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#40
by
Lars-J
on 30 May, 2019 20:22
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They "observed the aft cone doing something strange that we need to look at". An interesting set of euphemisms.
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#41
by
tp1024
on 30 May, 2019 20:22
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4 years ago they said they’d test the rocket in May 2019, they made it there. Heated to 90 deg, higher thrust. Called it a success. Everything worked very very well, observed aft exit cone “doing something strange”
Is there any material on the test, that confirms this? I especially want to know whether this is Celsius or Fahrenheit.
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#42
by
DaveS
on 30 May, 2019 20:38
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4 years ago they said they’d test the rocket in May 2019, they made it there. Heated to 90 deg, higher thrust. Called it a success. Everything worked very very well, observed aft exit cone “doing something strange”
Is there any material on the test, that confirms this? I especially want to know whether this is Celsius or Fahrenheit.
What that the Propellant Mean Bulk Temperature (PMBT) affects SRM performance? Yes there is, decades of it.
Here's one example, the first result off Google:
https://tfaws.nasa.gov/TFAWS08/Proceedings/Presentations/TFAWS-08-1006_presentation.pdf
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#43
by
whitelancer64
on 30 May, 2019 21:15
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4 years ago they said they’d test the rocket in May 2019, they made it there. Heated to 90 deg, higher thrust. Called it a success. Everything worked very very well, observed aft exit cone “doing something strange”
Is there any material on the test, that confirms this? I especially want to know whether this is Celsius or Fahrenheit.
This is the USA, so Fahrenheit.
They heat the entire booster in a giant heater over the course of several days, and they measure the internal temperature of the solid fuel to make sure it's at 90 before the test fire. Same thing for when they do minimum temperature test fire, they put it in a cooler for a week.
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#44
by
Star One
on 30 May, 2019 22:54
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Scott Manley’s edit(s) of the ‘incident’.
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#45
by
RotoSequence
on 30 May, 2019 23:49
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I wonder if the limited spread of the nozzle's failure was a case of good engineering or good fortune. That looks like it could have blown up the whole motor!
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#46
by
Lars-J
on 30 May, 2019 23:52
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I wonder if the limited spread of the nozzle's failure was a case of good engineering or good fortune. That looks like it could have blown up the whole motor!
It depends on the root cause... If a chunk of propellant came loose and struck the nozzle to make it fail, sure, but not if the nozzle was the root failure point. But if this happened in-flight as the tail end of the first stage burn, that would probably not be good - the stack could potentially be put under a lot of stress from asymmetric thrust.
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#47
by
Comga
on 31 May, 2019 00:00
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I wonder if the limited spread of the nozzle's failure was a case of good engineering or good fortune. That looks like it could have blown up the whole motor!
It depends on the root cause... If a chunk of propellant came loose and struck the nozzle to make it fail, sure, but not if the nozzle was the root failure point. But if this happened in-flight as the tail end of the first stage burn, that would probably not be good - the stack could potentially be put under a lot of stress from asymmetric thrust.
And without a nozzle there is no thrust vector control.
The rocket would be unguided.
While the cheerleaders say the thrust had fallen off there appeared to still be significant thrust at the time of “the event”.
Scott Manley called it a “failure”. How rude!
But it’s still good enough to compete with proven rockets for Air Force launch contracts.
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#48
by
RotoSequence
on 31 May, 2019 00:08
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I wonder if the limited spread of the nozzle's failure was a case of good engineering or good fortune. That looks like it could have blown up the whole motor!
It depends on the root cause... If a chunk of propellant came loose and struck the nozzle to make it fail, sure, but not if the nozzle was the root failure point. But if this happened in-flight as the tail end of the first stage burn, that would probably not be good - the stack could potentially be put under a lot of stress from asymmetric thrust.
The followup question to my concern is, was the spread of the nozzle failure limited because of deliberate engineering or luck? If the failure continued further up the nozzle, I'm not sure that the propellant case would have survived.
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#49
by
Rocket Science
on 31 May, 2019 01:49
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They "observed the aft cone doing something strange that we need to look at". An interesting set of euphemisms.
Yeah, it blew it's a$$ end off...
