I think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.
I think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.Though a crewed version of Dream Chaser in theory should beat both of them as far as landing safety goes.That was one one part of STS that actually had a good safety record.
Capsules can lose active control if they're already on the correct reentry path. Otherwise it will orbit forever, reenter too steep, or skip and then reenter too steep.
Quote from: Patchouli on 09/05/2017 01:33 amI think both the Star liner and Dragon beat Soyuz by having less separation events and three parachutes.Though a crewed version of Dream Chaser in theory should beat both of them as far as landing safety goes.That was one one part of STS that actually had a good safety record.I disagree. To land on a runway you give up being able to do ballistic re-entry. Star liner and Dragon can lose all active control and go balistic and they'll come down fine. All they need is the parachutes to pop open in a single event. Space planes need control surfaces and active control all the way down. It's much more complexity, which means more things that can go wrong.Dragon is the safest in concept because it has a backup for the parachutes -- it can fire its Super Dracos if the parachutes don't open for some reason.
NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.
Quote from: Space Ghost 1962 on 11/12/2017 05:40 pmNASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.What mission requires 30 CRS flights?As upset as everyone gets for trying to invent missions for Orion then there's obviously no need to do it for CC either.
Quote from: rayleighscatter on 11/12/2017 08:14 pmQuote from: Space Ghost 1962 on 11/12/2017 05:40 pmNASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.What mission requires 30 CRS flights?As upset as everyone gets for trying to invent missions for Orion then there's obviously no need to do it for CC either.Missed the point. And its CRS/CC flights, because the same configuration could be used for both. Duh.The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.Not static, ground determined analysis. Perhaps I need to resort to purple crayon to get my point across?
Because Congress doesn't want CC to follow Soyuz, they want the "big capsule" to. And, they can always blame CC for not flying, because "its too unsafe". Circular.add:What if CRS finds booster reuse is effective and accepts for flights? Then likewise CC might arrive at the same conclusion. NASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.How might 20-30 CRS/CC flights ... benefit LOC/LOM assessment/improvement? How much of this could also feed back into big capsule refinement? Might even improve Soyuz.
Quote from: Space Ghost 1962 on 11/12/2017 08:56 pmQuote from: rayleighscatter on 11/12/2017 08:14 pmQuote from: Space Ghost 1962 on 11/12/2017 05:40 pmNASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.What mission requires 30 CRS flights?The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.Your point is clear. Two little flaws though:- There won't be 30 missions to inform crew safety, not even when you add Cargo Dragon v2 missions into the mix.- Purely commercial, non-NASA missions, such as the planned circumlunar mission, do not inform crew safety because NASA insight into those will be almost non-existent.
Quote from: rayleighscatter on 11/12/2017 08:14 pmQuote from: Space Ghost 1962 on 11/12/2017 05:40 pmNASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.What mission requires 30 CRS flights?The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.
Quote from: Space Ghost 1962 on 11/12/2017 05:40 pmNASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.What mission requires 30 CRS flights?
Right now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.
Quote from: woods170 on 11/13/2017 07:13 amQuote from: Space Ghost 1962 on 11/12/2017 08:56 pmQuote from: rayleighscatter on 11/12/2017 08:14 pmQuote from: Space Ghost 1962 on 11/12/2017 05:40 pmNASA might be able to do a "block buy" and get perhaps 20-30 CRS/CC flights for every big capsule flight.What mission requires 30 CRS flights?The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.Your point is clear. Two little flaws though:- There won't be 30 missions to inform crew safety, not even when you add Cargo Dragon v2 missions into the mix.- Purely commercial, non-NASA missions, such as the planned circumlunar mission, do not inform crew safety because NASA insight into those will be almost non-existent.1. Builds on my point. We think of such vehicles as a limiting cost and so minimize to fewest use. Which caps are ability to reach ASAP's desired LOC. Past LV reuse, things get safer/cheap in net when we get to a fair fraction of 100. SX likely to reach hundreds of missions off of reuse, so we're likely to reach comparative numbers to Shuttle.2. AF contracts require all launches to "inform" on LV performance. A similar means to inform on crew safety under appropriate convention (possible in US but not Europe given certain laws) could supply such, part of adventurer contract of carriage.Am quite serious about means to achieve best provable crew vehicle LOC. Which is potentially transferable to other vehicles.QuoteRight now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.Yes we are both looking at the same thing. Beyond NASA. Where its just an occasional client.BTW, there are many "NASA's" inside of NASA. True of other agencies/ministries. Some see this too.Difference might be about where and how to achieve said "pivot". Perhaps as temporary conservator? Thus the above.
