Boeing's Starliner (CST-100) - Discussion Thread 6

[Thorny]

has successfully launched 150 missions.

Nitpick: 93.
150 is the total for ULA, including Delta II and Delta IV.

[WannaWalnetto]

Glad to see this bird get in the air, but I also have a question about video from this mission. 

I watched the NASA feed on YouTube.  I recall hearing that there would be more cameras on the next one around the time they were talking about all of the external cameras on this OFT-2 launch.

But a little after L+4:25 the video appears to freeze and they cut to an animation — and never return to live video. (This is about 1 hr past the start of the coverage.)  Is this perhaps an indication that the communications problems encountered on OFT-1 are still not quite resolved?

[DescartesWasBeautiful]

With respect to all of the moderators' live questions and discussion today about the "RELMOP" plots NASA was displaying after launch, these are rendezvous relative motion plots and have been a rendezvous planning and operations tool used for decades at JSC. I'm not sure who first used them as they are seen today, but here's a link to a lengthy, detailed paper from the NASA Technical Reports Server (NTRS) about the history of rendezvous techniques that have been used throughout NASA's manned spaceflight programs:
https://ntrs.nasa.gov/api/citations/20110023479/downloads/20110023479.pdf

You'll see many examples of similar kinds of relative motion plots in a variety of scenarios.  These kinds of plots are particularly important in defining rendezvous and proximity operations ("proxops", i.e., close-in) maneuvers and automated rendezvous and docking "scripts".  (Proxops planning concepts became a big deal I think as early as the Gemini 6 / 7 rendezvous, when it was noticed that thruster firings were disturbing the gold insulating foil covering the back of the Gemini adapter section and that thruster plume impingement during close-in maneuvers presented some unique problems. Likewise the Skylab crews noticed similar severe disturbances on the Skylab workshop contingency sunshields during close-in fly-around inspections with the CSM.)

As to the "SIMWORKS" tool mentioned in the title of the NASA plots, SIMWORKS is a highly sophisticated visualization and vehicle dynamics modeling package that has been actively developed and maintained by engineers at the McDonnell Douglas Technical Services Company (now Boeing) at NASA JSC going back, I believe, to the late 80's. SIMWORKS has been used on a variety of NASA programs starting with Shuttle as well as the DARPA "Orbital Express" automated rendezvous experiment.

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.

[NaN]

But a little after L+4:25 the video appears to freeze and they cut to an animation — and never return to live video. (This is about 1 hr past the start of the coverage.)  Is this perhaps an indication that the communications problems encountered on OFT-1 are still not quite resolved?

There were a few callouts at various points after S/C sep confirming that they had good forward command links. There's no reason to suspect that a video downlink issue is related, so all indications are that the comms issues were fixed.

[ChrisC]

NASA PAO really did a terrible job of "ducking", pausing their commentary when there was chatter from the control room.  Either that or the sound mix guy was asleep.  This has been happening a lot lately.  I used to blame it on an utterly starved budget, but they've been getting a lot more in recent years, so now what?

[lonestriker]

I have a question and although it's likely more Atlas related, the Starliner/Atlas is a "system".

Does it not seem that this launch system is inefficient from a payload perspective? This of course is even ignoring non-reusability of the launcher.
1 - The solids remain attached for some time, as dead weight, after burnout
2 - The skirt is additional weight that is eventually jettisoned. And the "hard edge" of the rear of the skirt can't exactly be optimally aerodynamic (although this may be a pretty small factor).

Regarding #2, I wondered about this as well.  Scott Manley answers that here:
https://twitter.com/DJSnM/status/1527423637195587585?s=20&t=OKzEAi2437sf3-5jMGlg7g

Atlas holds on to the boosters long after burnout because it's using a depressed trajectory which means it's deeper inside the atmosphere, so aerodynamic forces are higher.

They're not maximizing performance with the launch trajectory, but instead keeping the profile flatter to avoid abort blackout zones and to keep G forces within limits is my understanding.  Atlas has plenty of performance, so the dead weight is not a concern.  In fact, I recall them mentioning that they over-performed on the booster stage in the telecast.

[russianhalo117]

NASA PAO really did a terrible job of "ducking", pausing their commentary when there was chatter from the control room.  Either that or the sound mix guy was asleep.  This has been happening a lot lately.  I used to blame it on an utterly starved budget, but they've been getting a lot more in recent years, so now what?

Nothing because they are actively trying to get out of the public live broadcast realm. They are actively retiring hardware when spare parts run out and not seeking modern replacement hardware on many occasions. There is a thread dedicated to this cyclical event.

[SoftwareDude]

There is talk on Reddit of losing two of three thrusters in one "can", leaving a single point of failure.  Does that make sense?  Will NASA allow Starliner to approach ISS with a single point of failure? 

[gaballard]

There is talk on Reddit of losing two of three thrusters in one "can", leaving a single point of failure.  Does that make sense?  Will NASA allow Starliner to approach ISS with a single point of failure?

Reddit is trash. Don’t listen to “talk” on Reddit. The OMAC thrusters that failed aren’t involved in docking.

