second.
Note that any continuous laser can be made into a pulsed laser with the same
average power. There are two standard ways of doing this. One is called Q
switching. Q refers to the gain of the laser resonator, the ability of the
laser to amplify light. At low Q, the laser has no gain and its excited
atoms or molecules are not stimulated to emit light. They remain in their
excited states while all of the molecules get excited. Then the Q of the
laser is switched so the laser suddenly starts lasing. The result is a
sudden flood of light as the laser emits all of its stored energy at once in
a laser pulse. The Q of the laser resonator can be switched by simply having
one of the mirrors on the ends of the laser rotate. As long as the mirrors
are not exactly parallel, the light is not amplified, when the mirrors are
parallel, the laser suddenly pulses.
A second way of getting pulses from a laser is to have the laser emit light
at a number of very closely spaced frequencies. This is called mode
locking. Just as two close frequencies of sound will produce beats, where
the intensity of the sound rises and falls, so will two close frequencies of
light. Add more very closely spaced frequencies and the beats become very
sharp pulses with near zero intensity beween them.
A third way of getting high intensity pulses involves sending a laser pulse
through a dispersive material. The material is desgned in such a way that
the incoming laser pulse is the time reverse of an outgoing pulse of light
that started on teh other end of the dispersive material as a pulse of zero
duration and infinite intensity. As the laser pulse travels through the
dispersive material, it is effectively doing the reverse of what the
hypothetical time reversed pulse did, and it gets compressed to a super short
duration and extreme intensities. This is how lasers can get pulses lasting
only femtoseconds.
Some lasers seem to be intrinsicly pulsed. Free electron lasers, for
example.
Luke Campbell
> One of the possible problems with laser weapons is that absorbtion of
> the laser beam by the air, even though it is only slight, causes the air
> to expand and thus lowers its refractive index. The result is that the
> refractive index of the air in the middle of the beam is lower than that
> at the edge, which is the reverse of the pattern used in optical fibres
> to keep the beam on the straight and narrow. In brief, the beam spreads
> out, or blooms, as it passes through air. One way to avoid this is to
> use low beam intensities, but that makes it hard to deliver killing
> energy to a moving target. Another approach is to use such high beam
> intensities that all the air is blown out from the path of the beam in
> the first fraction of a millisecond, leaving an evacuated channel for
> the main body of the beam to travel through.
At visible and near visible frequencies, the primary loss mechanism from the beam seems
to be scattering rather than absorption, so heating of the air would be small. This
allows the option of using adaptive optics to pre-defocus the beam to undo what the
thermal blooming will do. Another possibility is to use pulses so short that the air
does not have time to expand before the beam passes. This latter solution has the
drawback that the super high intensities involved may be enough to ionize the air. If
so, and if the frequency of the light was not high enough to propagate through the
ionized air, the ionized air itself would absorb the laser beam, so the weapon would be
useless. This means that the latter possibility may or may not work.
> So in my SF setting laser weapons at pretty conspicuous: the beams are
> actually UV (at the higher tech levels), but beam intensities are high
> enough that they break down the oxygen and nitrogen molecules in their
At UV frequencies and above, the intensity of the beam is not an issue, each individual
UV photon has enough energy to ionize a molecule of oxygen, nitrogen, water, or CO_2, so
it will be rapidly absorbed. This is regardless of the total intensity. UV lasers,
except at a few windows very near the visible spectrum, will be rapidly absorbed by air.
> path. These recombine very rapidly, producing ozone and oxides of
> nitrogen as well as molecular nitrogen and oxygen, and also producing a
> blue flash like that seen in a lightning bolt or electrical spark. And
> the superheated air rushing out from the beam (and then rushing back)
> produces a sharp 'crack' like the sound of a big spark. Then there may
> be a whining sound like that from the electronic flash on a camera as
> the capacitors recharge for the next shot. So in addition to the
> steam-explosion in the target, the screams, and the stench of burning
> flesh there is a sharp bang, a bright flash like a flashbulb stretched
> out from the muzzle to the target, a whining sound, and a whiff of
> nitrous and ozone. And any survivors are likely to get sunburn from the
> UV scattered from the beam as it makes its evacuated channel.
Because UV lasers (except at the windows in the spectrum mentioned above) are so readily
absorbed by the air, they are unlikely to be used as weapons in atmospheres. One might
get the idea to make a very narrow beam of UV light so that the front of the laser pulse
heats the air to a near vacuum for the rest of the UV to pass through without getting
absorbed. Unfortuneately, if the beam starts out very narrow, it will quickly diffract
until it is quite wide. When it is wide, it will be ionizing a lot of atmosphere which
will be absorbing a lot of energy from the beam before the atmosphere is cooked away.
This greatly limits the range of such a UV laser to a few meters. At the soft x-ray
level, where diffraction is less of a problem, expect ranges of tens of meters, hard
x-rays and gamma ray beams could go hundreds of meters, even a few kilometers using this
technique. Of course, gamma rays can go fifty to hundred meters or so through the air
anyway before being absorbed.
X-ray and gamma ray lasers have their problems, though. The main problem is that they
are beams of ionizing radiation, and backscattered radiation can cause radiation
poisoning or genetic damage to the person using the weapon. If the weapon is on a
battle suit or armored fighting vehicle, this is much less of a problem than if it is a
hand weapon. The UV and soft x-rays from excited electrons of the air molecules and
atoms falling back to their ground states will also cause sunburn. Anyone hit by such a
weapon would recieve an instant lethal dose of radiation, death may be months or minutes
away, depending on the amount of radiation recieved. Forward scattering is more
pronounced than backscattering, so even near misses could cause radiation sickness.
