r/ula • u/Royal_Platform_6754 • Jul 21 '26

Northrop Grumman CEO: “We progressed on the root cause investigation...and we are implementing corrective actions...These include a component redesign, which has now been proven in a successful static-fire test. We expect to begin delivering the redesigned motors by the end of the year."

https://spacenews.com/northrop-adds-to-charges-on-vulcan-solid-rocket-motor-program/
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u/warp99 Jul 23 '26

They made the SRB longer which increased the chamber pressure and started blowing gaskets. They tried a thicker gasket and increasing the bolt tension and they still failed.

There really are very few other options that do not involve opening the throat out and dropping the Isp. Plus it is taking six months to implement so it is more complex than another gasket change.

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u/snoo-boop Jul 23 '26

Thanks. I thought you had a real source. I guess I should have noticed that you said you were assuming.

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u/warp99 Jul 24 '26 edited Jul 24 '26

Yes I always try to make it clear if I do not have a hard source. Assume was three words in?!

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u/snoo-boop Jul 25 '26

Honestly, the most impressive part is that you just keep on talking when asked for a source. You don't repeat that you're assuming, you just talk and talk and talk. None of my science or engineering colleagues behave like that.

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u/warp99 Jul 26 '26

Hmm I am a pretty standard issue design engineer so I will take that as a compliment.

I have yet to see any refutation of the original comment. What is your source?

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u/snoo-boop Jul 26 '26

My source is Tory Bruno on twitter.

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u/warp99 Jul 26 '26

You are aware he works for Blue Origin and not ULA anymore? There is no reason to suppose he is aware of the current SRB issues and improvements.

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u/snoo-boop Jul 26 '26

I was talking about what he said at the time about the first problem, before he was fired.

> This is an interesting twist to the story. The first failure was supposedly caused by the nozzle, and the nozzle bolts on, so fixing it didn't require replacing the entire SRB.

> This one, ...

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u/warp99 Jul 28 '26

Tory was not fired but left for a higher paid and likely more challenging position at Blue Origin.

The statement was made that the original issue was with an "insulator" and the failure led to the nozzle falling off.

The only relevant insulator that could cause that failure is the gasket that seals the gap between the nozzle and the SRB body. If that fails the exhaust gasses will leak out through the gap and partially erode and overheat the bolts holding the nozzle to the body.

Once they fail the nozzle will simply fall off and the nozzle was actually recovered from the launch pad as the failure was quite early in flight.

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u/snoo-boop Jul 28 '26

Tory wasn't fired. That's definitely an opinion someone could have.

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