Author Topic: ATK making progress on SRB propellant void issue  (Read 6630 times)

Offline Chris Bergin

Big, expansive feature article by Chris Gebhardt on the QM-1 booster, via L2 info and ATK assistance (really great cooperation on their part).

http://www.nasaspaceflight.com/2014/09/atk-making-progress-srb-propellant-void-issue/
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Online woods170

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Re: ATK making progress on SRB propellant void issue
« Reply #1 on: 09/15/2014 02:02 pm »
Superb article!

Offline Chris Bergin

Re: ATK making progress on SRB propellant void issue
« Reply #2 on: 09/15/2014 02:08 pm »
Superb article!

Yeah, Chris did a great job with it and ATK's help ensured it was super accurate.

And I'm posting the obvious here to bump this back to the top! Beats the negative thread! ;D
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Offline tesla

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Re: ATK making progress on SRB propellant void issue
« Reply #3 on: 09/15/2014 02:13 pm »
Superb article!

Yeah, Chris did a great job with it and ATK's help ensured it was super accurate.

And I'm posting the obvious here to bump this back to the top! Beats the negative thread! ;D

Awesome article!!! For articles like this I come to this site! Thank you!  :)
Go SLS and Orion! God bless America.

Offline dbooker

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Re: ATK making progress on SRB propellant void issue
« Reply #4 on: 09/15/2014 03:14 pm »
Very good article.  But it doesn't make me feel any better about the use of solid boosters for manned flights.  All this "characterizing of voids" eerily reminds me of characterization of tile loss on the shuttles.  My reading of this is that ATK and NASA are saying that since it hasn't caused any issues yet, the voids are okay.  Isn't that what they said about the old joints and the shuttle tile losses. 

Offline Rocket Science

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Re: ATK making progress on SRB propellant void issue
« Reply #5 on: 09/15/2014 03:33 pm »
Excellent article Chris G! :)
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Offline newpylong

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Re: ATK making progress on SRB propellant void issue
« Reply #6 on: 09/15/2014 05:22 pm »
Very good article.  But it doesn't make me feel any better about the use of solid boosters for manned flights.  All this "characterizing of voids" eerily reminds me of characterization of tile loss on the shuttles.  My reading of this is that ATK and NASA are saying that since it hasn't caused any issues yet, the voids are okay.  Isn't that what they said about the old joints and the shuttle tile losses.

If that's what you got out of the article I suggest re-reading it!

Very thorough article, sums things up well. Thanks for writing.
« Last Edit: 09/15/2014 05:22 pm by newpylong »

Offline Coastal Ron

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Re: ATK making progress on SRB propellant void issue
« Reply #7 on: 09/15/2014 10:29 pm »
Very good article.  But it doesn't make me feel any better about the use of solid boosters for manned flights.  All this "characterizing of voids" eerily reminds me of characterization of tile loss on the shuttles.  My reading of this is that ATK and NASA are saying that since it hasn't caused any issues yet, the voids are okay.  Isn't that what they said about the old joints and the shuttle tile losses.

If that's what you got out of the article I suggest re-reading it!

We flew Shuttle SRM's for 30 years, and the SLS SRM is based on that design, so discovering major defects is not something to be dismissed.  From the article:

"A year after discovering small voids between the solid propellant and the outer casing of the aft segment of a test motor for the massive 5-segment SRBs for NASA’s upcoming Space Launch System (SLS) rocket, ATK is making firm progress in their investigation and the mitigating factors toward correcting the issue ahead of the Qualification Motor -1 (QM-1) firing."

If it's taking them more than a year to find the cause and the fix, that sounds like a major problem.

Now maybe it could be argued that the size of the motors/castings make it difficult to iterate for finding a fix, but that would just be an argument for why SRM's are such a borderline design for this type of application.  Certainly it supports NASA's desire to compete future booster suppliers.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline KEdward5

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Re: ATK making progress on SRB propellant void issue
« Reply #8 on: 09/15/2014 10:38 pm »
It's no small problem, but no different to what most of the other companies endure with such large and complex pieces of hardware.

The difference is, ATK are honest enough and open enough to trust this site to provide updates on it. That does not make other companies "better" at such things, by sitting on their hands and tweeting "Retweet that we're cool. Free T-shirts for the first 50!"

And would you really want a competition between a company that has decades of booster experience, and one of those other companies with nothing close to the experience?

It's those "but we may save a few million bucks" fiscal responsibility champions that will ensure we never get anywhere, fast.