Being near something else that is hit by the beam could also cause radiation sickness.
While the radiation could knock out electronics and incapacititate even heavily armored
opponents, the radiation threat to the users means that x-ray and gamma ray lasersare
most likely to be used as artillery or on AFVs. Their short range in atmosphere
probably limits the ability of orbital vehicles or platforms to use these lasers against
ground targets, though the extremely low diffraction of the beam means that they are
likely to be the weapons of choice in space.
Peter White
>
>
> Lasers have considerable limitations for infantry use: line of sight,
> getting tortured by enemy soldiers, etc. So they wouldn't be used by
> infantry.
Agreed.
> Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
> sweep over the battlefield like a searchlight, covering large amounts
> of territory rapidly, over a long range, and has line of sight to
> almost everything. It is a high dollar unit, like an AWACS plane, and
> is protected appropriately. So, it does its job well, and is in little
> danger of destruction by revenge motivated grunts.
>
> What about their defenses? They can either keep their eyes on the
> ground 100% of the time, which will reduce their combat effectiveness,
> or wear protective eyewear. A big, expensive laser like this can be
> made to work on variable frequencies, so goggles may have to block the
> entire visible spectrum. This means the soldiers will be blind before
> the laser even gets to then.
The low-tech countermeasure is smoke cover. The resources required to
continuously entrench ones soldier in smoke I am not so sure about.
Certainly this would not be too difficult to maintain for days or weeks.
But for a longer campaign?
The high-tech countermeasure is to shoot down that C-130 with an
anti-aircraft laser. Of course practical blinding lasers are here
today, and it is anybodies guess when battlefield AA lasers will arrive.
--Peter White
Eric Tolle
> Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
> sweep over the battlefield like a searchlight, covering large amounts
Leaving aside the ethical questions, I can think of some technical
problems with the idea. But this may be something worth tossing
over to rec.arts.sf.science to let them pick at. Do you want to
port it over?
Eric Tolle
>
> >It's likely that even if the power supply problems were to be
> >worked out, slug throwers would remain the robust weapon of choice
> >for infantry. Simple, reliable, well understood...those are major
> On the other hand, slugthrower technology per se seems to have reached
> pretty much the end of what you can do to it; while there's been some
Plateaud out for a while at least, partially because the modern
small arm is highly efficient at what it does. Not suprisingly,
as it's the end product of what- four hundred years of intensive
technical innovation?
A lot of what will likely be done will be refinement of the concept
rather then completely new innovations. Still, the field of
integrating electronics with the weapons seems promising. And we
haven't even started much development with exotic elements like
liquid propellant. Frankly, a liquid-propellant rifle with a
"smart bullet" that homes in on the target seems as SF as any
energy weapon.
> effective lightweight fully automatic rifles). Laser weaponry is
> still in it's infantcy, and there are obvious places where engineering
> and technology could improve them significantly, including the areas
> you mentioned. In the long run they might well outstrip slugthrowers
Actually, based on the basic physics of involved, there may well be
areas where slug throwers have an advantage. Penetrating armor
is one of those areas, as there really isn't much one can do about
that. And of course there's the factor that if power supplies
get compact and powerful enough to let lasers outstrip chemical-
based slugthrowers, then those power supplies would probably also
work to make practical gauss weapons.
Mr. M.J. Lush
Peter White <dan...@peterwhite.org> wrote:
>Eric Stevenson wrote:
>>
>>
>> Lasers have considerable limitations for infantry use: line of sight,
>> getting tortured by enemy soldiers, etc. So they wouldn't be used by
>> infantry.
>
>Agreed.
>
>> What about their defenses? They can either keep their eyes on the
>> ground 100% of the time, which will reduce their combat effectiveness,
>> or wear protective eyewear. A big, expensive laser like this can be
>> made to work on variable frequencies, so goggles may have to block the
>> entire visible spectrum. This means the soldiers will be blind before
>> the laser even gets to then.
>
>The low-tech countermeasure is smoke cover. The resources required to
>continuously entrench ones soldier in smoke I am not so sure about.
>Certainly this would not be too difficult to maintain for days or weeks.
>But for a longer campaign?
A slightly higher tech countermeasure would be smoke mines
that went off when hit by a blinding laser (probably networked to
other smoke bombs to give battle field coverage)
A rather higher tech solution could peril sensitive sunglasses
ie ones that go black when hit by a blinding laser which would
might be fast enough to react before the optic nerve cooks...
I suppose an optimum system would be peril sensitive
goggles which go black if scattered blinding laser is detected
(to give it the time to respond) and a backup video system
so blinding laser can't be used to cover an advance...
--
Michael
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NPC rights activist | Nameless Abominations are people too.
Wolter RC
> Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
> territory rapidly, over a long range, and has line of sight to almost
> everything. It is a high dollar unit, like an AWACS plane, and is
> protected appropriately. So, it does its job well, and is in little
> danger of destruction by revenge motivated grunts.
> What about their defenses? They can either keep their eyes on the ground
> 100% of the time, which will reduce their combat effectiveness, or wear
> protective eyewear. A big, expensive laser like this can be made to work
> on variable frequencies, so goggles may have to block the entire visible
> spectrum. This means the soldiers will be blind before the laser even
> gets to then.
How long before they would be armed with laser homing stingers ?
