Carmack's Jet Vanes
Tom Merkle
John Carmack's switched from a multi-engine vehicle to a vehicle with
one big engine controlled with Jet Vanes.
http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=256">
Carmack says the jet vanes only subtract "a few percent" from the
engine due to drag, and there's small danger of them eroding in his
engine due to the lower temperatures than w/ traditional fuels.
Anybody heard of previous work done along these lines? Or is Armadillo
breaking some major new ground here? (I mean besides cost-wise.)
Any useful links would be appreciated.
Tom Merkle
Ruediger Klaehn
[snip]
> Anybody heard of previous work done along these lines? Or is Armadillo
> breaking some major new ground here? (I mean besides cost-wise.)
>
I think the german A4/V2 rocket used jet vanes. So this is not really new.
The nice thing about the armadillo mixture is that it burns so cold that
you do not need exotic materials for the rudders. They look like steel.
Derek Lyons
>Anybody heard of previous work done along these lines? Or is Armadillo
>breaking some major new ground here? (I mean besides cost-wise.)
There's a lot of previous work on jet vanes, but it's all quite old.
D.
--
Touch-twice life. Eat. Drink. Laugh.
jjrobinson2
"Ruediger Klaehn" <kla...@gamemakers.de> wrote in message
news:c7agh3$1jnr0$1...@ID-152049.news.uni-berlin.de...
I think Goddard had a gyro-steered vane scheme on some of his rockets
(http://www.astronautix.com/graphics/g/god37van.jpg). I also seem to
remember seeing this kind of thing on Redstones
(http://www.boeing.com/history/bna/redstone.htm, V2 derivative?). I didn't
read far enough into Carmack's description to understand why they want to go
back to such a "retro" steering scheme.
JJ Robinson II
Houston, TX
****************
* JOKE *
****************
*> SERIOUS <*
****************
* SARCASTIC *
****************
* OTHER? *
****************
John Schilling
>http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=256">
If by "links" you mean the www type, there is a slight problem in that
all the groundbreaking work was done before the invention of the digital
computer, much less the internet. So no, it's not new. Werner von Braun
and his crew were aiming for the stars and hitting London with rockets
steered by jet vane (and burning hotter than Carmack's mixed monoprop)
before most of us were born.
It does mean, as with so much of the really good technology in this field,
that to make use of it you have to actually, physically, delve into old
dusty archives that nobody ever bothered to html-ize.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schi...@spock.usc.edu * for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *
John Carmack
We certainly aren't doing anything new -- jet vanes are literally the
oldest trick in the book for steering rockets, and they are still
commonly used for various tactical missiles. The disadvantages are
well known: slight loss of performance and erosion issues.
In our particular case, the disadvantages don't really matter. Anyone
stressing over a few percent performance in a suborbital vehicle
doesn't have their priorities in the right order, and our exhaust
temperatures are low enough that stainless steel can run forever in it
without any erosion.
The advantages are in practical matters like less plumbing, easier
checkout, and no need to make multiple engines behave identically.
Practical matters are often not appreciated by people not involved in
actual vehicle construction -- I have gotten literally dozens of
emails with suggestions of adding "a few more engines" for various
schemes.
We are making fast progress on a bigger jet vane system for the full
scale vehicle, so there is an excellent chance we will have that in
the air next weekend.
John Carmack
www.armadilloaerospace.com
Derek Lyons
>The advantages are in practical matters like less plumbing, easier
>checkout, and no need to make multiple engines behave identically.
>Practical matters are often not appreciated by people not involved in
>actual vehicle construction
I.E. the vast majority of the aerospace industry, professional,
semi-professional, garage, and amateur.
John Schilling
>jo...@idsoftware.com (John Carmack) wrote:
>>The advantages are in practical matters like less plumbing, easier
>>checkout, and no need to make multiple engines behave identically.
>>Practical matters are often not appreciated by people not involved in
>>actual vehicle construction
>I.E. the vast majority of the aerospace industry, professional,
>semi-professional, garage, and amateur.
Quite the opposite w/re the "garage" segment, by definition I should think.
Professional, yes, most aerospace engineering degrees belong to people who
will never touch flight hardware and never put ink to paper on working
drawings of flight hardware. Ditto amateur if we open that up to armchair
critics, which I suspect is where many of the comments Carmack refers to
are coming from.
Pete Lynn
news:c0e0a1dd.04050...@posting.google.com...
>
>
> The advantages are in practical matters like less plumbing, easier
> checkout, and no need to make multiple engines behave
> identically. Practical matters are often not appreciated by people
> not involved in actual vehicle construction -- I have gotten
> literally dozens of emails with suggestions of adding "a few more
> engines" for various schemes.
>
Speaking of fewer extra engines, I have wondered if instead of using
many maneuvering jets pointing in every direction, with extras for
redundancy. It might be easier to use but three or four with
directional control, say the capacity to individually point up, down,
left, right, and directly outward. With advances in control systems
over the past thirty years, I am no longer sure which approach would be
best.
Pete.
Dick Morris
John Carmack wrote:
>
> Ruediger Klaehn <kla...@gamemakers.de> wrote in message news:<c7agh3$1jnr0$1...@ID-152049.news.uni-berlin.de>...
