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#60
by
Eric Hedman
on 20 May, 2022 13:24
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Suggestion to the moderators: If you want to know more about the relmop plots, contact the JSC public affairs office and ask for a reference to someone from Mission Planning & Operations. For more information about Simworks, contact Boeing in Houston. You might also look up former McDonnell Douglas engineer, author and occasional space contributor for NBC News Jim Oberg for general information about rendezvous.
JimO is a member of NSF and has been since probably close to the founding date of the forum, during Shuttle days. So too are others (I won’t mention) directly involved in rendezvous and prox/ops planning during Shuttle and even into the present day. Most people don’t recognize their usernames (which are more pseudonymous than JimO’s!) but Chris B. and the Mod Squad probably know who they are.
A few very well known people in the industry have told me that they regularly come to this site and checkout what is being said here. I don't know if they post here. But this site does get used by key people in the industry to stay current. I suspect it filters down to every level in the aerospace industry,
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#61
by
Herb Schaltegger
on 20 May, 2022 13:26
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I seem to recall Dragon lost some thrusters on early missions, too.
Yeah, I mentioned that last night in this very thread and the Usual Suspects came out to attack anyway.
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#62
by
haywoodfloyd
on 20 May, 2022 13:41
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During the broadcast I heard the commentator say "St. John's Nova Scotia". I assume he meant to say St. John's Newfoundland.
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#63
by
clongton
on 20 May, 2022 14:02
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OMAC thrusters failing on OI burn is not a small thing. ALL manned spacecraft have redundancy to take over when something fails, but imo 2 thrusters failing on what is a spacecraft demonstration flight is a problem. They had to exercise TWO (2) contingency conditions on a flight that for all intents and purposes SHOULD have been textbook perfect. If ANY flight must be textbook perfect, surely it would be the demo flight NASA will use to certify the spacecraft for crew. Remember, it is these same thrusters that will be used to deorbit the spacecraft to bring the crew home. What happens if the thrusters fail then? Sure, there are backups, but the chances of them actually needing them should be very, vary small. A LOT smaller than on THIS flight. This failure would make me nervous about whether or not this spacecraft could take me home. Remind me again how long they have been working on this spacecraft? Let's hope they have exhausted the unexpected difficulties and the rest of the mission actually is textbook perfect. They are upbeat about that happening but they have a questionable track record wrt this spacecraft. We'll see. I hope so, but we'll see.
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#64
by
meekGee
on 20 May, 2022 14:04
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I seem to recall Dragon lost some thrusters on early missions, too.
Yeah, I mentioned that last night in this very thread and the Usual Suspects came out to attack anyway.
Herb, I assume you're talking about the first "Lost in Space" Dragon episode, with the frozen fuel line.
That was much more serious issue, but what you're doing is a classic "whataboutism".
Besides, it turned out not to be part of a pattern, right?
I don't think failed thrusters would register as much if this was try #1.
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#65
by
edkyle99
on 20 May, 2022 14:12
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During the broadcast I heard the commentator say "St. John's Nova Scotia". I assume he meant to say St. John's Newfoundland.
Or Saint John, New Brunswick? It is opposite Nova Scotia on the Bay of Fundy.
There used to be a NASA tracking station near St. John's, Newfoundland, but it was shut down in 1983.
- Ed Kyle
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#66
by
DanClemmensen
on 20 May, 2022 14:13
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Two failures point to a system problem instead of a single-sample failure. What is the relationship between these thrusters and the valves that failed last August, other than being on the same spacecraft?
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#67
by
haywoodfloyd
on 20 May, 2022 14:22
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During the broadcast I heard the commentator say "St. John's Nova Scotia". I assume he meant to say St. John's Newfoundland.
Or Saint John, New Brunswick? It is opposite Nova Scotia on the Bay of Fundy.
There used to be a NASA tracking station near St. John's, Newfoundland, but it was shut down in 1983.
- Ed Kyle
That's possible.
A lot of people get St. John mixed up with St. John's. I always remembered it when I was much younger as St. John's has an "s" at the end, referring to "sea". Now it's just habit.