--
--
Ralf
** Don't bite my finger, look where I'm pointing **
- McCulloch -
Wayne Shaw
wrote:
>Wayne Shaw wrote:
>>
>> >It's likely that even if the power supply problems were to be
>> >worked out, slug throwers would remain the robust weapon of choice
>> >for infantry. Simple, reliable, well understood...those are major
>
>> On the other hand, slugthrower technology per se seems to have reached
>> pretty much the end of what you can do to it; while there's been some
>
>Plateaud out for a while at least, partially because the modern
>small arm is highly efficient at what it does. Not suprisingly,
>as it's the end product of what- four hundred years of intensive
>technical innovation?
Something like that. You're in the part of the curve where you have
to do a lot of work for fairly little gain in benefit.
>
>A lot of what will likely be done will be refinement of the concept
>rather then completely new innovations. Still, the field of
>integrating electronics with the weapons seems promising. And we
>haven't even started much development with exotic elements like
>liquid propellant. Frankly, a liquid-propellant rifle with a
>"smart bullet" that homes in on the target seems as SF as any
>energy weapon.
I'm not quite sure I consider binary propellant weapons orthodox
slugthrowers any more than I consider a mass driver or gyrojet weapon
one, though both technically deliver a chunk of metal to the target.
Of course, whether binary liquids can really deliver more bang than
orthodox is up in the air. As to electronics...targeting systems are
a seperate issue; a computer enchanced sight would be useful on almost
_any_ direct fire weapon.
>
>> effective lightweight fully automatic rifles). Laser weaponry is
>> still in it's infantcy, and there are obvious places where engineering
>> and technology could improve them significantly, including the areas
>> you mentioned. In the long run they might well outstrip slugthrowers
>
>Actually, based on the basic physics of involved, there may well be
>areas where slug throwers have an advantage. Penetrating armor
>is one of those areas, as there really isn't much one can do about
>that. And of course there's the factor that if power supplies
>get compact and powerful enough to let lasers outstrip chemical-
>based slugthrowers, then those power supplies would probably also
>work to make practical gauss weapons.
>
Sure, but at that point you still have some tradeoffs: absolute flat
trajectory (gauss guns would likely be better than orthodox weapons,
but it's still easier to deflect a pellet than a beam once you get to
high energy lasers) and the fact you have to shlep _both_ the power
supply and the ammo. As to penetration...it's hard to say. The vapor
burst effect is naturally a problem, but I've heard discussion of
using heat spalling to your benefit, so I think the issue is still
somewhat up in the air.
Eric Stevenson
: The low-tech countermeasure is smoke cover. The resources required to
: continuously entrench ones soldier in smoke I am not so sure about.
: Certainly this would not be too difficult to maintain for days or weeks.
: But for a longer campaign?
I hadn't thought of this, and it's a good point. Its does run into a
similar problem to the 'never look at the sky' counter measure:
visibility is heavily restricted. Or not. Perhaps a diffuse cloud would
allow enough visibility for infantry while still stopping the laser.
This is still a lot of trouble, and that's kind of the point. Initially,
a blinding laser would be a powerful weapon, and so counter measures
would be introduced, and the laser would become much less useful. I
haven't yet seen defenses that are cheap and easy enough to convince me
that the laser would be rendered useless, except maybe the peril-sensitive
goggles, depending on how effective they are.
The laser would go from a killer to a dangerous nuisance, interfering
with normal operations by requiring the countermeasures to be employed.
Perhaps even the peril-sensitive goggles could be defeated by a laser
capable of illuminating a large area on a semi-continuous basis, since
the goggle wearers would now experience temporary blindness while their
goggles were darkened. Perhaps a laser of this scale would not be
practical, though.
: The high-tech countermeasure is to shoot down that C-130 with an
: anti-aircraft laser. Of course practical blinding lasers are here
: today, and it is anybodies guess when battlefield AA lasers will arrive.
Another good point. I mentioned the AWACS plane as a comparison because
it is another big, slow, obvious object that manages to survive. If long
range AA lasers are available, planes will have to hide from them. Or
perhaps not. I would guess that a blinding laser would have greater range
than a damaging laser, since it doesn't have to have such a high energy
density on the target.
Eric Stevenson
: Eric Stevenson <es...@umr.edu> wrote:
: > Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
: > sweep over the battlefield like a searchlight, covering large amounts of
: > territory rapidly, over a long range, and has line of sight to almost
: How long before they would be armed with laser homing stingers ?
When your soldiers have laser homing stingers with a range of a hundred
miles, I'll quit using my airborne laser. As I mentioned, this is like an
AWACS plane. It's big, slow, and very easy to spot. It survives by
staying far from the enemy and having good fighter coverage. For now,
the AWACS plane is usable, so the laser plane will be as well.
Eric Stevenson
: Eric Stevenson wrote:
: > Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
: > sweep over the battlefield like a searchlight, covering large amounts
: Leaving aside the ethical questions, I can think of some technical
: problems with the idea. But this may be something worth tossing
: over to rec.arts.sf.science to let them pick at. Do you want to
: port it over?
Why not?
Luke Campbell
> Luke Campbell wrote:
> >
> > At UV frequencies and above, the intensity of the beam is not an issue, each individual
> > UV photon has enough energy to ionize a molecule of oxygen, nitrogen, water, or CO_2, so
> > it will be rapidly absorbed. This is regardless of the total intensity. UV lasers,
> > except at a few windows very near the visible spectrum, will be rapidly absorbed by air.
>
> Is there any reason why a laser weapon could not be produced with its
> frequency in one of the windows you mention? Or ought I to retcon laser
> weapons in Flat Black to visibile frequencies?