> > Tom Merkle wrote:
> >
> > [snip]
> > > Anybody heard of previous work done along these lines? Or is Armadillo
> > > breaking some major new ground here? (I mean besides cost-wise.)
> > >
> > I think the german A4/V2 rocket used jet vanes. So this is not really new.
> > The nice thing about the armadillo mixture is that it burns so cold that
> > you do not need exotic materials for the rudders. They look like steel.
>
> We certainly aren't doing anything new -- jet vanes are literally the
> oldest trick in the book for steering rockets, and they are still
> commonly used for various tactical missiles. The disadvantages are
> well known: slight loss of performance and erosion issues.
>
> In our particular case, the disadvantages don't really matter. Anyone
> stressing over a few percent performance in a suborbital vehicle
> doesn't have their priorities in the right order, and our exhaust
> temperatures are low enough that stainless steel can run forever in it
> without any erosion.
>
> The advantages are in practical matters like less plumbing, easier
> checkout, and no need to make multiple engines behave identically.
> Practical matters are often not appreciated by people not involved in
> actual vehicle construction -- I have gotten literally dozens of
> emails with suggestions of adding "a few more engines" for various
> schemes.
>
Another practical matter would be coupling between thrust-vector (or
aerodynamic) control systems, and propellant slosh, body-bending, or
other structural modes. (On SRAM we had digitally programmable notch
filters in the pitch and yaw commands going to the Fin Actuation
System.)
> We are making fast progress on a bigger jet vane system for the full
> scale vehicle, so there is an excellent chance we will have that in
> the air next weekend.
>
Good luck!
> John Carmack
> www.armadilloaerospace.com
Earl Colby Pottinger
> The advantages are in practical matters like less plumbing, easier
> checkout, and no need to make multiple engines behave identically.
> Practical matters are often not appreciated by people not involved in
> actual vehicle construction -- I have gotten literally dozens of
> emails with suggestions of adding "a few more engines" for various
> schemes.
I am one of those interested in designs that use a large number of engines.
One problem I noticed that you seem to have with multiple motors/valves is
the power required to run the valves.
So question, with a large number of motors which is the bigger problem:
Plumbing or the power/control circuits for the valves?
Earl Colby Pottinger
--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp
Earl Colby Pottinger
> derek...@nospamyahoo.com (Derek Lyons) writes:
>
> >jo...@idsoftware.com (John Carmack) wrote:
> >>The advantages are in practical matters like less plumbing, easier
> >>checkout, and no need to make multiple engines behave identically.
> >>Practical matters are often not appreciated by people not involved in
> >>actual vehicle construction
>
> >I.E. the vast majority of the aerospace industry, professional,
> >semi-professional, garage, and amateur.
>
>
> Quite the opposite w/re the "garage" segment, by definition I should think.
> Professional, yes, most aerospace engineering degrees belong to people who
> will never touch flight hardware and never put ink to paper on working
> drawings of flight hardware. Ditto amateur if we open that up to armchair
> critics, which I suspect is where many of the comments Carmack refers to
> are coming from.
I think you are closer to the truth. Remember a couple of years ago someone
was bad mouthing everyone including JC for using Hydrogen Peroxide, tell
everyone the only good oxidzer was LOX. After a little questioning it turns
out the this person had never used, design or built a rocket on any kind.
And I am including the cheap $29 rocket with three motors that you can buy at
your local Walmart. And yes that meant they had never handle LOX but
demanded others use it.
John Carmack
> jo...@idsoftware.com (John Carmack) :
>
> > The advantages are in practical matters like less plumbing, easier
> > checkout, and no need to make multiple engines behave identically.
> > Practical matters are often not appreciated by people not involved in
> > actual vehicle construction -- I have gotten literally dozens of
> > emails with suggestions of adding "a few more engines" for various
> > schemes.
>
> I am one of those interested in designs that use a large number of engines.
> One problem I noticed that you seem to have with multiple motors/valves is
> the power required to run the valves.
>
> So question, with a large number of motors which is the bigger problem:
> Plumbing or the power/control circuits for the valves?
>
> Earl Colby Pottinger
Neither. It is building the engines and getting them to all warm up
and perform close to exactly the same. Wiring and plumbing the
engines is no big deal with our systems, although it is certainly more
work now that we have spark plugs, thermocouples, and chamber pressure
transducers. For a complex engine like XCOR's high quality biprops,
assembling a vehicle with a large quantity of engines could get to be
a chore. The plumbing and wiring for biprops with torch igniters and
the various purges does add up if you are considering highly clustered
designs.
We had always thought that we would stick with differential as long as
our engines stayed simple, but if we ever went to something complex,
we would look hard at jet vanes. Our mixed monoprop engines got more
complicated than we expected, and jet vanes turned out to be easier
than expected, so here we are...
John Carmack
www.armadilloaerospace.com
Ruediger Klaehn
[snip]
>> So question, with a large number of motors which is the bigger problem:
>> Plumbing or the power/control circuits for the valves?
