Armadillo update

John Carmack posts only a Quick update this month with no photos or videos but it still has several interesting items. For example, they have built an additional modular style vehicle and he says "there is a decent chance that we will try to fly a dual module configuration in late January". They hope then to fly a four module configuration after that.

A graphic of a 4-module system.

Then he says,

We are almost finished with our AFRL phase I SBIR, and we are expecting to hear something in the next couple months about a possible phase II. If we get that, we should be building and flying an honest space vehicle in 2008. Note that I am not saying that we would necessarily be all the way through the test process to the point of flying to 100km, but we should be well on the way.

They are also "starting work for NASA involving flying our vehicles on lox / methane instead of lox / ethanol." (See the note about methane in his Dec.4.06 update.)

And

We still have several interesting commercial ventures in the works, but so far, none of them have reached the point of anyone writing us any checks.

He then details tests and re-design work they are doing to deal with the engine start problems they had at the X PRIZE Cup.

Posted 12/16/07 | 23:12:59 by TopSpacer | Filed under: Transport Companies

Comments

Great. I think that methane is a great propellant.

-It is dirt cheap
-It poses no environmental hazard when spilled
-It always has the same chemical composition
-It does not coke
-It offers better Isp than kerosene
-It has much higer density than LH2
-Its liquid range overlaps that of LOX, so no differential contraction when fueling a LOX/CH4 vehicle.
-It is self-pressurizing
-It can be created anywhere from CO2 and H2O

The only downside I can see is that you have to make sure that the CH4 boiloff and the LOX boiloff do not mix. But that should be manageable

Posted by anonymous at 12/17/07 06:03:34

I was at the xprize cup and got to talk to some of the armadillo team. As they were explaining their design and mentioning past problems with their seals and the fragility of the graphite, I started wondering about approaches which might help alleviate these issues. Now with his comments:

"We might wind up with just an orange-hot engine almost as-is. I was originally thinking about sliding injectors in the way we currently do with the aluminum jackets, but now I am thinking about just making stainless steel injectors and welding the entire thing together. Much as I hate machining stainless, there is something to be said for not having any o-rings or retaining rings on the engine."

I am wondering if one of my thoughts might help. Does anyone know if selective laser sintering has been tried for rocket motors? I am thinking about stuff like this:

http://www.tms.org/pubs/jou...
http://www.eos.info/product...

I think it could help with reproduceably fabricating a design as well as reducing complexity by permitting the system to be fabricated monolithicly rather than as parts needing assembly, seals, etc.

Anyone know if this has been tried or have any thoughts on whether it might work?

Posted by Blackjax at 12/17/07 07:11:03

post your suggestion at Spacefellowship Q&A thread with Armadillo folks. They are generally very receptive to ideas tossed around there.

Posted by kert at 12/17/07 14:07:16

We continue to look at various rapid prototyping methods, but they don't turn out to be quite as useful (yet) as they first appear. We may make an injector with SLS, but for a film cooled chamber it would only have the thermal characteristics of the bronze infiltrate, which is a lot worse than stainless steel.

Posted by John Carmack at 12/17/07 17:17:08

I'd actually been picturing a regeneratively cooled system made from Ti6Al4V

http://www.azom.com/details...

Figure 3 here implies that others are at least considering it for some parts:

http://www.azom.com/details...

Posted by Blackjax at 12/17/07 20:18:43

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