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#68
by
ppb
on 20 May, 2022 14:25
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OMAC thrusters failing on OI burn is not a small thing. ALL manned spacecraft have redundancy to take over when something fails, but imo 2 thrusters failing on what is a spacecraft demonstration flight is a problem. They had to exercise TWO (2) contingency conditions on a flight that for all intents and purposes SHOULD have been textbook perfect. If ANY flight must be textbook perfect, surely it would be the demo flight NASA will use to certify the spacecraft for crew. Remember, it is these same thrusters that will be used to deorbit the spacecraft to bring the crew home. What happens if the thrusters fail then? Sure, there are backups, but the chances of them actually needing them should be very, vary small. A LOT smaller than on THIS flight. This failure would make me nervous about whether or not this spacecraft could take me home. Remind me again how long they have been working on this spacecraft? Let's hope they have exhausted the unexpected difficulties and the rest of the mission actually is textbook perfect. They are upbeat about that happening but they have a questionable track record wrt this spacecraft. We'll see. I hope so, but we'll see.
My thoughts exactly. Boeing, after a long and distinguished history of engineering excellence, has badly tarnished their reputation with this program and others over the past few years. How much longer do we continue to give them the benefit of doubt? After the totally embarrassing valve problems, they STILL have a non-trivial propulsion issue. Yeah, sure, SpaceX’s very early Dragon flights had a minor propulsion issue. But that was quickly cleared up and we haven’t heard about any problems since. It’s just one non-trivial thing after another at a late point with this Starliner project.
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#69
by
meekGee
on 20 May, 2022 14:42
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This is every flight having significant problems, three out of three.
Three? I presume you are counting the pad abort then?
I'm counting stuck valves, as it was a launch attempt (and also resulted pretty much in LoV, but that's a different thing)
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#70
by
Chris Bergin
on 20 May, 2022 14:44
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Working other issues overnight. We'll see what the status update is when we get one, per go for docking or not.
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#71
by
kdhilliard
on 20 May, 2022 14:55
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... How many of the 12 OMAC thrusters could fail at any given time and the remainder still accomplish key functions like the deorbit burn?
I read upthread that 2 of 3 in a single "can" failed off...or fired but then stopped firing. But I'm not sure this leaves this Starliner in a single-point of failure. Are there 4 "cans," each with 3 thrusters? and even if all 3 in one can fail, can't the others get the job done (perhaps with some interesting attitude control by the smaller thrusters)?
Yes, there are three aft-facing OMAC thrusters in each doghouse ("can").
The three larger nozzles in these photos are are the 1,500 lbf OMAC thrusters and the two smaller are the 85 lbf RCS thrusters.
https://twitter.com/SciGuySpace/status/1527312605437521923But the loss of all three in one doghouse would still leave other options.
As shown
here, when the second port thruster failed late in the Orbital Insertion burn, they didn't switch to the third port one, but instead shut down the starboard one to compensate and shifted to firing two top and two bottom. Additionally, Steve Stich said that the capsule can be deorbited on RCS thrusters alone. (For comparison, the Crew Dragon's Draco thrusters are just barely more powerful at 90 lbf, and they make do by simply using longer burns. Presumably, an OMAC-less Starliner could make its deorbit burn with all eight aft-facing RCS thrusters in roughly half the time a Crew Dragon does with its four forward-facing Draco thrusters.)
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#72
by
Herb Schaltegger
on 20 May, 2022 15:20
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I seem to recall Dragon lost some thrusters on early missions, too.
Yeah, I mentioned that last night in this very thread and the Usual Suspects came out to attack anyway.
Herb, I assume you're talking about the first "Lost in Space" Dragon episode, with the frozen fuel line.
That was much more serious issue, but what you're doing is a classic "whataboutism".
Besides, it turned out not to be part of a pattern, right?
I don't think failed thrusters would register as much if this was try #1.
’
Call it “whataboutism” if you like - SpaceX has had plenty of other minor, non-mission critical issues too, but there have just been so many flights that it gets lost in noise. Shuttle lost TPS tiles on the first flight; computers failed; hell, once they landed with an APU fire.
Stuff happens, some of it serious, some of it not so much, but very, very few flights of ANY vehicle (even commercial aircraft that fly tens of thousands of times a day around the world) occurs with zero anomalies. They just don’t get press unless something dramatic happens or people die.