>>
>> Earl Colby Pottinger
>
> Neither. It is building the engines and getting them to all warm up
> and perform close to exactly the same.
>
That is specific to engines that use some kind of catalyst, isn't it?
[snip]
> For a complex engine like XCOR's high quality biprops,
> assembling a vehicle with a large quantity of engines could get to be
> a chore. The plumbing and wiring for biprops with torch igniters and
> the various purges does add up if you are considering highly clustered
> designs.
>
Is that the reason you did not just buy engines from XCOR? Or were they too
expensive?
> We had always thought that we would stick with differential as long as
> our engines stayed simple, but if we ever went to something complex,
> we would look hard at jet vanes. Our mixed monoprop engines got more
> complicated than we expected, and jet vanes turned out to be easier
> than expected, so here we are...
>
Good Luck!
Henry Spencer
Ruediger Klaehn <kla...@gamemakers.de> wrote:
>> Neither. It is building the engines and getting them to all warm up
>> and perform close to exactly the same.
>
>That is specific to engines that use some kind of catalyst, isn't it?
Some of the warmup issues are, but matching performance isn't. For big
multi-engine rockets, for example, the engines are tested individually on
a heavily-instrumented test stand, and their performance is adjusted to
closely match the spec. As manufactured, they do vary a bit. (And this
is sometimes exploited -- when Rocketdyne was building engines by the
hundred for the big Atlas ICBM production run circa 1960, the ones with
the very highest performance got set aside for Project Mercury.)
It's even more fun with solids, which *can't* be tested beforehand.
Elaborate precautions are taken to minimize mismatches between the left
and right SRBs on the shuttle, including a rule that the corresponding
segments in the two SRBs must come from the same fuel casting run.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. | he...@spsystems.net
John Carmack
> John Carmack wrote:
>
> [snip]
> >> So question, with a large number of motors which is the bigger problem:
> >> Plumbing or the power/control circuits for the valves?
> >>
> >> Earl Colby Pottinger
> >
> > Neither. It is building the engines and getting them to all warm up
> > and perform close to exactly the same.
> >
> That is specific to engines that use some kind of catalyst, isn't it?
>
Fabricating reusable biprops is a lot more work, but they should run
more repeatably. The overall complexity of the vehicle more than
doubles, though.
> [snip]
> > For a complex engine like XCOR's high quality biprops,
> > assembling a vehicle with a large quantity of engines could get to be
> > a chore. The plumbing and wiring for biprops with torch igniters and
> > the various purges does add up if you are considering highly clustered
> > designs.
> >
> Is that the reason you did not just buy engines from XCOR? Or were they too
> expensive?
I am an investor in XCOR, but purchasing engines from them hasn't been
a real option (although we did buy a torch igniter from them) for
several reasons:
Even for an existing class of engine, pricing would have been much
higher than I spent on our own engines, even counting all the
development expenses. It would have been faster than the six+ months
we spend working out the mixed monoprop, but still more expensive.
They don't have engines in the size class that we need. Paying them
to develop them would be even more expensive.
The bigger XCOR engines are not throttleable, something that is
crucial for a powered landing vehicle.
We still feel there there are significant system and operational
advantages to monoprop propulsion over cryogenic biprops.
And finally, we like developing our own engines. We want to know our
systems from top to bottom, and we want the freedom to reconfigure
things at the drop of a hat. Plus, it is fun...
John Carmack
www.armadilloaerospace.com
Henry Spencer
John Carmack <jo...@idsoftware.com> wrote:
>And finally, we like developing our own engines. We want to know our
>systems from top to bottom, and we want the freedom to reconfigure
>things at the drop of a hat. Plus, it is fun...
And as Gary Hudson observed in the glory days of Rotary, there is
competitive advantage to be had in building your own engines. Whether it
is worth the trouble depends on how much you need extra competitive
advantage... and on how hard you think engine development is. (And, for
that matter, on how much you mind being at the mercy of an engine supplier,
given how rare it is to have two similar engines to chose from.)
Sander Vesik
>
> And finally, we like developing our own engines. We want to know our
> systems from top to bottom, and we want the freedom to reconfigure
> things at the drop of a hat. Plus, it is fun...
>
And without doing it you certainly canot start your own line of engines.
>
> John Carmack
> www.armadilloaerospace.com
--
Sander
+++ Out of cheese error +++
Tom Merkle
>
>
> If by "links" you mean the www type, there is a slight problem in that
> all the groundbreaking work was done before the invention of the digital
> computer, much less the internet. So no, it's not new. Werner von Braun
> and his crew were aiming for the stars and hitting London with rockets
> steered by jet vane (and burning hotter than Carmack's mixed monoprop)
> before most of us were born.
>
> It does mean, as with so much of the really good technology in this field,
> that to make use of it you have to actually, physically, delve into old
> dusty archives that nobody ever bothered to html-ize.
Yep, that's what I'm coming to understand. Yet it seems
(retroactively, of course) like such an obvious simplifier, based on
current technology, that I'm pretty amazed no one's recently done this
in a major way. It's closely related to other types of extreme
aviation control, like air-to-air missile control and military fighter
jet thrust-vectoring. Despite this, NASA has basically never really
touched this. Why? Because they've never done it that way. Oh, and
that few percent of performance. But as John Carmack points out above,
if you're worried about that few percent for a suborbital vehicle,
you've got your priorities in the wrong order.
