Boeing Starliner
Discussion
“scrubbed today’s launch attempt due to the computer ground launch sequencer not loading into the correct operational configuration after proceeding into terminal count. The ULA team is working to understand the cause.”
- NASA Commercial Crew.
Next available window Is tomorrow, Sunday 2nd at 12.03pm local time / 5.03 pm UK time.
I can’t help feeling that the infrequency of ULA launches is part of the problem. This will be the first Atlas V launch from this pad (SLC-41) this year. The last one was October 2023.
They did launch a Vulcan rocket from this pad in January, but that’s a methane / oxygen powered so will use different plumbing and presumably different ground control computers.
- NASA Commercial Crew.
Next available window Is tomorrow, Sunday 2nd at 12.03pm local time / 5.03 pm UK time.
I can’t help feeling that the infrequency of ULA launches is part of the problem. This will be the first Atlas V launch from this pad (SLC-41) this year. The last one was October 2023.
They did launch a Vulcan rocket from this pad in January, but that’s a methane / oxygen powered so will use different plumbing and presumably different ground control computers.
One quote about all this made me laugh was: "that Boeing couldn't pour piss out of a boot if the instructions were on the heel."
To be fair, it's more an ULA issue by the sound of it. Boeing just can't catch a break right now.
It's complicated by the fact it's an instantaneous launch window, because it's on an intercept with the ISS.
There's just no time to reassess and recycle in less than ~24hrs on these.
Plus being the initial manned test flight, the have a hair trigger with any safety issue.
To be fair, it's more an ULA issue by the sound of it. Boeing just can't catch a break right now.
It's complicated by the fact it's an instantaneous launch window, because it's on an intercept with the ISS.
There's just no time to reassess and recycle in less than ~24hrs on these.
Plus being the initial manned test flight, the have a hair trigger with any safety issue.
Beati Dogu said:
It's complicated by the fact it's an instantaneous launch window, because it's on an intercept with the ISS
Would the fact that they're trying for an instantaneous launch window of the first manned test flight indicate that the vehicle lacks the capability to reach the ISS from a lower phasing orbit ?I’m sure Atlas V is more than capable of doing what’s required, but ULA have been tasked by NASA with taking Starliner on a low, flat suborbital trajectory. This is so that if the rocket has problems, the capsule can escape with minimal G force load on the crew. It'll also have enough atmosphere & horizontal velocity to aerobrake before safe parachute deployment. And if the Starliner's rocket engines don't ignite after release, it'll naturally reenter within hours & not get stuck in a slowly decaying orbit.
The most efficient way to get to the ISS is to launch as it passes directly over the pad. Then you don’t have to waste delta V by doing dogleg manoeuvres etc. you’re just chasing after the ISS from behind and below. Timing is important for this, so they tend to have instantaneous launch windows or very narrow ones. I think the Shuttle had 10 minute ISS windows, but they would normally try to launch at the start of it. Due to the higher drag, low suborbital path, Atlas V also doesn't have the fuel budget available for anything but an instantaneous launch. Its upper stage has 2 RL-10 engines to help with this unique mission profile. The side boosters are also held on much longer than normal after burn out so they don't dump them intact into the Atlantic shipping lanes.
It seems that ULA have 3 computers for control of the explosive bolts holding the rocket to the pad, For launch, all 3 have to be operational. 2 of them came up ok, but a 3rd was slow to react and that triggered the hold.
The most efficient way to get to the ISS is to launch as it passes directly over the pad. Then you don’t have to waste delta V by doing dogleg manoeuvres etc. you’re just chasing after the ISS from behind and below. Timing is important for this, so they tend to have instantaneous launch windows or very narrow ones. I think the Shuttle had 10 minute ISS windows, but they would normally try to launch at the start of it. Due to the higher drag, low suborbital path, Atlas V also doesn't have the fuel budget available for anything but an instantaneous launch. Its upper stage has 2 RL-10 engines to help with this unique mission profile. The side boosters are also held on much longer than normal after burn out so they don't dump them intact into the Atlantic shipping lanes.
It seems that ULA have 3 computers for control of the explosive bolts holding the rocket to the pad, For launch, all 3 have to be operational. 2 of them came up ok, but a 3rd was slow to react and that triggered the hold.
Edited by Beati Dogu on Tuesday 4th June 22:47
Beati Dogu said:
It seems that ULA have 3 computers for control of the explosive bolts holding the rocket to the pad, For launch, all 3 have to be operational. 2 of them came up ok, but a 3rd was slow to react and that triggered the hold.
But do we really need three computers just to control explosive bolts? I bet Apollo didn't use any.It seems that the more 'tech' we add into rockets, the more problems we add too. The more stuff you add on, the more stuff there is to fail.
In other news, the Chinese land a probe to collect soil samples on the dark side of the moon, with satellite relay so they can see what they're doing.
Simpo Two said:
But do we really need three computers just to control explosive bolts? I bet Apollo didn't use any.
It seems that the more 'tech' we add into rockets, the more problems we add too. The more stuff you add on, the more stuff there is to fail.
In other news, the Chinese land a probe to collect soil samples on the dark side of the moon, with satellite relay so they can see what they're doing.
The Ground Launch Sequencer automatically controls launch in final minutes of the countdown. It monitors all measurements that need immediate reaction and issues commands to the suppression system, igniters, umbilical connections and hold down clamps.It seems that the more 'tech' we add into rockets, the more problems we add too. The more stuff you add on, the more stuff there is to fail.
In other news, the Chinese land a probe to collect soil samples on the dark side of the moon, with satellite relay so they can see what they're doing.
The computer used by Apollo for this role was called the Terminal Countdown Sequencer and it took over automatic control a T-3 minutes and 7 seconds. It triggered a hold at T-30 seconds on Apollo 17.
https://www.nytimes.com/1972/12/07/archives/flight...
https://www.nasa.gov/history/afj/launchwindow/scru...
Even Mercury-Redstone had an automatic sequencer to automatically control the final 35 seconds of the countdown sequence.
Yes and it's not that 3 computers are controlling just the explosive bolts. According to ULA boss Tory Bruno, their ground control system uses 3 computers for triple redundancy, They will all have cards in them to control various tasks like fuel and O2 loading, retracting the umbilicals and the pyrotechnic bolt release charges. Normally if one of the computers goes down, they can just switch to another and carry on.
During the countdown they run a routine health check on them and it was at that point that one of the 3 launch sequencer (bolt release) cards was slow to come up. For extra safety reasons, the system requires ALL 3 computer cards be working for this critical task, so an automatic hold was triggered.
Now they're looking at Wednesday, 5th June to finally launch this thing. With 6th June being the alternate
That'd be at:
10:52 am. EDT (3:52 pm UK time) on the 5th June
or
10:29 am EDT (3:29 pm UK time) on the 6th June
During the countdown they run a routine health check on them and it was at that point that one of the 3 launch sequencer (bolt release) cards was slow to come up. For extra safety reasons, the system requires ALL 3 computer cards be working for this critical task, so an automatic hold was triggered.
Now they're looking at Wednesday, 5th June to finally launch this thing. With 6th June being the alternate
That'd be at:
10:52 am. EDT (3:52 pm UK time) on the 5th June
or
10:29 am EDT (3:29 pm UK time) on the 6th June
lost in espace said:
Solid boosters, can't be stopped once started!
Remember being at a talk by Chris Hadfield a few years back and he mentioned that regarding the shuttle launch."Once they start it, you're definitely going somewhere !"
Glad it's finally launched and seemingly all to plan
Gassing Station | Science! | Top of Page | What's New | My Stuff