The final assessment. I’m selfishly hoping they’ll delay past the 7th, because we get in from London at 2 AM on that date, and won’t be in a mood for a drive up to Vandenberg.
[Update a few minutes later]
Return to flight now scheduled for Sunday night. We’ll try to watch from the beach, if the weather is clear.
A good assessment by SpaceX and all involved, or they could have just read the comments here and got everything but the actual ignition part. ^_^
If LOX got under any kind of seam or fissure and then froze solid, thawing should produce about 2,000 psi because LOX is much less dense than solid oxygen. That much force in a crack was going to do something, and that something would be bad.
Their feeling seems to be that it could have ignited the carbon fiber due to either friction or breaking strands.
I think another solution might be to overcoat the COPV vessel so liquids can’t possibly get into the fibers, though I’m not sure what would make a good coating at those temperatures.
I sure hope that SpaceX is feverishly working internally on a substantial redesign of the hydrogen pressure vessel as another failure in the next 24 months could give the company some very real problems with customers. I realize that the two second stage failures were most likely unrelated, but there does seem to be a fragility around the design of the second stage that needs to be addressed proactively.
I think you mean the helium tanks.
Perhaps this was another one that was due to a failure of imagination. “We didn’t think a helium tank could blow up!”
My current thought is to coat the outside of the COPV with an inert noble metal like gold or platinum. My follow up thought is that this idea might meet some resistance on the financial side.
Yes, I meant the helium tanks.
George, vapor deposit a thin layer. I don’t know if aluminum will work (may have an ignition problem in Lox) but a very thin gold layer shouldn’t be too expensive.
As I understand the explanation:
The helium tank is constructed as an aluminum liner over-wrapped with carbon fiber. The carbon wrap being slightly porous is expected, and not a problem absent further complications. If the tank is loaded with excessively cold helium, the aluminum contracts and the carbon fiber buckles. This leaves pockets for oxygen, and friction as the fibers shift. Worse, the excessively cold helium may freeze the already sub-cooled LOX. With localized friction as an ignition source, the LOX soaked carbon fiber can go off like an explosive.
…
But I still think the publicly released video looks like an explosion just outside the LOX tank. And something is thrown =up= from the point at which the explosion is first visible.
I still don’t see a projected liftoff time in that article. Perhaps I missed it. I’ve also seen on line that the weather forecast for Vandenberg isn’t all that great on Sunday. IIRC, there is a 50% chance of rain. It gets better a day or two later.
No time listed there, but someone has twittered 10:28am local.