Nobody knows how far Armadillo or the industry in general will be able
to take this idea. But either way, it's something nobody was really
working on five years ago.
It appears X-prize is beginning to bear fruit in just the way Peter
Diamandis always claimed it would: not just by breaking the
psychological barrier of reusable rockets, but by also launching whole
new fields of technology in completely unexpected directions! (Well,
maybe it's just me who's suprised...)
Congrats to Armadillo.
Tom Merkle
Henry Spencer
Tom Merkle <merk...@msn.com> wrote:
>...I'm pretty amazed no one's recently done this
>in a major way. It's closely related to other types of extreme
>aviation control, like air-to-air missile control and military fighter
>jet thrust-vectoring. Despite this, NASA has basically never really
Uh, NASA's first manned space missions were launched on rockets steered
by jet vanes. (Redstone used vanes.)
The reason why NASA hasn't used jet vanes recently is that NASA doesn't do
much low-performance rocketry. Vanes don't work well in hot exhaust jets
or in applications where every second of Isp is precious.
(In fact, of late NASA hasn't done much serious rocketry of any kind.)
>that few percent of performance. But as John Carmack points out above,
>if you're worried about that few percent for a suborbital vehicle,
>you've got your priorities in the wrong order.
And NASA has built how many suborbital rocket vehicles lately?
John Schilling
>schi...@spock.usc.edu (John Schilling) wrote in message news:<c7bhq9$q56$1...@spock.usc.edu>...
>> If by "links" you mean the www type, there is a slight problem in that
>> all the groundbreaking work was done before the invention of the digital
>> computer, much less the internet. So no, it's not new. Werner von Braun
>> and his crew were aiming for the stars and hitting London with rockets
>> steered by jet vane (and burning hotter than Carmack's mixed monoprop)
>> before most of us were born.
>> It does mean, as with so much of the really good technology in this field,
>> that to make use of it you have to actually, physically, delve into old
>> dusty archives that nobody ever bothered to html-ize.
>Yep, that's what I'm coming to understand. Yet it seems
>(retroactively, of course) like such an obvious simplifier, based on
>current technology, that I'm pretty amazed no one's recently done this
>in a major way.
Until recently, virtually all of the work in this field was being done
by people for whom "simplifier" was a *bad* word.
>It's closely related to other types of extreme aviation control, like
>air-to-air missile control and military fighter jet thrust-vectoring.
>Despite this, NASA has basically never really touched this. Why? Because
>they've never done it that way.
No, because other people *did* do it that way. NASA is by charter an
R&D operation, and has no business simply running an operational space
transportation system based on old technology. If Werner von Braun had
not gotten jet vanes down pat, NASA could have and probably would have
justified an extensive technology development program for jet vanes.
Because he did, NASA was motivated to find something new, anything but
jet vanes.
Which is not a *bad* thing, as some of the other systems do work better
if you can make them work right, and NASA could devote the resources to
make them work right.
But if you're not NASA, you don't necessarily want to take NASA's path.
Tom Merkle
> Until recently, virtually all of the work in this field was being done
> by people for whom "simplifier" was a *bad* word.
>
> >It's closely related to other types of extreme aviation control, like
> >air-to-air missile control and military fighter jet thrust-vectoring.
> >Despite this, NASA has basically never really touched this. Why? Because
> >they've never done it that way.
>
> No, because other people *did* do it that way. NASA is by charter an
> R&D operation, and has no business simply running an operational space
> transportation system based on old technology. If Werner von Braun had
> not gotten jet vanes down pat, NASA could have and probably would have
> justified an extensive technology development program for jet vanes.
> Because he did, NASA was motivated to find something new, anything but
> jet vanes.
I think we're cross-talking here. I mean, by that logic, NASA wouldn't
research de-icing technology or fire-related stuff because it's
operational and based on old technology. Gimme a break.
>
> Which is not a *bad* thing, as some of the other systems do work better
> if you can make them work right, and NASA could devote the resources to
> make them work right.
>
I disagree, that is a *bad* thing. What I'm saying is, although NASA
had the background and ability to research this, they never did,
because NASA's focus was on achieving the impossible at any cost.
Waste everything but time, right?
Fine, but once they bypassed that control method to achieve what they
needed in the short term, it was essentially discredited entirely as a
control method--despite the fact that, as we're seeing, very primitive
research had been done in this area. Although gimbaling works great,
it's so complex--maybe there are some applications we've been using
gimbaling for out of default when in many cases jet vanes would have
sufficed. I'm saying it hasn't generally been considered,
because...gimballing is always necessary if you're serious, right?
> But if you're not NASA, you don't necessarily want to take NASA's path.
Even NASA shouldn't necessarily had taken the path they did...
Tom Merkle
Derek Lyons
>I disagree, that is a *bad* thing. What I'm saying is, although NASA
>had the background and ability to research this, they never did,
>because NASA's focus was on achieving the impossible at any cost.