Absolutely no reason whatsoever. In fact, lasers exist today that operate in those
frequencies (about 400 to 300 nm wavelength). At these bands, the UV light will not produce
ionization through the photoionization effects described above, only through classical
electric field effects. However, the intensity of light necessary to ionize air through
electric field effects goes as the fourth power of the frequency, so unless your laser is
very tightly focused (or has an amazingly powerful beam) there will be no ionization. Of
coures, to attain a very tight focus, you need a wide beam to start out with or diffraction
effects will quickly spread the beam. This means that a near visible UV beam in one of the
windows of transparency will not have the extremely obvious ionization trail along its entire
length, at most only very near the target. Light scattered from the beam itself will not be
visible either, unless you have special optics (or are a bird, reptile, or insect, which can
apparently see into the UV A band). At most, you will have a sparkly beam as isolated dust
particles floating in the air are heated to incandescence.
Rayleigh scattering from air molecules also goes up as the fourth power of the frequency, so
UV light will scatter more from the beam path than visible or IR. This means that at the
higher frequencies in the atmospheric UV window, you could easily get the sunburn effects you
described. If the photon energies are high enough to cause radiation related cell death
(that is what causes sunburn), wounds caused by the laser may never heal, due to the death of
the tissue immediately around the wound.
> > absorbed. Unfortuneately, if the beam starts out very narrow, it will quickly diffract
> > until it is quite wide. When it is wide, it will be ionizing a lot of atmosphere which
> > will be absorbing a lot of energy from the beam before the atmosphere is cooked away.
> > This greatly limits the range of such a UV laser to a few meters.
>
> That isn't much of a problem. Smallarms are mostly used at a range of
> five metres or less. And my back-of envelopes suggest that if you used a
> 500 nm laser with a 5mm objective, fixed focus to a classical point at
> 50m, the beam would still be only 5mm wide at 50m. That should be enough
> for a handgun, shouldn't it?
A 5mm beam will be expending a lot of energy just ionizing the air (if you are going for the
air-ionizing lasers). The calculations I used all assumed beam diameters from 0.3 to 0.1 mm,
giving a cross sectional area across the beam of 250 to 2500 times smaller than the 5mm
diameter you described, thus, with a 5mm beam, your ranges will be reduced by a factor of 250
to 2500 (I still have the original notes for these calculations around somewhere... . They
involve a lot of approximations, but give a rough estimate of the atmospheric performance of
ionizing beam weapons). Starting with a 0.3 mm beam will give major problems keeping a
collumated beam due to diffraction effects at UV frequencies. This is less of a problem with
x-ray and gamma ra y lasers, of course.
Incidently, 500 nm is smack in the middle of the visible spectrum, blue-green, if I recall
correctly. The visible range goes from around 700 to 750 nm (deep red, depends on the person
viewing, some can seem longer wavelengths than others) to 400 nm (violet). I believe the
shortest wavelengths that can be transmitted by the atmosphere are somewhere around 200 to
250 nm, but I may be mistaken, I do known that 290 nm UV passes throught the atmosphere since
this is the wavelength that synthesizes vitamin D from its precursors in living vertebrates.
Hope this helps,
Luke
Luke Campbell
> Luke Campbell wrote:
> >
>
> > Light can (and does) scatter off of air molecules. This is why the sky is
> > blue - blue light scatters more than red light, so beams of sunlight
> > passing through the air overhead get blue light scattered out of them so
> > that we can see them.
>
> Are you sure? I would have thought that light would only scatter off
> particles with a diameter comparable to the wavelength of the light. And
> I thought the it was scattering by dust that made the sky blue and
> sunsets red.
Yup. Put a molecule in an electric field. The molecule becomes polarized as
the electron cloud is attracted one way and the oppositely charged nucleus is
attracted in the other direction. Light is an electromagnetic wave. It has an
electric field that oscilates back and forth (at the frequency of the light,
obviously). A molecule in the electric field of this light will be alternately
polarized one way and then the other as the electric field oscilates. This
causes the charge carriers to accelerate as they move back and forth, and
accelerated electric charge produces radiation at the frequency at which it is
accelerated. Thus, each molecule acts as a tiny antenna radiating light of the
frequency of the light that is going past it. This means that the molecule is
scattering the light from its original direction (it reduces the amplitude of
the light beam as well, the "forward scattered" light interferes with the
incident light to negate part of the incident beam. As expected, the energy of
the forward scattered beam that is negated by this process is equal to the
energy radiated elsewhere).
This process is called Rayleigh scattering. The formula for the Rayleigh
scattering cross section of a molecule is given in Jackson's standard text on
electrodynamics titles "Classical Electrodynamics". The formula is
sigma(nu)=8 pi/3 (2 pi nu/c)^4 alpha^2(nu)
where I am neglecting the anisotropic component of the scattering due to the
isotropic distribution of the orientation of the air molecules. Here, sigma is
the cross section, nu is the frequency of light, c is the speed of light in
vacuum, alpha is the polarizability of the molecule, and pi is the ratio
between the circumferance and diameter of a circle in a Euclidan plane
(=3.14...).
The 71st edition of the CRC lists the polarizability of nitrogen as
alpha=1.7*10^-24 cm^3. This is the static polarizability, the polarizability
at optical frequencies may be "off by several percent", close enough for this
estimate.
The mean free path, lambda, of light is defined as the distance at which a beam
of light is reduced in intensity by a factor of the inverse of the base of the
natural logarithm (1/e = 0.368...), and can be found by lambda=1/(sigma *
number density), where the number density is the number of scattering molecules
per unit volume. This gives a mean free path in dry nitrogen at STP of
lambda=25 km for violet light at 400 nm, lambda=175 km for red light at 650
nm. Since the polarizabilities of oxygen and argon (the other two major
components in our atmosphere) are both 1.6*10^-24 cm^3 to two significant
digits, we can take these mean free paths to be representative of the mean free
path of light in a perfectly clean atmosphere. The intensity I of light after
passing a distance x through the air will thus be I=Io exp(-x/lambda), where Io
is the initial intensity of the light.
