Space Launch System - Orion
Discussion
The launch escape system would take the capsule off the rocket and they’d splashdown in the Atlantic. Not ideal though, of course.
I think the solid boosters fire for 2 minutes, so they’d only be partway through that as well.
No, they’ll have to do the full burn again, so like the Shuttle it means removing all the engines to check them over. Another month or two wasted.
I think the solid boosters fire for 2 minutes, so they’d only be partway through that as well.
No, they’ll have to do the full burn again, so like the Shuttle it means removing all the engines to check them over. Another month or two wasted.
I suppose they might have 4 other engines ready to swap in.
Can they even remove and replace engines in situ on the stand, or is that a return down the river to the factory job?
They fitted them all in a couple of days in the factory I recall. They took their time over the first one, but the other three took a few hours each.
Can they even remove and replace engines in situ on the stand, or is that a return down the river to the factory job?
They fitted them all in a couple of days in the factory I recall. They took their time over the first one, but the other three took a few hours each.
At the press conference they confirmed they do have spare engines at Stennis and they can swap them on site. Takes a week to ten days to do.
The engines were running at 109% thrust when a flash was seen on engine 4 it seems. The engine’s computer shut itself off and they terminated the test.
They said they have a lot of data to investigate over the next few days before they can decide their next step. It’s going to put things back weeks clearly, so a 2021 launch is very unlikely.
The engines were running at 109% thrust when a flash was seen on engine 4 it seems. The engine’s computer shut itself off and they terminated the test.
They said they have a lot of data to investigate over the next few days before they can decide their next step. It’s going to put things back weeks clearly, so a 2021 launch is very unlikely.
I think if they ran the test again within three weeks (minimum time to dry out the engines apparently) I'd possibly be more concerned than if they delayed for six months. If they ran it again straight away, having spent so long planning, testing, checking and re-checking, you would have to wonder how they missed something that was presumably very straightforward.
In the presser afterwards they said that they received a "Major Component Failure" signal. Using the word "signal" possibly implies they think it was an erroneous reading rather than anything actually failing? Given everything shut down cleanly I suppose that's possible, although I think (Eric probably can confirm this off the top of his head) that the RS-25s in the Shuttle days also shrugged off various off-nominal events (e.g. swallowing a bolt?).
In the presser afterwards they said that they received a "Major Component Failure" signal. Using the word "signal" possibly implies they think it was an erroneous reading rather than anything actually failing? Given everything shut down cleanly I suppose that's possible, although I think (Eric probably can confirm this off the top of his head) that the RS-25s in the Shuttle days also shrugged off various off-nominal events (e.g. swallowing a bolt?).
The RS-25 was a very reliable engine - although in its early days when being tested prior to the first Shuttle flight they had a few explosions on the test stands.
These RS-25s have been heavilly modified for SLS. For example, they have been uprated to a higher thrust setting than when used on the Shuttle. This is because they are now expendable and don't have to be "saved" for future missions.
Also, they have never fired four of these in a cluster of four before (there were three on each Orbiter) so there may have been unexpected resonances and vibrations experienced with all four engines running together. That was part of the reason for running this test. Despite all your best predictions and modelling, there will be some unknowns every time you do something for the first time.
These RS-25s have been heavilly modified for SLS. For example, they have been uprated to a higher thrust setting than when used on the Shuttle. This is because they are now expendable and don't have to be "saved" for future missions.
Also, they have never fired four of these in a cluster of four before (there were three on each Orbiter) so there may have been unexpected resonances and vibrations experienced with all four engines running together. That was part of the reason for running this test. Despite all your best predictions and modelling, there will be some unknowns every time you do something for the first time.
On the same test stand I believe. Although it only had to run for about 2.5 minutes before it was done.
https://www.youtube.com/watch?v=-rP6k18DVdg
https://www.youtube.com/watch?v=-rP6k18DVdg
Eric Mc said:
Thanks. I hadn’t taken that on board, even though I’ve been reading about this stuff for years.
Full details in Alan Lawrie's bookhttps://www.amazon.co.uk/Saturn-Complete-Manufactu...
Beati Dogu said:
On the same test stand I believe. Although it only had to run for about 2.5 minutes before it was done.
https://www.youtube.com/watch?v=-rP6k18DVdg
When you're converting 15 tonnes of fuel per second into heat, light and noise 2 minutes probably seems like a long time.https://www.youtube.com/watch?v=-rP6k18DVdg
They test fired a single RS-25 SLS engine at Stennis earlier. This is a new, development engine, not one taken from the Shuttle program. It is being test fired to give data to its manufacturer, Aerojet Rocketdyne. They're making engines to be used once NASA runs out of ex-Shuttle engines after four SLS flights.
https://www.youtube.com/watch?v=gaJTDvOIXbk
Ignition at 9 mins in and it ran for the full 8 minutes.
https://www.nasa.gov/centers/stennis/news/releases...
https://www.youtube.com/watch?v=gaJTDvOIXbk
Ignition at 9 mins in and it ran for the full 8 minutes.
https://www.nasa.gov/centers/stennis/news/releases...
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