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#73
by
Perchlorate
on 20 May, 2022 15:29
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... How many of the 12 OMAC thrusters could fail at any given time and the remainder still accomplish key functions like the deorbit burn?
I read upthread that 2 of 3 in a single "can" failed off...or fired but then stopped firing. But I'm not sure this leaves this Starliner in a single-point of failure. Are there 4 "cans," each with 3 thrusters? and even if all 3 in one can fail, can't the others get the job done (perhaps with some interesting attitude control by the smaller thrusters)?
Yes, there are three aft-facing OMAC thrusters in each doghouse ("can").
The three larger ports in these photos are are the 1,500 lbf OMAC thrusters and the two smaller are the 85 lbf RCS thrusters.
https://twitter.com/SciGuySpace/status/1527312605437521923
But the loss of all three in one doghouse would still leave other options.
As shown here, when the second port thruster failed late in the Orbital Insertion burn, they didn't switch to the third port one, but instead shut down the starboard one to compensate and shifted to firing two top and two bottom. Additionally, Steve Stitch said that the capsule can be deorbited on RCS thrusters alone. (For comparison, the Crew Dragon's Draco thrusters are just barely more powerful at 90 lbf, and they make do by simply using longer burns. Presumably, an OMAC-less Starliner could make its deorbit burn with all eight aft-facing RCS thrusters in roughly half the time a Crew Dragon does with its four forward-facing Draco thrusters.)
"Asked and answered," as the lawyers would say. Thank you, sir.
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#74
by
DaveS
on 20 May, 2022 15:34
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Multiple shuttle missions had RCS failures on-orbit. For example STS-63 (Mir rendezvous) had three RCS jets fail (F1F failed leak, R1U failed off due to oxidizer temp and L2D failed off because of low chamber pressure). These failures nearly caused the Mir rendezvous to be called off because the Russians were concerned that more jets would fail during the prox ops with Mir (closest approach was 37 ft).
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#75
by
kdhilliard
on 20 May, 2022 16:01
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From the OFT-2 mission thread:
... Boeing, after a long and distinguished history of engineering excellence, has badly tarnished their reputation with this program and others over the past few years. How much longer do we continue to give them the benefit of doubt? ...
How long? As long as they keep working to fix it on their own dime.
Firm fixed price, baby!
(Answered here in hope of corralling this general programmatic discussion in one place, even if the latest concerns arise from OFT-2.)
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#76
by
otisbow
on 20 May, 2022 16:12
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Face the Facts Folks...Boeing has build a Ford Edsel!
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#77
by
DanClemmensen
on 20 May, 2022 16:17
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From the OFT-2 mission thread:
... Boeing, after a long and distinguished history of engineering excellence, has badly tarnished their reputation with this program and others over the past few years. How much longer do we continue to give them the benefit of doubt? ...
How long? As long as they keep working to fix it on their own dime.
Firm fixed price, baby!
(Answered here in hope of corralling this general programmatic discussion in one place, even if the latest concerns arise from OFT-2.)
True in general, but there are some additional issues:
--The most basic: we need a second operational CCP spacecraft and we don't have it.
--NASA is incurring additional costs for salaries and facilities
--Boeing had exactly 8 Atlas Vs allocated, enough for OFT-2, CFT, and Starliner 1 through Starliner 6. If OFT-3 is needed, they are forced to qualify Starliner on Vulcan (or something). They would have needed this anyway to do any non-NASA flights, but now they would need it for the last NASA flight. I guess (no actual info) that the NASA flights are more profitable and are needed to keep Starliner profitable or reduce the loss.
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#78
by
mclumber1
on 20 May, 2022 16:18
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From the OFT-2 mission thread:
... Boeing, after a long and distinguished history of engineering excellence, has badly tarnished their reputation with this program and others over the past few years. How much longer do we continue to give them the benefit of doubt? ...
How long? As long as they keep working to fix it on their own dime.
Firm fixed price, baby!
(Answered here in hope of corralling this general programmatic discussion in one place, even if the latest concerns arise from OFT-2.)
It wont happen, but could Boeing just "give up" and walk away from this contract? If so, are there any penalties involved?
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#79
by
deadman1204
on 20 May, 2022 16:31
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Comparisons to other vehicles with a bad thruster are missing the point here.
Two thrusters failing at the same time points to a system issue, not simply a "bad thruster".