Let us consider these numbers for a moment to see if they make sense. At
midday, sunlight does not have to penetrate more than a few kilometers of air
(actually, we need to consider collumn density since the atmosphere becomes
more rarefied at higher elevations, for these purposes I am ignoring this), a
small percentage of the blue light will be scattered from the incident light
but almost no red light will be scattered, so sunlight will still appear white
while the sky is blue. At sunset, the sunlight must pass through several tens
of kilometers of air, so most of the blue light will have been scattered from
the beam while much of the red light is still present, so the sun appears red
at sunset.
So how bright is a laser beam passing through air? The amount of light
radiated from the beam is (-1 times) the rate at which the beam intensity
decreases with distance, or -dI/dx=Io/lambda*exp(-x/lamda)=I/lambda. Thus, if
we have a combat laser with a 10 kilojoule pulse of 650 nm red light, the beam
will be radiating 10 kJ/175 km=0.06 J/m. If we assume that the human eye has
an integration time of 1/25 of a second (that is, it collects light over a 1/25
second interval to make one "picture" to send to the brain, so flashes less
than 1/25 second long look as if they are 1/25 second long), the beam will look
as bright as a red streak radiating 25*0.06=1.4 watts/meter. Consider that a
fluorescent tube puts out about one to two watts per meter, and you can see
that even this low powered combat laser operating in the part of the visible
range with the least amount of scattering will still be quite visible in
daylight. Higher energy pulses, or higher frequencies, will scatter even more
light and be even more visible.
Dust, pollen, mist, and smoke will, of course, scatter even more light, and
cause an even more pronounced effect.
Cheers,
Luke
Luke Campbell
target will make a VERY bright flash of light. The flash will be of the same
color as the laser beam. This is due to the light from the laser that is
scattered from the target rather than absorbed by the target. This flash is
likely to be much brighter than a flashbulb or high intensity spotlight, and
may well obscure other visual effects, such as the light scattered from the
actual beam itself. Persons near the target that was hit and looking at the
target may well be dazzled or even blinded (temporarily or possibly
permanently) by the flash. This flash is likely to be the most obvious effect
of any kind from visible light lasers.
Luke
Brett Evill
>
> Light can (and does) scatter off of air molecules. This is why the sky is
> blue - blue light scatters more than red light, so beams of sunlight
> passing through the air overhead get blue light scattered out of them so
> that we can see them.
Are you sure? I would have thought that light would only scatter off
particles with a diameter comparable to the wavelength of the light. And
I thought the it was scattering by dust that made the sky blue and
sunsets red.
Regards,
Brett Evill
Brett Evill
>
> At UV frequencies and above, the intensity of the beam is not an issue, each individual
> UV photon has enough energy to ionize a molecule of oxygen, nitrogen, water, or CO_2, so
> it will be rapidly absorbed. This is regardless of the total intensity. UV lasers,
> except at a few windows very near the visible spectrum, will be rapidly absorbed by air.
Is there any reason why a laser weapon could not be produced with its
frequency in one of the windows you mention? Or ought I to retcon laser
weapons in Flat Black to visibile frequencies?
> absorbed. Unfortuneately, if the beam starts out very narrow, it will quickly diffract
> until it is quite wide. When it is wide, it will be ionizing a lot of atmosphere which
> will be absorbing a lot of energy from the beam before the atmosphere is cooked away.
> This greatly limits the range of such a UV laser to a few meters.
That isn't much of a problem. Smallarms are mostly used at a range of
five metres or less. And my back-of envelopes suggest that if you used a
500 nm laser with a 5mm objective, fixed focus to a classical point at
50m, the beam would still be only 5mm wide at 50m. That should be enough
for a handgun, shouldn't it?
Regards,
Brett Evill
Brett Evill
>
> I suppose an optimum system would be peril sensitive
> goggles which go black if scattered blinding laser is detected
> (to give it the time to respond) and a backup video system
> so blinding laser can't be used to cover an advance...
That sounds feasible. 'Peril-sensitive' welder's goggles and masks are
commercially available, and I understand that the US Air Force has even
better ones for the crews of nuclear bombers.
Regards,
Brett Evill
Brett Evill
>
> Hope this helps,
It does. Thank you.
Brett Evill
Mr. M.J. Lush
>Another good point. I mentioned the AWACS plane as a comparison because
>it is another big, slow, obvious object that manages to survive. If long
>range AA lasers are available, planes will have to hide from them. Or
>perhaps not. I would guess that a blinding laser would have greater range
>than a damaging laser, since it doesn't have to have such a high energy
>density on the target.
The plane will have to be totally blacked while using the
blinding laser because a) you could use a blinding laser in an AA role
and b) simple corner reflectors (1) scattered over the battlefeald
would be capable of returning the laser fire directly to the attacking plane
(1) Corner reflectors ie three mirrors at right angles to each other
reflect any beam of light directly back to its source.... Come to think
of it this may make blinding lasers a very dangerous proposition to use
since they are not powerful enough to damage the reflector attacking laser
fire could be returned unto the aggressor (this may not annoy the plane
but it would certainly vex any friendly troops in the area if a glitter-ball
was used instead of a corner reflector)
--
Michael Ban DHMO Now!! <http://www.dhmo.org/>
Mr. M.J. Lush
>Wolter RC <rcwo...@rescue.cs.vu.nl> wrote:
>: > Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
>: > territory rapidly, over a long range, and has line of sight to almost
> ^^^^^^^^^^
>: How long before they would be armed with laser homing stingers ?
