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?
This (the Castor 600) IS the center core. If it wasn't damaged by the shrapnel here, and it didn't appear to be, I don't see why it would be in flight. Especially since in flight, the shrapnel will fall away rather than around.
Now, if this happened much earlier in the test, while the GEM 60 boosters would still be attached in flight, that would probably be an issue. As is I don't think shrapnel is a problem.
4 years ago they said they’d test the rocket in May 2019
That article is from three years ago! Maybe they became a more optimistic from the prediction in 2015. :-)
First of all, thankyou to Northrop Grumman for showing this live. Who doesn't like seeing big motors being tested!
Here's the sequence of frames of the nozzle failure. We can clearly see a large fireball erupting from the left side of the nozzle along with some debris heading upwards.
I'm an engineer and I do tests all the time. When a test does not go to plan, my reaction is one of head down. There's a problem with the design that's going to take time to fix. Its the reason why we test, to get the bugs out of the design. I certainly don't jump out of my chair and shout "Success!". That's taurus excretus. When the test does work, that's when I give the fist pump and have a big smile on my face. :-)
Some engineering philosophy:
I was told and I forgot.
I saw and I remembered.
I did and I understood.
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?
Clearly the motor, or at least the nozzle, suffered a failure during this test. This cannot happen during a flight, and now it won't happen thanks to this test. This was a "successful" test in the same way that the CST-100 and Dragon ground abort tests were "successful" - by rooting out flaws.
- 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?
Clearly the motor, or at least the nozzle, suffered a failure during this test. This cannot happen during a flight, and now it won't happen thanks to this test. This was a "successful" test in the same way that the CST-100 and Dragon ground abort tests were "successful" - by rooting out flaws.
- Ed Kyle
Agree very much with this.
I will say it draws into question the "low technical risk" rating, HOWEVER tests are tests. This is a very useful test.
And I REALLY don't like investing a bunch of money into OmegA/son-of-the-Stick (it cannot be rapidly reusable, which is essential to a shiny space future), but the NG/ATK/Orbital team has shown an impressive ability to lean forward and bend metal and layup carbon fiber. I will always respect a hardware-rich stance, even if I don't happen to like the architecture.
And I consistently want folks to do more hardware tests, not fewer, and part of that means accepting a significant possibility of uncovering real problems in those hardware tests. So I'm glad NG pushed for this test. And I'm not going to beat them up because it uncovered a problem.
NG had a bad day yesterday. But this what tests are for. And good on them for having the courage to go for it.
I totally agree. Success and failure are rarely as black and white as we all like to pretend they are. Even if we start talking about payloads reaching orbit as successes and failures, that's whole cloth ignoring near-misses that are very clear failures of certain systems (Atlas V engine valve issue comes to mind).
Kudos to NGIS for airing this even with a very clear failure of the nozzle. Kudos to NGIS for hitting their schedule for static fire, that's really tough to do.
Speculation hat on: I think this was a burn through of the nozzle followed by a structural failure because of the burn through. If that's true, it's a very solvable problem.
4 years ago they said they’d test the rocket in May 2019
That article is from three years ago! Maybe they became a more optimistic from the prediction in 2015. :-)
This seems like a great example of "Gradatim Ferociter". You plan to do a test 3-4 years from now. That's "Gradatim". Then you actually fire a big honking rocket engine for a full thrust, full duration test - that's "Ferociter".
Scott Manley’s news report on the test as well as the OmegA launcher. He does put forward an argument in the video which I am assuming explains why he uses the word failure in the title.
[MEDIA=youtube]1mTCxpGSIbI[/MEDIA]
I totally agree. Success and failure are rarely as black and white as we all like to pretend they are. Even if we start talking about payloads reaching orbit as successes and failures, that's whole cloth ignoring near-misses that are very clear failures of certain systems (Atlas V engine valve issue comes to mind).
Kudos to NGIS for airing this even with a very clear failure of the nozzle. Kudos to NGIS for hitting their schedule for static fire, that's really tough to do.
Speculation hat on: I think this was a burn through of the nozzle followed by a structural failure because of the burn through. If that's true, it's a very solvable problem.
I hope it's just a nozzle thermal or structural issue, but the "bang" sound and violent ejection of pieces suggest more than just a burn-through to me. My first guess was the nozzle throat insert failed from the mechanical/thermal stress of the firing, and just let go suddenly with a "bang," taking part of the exit cone with it.
Usually the throat insert is a separate torus of carbon/carbon material supported by the rest of the nozzle assembly. If there was a CTE mismatch or a manufacturing defect, the throat insert may just not have been able to take the stress.
The sequence of events also seems consistent with ejection of a chunk of propellant, impacting the nozzle throat and causing the "bang" and shattering the nozzle. But as you said, we can/should hope that wasn't the case.