They didn't research it because they rapidly outgrew the (relatively
speaking) low thrust rockets for which vanes are suitable. Other than
low thrust vertically traveling rockets, there is essentially no need
for vanes.
>Fine, but once they bypassed that control method to achieve what they
>needed in the short term, it was essentially discredited entirely as a
>control method--despite the fact that, as we're seeing, very primitive
>research had been done in this area.
It wasn't discredited, it was abandoned as obsolete. There's a huge
difference.
> Although gimbaling works great, it's so complex--maybe there are some
>applications we've been using gimbaling for out of default when in many
>cases jet vanes would have sufficed. I'm saying it hasn't generally been
>considered, because...gimballing is always necessary if you're serious,
>right?
We use gimbaling by default in current launchers because vanes are
unsuitable.
Henry Spencer
Derek Lyons <derek...@nospamyahoo.com> wrote:
>They didn't research it because they rapidly outgrew the (relatively
Well, only sort of rapidly. Scout was in service until the early 90s.
Zzed
> Ruediger Klaehn <kla...@gamemakers.de> wrote in message news:<c7d0tn$2f98f$1...@ID-152049.news.uni-berlin.de>...
> > John Carmack wrote:
<trimmed>
> I am an investor in XCOR, but purchasing engines from them hasn't been
> a real option (although we did buy a torch igniter from them) for
> several reasons:
oh my you do have all the bases covered :>
once more i have to admire your openness in giving us the background
to your project. i read your weekly reports on
http://www.armadilloaerospace.com/n.x/Armadillo/Home - it's a
fascinating read, thanks!
a question i'm sure many would like to have answered is: how much is
it all costing and what do you expect the final cost to be?
sub astra!
Derek Lyons
>In article <40a3c1df...@supernews.seanet.com>,
>Derek Lyons <derek...@nospamyahoo.com> wrote:
>
>>They didn't research it because they rapidly outgrew the (relatively
>>speaking) low thrust rockets for which vanes are suitable...
>
>Well, only sort of rapidly. Scout was in service until the early 90s.
True. But it was a more-or-less mature vehicle, not an ongoing
development program.
John Carmack
> merk...@msn.com (Tom Merkle) wrote:
> >I disagree, that is a *bad* thing. What I'm saying is, although NASA
> >had the background and ability to research this, they never did,
> >because NASA's focus was on achieving the impossible at any cost.
>
> They didn't research it because they rapidly outgrew the (relatively
> speaking) low thrust rockets for which vanes are suitable. Other than
> low thrust vertically traveling rockets, there is essentially no need
> for vanes.
What does low thrust have to do with it? You take an efficiency hit
from sticking something in the exhaust flow, but there isn't any
inherent scalability problem. In larger engines the vanes would need
to get thicker, but it would be proportional to increased nozzle size,
so there isn't any scaling factor working against it.
BTW, vanes are used in all sorts of horizontally fired tactical
missiles today.
> > Although gimbaling works great, it's so complex--maybe there are some
> >applications we've been using gimbaling for out of default when in many
> >cases jet vanes would have sufficed. I'm saying it hasn't generally been
> >considered, because...gimballing is always necessary if you're serious,
> >right?
>
> We use gimbaling by default in current launchers because vanes are
> unsuitable.
>
> D.
In what way are they unsuitable? Launch vehicles today operate on a
wide range of propellant Isp's, from storables through lox/hydrogen,
so something can't be dismissed out of hand just because it steals a
few percent of performance.
I probably wouldn't argue for vanes in a mature system that is
undergoing incremental optimization, but I think the most important
thing for everyone to consider is that development cost is, to a first
approximation, EVERYTHING. A crummy, low performance RLV that
actually gets built and flown will be vastly more important than the
hundreds of higher performance designs that never make it off the
drawing board.
The bottom line is that in the last three years we have built and
flown vehicles with differential throttling, attitude jets, and jet
vanes, and I currently feel that jet vanes are going to make future
vehicle development easier and more reliable. Some of the benefits
are specific to our unusual propellant, but other benefits are
generic.
John Carmack
www.armadilloaerospace.com
John Carmack
We crossed the million-dollars-spent mark around the beginning of the
year. I haven't been all that frugal -- next-day shipping costs
account for a significant percentage of most of my twice-weekly
McMaster-Carr orders, and I rarely look at used or surplus deals.
With the bigger vehicles, the true costs are going up some, but it
could probably still be done for about half that if you were
scrounging and not trying to do multiple things at the same time. It
would take a lot longer, cover less ground, and certain technical
choices might be different, but building simple vehicles of a size
suitable for manned suborbital flights really doesn't require huge
capital expenditures.
I think there is less than $500,000 more to spend on development
before we could do manned suborbital flights, and that is including
building a completely new vehicle after we inevitably crash the
current one. The big issue is range costs -- White Sands gave us a
rough quote of $750,000 for FOUR test flights, and we really want at
least twice that before considering putting a person on board. I
truly hope that one of the new commercial spaceports gets their
environmental work done soon so we can plan on flying there.
