Author Topic: Commercial Crew Schedule Analysis  (Read 185060 times)

Offline SWGlassPit

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Re: Commercial Crew Schedule Analysis
« Reply #560 on: 07/11/2018 04:22 PM »
nobody knows where these contractors stand in regard to completion.

We do now.

Even that table -- inconclusive as it is -- doesn't really tell the whole story.  There's a veritable mountain of certification products that have to be completed as well, and none of that is reflected in the status of a hardware build.

Online gongora

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Re: Commercial Crew Schedule Analysis
« Reply #561 on: 07/11/2018 04:22 PM »
Looks like In-flight abort from 39A on Block 5 in crew configuration (full launch vehicle).

Quote
To better understand the propellant loading procedures, the program and SpaceX agreed to
demonstrate the loading process five times from the launch site in the
final crew configuration prior to the crewed flight test. The five events
include the uncrewed flight test and the in-flight abort test. Therefore,
delays to those events would lead to delays to the agreed upon
demonstrations, which could in turn delay the crewed flight test and
certification milestone.

Offline butters

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Re: Commercial Crew Schedule Analysis
« Reply #562 on: 07/11/2018 04:28 PM »
It's not clear whether Boeing or SpaceX is more prepared for commercial crew certification than the other. But what seems increasingly clear to me is that NASA is less prepared than either of the providers.

Re: Commercial Crew Schedule Analysis
« Reply #563 on: 07/11/2018 04:31 PM »
nobody knows where these contractors stand in regard to completion. SpaceX has encountered plenty of delays so the previous post is incorrect. the ideas regarding vertical integration being naturally fsater is a theory that may or may not be true. The idea that using proven components should be a faster development approach is likewise a theory that may or may not be true. both hypotheses are going to be put to the test, so we will know which hypothesis is more valid  - in this case - within a few months, most likely.

I wasn't talking about Commercial Crew... In 15 years SpaceX has developed 3 LVs, of which 2 reusable and one the largest operational rocket in the world, 2 space capsules capable of atmospheric reentry with in house build heath shield, of which one is crewed, 5 families of engines etc. That's what I was talking about.

And yes, that's undeniably faster than the traditional approach, even more impressive if you factor in the amount of money spent.
« Last Edit: 07/11/2018 04:33 PM by AbuSimbel »
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Online rockets4life97

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Re: Commercial Crew Schedule Analysis
« Reply #564 on: 07/11/2018 04:46 PM »
It's not clear whether Boeing or SpaceX is more prepared for commercial crew certification than the other. But what seems increasingly clear to me is that NASA is less prepared than either of the providers.

So this would mean that if (big if) the providers could pull off crewed missions in the first half next year, they would have to wait a year to fly again on a certified mission?

Online envy887

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Re: Commercial Crew Schedule Analysis
« Reply #565 on: 07/11/2018 04:55 PM »
It's not clear whether Boeing or SpaceX is more prepared for commercial crew certification than the other. But what seems increasingly clear to me is that NASA is less prepared than either of the providers.

So this would mean that if (big if) the providers could pull off crewed missions in the first half next year, they would have to wait a year to fly again on a certified mission?

Perhaps. But if the crewed test missions are successful, NASA will be under an incredible amount of pressure to move to operational flights as soon as possible. Why do you think they are moving towards making the Boeing OFT an "operational" mission?

Offline Adriano

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Re: Commercial Crew Schedule Analysis
« Reply #566 on: 07/12/2018 04:11 AM »
I have not been following closely the development of crew capsules, but the possible delay of another year or two does not make any sense to me. These capsules are not that complicated, and the current Dragon has been flying for years without, I think, major problems that would have threatened the survival of a live passenger (animal, or human).  Capsules from Mercury and Apollo to the current Dragon have accumulated an impressive number of successful flights, and I think much is known of the unbreakable Soyuz capsules, so the requirements should be well documented. Are the developers facing continuing changes of specs from NASA in search of ever increasing reliability, after the Shuttlle fiasco ( much more dangerous than thought at the time?). In my career I faced several times the problem of project managers less competent than developers that simply did not have the knowledge and the brains for judging solutions and to develop clear and final specs, the balls for pulling the trigger, or the honesty to admit that the technical issues were over their heads and hence constantly chasing windmills...