>
>When your soldiers have laser homing stingers with a range of a hundred
>miles,
I dont think you'll get a blinding laser to work over a hundred
miles range, smoke, mist, rain, cloud and terrain is going to get in
the way.. the only place you'll get 100 miles is in the Middle East.
Remember you'll also have to fly below cloud cover AWACS planes don't do
that.
> I'll quit using my airborne laser. As I mentioned, this is like an
>AWACS plane. It's big, slow, and very easy to spot. It survives by
>staying far from the enemy and having good fighter coverage. For now,
>the AWACS plane is usable, so the laser plane will be as well.
Luke Campbell
> Which begs the question - who is going to want to use a laser rifle,
> if seeing it hit the target is likely to blind the firer? It could be
> avoided by a sight that blanks out when you pull the trigger, but that
> doesn't help your buddies who happen to be looking the same way.
This is a serious issue. If the main danger is dazzling or temporary blindness,
you could just use a laser tuned to the near infrared or near ultraviolet,
especially if you were fighting some funky science fiction race that could see
into the infrared or ultraviolet. On the other hand, if the intensity of the
flash is enough to cause permanent vision problems, the frequency will not matter,
your eyesight will be damaged by the light focused on your retina whether or not
you can actually see it. I do not know, off the top of my head, at what power
levels the diffusely scattered light from a laser can cause permanent eye damage
(the light from the direct beam, or from specular reflection, can of course, cause
blindness even at low power levels).
If blinding, either permanent or temporary, is an issue, troops with laser weapons
will likely have protective eyegear that turns black the instant it is exposed to
high intensity light, and becomes transparent as soon as the light levels return
to normal. If the combat lasers are not tuneable, these special goggles may even
be frequency specific to the particular frequency of light emitted by the laser,
all other light gets past even when the goggles are opaque to the laser light.
Permanent blinging effects from diffusely scattered light may severely limit the
roles of laser weapons for peacetime purposes such as law enforcement or hunting.
If the most the laser did to vision was merely dazzle those looking at the target
and not wearing special goggles, this may not be so much of an issue and may, in
fact, make them popular with the cops.
Luke
Jim Davies
Which begs the question - who is going to want to use a laser rifle,
if seeing it hit the target is likely to blind the firer? It could be
avoided by a sight that blanks out when you pull the trigger, but that
doesn't help your buddies who happen to be looking the same way.
Jim Davies
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Eric Pawtowski
> In article <3845634f$1...@news.cc.umr.edu>, Eric Stevenson <es...@umr.edu> wrote:
> >Wolter RC <rcwo...@rescue.cs.vu.nl> wrote:
> >: Eric Stevenson <es...@umr.edu> wrote:
> >: > Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
> >: > sweep over the battlefield like a searchlight, covering large amounts of
> >: > territory rapidly, over a long range, and has line of sight to almost
>
> I dont think you'll get a blinding laser to work over a hundred
> miles range, smoke, mist, rain, cloud and terrain is going to get in
> the way.. the only place you'll get 100 miles is in the Middle East.
> Remember you'll also have to fly below cloud cover AWACS planes don't do
> that.
I agree with the above. The ABL (Air Borne Laser) the Air Force is working
on is a 747 with a laser turret in the nose, designed to shoot down balistic
missiles
shortly after they launch (theoreticaly it could shoot at an incoming ICBM, but
the targeting system won't be able to handle anything moving that fast). This
is a *large* laser, it will fill the entire plane. Chemicaly powered, and
the plane only gets on the order of a dozen shots before it's out of
chemicals.
It will fly above the clouds, and will only fire at missiles that are also above
all cloud cover. It would not be that great at hitting ground targets, the
atmosphere is too thick and filled with too much junk, particularly near
battlefields.
This is still something of an experimental program- the first plane to
be laser-equipped is still in the factory. Most of the elements that
make up the laser have been tested individually in labs, but the
full system has not been assembled and tested as a whole yet.
Eric Tolle
> : > Let's put a big-ass blinding laser in a plane, perhaps a C-130. It can
> : > sweep over the battlefield like a searchlight, covering large amounts
>
> : problems with the idea. But this may be something worth tossing
> : over to rec.arts.sf.science to let them pick at. Do you want to
> : port it over?
> Why not?
Why not indeed? I'll be looking for it.
Eric Tolle
> >Plateaud out for a while at least, partially because the modern
> >small arm is highly efficient at what it does. Not suprisingly,
> Something like that. You're in the part of the curve where you have
> to do a lot of work for fairly little gain in benefit.
True. Though there's still a possibility we may see another burst
of innovation based on a currently unforeseen technological
development. I wouldn't hold my breath though.
> >A lot of what will likely be done will be refinement of the concept
> >rather then completely new innovations. Still, the field of
> >integrating electronics with the weapons seems promising. And we
> >haven't even started much development with exotic elements like
> >liquid propellant. Frankly, a liquid-propellant rifle with a
> >"smart bullet" that homes in on the target seems as SF as any
> >energy weapon.
>
> I'm not quite sure I consider binary propellant weapons orthodox
> slugthrowers any more than I consider a mass driver or gyrojet weapon
> one, though both technically deliver a chunk of metal to the target.
I'd consider them at least as orthodox as say, putting powder in a
cartridge rather then pouring it down the rifle barrel. Either
way your using a combustion reaction to send a slug to a target.
