Aethon

Blue Origin Thread (merged)

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No, I agree completely, I was just musing on the difference between man rating the current commercial crew vehicles and launch vehicles, vs SLS/Orion.

Under the (perhaps misguided :wink: ) assumption that SpaceX stops tweaking F9 and launches a definitive vehicle, the LV for Dragon 2 will have multiple tests under its belt, with loads of data. That data will include failures that were addressed before return to flight, then at some point they have X launches of the definitive crew version, then they will do an unmanned test, then at some point manned tests (the same for CST-100).

Whatever number X is, it's certainly going to be larger than SLS's number of tests for EM-2, and both will be vastly lower than the theoretical value of 500 (I realize this is a probability, not a real number) . Presumably the 500 number is a response to shuttle, and shuttle was done without these metrics. I'm also curious at what point they might (if ever) un-rate a vehicle. It would be interesting to apply the same criteria use for 1:500 to Shuttle as designed, without considering the actual failure modes, and see what the risk metrics show. If back-analyzing Shuttle doesn't provide theoretical risk levels concordant with the actual risk, then those theoretical tools might not be very useful.

Edited by tater

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24 minutes ago, Nibb31 said:

This is all why "man rating", like most certification processes, is such an expensive thing, even though it's mainly just a lot of paperwork. Think ISO9000 on steroids. This is also why the aerospace industry uses aerospace-certified components and frowns upon SpaceX's conduct of buying"off-the-shelf" struts and fasteners

Agreed, but in the consumer electronics industry ISO 9001 doesn't guarantee all that much.    Any large company (as opposed to a small, family run repair shop) will have to have a system to log what it's engineers do anyway.   Someone creates some flowery sounding documents describing how things are done , and there you go , you're ISO 9001 compliant.  Employees may have never read these process control documents, let alone adhere to them.   Just so long as the inspector can be shown that they exist.     Even then, design tolerances, employees caring about the quality of their work matters more than rigidly following some document written by someone who isn't even an engineer.

As for MTBF,    build 1000 circuit boards containing dodgy capacitors (or simply under-specced ones, or that are being subject to high temperature).  Test these 1000 circuit boards for 1000 hours each and get zero fails,  you can advertise the component of having a MTBF of "better than a million hours".   In practice, these boards start dying after 1200 hours operation and by 1600 hours the mortality rate has risen to 80%.   

Finally,  I recently had to memorise an incredibly dull presentation on soldering quality control.   What a Level 3 (mission critical) certified solder joint looks like, in terms of miniscus, overlap, fillet etc. etc. etc.. zzzzzz

I suppose I'd want my space suit life support to have great looking solder joints on its pcbs too, but it's by no means the whole story.   The components could still be overstressed , under specced, poor quality plagued by noise emi etc. or poor design  but  at least it's shiny !

But yes, Aerospace is a different ball game,and it's not just about paying lip service.

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28 minutes ago, tater said:

No, I agree completely, I was just musing on the difference between man rating the current commercial crew vehicles and launch vehicles, vs SLS/Orion.

Under the (perhaps misguided :wink: ) assumption that SpaceX stops tweaking F9 and launches a definitive vehicle, the LV for Dragon 2 will have multiple tests under its belt, with loads of data. That data will include failures that were addressed before return to flight, then at some point they have X launches of the definitive crew version, then they will do an unmanned test, then at some point manned tests (the same for CST-100).

Whatever number X is, it's certainly going to be larger than SLS's number of tests for EM-2, and both will be vastly lower than the theoretical value of 500 (I realize this is a probability, not a real number) . Presumably the 500 number is a response to shuttle, and shuttle was done without these metrics. I'm also curious at what point they might (if ever) un-rate a vehicle. It would be interesting to apply the same criteria use for 1:500 to Shuttle as designed, without considering the actual failure modes, and see what the risk metrics show. If back-analyzing Shuttle doesn't provide theoretical risk levels concordant with the actual risk, then those theoretical tools might not be very useful.

I heard somewhere that Apollo was designed to a failure rate of 1 in 1000. So I would be surprised if the Shuttle wasn't designed to some similar figure.

The problem is not really the calculation of risk, you have to do it (there is no way of doing it otherwise). And generally, you overestimate the risks (as in: You guess that an engine fails 1 in 1000 launches, but you enter a failure rate of 1 in 500 into the calculation).

