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Official Armadillo Q&A thread

Posted by: John Carmack - Tue Jun 15, 2004 8:01 am
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Official Armadillo Q&A thread 
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Post Re: Official Armadillo Q&A thread   Posted on: Sat Jan 29, 2011 8:47 am
Marcus Zottl wrote:
@ WarKosign
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THANK YOU!

Very excited to see Armadillo finally getting to the edge of space. Thanks for the update and for the pointers to arocket -- looks like I have some fun catching up to do :-D

Cheers!
Rob


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Post Re: Official Armadillo Q&A thread   Posted on: Wed Feb 02, 2011 7:10 pm
I think that in the initial flight path does not make sense to take on board oxygen. need to start using jet turbine engine, then Supersonic Combustion RAMJET — scramjet engine, and in the upper atmosphere - reactive


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Post Re: Official Armadillo Q&A thread   Posted on: Thu Feb 03, 2011 10:08 pm
Feel free to run the math on that and get back with us. The rocket equation is very simple. Please also forward plans for a hydrocarbon scramjet with a T/W of 50 or better.


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Post Re: Official Armadillo Q&A thread   Posted on: Thu Feb 03, 2011 10:39 pm
I think adding any exotic jets is irrational for AA. simply way too expensive to develop that for them. but I could believe that strapping a rocket to an old plane and getting it as high and fast as possible before letting it go could be rational because you might be able to hitch a ride for cheap and you might save a lot of rocket mass by having it start at 10km going 900km/h in the right direction or slightly inclined. maybe a factor 3? no small margin.


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Feb 04, 2011 9:09 am
Lot of money being spent around the world trying to make supersonic ramjets - think they have run for a few seconds so far. Very expensive, much more than AA could fund.

As to strapping a rocket to a plane. Not a simple job - XCOR are trying to do it, and others have gone bust trying to do it. Or you could just hitch a ride on a SpaceShip2, which is already under development. And there's the rocket racers but they won't be high altitude. It's not just a matter of 'strapping it on' - lots of thrust needs to be contained somewhere in the airframe, and I doubt many airframes could manage it, which is presumably why the Rocket Racers are pretty much custom.

Seems like a dead end for AA to do something like that - why bother when others are already doing it and ahead on the curve. Better to concentrate on VTVL IMO where they are very much at the forefront, and use the tube rocket for high speed/high altitude testing in prep for doing it, which is I believe the plan.


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Feb 04, 2011 2:46 pm
I think you misunderstood, James. we're not talking about rocket boosting a plane. but plane boosting a rocket


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Post Re: Official Armadillo Q&A thread   Posted on: Sat Feb 05, 2011 12:21 pm
Using some realistic (and existing) airplane does not bring a big improvement -- nothing in the range of 3-times. Just do the calculations. For a 306s ISP 2 stage (same dV stages) reduces mass fraction of each stage by about 10%. For SSTO (well when it's off the plane it's not real SSTO, just SRSTO (single rocket stage to orbit) gain is a bit higher at roughly 20%.


@Ben: WRT air augmentation -- how about very simplistic duct (with very simple geometry like just a cylinder or part of a cone) just around the engine? It won't buy large gains like there were in russian GNOM rocket (automobile launched ICBM design) which had like 100% ISP boost (it's 2nd stage had about 560s ISP out of dense fuel AFAIR). But it might buy like 20% more thrust (as some back of the envelope calculations indicate) for the same fuel (thus about 20% ISP improvement). Wouldn't it be worth a try?

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Post Re: Official Armadillo Q&A thread   Posted on: Sat Feb 05, 2011 5:17 pm
well if your math is correct that it's only about 10% heavier launching from the ground then it's not worth it. but then again, does AA have 306 Isp engines. I guess even at lower Isp the difference is not that great.

surprising that a rocket can lift itself to 10km and 1000km/h using only 10% of it's mass.


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Post Re: Official Armadillo Q&A thread   Posted on: Sun Feb 06, 2011 11:37 pm
Thanks for the update, Ben and Matt!

Ben, you've been posting a lot of engine tests on twitter, but how are these engines different than the ones on the mod or rocket racer? I don't see any obvious changes like regen cooling. Are they more efficient, safer, easier to manufacture? Don't be afraid to toot your own horn!


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Post Re: Official Armadillo Q&A thread   Posted on: Mon Feb 07, 2011 9:46 am
Dan Frederiksen wrote:
I think you misunderstood, James. we're not talking about rocket boosting a plane. but plane boosting a rocket


Fair point - misread your post.


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Post Re: Official Armadillo Q&A thread   Posted on: Sat Feb 12, 2011 5:35 pm
Dan Frederiksen wrote:
surprising that a rocket can lift itself to 10km and 1000km/h using only 10% of it's mass.

While I agree that this is can indeed be a surprising fact, I have to wonder about your use of the word "only".

Example: a "classic", ISS-like ~90 minute orbit, a little bit above 300 km altitude, with an orbital velocity of about 28.000 km/h.

With those numbers in mind 10% of a rockets mass to reach 3.3% of the targeted altitude and 3.5% of the required velocity sounds like quite a lot to me.

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Post Re: Official Armadillo Q&A thread   Posted on: Sat Feb 12, 2011 7:27 pm
sure, orbit is no picnic. but you try making a rocket with 90% mass payload to 1000km/h at 10km :)
300Isp makes all the difference


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Post Re: Official Armadillo Q&A thread   Posted on: Wed Feb 16, 2011 8:06 am
I just noticed some more pictures of the new hardware on weldman's Flickr stream, posted on 1/22, that I hadn't seen before. Tube rocket and what is presumably NASA's CRuSR platform, at various stages of production (but mainly focusing on the welding, predictably :).

For those who are interested:
http://www.flickr.com/photos/29153024@N07/


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Feb 25, 2011 12:27 pm
Phis wrote:
I just noticed some more pictures of the new hardware on weldman's Flickr stream, posted on 1/22, that I hadn't seen before. Tube rocket and what is presumably NASA's CRuSR platform, at various stages of production (but mainly focusing on the welding, predictably :).

For those who are interested:
http://www.flickr.com/photos/29153024@N07/


Thanks.
The 'NASA' set look like a new Methane/LOX quad (all 4 tanks have insulation whereas ethane/LOX Pixel only had it on LOX tanks).


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Feb 25, 2011 12:38 pm
Alex A wrote:
The 'NASA' set look like a new Methane/LOX quad (all 4 tanks have insulation whereas ethane/LOX Pixel only had it on LOX tanks).


Ah it's the "Super Quad". See this presentation form Neil Milburn thread:
http://www.aiaa.org/pdf/industry/presentations/Neil_Milburn.pdf

Lots of exiting stuff in there. Unmanned flight of 'boiler plate' manned sRLV this year!


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