Offline pathfinder_01

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Re: ATK making progress on SRB propellant void issue
« Reply #9 on: 09/15/2014 10:54 pm »
Yes, such an competition would allow new ideas and new concepts to be used. Not everything is learned by experience. As for the voids, ah I got the distinct feeling that they shouldn't be there to begin with. I could be wrong, but I think they are trying to normalize what shouldn't be there. It could be harmless, but doesn't sound so.

Offline Coastal Ron

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Re: ATK making progress on SRB propellant void issue
« Reply #10 on: 09/15/2014 11:45 pm »
It's no small problem, but no different to what most of the other companies endure with such large and complex pieces of hardware.

My point was that the SRM's are supposed to be a mature technology, yet here we have a problem that has stymied them for over a year.

Quote
The difference is, ATK are honest enough and open enough to trust this site to provide updates on it.

Kind of hard to hide the fact that you haven't been able to proceed for over a year.  I don't question their processes that led to the discovery, or the processes that they are using to find a solution.  Just that solid rocket motors may have an upper limit of use that we have already reached.  But I'm not an engineer, so I'm not making a technical determination, just an observation.

Quote
That does not make other companies "better" at such things, by sitting on their hands and tweeting "Retweet that we're cool. Free T-shirts for the first 50!"

I wasn't aware that I've been missing out on getting an Aerojet t-shirt just for retweeting something...  ;)

Quote
And would you really want a competition between a company that has decades of booster experience, and one of those other companies with nothing close to the experience?

No doubt ATK has lots of experience, but they are not the only ones with solid fuel experience, nor are solid fuels the only option.  NASA's Gerstenmaier is on record saying that SRM's were not the long term booster solution, and that liquid-fueled boosters were the likely solution.  And liquid-fueled boosters are essentially single core rockets, which lots of companies have experience with.

Quote
It's those "but we may save a few million bucks" fiscal responsibility champions that will ensure we never get anywhere, fast.

There are no short-term alternatives, but it validates the need for opening up future booster needs to competition.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline JBF

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Re: ATK making progress on SRB propellant void issue
« Reply #11 on: 09/16/2014 12:01 am »
Remember this whole issue came about because of the shift away from asbestos.  So it wasn't a case of they don't know what they are doing but more of a new materials issue, which is why they test.
"In principle, rocket engines are simple, but that’s the last place rocket engines are ever simple." Jeff Bezos

Offline newpylong

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Re: ATK making progress on SRB propellant void issue
« Reply #12 on: 09/16/2014 01:36 pm »
Very good article.  But it doesn't make me feel any better about the use of solid boosters for manned flights.  All this "characterizing of voids" eerily reminds me of characterization of tile loss on the shuttles.  My reading of this is that ATK and NASA are saying that since it hasn't caused any issues yet, the voids are okay.  Isn't that what they said about the old joints and the shuttle tile losses.

If that's what you got out of the article I suggest re-reading it!

We flew Shuttle SRM's for 30 years, and the SLS SRM is based on that design, so discovering major defects is not something to be dismissed.  From the article:

"A year after discovering small voids between the solid propellant and the outer casing of the aft segment of a test motor for the massive 5-segment SRBs for NASA’s upcoming Space Launch System (SLS) rocket, ATK is making firm progress in their investigation and the mitigating factors toward correcting the issue ahead of the Qualification Motor -1 (QM-1) firing."

If it's taking them more than a year to find the cause and the fix, that sounds like a major problem.

Now maybe it could be argued that the size of the motors/castings make it difficult to iterate for finding a fix, but that would just be an argument for why SRM's are such a borderline design for this type of application.  Certainly it supports NASA's desire to compete future booster suppliers.

There's your straw man argument again.

Did anyone say it wasn't a major problem? Who is dismissing it?

What I read is that insulation voids are acceptable and bond line voids are not. The change to the new insulation and/or processes have been narrowed down to be the root. A fix is in place based on the investigation and a replacement case is being filled that should resolve the bond issues.

To me that seems the issue is getting much attention and they are not cutting corners.




Offline notsorandom

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Re: ATK making progress on SRB propellant void issue
« Reply #13 on: 09/16/2014 02:00 pm »
It is hard to compare apples to apples here. SLS like STS is not like the commercial operations it routinely gets compared to. For example when the shuttle had a hydrogen leak not only did people know what the cause of the mission delay was they could log into this very website and get a detailed rundown of the offending hardware with pictures and every thing. We are just not going to get that level of detail out of a commercial program. Both commercial resupply providers ran into problems with their propulsion systems as well. Propulsion is after all rocket science. The difference is not that other launch systems don't run into problems, its that they are less sharing of the minutia of what went wrong.

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