Official Armadillo Q&A thread

The shuttle, or the ginormous plume of aluminum oxide?

John Carmack's tube rockets have suffered failures
during launch attempts. (More details to come)
Each launch item must cost over 100,000 dollars;
I'm glad he can afford it.
John? If you're reading this, nice try, don't give up!
Kudos to you and your team.
You'll learn more from these failures than successes.

Afterall...How many failures did the USAF have in their
attempt to launch the first successful Atlas missile?
Five? Six?

But when Atlas finally got a reasonably good track record,
John Glenn, Ranger 7, Mariner 4, Mariner 2 all owe their success
to it.

Ouch. Two failures in two flights (that we know of). Still, sounds like an awful lot of learning was done in those two flights, so not wasted by any stretch.

Just goes to show how difficult rocket engineering is, even with 10 years worth of experience, they are still learning with every flight.

That dalek really took off fast!

Yeah. Still, this isn't the first time they've had problems with transport-induced damage. That goes all the way back to the first Lunar Lander Challenge IIRC. Perhaps they should set up a 100 mile circuitous route to the field for every hover test from now on? Literally shake out any bugs?

Anyway, if you think about it not that much did go wrong. Stig has some control issues, which I suppose were to be expected given the somewhat unconventional design, and they knew full well that that was a pretty high-risk endeavour. It seems to me that Dalek should have worked just fine if it weren't for the transport damage. Yes, it's a setback, and a costly one, but they are really very close. So to everyone at AA: stick with it! You're close, and you will make it. One more time around...

I second that.

Bob Clark

And I second that.

You mean, you third that.

No, he highlighted a different part of the text.

John? If you are reading this, please reply & let us know if
the suggestion I give is worth spit?
In fact, if any employee of AA is reading this, please pass on my suggestion to John. Thanx.

Apparently, the failure of these two recent planned 100K ft altitude launch attempts may have been prevented had you had repair facilities available
at your remote launching location IF my understanding is correct.

My suggestion is? Why not purchase an large (Airstream?) trailer and gut
it and convert it to a PORTABLE onsite repair and maintenance shop that you can tow to a future launch site?
Your tuberockets couldn't be THAT LARGE that they wouldn't fit
into such an ad hoc portable facility.
So, Mr. Carmack? What do you think? A worthwhile suggestion, or not?

Any big race car trailer with workshop would do the job I would think.

I don't know if Ben or John are reading this post.
But here goes!
John? You used to be enthusiastic about using hydrogen peroxide
as either a liquid monopropellant or bipropellant with kerosene.
These are liquids of course.

But, since you are familiar with chemistry, while I'm only self-taught in it,
using college text books, I'd like to ask you about your assessment of
sodium percarbonate (used in organic bleach; hydrogen peroxide molecules are linked with the substance; and is a solid at room temperature).
Would such a substance make an fair or acceptable solid-propellant
oxidizer, either with a hybrid system or with the use of a hydrocarbon solid
as fuel?

Hi OJ (?)

You might be better off asking that question on the arocket list - John Carmack is on there, but also a LOT of other rocket people who would be able to answer the question too.

I think the reasons Armadillo went away from peroxide was lack of availability of high concentration peroxide, but I may be misremembering.

RPA doesn't have the adduct of sodium percarbonate, but it does have the two individual chemicals. Running them with HTPB at optimum mixture ratio (8.481) at 600psi chamber pressure gives an optimum expanded sea level ISP of 181.58.

That's low compared to a good solid, even worse than sorbitol-KnO3, at 227s optimum. APCP at the same pressure and expansion is 244s. (Other solid people, is that sorbitol number right? I can't see having done it wrong, but that seems high.)

On a practical level, it may be difficult to work with, or it may be detonation-prone when mixed with fuel; I'd expect it to be. You'd have to ask on AR if anyone has actually heard of it.

I'm only seeing about 120 theoretical seconds from 106/52/14 Na2CO3:H2O2:HTPB @600PSI to sea level pressure. The binding energy between the peroxide and the sodium carbonate is indeed small enough to ignore in PROPEP.
From the SSTS stuff, KNSB is ~157s theoretical from 1000PSI. I believe you can expect a bit less than 140s practically. Sodium percarbonate is at core a decent if somewhat reactive oxidiser stabilized with something that you could smother a fire with.