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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: Thu Mar 17, 2011 4:16 am
In that test the red parachute was just a placeholder, it's not the real main, and as you can see it wasn't packed in real well. It was blocking the pressure sense port; the actual pressure where it pops isn't 15psi.

Thermal effects are important, the assembly holding it together will change the amount of force required depending on temperature. But at least for this first flight to ~100,000, there isn't a lot of time for it to cool off in space, and the heat load on the way down isn't very high.

A final minimum recovery pressure hasn't been defined, but it'll be something north of 30psi. An initial (albeit weaker) test article actually exploded at a similar pressure, so it's probable that an opening will be made somehow.

The tube section itself is actually stronger than the propellant tanks, so it could be pressurized to hundreds of psi. The nose is the weakest joint in all cases.

Thanks for the questions. Though I keep failing to update the blog, there is utility for us in getting reasonable queries; you don't truly know something until you can explain it to someone else.


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Post Re: Official Armadillo Q&A thread   Posted on: Mon Mar 21, 2011 11:25 pm
Okay, here's a reasonable question. How does your launch stand work? It looks like you might be using bungees to pull the arms away from the rocket after it launches, but how does it hold on to the rocket in the first place? Is it your own design, or is there some conventional way of doing this?

I've only used launch lugs myself, and I've seen HPR guys use launch rails, but of course those are unguided rockets that need the tower to stay straight until they're going fast enough for the fins to work.


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Post Re: Official Armadillo Q&A thread   Posted on: Tue Mar 22, 2011 1:54 am
The rocket does have fins, it's essentially passively stable like a HPR rocket, but with the addition of a gimbaled engine so it can do guided flight (and hover, as it did today).

The Mk. 1 concept for the launch stand was just a rail, very similar to what a lot of folks use. However, people were worried what it would do after the first button came off but before the second button, since it is relying on the engine movement to stay stable initially, and being pinned at one spot could do weird things to the control.

So I moved to another idea, which was two short rails, and two buttons offset about 30 degrees around the axis. So it'd slide along the rails like normal and come off both at the same time, and be free to fly away. The issue there is that they wanted the launch stand to essentially move away from the rocket after it was released, and there wasn't any particularly good way to do that.

So the Mk. 3, which is the one that got built and is working fairly well, is essentially the rail/button concept inside-out. There are two sets of two arms. Each set looks like a Y when the rocket is on the stand, with the tip of each side of the Y in a slot on the rocket. When the rocket moves up, the Y is no longer held together, and it basically breaks in half.

(I'll put a video up of this in the next update. I know a textual description isn't very clear.)

The weight of the rocket is held up with an arm at the bottom bulkhead, which swivels up to get out of the way. The Y arms just hold the rocket from falling over and torsional loads. That said, getting the assembly of 1000+ pounds of rocket hanging off a ~100 lb steel structure in 30MPH wind, and it sways a bit when you're at the top of the ladder.

So in the end the rocket sits on the stand. The engine starts, it looks ok, it throttles up, and when it moves up about three inches it suddenly finds itself completely free and a foot and a half from the nearest object.

Some of the guys don't like the stand because it doesn't go from horizontal to vertical like a proper mobile big rocket launcher. So that will be the next iteration, and I have another idea on how to hold it that is a bit more aerodynamic and will make it possible to do the static tests on the trailer, or a full-thrust-before-release checkout.

The SpaceX rockets do a full checkout, the Russians do not. There are good justifications for both.


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Post Re: Official Armadillo Q&A thread   Posted on: Tue Mar 22, 2011 1:59 am
There were of course other ideas before that. Russ modeled a cool launch stand that looked like one of the Russian launchers, with the vertical support arms hinged with the load support arms, so that as it took off the vertical supports would fall away. I did a parallelogram version of it that had an interesting movement, but the thing we ended up building was quicker to get together and works fine for now.

Given the full gimbal control, you could put the thing on casters and launch it off a ramp, or hang it on a hook and have it just fly off. Having it sit still while loading propellants is part of the reason for the stand.