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#50
by
WindnWar
on 31 May, 2019 03:14
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Watching the video the exhaust plume seemed to get a lot brighter for a the last few seconds before it let go. Maybe that's normal or just the camera?
Either way, hard to call it a success when you lose a flight critical piece of the rocket during the test.
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#51
by
Chris Bergin
on 31 May, 2019 03:31
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#52
by
edkyle99
on 31 May, 2019 03:58
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From the USAF point of view, integral part of development process: Sanjume - working very closely and plan forward from me. Press conference over
Bravo to USAF and Northrop Grumman for showing the test, even the off-nominal bit, and talking about it in a press conference. It seems clear from the information shared with the public that some very good lessons will be learned from this test, thanks to the "strange" event at the end. That's why Rominger called it a "successful test".
- Ed Kyle
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#53
by
Lars-J
on 31 May, 2019 05:50
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From the USAF point of view, integral part of development process: Sanjume - working very closely and plan forward from me. Press conference over
Bravo to USAF and Northrop Grumman for showing the test, even the off-nominal bit, and talking about it in a press conference. It seems clear from the information shared with the public that some very good lessons will be learned from this test, thanks to the "strange" event at the end. That's why Rominger called it a "successful test".
- Ed Kyle
One certainly learns from all test failures, but that does not make it a "successful test". That's a very low bar for "success". And what would you call a test where the nozzle didn't fail?
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#54
by
ccdengr
on 31 May, 2019 06:22
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Putting a positive spin on a less-than-perfect outcome is hardly an action unique to NGIS. As rocket motor failures go, this one was a lot more benign than many (do I need to name names?) and more publicly presented.
I still wonder if all of the full range nozzle gimbaling had anything to do with the problem.
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#55
by
Star One
on 31 May, 2019 06:37
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I wonder if the limited spread of the nozzle's failure was a case of good engineering or good fortune. That looks like it could have blown up the whole motor!
It depends on the root cause... If a chunk of propellant came loose and struck the nozzle to make it fail, sure, but not if the nozzle was the root failure point. But if this happened in-flight as the tail end of the first stage burn, that would probably not be good - the stack could potentially be put under a lot of stress from asymmetric thrust.
And without a nozzle there is no thrust vector control.
The rocket would be unguided.
While the cheerleaders say the thrust had fallen off there appeared to still be significant thrust at the time of “the event”.
Scott Manley called it a “failure”. How rude!
But it’s still good enough to compete with proven rockets for Air Force launch contracts.
Is calling it a failure all that far off the mark though. It’s certainly something that could I thought have led to an actual launch failure?
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#56
by
FutureSpaceTourist
on 31 May, 2019 08:39
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#57
by
JEF_300
on 31 May, 2019 08:41
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Is calling it a failure all that far off the mark though. It’s certainly something that could I thought have led to an actual launch failure?
It's hard to say. They'll have to look at the data, but at the press conference they said that if it happened late enough in the test, it might have been endurable in flight.
That said, I'm still not convinced the people at the conference had seen the footage. They very well may watched the test in person, from several miles away, and then bused back to the office and went straight into the conference.
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#58
by
JEF_300
on 31 May, 2019 08:56
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We've gotta remember that this was the first Castor 600 test firing ever. The FIRST test. NGIS primary concern wasn't if, for example, the nozzle had enough ablator or the gimbal would work; they were asking big obvious simple questions.
Will it fire for as long as expected?
Will it produce anywhere near as much thrust as expected?
Will the casing hold?
Does it work at all?
And on all those counts, the test was a success. Those were the things that really mattered; everything else was a bonus.
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#59
by
Star One
on 31 May, 2019 08:57
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Is calling it a failure all that far off the mark though. It’s certainly something that could I thought have led to an actual launch failure?
It's hard to say. They'll have to look at the data, but at the press conference they said that if it happened late enough in the test, it might have been endurable in flight.
That said, I'm still not convinced the people at the conference had seen the footage. They very well may watched the test in person, from several miles away, and then bused back to the office and went straight into the conference.
Couldn’t all that shrapnel flying off it have done serious damage to the centre core?