Offline woods170

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Re: Commercial Crew Schedule Analysis
« Reply #567 on: 07/12/2018 07:02 AM »
nobody knows where these contractors stand in regard to completion.

We do now.

No we don't. The information in that table has been outdated for months.
It provides a snapshot of the status as it was at the start of the second quarter of calendar year 2018.
We now are in the third quarter of calendar year 2018.

The CCP contractors are closer to completion than this table suggests.

Offline Ike17055

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Re: Commercial Crew Schedule Analysis
« Reply #568 on: 07/12/2018 12:33 PM »
nobody knows where these contractors stand in regard to completion.

We do now.

No we don't. The information in that table has been outdated for months.
It provides a snapshot of the status as it was at the start of the second quarter of calendar year 2018.
We now are in the third quarter of calendar year 2018.

The CCP contractors are closer to completion than this table suggests.

moreover, the key word that appears over and ovre in the last column is "plans"...plans to this, plans to that. all is subject to change. we know people's intentions,  -- maybe -- but we sure don't have anything definitive about when we are flying.

Online rockets4life97

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Re: Commercial Crew Schedule Analysis
« Reply #569 on: 07/12/2018 01:32 PM »
I'm not too familiar with risk analysis, so correct me if I'm wrong.

Won't flying the uncrewed demonstration missions successfully retire a significant amount of schedule risk? In other words, the range of expected certification dates should shrink.

As an example the current average dates from the risk assessment are end of year 2019/early 2020. If the uncrewed demonstrations come off successfully at the end of the year(ish), might we not expect the risk assessment average to move up into the middle of the second half of 2019?

Online johnfwhitesell

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Re: Commercial Crew Schedule Analysis
« Reply #570 on: 07/12/2018 01:40 PM »
I'm not too familiar with risk analysis, so correct me if I'm wrong.

Won't flying the uncrewed demonstration missions successfully retire a significant amount of schedule risk? In other words, the range of expected certification dates should shrink.

As an example the current average dates from the risk assessment are end of year 2019/early 2020. If the uncrewed demonstrations come off successfully at the end of the year(ish), might we not expect the risk assessment average to move up into the middle of the second half of 2019?

I might be behind the times but I believe at this point the sticking point on the risk analysis has to do with the time in orbit more then the launch.  Objects in LEO get hit by micrometeorites which can cause damage that turns fatal upon reentry.

Online gongora

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Re: Commercial Crew Schedule Analysis
« Reply #571 on: 07/12/2018 01:47 PM »
The uncrewed flights will retire a significant amount of risk but they may or may not retire specific risks that are the long poles in the schedule.  There are still lots of certification activities for the launch vehicles that won't go away with a single flight.  NASA will still have to work through all of the certification products.

Online meberbs

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Re: Commercial Crew Schedule Analysis
« Reply #572 on: 07/12/2018 02:00 PM »
I'm not too familiar with risk analysis, so correct me if I'm wrong.

Won't flying the uncrewed demonstration missions successfully retire a significant amount of schedule risk? In other words, the range of expected certification dates should shrink.

As an example the current average dates from the risk assessment are end of year 2019/early 2020. If the uncrewed demonstrations come off successfully at the end of the year(ish), might we not expect the risk assessment average to move up into the middle of the second half of 2019?

I might be behind the times but I believe at this point the sticking point on the risk analysis has to do with the time in orbit more then the launch.  Objects in LEO get hit by micrometeorites which can cause damage that turns fatal upon reentry.
You are talking about something completely different. Rockets4life97 is asking about the program schedule uncertainty, not the loss of crew risk. The latter is a single (important) analysis that has to be sold off, but unless NASA is not reviewing documentation fast enough (quite possible) it should not be a schedule driver in any way, it should be purely parallel to just about everything else.