Likewise I'd consider similar esoteria like gyrojet weapons to be
slugthrowers as well.
> Of course, whether binary liquids can really deliver more bang than
> orthodox is up in the air. As to electronics...targeting systems are
> a seperate issue; a computer enchanced sight would be useful on almost
> _any_ direct fire weapon.
True- I agree that liquid propellants are highly speculative at
this point. As for electronics...try putting electronics in the
bullet- make it laser homing, or give it aerodynamic controls to
keep on course. I've done similar "smart bullet" technology in
write-ups for both Alternity and Trinity- both gave the effect of
making "plain" slugthrowers more futuristic...without getting into
that odious cyberpunk mentality.
> >Actually, based on the basic physics of involved, there may well be
> >areas where slug throwers have an advantage. Penetrating armor
> >is one of those areas, as there really isn't much one can do about
> >that. And of course there's the factor that if power supplies
> >get compact and powerful enough to let lasers outstrip chemical-
> >based slugthrowers, then those power supplies would probably also
> >work to make practical gauss weapons.
> >
>
> Sure, but at that point you still have some tradeoffs: absolute flat
> trajectory (gauss guns would likely be better than orthodox weapons,
> but it's still easier to deflect a pellet than a beam once you get to
> high energy lasers) and the fact you have to shlep _both_ the power
I agree about the power-source + bullets problem with the gauss
weaponry. Frankly, I'm not sure what real advantage a gauss rifle
would give (other then the ability to make a high-tech blunderbuss;
toss anything ferrous down the barrel).
I suppose I could make a qualified statement that if you get power
supplies small and powerful enough, and if you develop high-
efficiency, high power lasers, and if you get the heat buildup and
focusing issues dealt with..._then_ you may have hand lasers that
outstrip slugthrowers. There. That good enough? ;'/
In the final analysis from a game designer POV, utility aside and
outside of a scenario that prohibits them (like Albedo) it's lasers
or _some_ sort of energy weapon are likely to be on the weapon's
list, because players expect them. Otherwise they're going to be
wandering around muttering "If this is the future, where's the
phaser guns?" ;')
Nis Haller Baggesen
> I agree about the power-source + bullets problem with the gauss
> weaponry. Frankly, I'm not sure what real advantage a gauss rifle
> would give (other then the ability to make a high-tech blunderbuss;
> toss anything ferrous down the barrel).
Well I could think of some other advatages - They are just suggestions and
since I'm no gun-smith I might be way of the mark.
Since each bullet does not need to carry its own power source, as it is the
case with standard slugthrowers, bullets would take up much less space, and
weigh less, so you could carry around many more. Of course the weight of
the powerpack might counter this, but it might be an advatage for weapons
installations. But it would counter some of the powerpack plus ammo
problem.
Also since you can launch anything you can affect with a magnetic field,
ammo would be easy to produce. If the powerpack is easily recharged (Using
solar power or something like that) it would be a good choice for people
working far from civilisation - Like scouts, guerilla soldiers, space
colonists etc.
In the same track you would be able to lauch 'anything' that carries a
current. And a projectile might experiece less stress, since the intire
projectile would be affected equally, and not simply pushed out from
behind. This might make gauss weapons more 'friendly' to 'intelligent'
bullets, since electronics might be damaged by the sudden jolt experienced
in at conventional slugthrower.
Lowered stress might also make higher exit velocities possible.
Ans since the bullets would have no casings that have to be removed, and
since the barrel woul not be heated up by friction and exploding gunpowder,
you could achieve a higher rate of fire.
Fewer moving parts (You don't have to remove casings, there is no firing
pin) and the lack of gunpowder in the barrel might mean lesser maintenance.
You might be able to use a variety of new projectile shapes, like discs for
cutting people up, super thin needles for piercing armour, barbs to
complicate the removal of the projectile, even bolas to trip people up.
Weapon designers could propably come up with more ideas. These projectiles
would propably be harder to implement in conventional slugthrowers since
they require that the projectile has a surface to push against.
You might be able to create smaller projectiles, and since that wouldn't
mean less gunpowder it wouldn't necessarily mean less punch from the
projectile, since you could increase the exit velocity. But it would mean
less recoil, since that comes form the momentum of the bullet.
You would also be able to adjust the power of the weapon to the needed
level. That way you might be able to simply stun soldiers, while you still
carry the punch to fire through a tank (Depending on the effectiveness of
the powercell etc.)
You would always have a battery handy, if you needed it for some other
equipment. And vice versa. Not to talk of the electromagnet - PC's can find
a lot of uses for that.
A gauss gun would work in space, without any extra space-proofing.
No muzzleflash, no sound from exploding propellant, no rifling or pin-marks
on the bullet. That might be advantages in some cases.
There are propably more advantages, but it can't think of them right now.
mvh
Nis
Luke Campbell
> Eric Tolle wrote:
>
> Since each bullet does not need to carry its own power source, as it is the
> case with standard slugthrowers, bullets would take up much less space, and
> weigh less, so you could carry around many more. Of course the weight of
> the powerpack might counter this, but it might be an advatage for weapons
> installations. But it would counter some of the powerpack plus ammo
> problem.
Since you could carry the powerpack on your back or at your belt rather than
attached to the weapon, it would cut down on the bulk of the weapon.
> In the same track you would be able to lauch 'anything' that carries a
> current. And a projectile might experiece less stress, since the intire
> projectile would be affected equally, and not simply pushed out from
> behind. This might make gauss weapons more 'friendly' to 'intelligent'
> bullets, since electronics might be damaged by the sudden jolt experienced
> in at conventional slugthrower.