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Post Re: Official Armadillo Q&A thread   Posted on: Tue Mar 22, 2011 10:49 am
Ben wrote:
and hover, as it did today.


Video? That would be worth seeing!


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Post Re: Official Armadillo Q&A thread   Posted on: Wed Mar 23, 2011 2:29 am
Thanks for the response, Ben!


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Mar 25, 2011 3:47 am
So looking at the pictures here:
http://www.parabolicarc.com/2011/03/24/ ... s-rockets/

Any thoughts on say a 'Super STIG' series of rockets in the 2 meter to 2.5 meter diameter range coupled with a heat shield equipped SOST on top? Seems like that would be edging close to orbital capability with a S-STIG-V or VII configuration.


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Mar 25, 2011 8:20 am
TJ wrote:
So looking at the pictures here:
http://www.parabolicarc.com/2011/03/24/ ... s-rockets/

Any thoughts on say a 'Super STIG' series of rockets in the 2 meter to 2.5 meter diameter range coupled with a heat shield equipped SOST on top? Seems like that would be edging close to orbital capability with a S-STIG-V or VII configuration.


Forgive my ignorance, but what does SOST mean? Done a google search but found nothing of relevance (or I thought was relevant!)


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Mar 25, 2011 8:35 am
From that link, it is apparently: Sub-Orbital Space Transport


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Post Re: Official Armadillo Q&A thread   Posted on: Tue Mar 29, 2011 1:35 am
From a-rocket:
Quote:
Things are looking good for an attempt at flying over 100,000' this weekend with our big tube rocket.

For reasons that still aren't exactly clear to me, this vehicle took longer to build than any of our previous ones. With all the full time salaries, that also makes it the most expensive vehicle we have made. I have said that watching one of our serial-produced mods crash from an altitude flight is "like watching a BMW fall out of the sky". Losing this vehicle will be more like planting a Ferrari. A turbo Ferrari. Realistically, it is almost inevitable. If we get a successful first flight, everything will work out fine, but I imagine the mood in the shop will be pretty grim while building up a new version of this vehicle if all we got out of the previous one was a couple hover tests and a crash.

Despite being extremely upset with how long it took us to get to flight-ready, I find myself now wishing we had another week to run additional tests, but we have already postponed launch once at Spaceport America, and we really should take our shot now.

If we get the vehicle back and it performs as expected, we should be able to take it over 100km by upgrading various parts of the vehicle in a couple months.

John Carmack


w00t! and good luck!


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Post Re: Official Armadillo Q&A thread   Posted on: Tue Mar 29, 2011 6:37 am
Good luck!
I feel nervous for them!

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Post Re: Official Armadillo Q&A thread   Posted on: Thu Mar 31, 2011 8:44 am
Correct me if I'm wrong:
In one of the old Armadillo news articles (few years ago) John talks about the OTRAG concept having met Lutz Kayser and his belief that clustered modules are the way to low cost orbit so I'd say the variants of the Stig would be this coming to fruition.


Iain


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Apr 01, 2011 5:16 am
I was up until midnight last night editing video and writing text, spent a good portion of the drive to NM going through photos and editing another video, and up again tonight getting the code together. I hope you enjoy. :-)

Armadillo update: http://goo.gl/pz6SO


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Apr 01, 2011 9:37 am
Awesome update, Ben. Thanks!

Can't wait to see this thing fly.

Something unrelated I've wanted to know since the early Mod work: Would it ever be conceivable to get a tube rocket to do a loop de loop? If you get to the stage of doing additional mid-altitude hops in testing, it would be a kick to see that rocket doing a little mid-air acrobatics.

Good luck this weekend!


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Post Re: Official Armadillo Q&A thread   Posted on: Fri Apr 01, 2011 11:38 am
Thanks for your efforts Ben! It is always great to see some progress! :)

Good luck on Saturday to the entire Armadillo Crew!

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