As for the schedule risk it depends on what assumptions went into the risk analysis, and what the meaning of the given range is. Things can be pulled in from a "most likely" date, but if a range starts at the best case, then that end of the range won't move, just the end of the range gets pulled in. (The "best case" date could theoretically move in if things happened ahead of schedule, but being honest that almost never happens, so no one prepares for it to happen, and timed events on the schedule for big projects will often prevent the best case from getting pulled in.)

Offline SWGlassPit

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Re: Commercial Crew Schedule Analysis
« Reply #573 on: 07/12/2018 03:08 PM »
I have not been following closely the development of crew capsules, but the possible delay of another year or two does not make any sense to me. These capsules are not that complicated, and the current Dragon has been flying for years without, I think, major problems that would have threatened the survival of a live passenger (animal, or human).  Capsules from Mercury and Apollo to the current Dragon have accumulated an impressive number of successful flights, and I think much is known of the unbreakable Soyuz capsules, so the requirements should be well documented. Are the developers facing continuing changes of specs from NASA in search of ever increasing reliability, after the Shuttlle fiasco ( much more dangerous than thought at the time?). In my career I faced several times the problem of project managers less competent than developers that simply did not have the knowledge and the brains for judging solutions and to develop clear and final specs, the balls for pulling the trigger, or the honesty to admit that the technical issues were over their heads and hence constantly chasing windmills...

Know how I can tell you've never been involved in a spacecraft development project?

I'll save you the point-by-point breakdown and just say this: nearly every single thing you said in this post is wrong.

Offline butters

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Re: Commercial Crew Schedule Analysis
« Reply #574 on: 07/12/2018 04:55 PM »
I'm not too familiar with risk analysis, so correct me if I'm wrong.

Won't flying the uncrewed demonstration missions successfully retire a significant amount of schedule risk? In other words, the range of expected certification dates should shrink.

As an example the current average dates from the risk assessment are end of year 2019/early 2020. If the uncrewed demonstrations come off successfully at the end of the year(ish), might we not expect the risk assessment average to move up into the middle of the second half of 2019?

I might be behind the times but I believe at this point the sticking point on the risk analysis has to do with the time in orbit more then the launch.  Objects in LEO get hit by micrometeorites which can cause damage that turns fatal upon reentry.

Dragon 1 has accumulated lots of time in the exact same orbital environment in which Dragon 2 will operate. My understanding is that NASA has decided not to include empirical data on MMOD from CRS missions into its theoretical risk analyses for CCP. My assumption is that they're justifying this on the grounds that Dragon 2 is not identical to Dragon 1 and therefore nothing about the observed reliability of Dragon 1 can be used to inform the risk assessment for Dragon 2.

Offline Coastal Ron

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Re: Commercial Crew Schedule Analysis
« Reply #575 on: 07/12/2018 05:03 PM »
Dragon 1 has accumulated lots of time in the exact same orbital environment in which Dragon 2 will operate. My understanding is that NASA has decided not to include empirical data on MMOD from CRS missions into its theoretical risk analyses for CCP. My assumption is that they're justifying this on the grounds that Dragon 2 is not identical to Dragon 1 and therefore nothing about the observed reliability of Dragon 1 can be used to inform the risk assessment for Dragon 2.

Which is odd, since they should be able to use actual MMOD data from all the flights to date to help validate their models for predicted strikes, since Dragon 1 is very close in size to Dragon 2.
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Online gongora

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Re: Commercial Crew Schedule Analysis
« Reply #576 on: 07/12/2018 05:12 PM »
Dragon 1 has accumulated lots of time in the exact same orbital environment in which Dragon 2 will operate. My understanding is that NASA has decided not to include empirical data on MMOD from CRS missions into its theoretical risk analyses for CCP. My assumption is that they're justifying this on the grounds that Dragon 2 is not identical to Dragon 1 and therefore nothing about the observed reliability of Dragon 1 can be used to inform the risk assessment for Dragon 2.