Somehow I think that extreme magnetic fields and super-high electric currents
will not be friendly to electronics. If you shield the electronics from the
electric and magnetic effects of launch, then they are subjected to the
inertial effects of launch.
> Lowered stress might also make higher exit velocities possible.
>
> Ans since the bullets would have no casings that have to be removed, and
> since the barrel woul not be heated up by friction and exploding gunpowder,
> you could achieve a higher rate of fire.
The barrel would be heated up by electrical resistance from conducting the
high currents necessary to generate the magnetic field and to pass through the
projectile so that the magnetic field has something to act on. Of course, if
you assume room temperature superconductors with very high critical fields, or
near zero resistance carbon nanotube wires, you might eliminate this problem.
One of the main problem with current electromagnetic propulsion devices is
that they heat up so much during firing that they need a long time to cool
off.
> You might be able to create smaller projectiles, and since that wouldn't
> mean less gunpowder it wouldn't necessarily mean less punch from the
> projectile, since you could increase the exit velocity. But it would mean
> less recoil, since that comes form the momentum of the bullet.
High velocity projectiles also mean a flatter trajectory, making the weapon
easier to aim at long distances. It also means a smaller cross sectional area
for a given projectile energy, and thus greater armor penetration. At extreme
velocities (5+ km/s) the projectile will vaporize when it strikes solid
material, and act much like an explosive or energy weapon in this respect,
except that when the bullet vapor recondenses, it is still a high velocity jet
of abrasive particles that give it excellent armor penetration, much like a
shaped charge warhead.
Nis Haller Baggesen
> Nis Haller Baggesen wrote:
>
> > Eric Tolle wrote:
> >
> > Since each bullet does not need to carry its own power source, as it is the
> > case with standard slugthrowers, bullets would take up much less space, and
> > weigh less, so you could carry around many more. Of course the weight of
> > the powerpack might counter this, but it might be an advatage for weapons
> > installations. But it would counter some of the powerpack plus ammo
> > problem.
>
> Since you could carry the powerpack on your back or at your belt rather than
> attached to the weapon, it would cut down on the bulk of the weapon.
>
> > In the same track you would be able to lauch 'anything' that carries a
> > current. And a projectile might experiece less stress, since the intire
> > projectile would be affected equally, and not simply pushed out from
> > behind. This might make gauss weapons more 'friendly' to 'intelligent'
> > bullets, since electronics might be damaged by the sudden jolt experienced
> > in at conventional slugthrower.
>
> Somehow I think that extreme magnetic fields and super-high electric currents
> will not be friendly to electronics. If you shield the electronics from the
> electric and magnetic effects of launch, then they are subjected to the
> inertial effects of launch.
There is that - I actually thought about it when I wrote the post, but I must
have forgotten to mention it. But if the technology is available you could use
optical system - They might not be affected as much by magnetic fields. Or you
could switch the electronics on just after the projectile leaves the barrel. But
true - It was a long shot, that this would be an advantage.
> > Lowered stress might also make higher exit velocities possible.
> >
> > And since the bullets would have no casings that have to be removed, and
> > since the barrel woul not be heated up by friction and exploding gunpowder,
> > you could achieve a higher rate of fire.
>
> The barrel would be heated up by electrical resistance from conducting the
> high currents necessary to generate the magnetic field and to pass through the
> projectile so that the magnetic field has something to act on. Of course, if
> you assume room temperature superconductors with very high critical fields, or
> near zero resistance carbon nanotube wires, you might eliminate this problem.
> One of the main problem with current electromagnetic propulsion devices is
> that they heat up so much during firing that they need a long time to cool
> off.
Since superconducting wire is one of the best bets for high capacity, low volume
batteries I've see, I was propably assuming the superconductors would be
available, if you had energy weapons. But I should have stated it explicitly of
course.
> > You might be able to create smaller projectiles, and since that wouldn't
> > mean less gunpowder it wouldn't necessarily mean less punch from the
> > projectile, since you could increase the exit velocity. But it would mean
> > less recoil, since that comes form the momentum of the bullet.
>
> High velocity projectiles also mean a flatter trajectory, making the weapon
> easier to aim at long distances. It also means a smaller cross sectional area
> for a given projectile energy, and thus greater armor penetration. At extreme
> velocities (5+ km/s) the projectile will vaporize when it strikes solid
> material, and act much like an explosive or energy weapon in this respect,
> except that when the bullet vapor recondenses, it is still a high velocity jet
> of abrasive particles that give it excellent armor penetration, much like a
> shaped charge warhead.
Well - Seems I had one good point after all ::)
Nis
Luke Campbell
> > High velocity projectiles also mean a flatter trajectory, making the weapon
> > easier to aim at long distances. It also means a smaller cross sectional area
> > for a given projectile energy, and thus greater armor penetration. At extreme
> > velocities (5+ km/s) the projectile will vaporize when it strikes solid
> > material, and act much like an explosive or energy weapon in this respect,
> > except that when the bullet vapor recondenses, it is still a high velocity jet
> > of abrasive particles that give it excellent armor penetration, much like a
> > shaped charge warhead.
>
> Well - Seems I had one good point after all ::)
A neat visual effect of these ultra high velocity projectiles is that atmospheric
friction will heat both the surface of the projectile and the atmosphere it passes
through into an incandescent vapor. Firing the weapon will cause a bright streak
in just the same way that pinhead sized micrometeors become shooting stars when
they hit earth's atmosphere. With a visible "bolt" or "beam" and an explosion at
the target when the projectile hits, the ultra high velocity mass driver weapon
will resemble a beam weapon.
Luke