This is a bit more expensive than my previous turbo-ferrari habit, but
not too bad. I can sustain this development process for quite some
time, regardless of what happens with the X-Prize or any emerging
markets.
John Carmack
www.armadilloaerospace.com
jjrobinson2
> derek...@nospamyahoo.com (Derek Lyons) wrote in message
news:<40a3c1df...@supernews.seanet.com>...
> > merk...@msn.com (Tom Merkle) wrote:
> What does low thrust have to do with it? You take an efficiency hit
> from sticking something in the exhaust flow, but there isn't any
> inherent scalability problem. In larger engines the vanes would need
> to get thicker, but it would be proportional to increased nozzle size,
> so there isn't any scaling factor working against it.
>
---clip---
> John Carmack
> www.armadilloaerospace.com
What about the durability of the vanes in a high-temperature, supersonic
flow? I think Redstone was already using some kind of carbon composite for
the vanes. It would seem to pose a reliability problem with modern
high-performance engines, especially if restart or reuse is desired. It's
been a while since I took thermodynamics, but I think the ability of the
engine to convey heat to the exhaust stream ultimately determines the
available efficiency of the engine, and probably its scalability, too. Is
there any prospect for a low-temperature version of the Saturn V, for
example, say, using catalytic decomposition of H2O2, or maybe hydrazine?,
etc.?
Scott Lowther
> We crossed the million-dollars-spent mark around the beginning of the
> year.
Pah! A mere piker. I've seen that much get blown on proposal efforts
lasting just a few months, with nothing produced but paper, frazzled
engineers (how the hell am *I* supposed to know how many man-hours
it's gonna take to develop a wholly new hybrid engine?!?!?!) and
broken dreams.
You've a long way to go before you can enter the ranks of Real
Aerospace Engineering. Are you even ISO1400901K certified? Do you have
regularly scheduled diversity, tolerance and sexual harassment
training? Huh? Do ya??
> This is a bit more expensive than my previous turbo-ferrari habit, but
> not too bad. I can sustain this development process for quite some
> time,
Man... I wish *I* could say that...
Scott Lowther
> We certainly aren't doing anything new -- jet vanes are literally the
> oldest trick in the book for steering rockets,
Might not be the best possible omen, but the manned Bachem Natter was
also jet-vane steered during it's first few seconds. As with the A-4,
the vanes burned away... but that was okay, because by that time the
airspeed was enough that the aero surfaces worked.
John Carmack
> What about the durability of the vanes in a high-temperature, supersonic
> flow? I think Redstone was already using some kind of carbon composite for
> the vanes. It would seem to pose a reliability problem with modern
> high-performance engines, especially if restart or reuse is desired. It's
> been a while since I took thermodynamics, but I think the ability of the
> engine to convey heat to the exhaust stream ultimately determines the
> available efficiency of the engine, and probably its scalability, too. Is
> there any prospect for a low-temperature version of the Saturn V, for
> example, say, using catalytic decomposition of H2O2, or maybe hydrazine?,
> etc.?
>
> JJ Robinson II
> Houston, TX
In general, specific impulse is proportional to the square root of
temperature, so high performance rockets tend to be high temperature.
The exception are extremely low molecular weight exhausts, like
nuclear-thermal, which actually run quite cool for their delivered
performance. That would be amusing -- a nuclear-thermal booster with
jet vanes. :-)
Most early jet vane vehicles used graphite, but modern tactical
missiles often use tungsten. I strongly suspect that a refractory
metal (tungsten/columbium/molybdenum), with either a disilicide or
irridium coating, or perhaps a silicon carbide / silicon carbide
composite, would last a very long time under a high performance liquid
engine. Making jet vanes is a lot easier than making combustion
chambers, and the temperature has dropped a lot by the end of the
nozzle. Based on our work with refractory chambers, it would cost
under $10k to make a set of jet vanes for an X-Prize class biprop
engine.
John Carmack
www.armadilloaerospace.com
Henry Spencer
John Carmack <jo...@idsoftware.com> wrote:
>Most early jet vane vehicles used graphite, but modern tactical
>missiles often use tungsten. I strongly suspect that a refractory
>metal (tungsten/columbium/molybdenum), with either a disilicide or
>irridium coating, or perhaps a silicon carbide / silicon carbide
>composite, would last a very long time under a high performance liquid
It's also not unthinkable to actively cool jet vanes, if it comes to that.
jjrobinson2
> In general, specific impulse is proportional to the square root of
> temperature, so high performance rockets tend to be high temperature.
> John Carmack
> www.armadilloaerospace.com
Oh, specific impluse---It's been too long since my Estes rocket days. So
the weight of the required structure grows with size much faster than the
available total energy storage in the propellant at a given working
temperature?
What was the name of the successfully tested, but blessedly never
implemented, nuclear cruise missile engine project? I think it was covered
by the Wings channel or something, but I can no longer find it. You might
not get as much acceleration of the exhaust molecules by nuclear heating of
a gas stream, but I guess you could keep it up longer for a given liftoff
weight.
JJ Robinson II
Houston, TX
jjrobinson2
"Henry Spencer" <he...@spsystems.net> wrote in message
news:HxpJK...@spsystems.net...