The problem is that you are going to miss some possible failure modes or misidentify the actual failure rate of a component. Nobody really bothered about the risk created by the O-ring design until after Challenger. The probability that the Shuttle's heat shield could be fatally damaged by foam from the external tank was also underestimated until Columbia.

In hindsight, NASA estimated the risk of failure for the Shuttle during the first flights to be 1 in 9, while the later ones were 1 in 90 (i.e. barely acceptable). But that is in hindsight and doesn't help with the development of a spacecraft, other than showing that targeting such an extreme reliability as 1 in 500 or more is a good idea.

Doing lots of test flights or man-rating a cargo rocket, makes it easier to estimate the risks, since you can analyse the results of those flights. But this in turn also means that you can use sharper estimates on the risk of different failures, and thereby reduce the amount of over-engineering to be really sure that you achieve the desired reliability, and thereby making the development cheaper.

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What is UTC / rfc-2822 date/time of promised announcement? PST->UTC converters give contradicting results, "tomorrow" is also non-ISO date...

 

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21 minutes ago, WildLynx said:

What is UTC / rfc-2822 date/time of promised announcement? PST->UTC converters give contradicting results, "tomorrow" is also non-ISO date...

 

It's 10:45 PST right now. Elon posted that at 4:45 pm PST on the 26th, so the announcement would be at 9:00 pm UTC on the 27th:

http://bit.ly/2mwG7Rs

 

Edited by Mad Rocket Scientist

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2 minutes ago, Mad Rocket Scientist said:

It's 10:45 PST right now. Elon posted that at 4:45 pm PST on the 26th, so the announcement would be at 9:00 pm UTC on the 27th:

http://bit.ly/2mwG7Rs

 

Thank you sir.

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9 hours ago, Steel said:

what would you adopt as the standard?

Boeing basically just recolored the ACES. Orion is using ACES.

What's wrong with using ACES as a standard?

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22 minutes ago, _Augustus_ said:

Boeing basically just recolored the ACES. Orion is using ACES.

What's wrong with using ACES as a standard?

Can't fit in dragon I believe.

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Not terribly punctual.

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30 minutes ago, _Augustus_ said:

Boeing basically just recolored the ACES. Orion is using ACES.

What's wrong with using ACES as a standard?

Orion ACES is also heavily modified, because it's intended to act as an EVA suit (I think with the addition of another layer, like the apollo suits). It also doesn't have quite as much volume restriction due to Orion's size.

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2 minutes ago, Mad Rocket Scientist said:

 

Isn't one of the x prize contestants using a falcon 9?

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Just now, Mad Rocket Scientist said:

Now that's really awesome, it also means that people will likely take SpaceX more seriously in a Mars mission.

Who's going up though?

 

Also, I'll get to see a manned Moon flight :D

Spoiler

If you can't tell, I was born well after the Apollo era

 

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1 minute ago, insert_name said:

They could beat NASA to it potentially

Very likely if the push for crew on EM-1 goes into effect, as it pushes the timeline another year.

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4 minutes ago, insert_name said:

They could beat NASA to it potentially

Pretty much certainly, even if in Musk fashion they are a couple years behind schedule, frankly. There is about zero chance of EM-1 before 2019 at this point anyway, and I doubt they send crew.

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How long until I can go to the Moon? Does it count as studying abroad for college?

More seriously, this will make a lot of kids and adults alike think "I want to do that!" which is really good for spaceflight. I wonder if they'll do a moon landing at some point? FH would be capable of it, judging by mass alone.

Edited by cubinator

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3 minutes ago, cubinator said:

How long until I can go to the Moon? Does it count as studying abroad for college?

More seriously, this will make a lot of kids and adults alike think "I want to do that!" which is really good for spaceflight. I wonder if they'll do a moon landing at some point? FH would be capable of it, judging by mass alone.

I was thinking that two FH could do a lunar landing, if Masten Space systems gets involved, they could get a lander.

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Now all they need to do is get back on schedule.

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2 minutes ago, tater said:

Now all they need to do is get back on schedule.

Step one is to start relaunching Falcon boosters.

Edited by Spaceception

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