The total time of all CRS Dragons docked at ISS so far is a little more than the duration of two CCTCAP missions.  That's a small sample size.  There were also reports of NASA introducing small defects into CRS Dragon TPS to simulate MMOD damage, which would feed into the models.

Offline SWGlassPit

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Re: Commercial Crew Schedule Analysis
« Reply #577 on: 07/12/2018 06:40 PM »
Dragon 1 has accumulated lots of time in the exact same orbital environment in which Dragon 2 will operate. My understanding is that NASA has decided not to include empirical data on MMOD from CRS missions into its theoretical risk analyses for CCP. My assumption is that they're justifying this on the grounds that Dragon 2 is not identical to Dragon 1 and therefore nothing about the observed reliability of Dragon 1 can be used to inform the risk assessment for Dragon 2.

Which is odd, since they should be able to use actual MMOD data from all the flights to date to help validate their models for predicted strikes, since Dragon 1 is very close in size to Dragon 2.

The area-time product of flown Dragon vehicles just isn't big enough to provide much, if any, statistical significance to the observations for any particle size that matters.

Hell, the area-time product of ISS as a whole only barely approaches a statistically significant sample for a lot of the relevant particles.

Offline rayleighscatter

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Re: Commercial Crew Schedule Analysis
« Reply #578 on: 07/12/2018 09:34 PM »
I'm not too familiar with risk analysis, so correct me if I'm wrong.

Won't flying the uncrewed demonstration missions successfully retire a significant amount of schedule risk? In other words, the range of expected certification dates should shrink.

As an example the current average dates from the risk assessment are end of year 2019/early 2020. If the uncrewed demonstrations come off successfully at the end of the year(ish), might we not expect the risk assessment average to move up into the middle of the second half of 2019?

I might be behind the times but I believe at this point the sticking point on the risk analysis has to do with the time in orbit more then the launch.  Objects in LEO get hit by micrometeorites which can cause damage that turns fatal upon reentry.

Dragon 1 has accumulated lots of time in the exact same orbital environment in which Dragon 2 will operate. My understanding is that NASA has decided not to include empirical data on MMOD from CRS missions into its theoretical risk analyses for CCP. My assumption is that they're justifying this on the grounds that Dragon 2 is not identical to Dragon 1 and therefore nothing about the observed reliability of Dragon 1 can be used to inform the risk assessment for Dragon 2.

That might be a reach as a conclusion. There are a lot of variables we just don't know. Did SpaceX review each craft with the sort of scrutiny a manned craft would receive? Was it handled with the sort of oversight that would allow them to quantify if a scratch in the paint was caused before launch, during launch, by MMOD, during reentry, during splashdown, during recovery, during ground handling? This sort of diligence is time consuming and costs much more than simply completing an unmanned mission and examining the craft for worthiness for a future flight.

While not engaging in that kind of diligence is cheaper and not necessary for launching and recovering cargo, it does invalidate a lot of potential data for future use in man-rating a somewhat identical craft.

Offline Comga

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Re: Commercial Crew Schedule Analysis
« Reply #579 on: 07/13/2018 05:02 AM »
(snip)
Hell, the area-time product of ISS as a whole only barely approaches a statistically significant sample for a lot of the relevant particles.

That's by design
The ISS is flown at an altitude in the exosphere that minimizes the population of debris.  Light objects, even up to the several kilograms of cubesats, have very short orbital lifetimes at those altitudes.

On the other hand, there are hundreds of square meters of surface on the ISS that can be watched.   If that's not "statistically significant" then it doesn't seem like it would be THE driving safety requirement for commercial crew.
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