The previously mentioned Bachem Natter seems to have had temporarily
water-cooled steel vanes at liftoff.
JJ Robinson II
Houston, TX
J. Steven York
water filled, and that the water boiled off to provide a crude (and
short-lived) cooling system. Now, I know that isn't correct, but I
had to have gotten the idea from somewhere. My guesses:
I read a book that got it completely wrong.
I was reading about some other rocket, and mixed it up with the V-2.
Such a thing was proposed but never implemented.
This ringing any bells with anyone?
On Fri, 14 May 2004 14:14:34 GMT, he...@spsystems.net (Henry Spencer)
wrote:
>In article <c0e0a1dd.04051...@posting.google.com>,
>John Carmack <jo...@idsoftware.com> wrote:
>>Most early jet vane vehicles used graphite, but modern tactical
>>missiles often use tungsten. I strongly suspect that a refractory
>>metal (tungsten/columbium/molybdenum), with either a disilicide or
>>irridium coating, or perhaps a silicon carbide / silicon carbide
>>composite, would last a very long time under a high performance liquid
>>engine...
>
>It's also not unthinkable to actively cool jet vanes, if it comes to that.
-------------------------------------------------
J. Steven York's Multiplex of the Mind
http://member.newsguy.com/~jsteven/
Mike Walsh
"jjrobinson2" <jjrob...@death.to.spam.houston.rr.com> wrote in message
news:OLapc.104319$Dn1....@fe2.texas.rr.com...
>
at a given working
> temperature?
>
> What was the name of the successfully tested, but blessedly never
> implemented, nuclear cruise missile engine project? I think it was
covered
> by the Wings channel or something, but I can no longer find it. You might
> not get as much acceleration of the exhaust molecules by nuclear heating
of
> a gas stream, but I guess you could keep it up longer for a given liftoff
> weight.
>
If my memory is correct (always a problem)
it was called Project Pluto.
Maybe someone looking at real documentation can confirm or deny
this.
Mike Walsh
Charles Buckley
Project Pluto.
Supposed to be in a parking location over the ocean. Just
running circles. Then, on order, it would fly over the USSR,
drop it's bombload, then crisscross the country at very low
altitude.
johnhare
"jjrobinson2" <jjrob...@death.to.spam.houston.rr.com> wrote in message
news:OLapc.104319$Dn1....@fe2.texas.rr.com...
>
> news:c0e0a1dd.04051...@posting.google.com...
> ---clip---
> > In general, specific impulse is proportional to the square root of
> > temperature, so high performance rockets tend to be high temperature.
> ---clip---
> > John Carmack
> > www.armadilloaerospace.com
>
> Oh, specific impluse---It's been too long since my Estes rocket days. So
> the weight of the required structure grows with size much faster than the
> available total energy storage in the propellant at a given working
> temperature?
>
one second. Hydrogen/Oxygen in vacuum, about 450 lbs of thrust
for one second with one lb of propellant, Specific impulse 450
Kerosine/Oxygen at sea level, about 300 lbs of thrust for one
second, Specific impulse 300. Secret Squirrel Juice, Specific
impulse 145.
Rockets seem to scale fairly well on mass at a given Isp, which retains
similar scaleable structure mass at different sizes. Computers and such
non scaleables favor the larger vehicle.
Isp is roughly the square root of temperature divided by molecular mass
of the exhaust. Double the temperature of similar exhaust composition
to gain 40% in Isp.
John Carmack
> In article <c0e0a1dd.04051...@posting.google.com>,
> John Carmack <jo...@idsoftware.com> wrote:
> >Most early jet vane vehicles used graphite, but modern tactical
> >missiles often use tungsten. I strongly suspect that a refractory
> >metal (tungsten/columbium/molybdenum), with either a disilicide or
> >irridium coating, or perhaps a silicon carbide / silicon carbide
> >composite, would last a very long time under a high performance liquid
> >engine...
>
> It's also not unthinkable to actively cool jet vanes, if it comes to that.
Yeah, but then you have really lost the simplicity of the system, and
other methods would probably be better.
John Carmack
www.armadilloaerospace.com
Scott Lowther
Not necessarily, depending on how far you want to stretch the word
"active," and how long to want to cool the vanes for. Hollow vanes
filled with a solid (wax, solder, polyethylene, ice, whatever) that will
melt and ooze out fine pores can be made.
--
Scott Lowther, Engineer
Remove the obvious (capitalized) anti-spam
gibberish from the reply-to e-mail address
Henry Spencer
John Carmack <jo...@idsoftware.com> wrote:
>> It's also not unthinkable to actively cool jet vanes, if it comes to that.
>
>Yeah, but then you have really lost the simplicity of the system, and
>other methods would probably be better.
Probably, but I wouldn't say it's absolutely certain. A row or two of
orifices on the leading edge of the vane, fed with pressurized water
through a hollow axle, is not all that complex, although *development*
would be more work than for simple refractory vanes.
It wouldn't be my first choice, but it's worth filing under "odd approaches
that might be useful in unusual situations".