[Lars-J]

There is talk on Reddit of losing two of three thrusters in one "can", leaving a single point of failure.  Does that make sense?  Will NASA allow Starliner to approach ISS with a single point of failure?

Reddit is trash. Don’t listen to “talk” on Reddit. The OMAC thrusters that failed aren’t involved in docking.

You sound just as generalizing as the people saying that all Starliner thrusters are trash. You might as well say that TV is trash, newspapers are trash, the internet is trash. Etc.

There is good and bad info to be had on Reddit, just as it is on twitter, NSF, and elsewhere. Just be more discriminating about the poster.

[meekGee]

A lot of people forget, but one or two of the very earliest Dragon (1) flights had thruster issues. Didn’t hinder the mission for SpaceX and provided there aren’t more failures, it won’t hinder Starliner. Stuff happens. Systems are designed and built with redundancy and resilience.

I remember that incident well.

But regarding this incident, the fact that redundancy is saving the day doesn't justify that two thrusters failed.  This is test flight #3 already.  This is not some "stuff happens" that occurs statistically over many flights.

This is every flight having significant problems, three out of three.

[rpapo]

This is every flight having significant problems, three out of three.

Three?  I presume you are counting the pad abort then?

[Svetoslav]

This is every flight having significant problems, three out of three.

Three?  I presume you are counting the pad abort then?

Yes, he's counting the pad abort and the fact a parachute didn't deploy.

[lonestriker]

This is every flight having significant problems, three out of three.

Three?  I presume you are counting the pad abort then?

Yes, he's counting the pad abort and the fact a parachute didn't deploy.

Or the previous OFT-2 non-launch attempt where the valves were corroded stuck counts as #2 (original OFT-1 #1, OFT-2 thrusters #3.)

I agree with meekGee here.  The thruster failures is more serious than can be attributed to the "this is just a test flight" scenario.  Most systems have redundancy, but you don't want to use up that margin if at all possible, and certainly not before you're done depending the system in question (i.e. the de-orbit burn later.)  Given they had serious issues with software previously that resulted in the propulsion system going wild, that should have been a particular point of focus and testing.

I'm glad it's made orbit and will arrive at the ISS and we'll have two viable systems for crew transport when all is said and done.  But these types of failures only further delays that redundancy.  The failure root-cause analysis will be interesting.

[TrevorMonty]

The 2 thrusters shutdown earlier which doesn't mean they failed. Sounds like control system detect anomaly and shut them down. Fault could be SW, sensors, faulty thrusters or dozen other things.
Still not good having 2 out of 3 stop working, 1 would be acceptable and not totally unexpected.

https://twitter.com/lorengrush/status/1527457664321654785?t=nXDTp5p92uUjR75x9agkTA&s=19

Sent from my SM-G570Y using Tapatalk

[woods170]

Member:
Where are all the happy comments?

Boeing and company are farther along to success now than ever on the previous flight.

Perhaps all of you are waiting for a successful rendezvous and docking.  That's fair.

I won't make a happy comment until this testflight is over and the major milestones have been completed.
Until that time I will just observe.

P.S. I did the same for DM-1.

[Perchlorate]

This is every flight having significant problems, three out of three.

Three?  I presume you are counting the pad abort then?

Yes, he's counting the pad abort and the fact a parachute didn't deploy.

Or the previous OFT-2 non-launch attempt where the valves were corroded stuck counts as #2 (original OFT-1 #1, OFT-2 thrusters #3.)

I agree with meekGee here.  The thruster failures is more serious than can be attributed to the "this is just a test flight" scenario.  Most systems have redundancy, but you don't want to use up that margin if at all possible, and certainly not before you're done depending the system in question (i.e. the de-orbit burn later.)  Given they had serious issues with software previously that resulted in the propulsion system going wild, that should have been a particular point of focus and testing.

I'm glad it's made orbit and will arrive at the ISS and we'll have two viable systems for crew transport when all is said and done.  But these types of failures only further delays that redundancy.  The failure root-cause analysis will be interesting.

First of all, I congratulate Boeing on the successes thus far, and wish them well for the rest of the mission.  I'm a big SpaceX fan, but I'm a bigger Space fan, and I want the best outcomes for everyone.

I haven't the technical chops to dig very deep into the OMAC thruster issue.  But as the mission proceeds, I'm interested in one particular question:  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)?

In other words, how many of the OMAC thrusters would have to fail to create a LOM/LOC situation?  And, I wouldn't be surprised if there's not one single answer, but that it depended on how the failed thrusters were distributed among the 4 "cans."

<  now standing by for the wizards to enlighten... >

[Herb Schaltegger]

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.

[Robotbeat]

I seem to recall Dragon lost some thrusters on early missions, too.

[king1999]

I seem to recall Dragon lost some thrusters on early missions, too.

https://www.cbsnews.com/network/news/space/home/spacenews/files/71de54c481c373b0eeeb107e2f4b3596-552.html

Yes, stuck valves and they were able to fix it quickly. Hopefully Boeing can do something similar.