Earlier quoted context omitted.
Maybe they can use liquid nitrogen?
This is almost certainly the answer. Cheap, inert and cryogenic.
Turns out that's what they were using today. It was nitrogen pressure test!
SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
151–160 of 265 posts
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#152"Was that the primary buffer panel?"
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#153And that's why they are testing it.
Yea, there is something about all the attention on this thing that stresses me out. Its a prototype, right? There is going to be things that appear bad, but its really just a treasure chest of data.
It depends on whether or not there was a reasonable expectation that the test was going to result in a failure.
Suppose you bought a used car, and the brakes failed before you could drive it off the dealer's lot. The dealer graciously fixes the problem, and points out the great news - that nothing catastrophic happened, and that the problem is now fixed!
You would, of course, start wondering - what other unexpected failures are going to take place, after you drive out of the dealership. Maybe nothing. Maybe something life-threatening.
If the failure was a surprise for everyone involved, I'd be worried - because other surprises might not get caught in testing. If it was a 'Well, we're not sure what would happen', I'd be less worried.
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#154And that's why they are testing it.
Depends on what kind of test that was supposed to be. If they pumped it until it explodes it would be a kind of test (also called experiment) where it makes sense. If you design something with a margin of safety, then pump it to working pressure and it blows, then it means you made a mistake. If you made a mistake it shows you don't know what is necessary to design a rocket (yet). Seriously, they don't build skyscrap…
This and the Mk2 prototype in Florida are mostly experiments with manufacturing processes; I would not be surprised if there were a reliability problem with their methods that weakened the product.
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#155Nothing blows up means you aren't innovative enough.
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#156Oh dear! It looks like someone accidentally divided by 2 for the cylindrical hoop stresses, forgetting that they're not the same equation as for spherical stresses. :) Less facetiously, a thin-walled cylinder's stress is a function of pressure, radius and thickness with the equation: sigma = P*r/t whereas for a sphere (including the spherical end caps on a cylindrical pressure vessel), it follows the equation: sigma…
They left the nose cone off to save money. I wonder if the designer counted on some portion of the cone weight to support the cylinder head in their design?
I don't think you can really count in weight on an object capable of flying into orbit or interplanetary space...
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#157Earlier quoted context omitted.
I think SpaceX has proven they know how to design rockets. But they are newcomers to building rockets from welded steel.
> But they are newcomers to building rockets from welded steel. AFAIK everybody is.
Atlas was steel. The first US ICBM and an early space launch vehicle.
To this day, the Centaur hydrogen upper stage with RL10 engine is steel. Balloon tanks. They inspired SpaceX heavily.
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#158Earlier quoted context omitted.
Assuming I remember my high school physics correctly, the socket would be moving ~50mph on impact. Definitely a recipe for a bad day.
For reference, the average human seems (from a very brief search) to swing an 8lb sledgehammer at ~25mph. So it's a bit like someone very, very strong (think strongman competitions) nailing the thing as hard as they can with a sledgehammer.
It would be a glancing blow, though. Bad, but not as bad as a blow striking orthogonal to the surface.
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#159Earlier quoted context omitted.
Rockets are actually pretty easy to poke holes in. They're meant to keep stuff in, not out. A dropped torque wrench blew up a Titan. https://en.m.wikipedia.org/wiki/1980_Damascus_Titan_missile_...
It's somewhat impressive that the actual nuclear warhead didn't so much as leak. Which is what's supposed to happen but still you don't usually design something to withstand a botched missile launch capable of 'catapulting' a 740 ton door.
Once you've already designed something to survive a very steep and fast atmospheric re-entry with delicate electronics intact, it's going to withstand other kinds of punishment pretty well too.
Re: SpaceX's Starship Mk1 just blew off its bulkhead in a pressurization accident
#160Earlier quoted context omitted.
Looks like the welds holding the bulkhead on failed. For those who aren't keeping up with this the failure was on the Mk1 prototype. Mk2 has been build nearly in parallel with Mk1 and will take over early flight testing (20km hop). Elon has tweeted that this team will jump to Mk3 instead of trying to repair Mk1.
Is the mk2 in the parallel location?
Yes, SpaceX is currently building Mk2 in Cocoa, Florida.
Here's an aerial video from beginning of october: https://www.youtube.com/watch?v=ChXMhSmqYqs