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Ekaros parent
In normally run project, it would be pretty big. As you would need to do proper analysis just what failed and how. And then decide, design and implement needed fixes. With SpaceX engineering culture who knows...
m4rtink
In "normal" project a serious misshap of this kind often ends the project - see how the DC-X VTVL rocket testbed fell over due to one landing leg not extending, ending the whole project. Nothing related to what was being tested or developed and it ended the whole project.

As a result we got booster landings delayed by 20 years - and SpaceX would also not get there with Falcon 9 if they would call it quit after spcetacular failures (see Falcon 9R test bed).

peterfirefly
They were incredibly crazy to use the RL-10 hydrogen engine for the supposedly cheap prototype flights.
m4rtink
I think those were available off the shelf at thet time ? Not sure what else would be suitable in early 90s, provided you did not build your own like basically all modern rocket companies since then.
peterfirefly
Armadillo Aerospace (and many others, a decade or two ago) showed that rocket engines could be developed and built quickly and cheaply. The cost is in the optimization.

Choosing a hydrogen engine (which only really makes sense for upper stages) also means you need a hydrogen tank... a cryogenic hydrogen tank. They chose to make such a tank with a weird shape that fit the unnecessarily weird shape of their prototype. I think the major cost of getting their craft repaired (or more realistically, having a new one built) was to build a new custom hydrogen tank.

Crazy, when they didn't need anything optimized/complicated for testing launch and landing.

Also wild that they went with an F/A-18 accelerometer/gyro package. The first commercial mass market MEMS accelerometer was introduced in 1991 and was in volume production in 1993. I mean, they had to pick something and the ADXL50 wasn't ready yet (and they would still have had to design a 3-axis solution around it if it were), so I don't blame them for that (expensive) decision.

https://qringtech.com/TryMe/wp-content/uploads/2014/01/Histo... https://www.analog.com/media/en/technical-documentation/obso...

I do very much blame them for the choice of the RL-10, though. And for going immediately to such a large size -- that's the same thing as saying "we plan on not making any mistakes".

m4rtink
I agree, but still - what could they have used that was not "build your own engine" ? They seemed to have preferred (or maybe were forced to ?) use off the shelf hardware, even if sub-optimal.

The only engines that were not hypergolic & used kerolox were those used on the Atlas rockets or on the Deltas. Not sure if they had the necessary throttling range and other characteristics. I guess now I need to find some sort of a biography from someone working on the DC-X project. :D

As for Armadillo Aerospace - their efforts were admirably and I really enjoyed watching their progress. And they did manage to get a working engine. :)

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