Henry Spencer
Charles Buckley <rijr...@frii.com> wrote:
>>>What was the name of the successfully tested, but blessedly never
>
>Project Pluto.
>Supposed to be in a parking location over the ocean. Just
Not quite. The flying-circles-over-the-ocean business was for testing.
Putting that much power output into that small a package meant that even
nuclear fuel was consumed relatively rapidly; the engine had an operating
life measured in hours, not years. Operational missiles would have been
on the ground until an attack order was given.
(A prototype nuclear ramjet was tested, on the ground, and worked. The
propulsion technology seemed to be pretty much in hand, although the
high-temperature ultra-rad-hard guidance electronics might have been more
of a problem. Pluto had a number of higher-level practical problems, like
the difficulty of doing safe testing, but the big thing that killed it was
simply that the requirement never really materialized. The project was
started as a hedge against the possibility that effective defences against
ICBMs would materialize quickly. They didn't.)
Paul F. Dietz
> The project was
> started as a hedge against the possibility that effective defences against
> ICBMs would materialize quickly. They didn't.)
Does this mean that if BMD now starts to be practical, the concept will
come back?
Paul
Scott Lowther
It apparently alreasdy has, sorta. The Russians announced a BMD-proof
hypersonic cruise missile a few months back. Might be BS, might not.
Obviously not a nuclear powerplant, but the same idea otherwise.
Henry Spencer
We can hope not. :-)
In practice, it seems fairly unlikely. This was not a low-tech project;
it's up in the superpowers-only range. The Russians might have the
incentive, but they no longer have the money. The US lacks the incentive,
at least until BMD systems get cheap and common.
Also, intercontinental cruise missiles are no longer that much of a
problem to build. The state of the art in conventional jet engines has
advanced enormously. Even a final sprint at Mach 3 at treetop height is
within reach, as witness the Russian Moskit antiship missile (Mach 3 at
wavetop height on a conventional ramjet, and a very unpleasant surprise to
the NATO navies, who knew it was fast but didn't expect anything like that).
The one advantage of the nuclear engine is *sustained* extreme speed, and
that has as many drawbacks as virtues. Notably, it yields about the most
conspicuous vehicle you can possibly imagine, the polar opposite of
stealth anything. As witness the demise of the B-70, sheer speed is no
longer considered a very effective way of evading defences, not if they
can see you coming.
Greg D. Moore (Strider)
>
> The one advantage of the nuclear engine is *sustained* extreme speed, and
> that has as many drawbacks as virtues. Notably, it yields about the most
> conspicuous vehicle you can possibly imagine, the polar opposite of
> stealth anything. As witness the demise of the B-70, sheer speed is no
> longer considered a very effective way of evading defences, not if they
> can see you coming.
True, but you really want to blow up a Pluto FAR from the site you're
defending.
It's not much good if you land it one your head.
John Schilling
In particular, whatever fluid you were going to pump halfway down the
nozzle and back to cool the vanes, could just be pumped halfway down
the nozzle and injected into the exhaust. Fluid injection is a fine
method of thrust vectoring, with no more of a performance hit than
the vanes cost.
You'd need something else for roll control, of course.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schi...@spock.usc.edu * for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *
George William Herbert
>In particular, whatever fluid you were going to pump halfway down the
>nozzle and back to cool the vanes, could just be pumped halfway down
>the nozzle and injected into the exhaust. Fluid injection is a fine
>method of thrust vectoring, with no more of a performance hit than
>the vanes cost.
It's not *quite* that simple; there are a lot of gotchas in
LITVC, but it can be pretty simple and robust.
>You'd need something else for roll control, of course.
Naww. That's easy.
I have, on and off, been a big fan of nozzle exit paddles,
LITVC, and vanes. Now I am less a fan of any of them technically
and more a fan of whatever I can get to work faster.
-george william herbert
gher...@retro.com
Derek Lyons
>In particular, whatever fluid you were going to pump halfway down the
>nozzle and back to cool the vanes, could just be pumped halfway down
>the nozzle and injected into the exhaust. Fluid injection is a fine
>method of thrust vectoring, with no more of a performance hit than
>the vanes cost.
>
>You'd need something else for roll control, of course.
Only single engine birds/stages need additional roll control.
Multiple engine birds/stages simply use a clever arrangement of the
injection points.
Henry Spencer
Greg D. Moore \(Strider\) <mooregr_d...@greenms.com> wrote:
>> ...As witness the demise of the B-70, sheer speed is no
>> longer considered a very effective way of evading defences, not if they
>> can see you coming.
>
>True, but you really want to blow up a Pluto FAR from the site you're
>defending.
>It's not much good if you land it one your head.
Even having it land on your head is better than having one of its nuclear
weapons detonate on your head. Agreed that intercepting it far away is
preferable, though.
Phil Fraering
>In particular, whatever fluid you were going to pump halfway down the
>nozzle and back to cool the vanes, could just be pumped halfway down
>the nozzle and injected into the exhaust. Fluid injection is a fine
>method of thrust vectoring, with no more of a performance hit than
>the vanes cost.
>You'd need something else for roll control, of course.
If you have more than one engine, fluid injection could be used for
roll control.
--
pgf