So what you are proposing is that commercial providers surrender their technology and data to the public good?
Because that proposal isn't compatible with the current proprietary nature. Unless the intent is to create a de-facto eternal duopoly.
Quote from: woods170 on 11/13/2017 07:13 am...QuoteRight now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.Yes we are both looking at the same thing. Beyond NASA. Where its just an occasional client....
...QuoteRight now the CRS/CCP providers need NASA to survive. As such they are willing to put up with the additional crew-safety burden that NASA places on them. But IMO there will come a time when at least one of those providers no longer needs NASA to achieve its goals. When that time comes it will shed NASA and its associated burdensome bureaucracy. Regardless of its his current habit of praising NASA.Yes we are both looking at the same thing. Beyond NASA. Where its just an occasional client....
Quote from: rayleighscatter on 11/25/2017 01:56 pmSo what you are proposing is that commercial providers surrender their technology and data to the public good?Would you please explain this otherwise irrational conclusion?Referenced posts say nothing of the kind. Perhaps something else not visible, possibly emotional, is being triggered?Honestly have no idea where this comes from in the above discussion and would like to know if substantive, because it entirely escapes me and frankly no I don't comment to annoy anyone here as that is my only conclusion as to meaning.QuoteBecause that proposal isn't compatible with the current proprietary nature. Unless the intent is to create a de-facto eternal duopoly.When has anyone advocated that, please?Don't get any of this. Asking for advice/help from others, as I'm completely at sea here - help!
The point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.
Ok, to dumb it down then:Quote from: Space Ghost 1962 on 11/12/2017 08:56 pmThe point is that actual, repeated flight data of vehicle gives you bounds/reasons/means for safety improvement.How is this accomplished? Do other companies get access to the flight/machine data, or do all future contacts go to the same two companies because they're the only ones who have access to the data needed to improve safety. Unless you have another thought in mind on how, say, Lockheed could benefit from SpaceX's proprietary heatshield designs and data.
At SpaceX, every design and operation decision is driven by safety and reliability. SpaceX recognizes thatsome proposed operating procedures for the crew transportation system differ from those on the SpaceShuttle Program. SpaceX has elected to adopt certain approaches, including propellant loading afterastronauts have been secured in the spacecraft and the launch escape system is enabled, because they offer the potential to improve safety for both astronauts and ground crew. Under SpaceX’s operations plan, afterastronauts board the spacecraft, the ground crew will close out the vehicle and will leave the launch site.Launch vehicle propellant loading will begin only after the escape system is armed. This approach ensuresthat astronauts have escape capability during any time propellant is on the launch vehicle, and it does notexpose ground crew to unnecessary risk. Notably, the Space Shuttle continued loading liquid hydrogen forthree hours (“Space Shuttle Replenish” procedure) after astronauts were aboard; propellant loading onFalcon 9 consumes approximately 30 minutes, reducing the time astronauts are exposed to loadingoperations.We have also worked closely with NASA to further enhance the robustness of our composite overwrappedpressure vessels (COPVs) and to ensure NASA is comfortable with their performance in a variety of flightenvironments. We are confident that this process is safe, and we are working closely with NASA tocomplete the ongoing, rigorous analysis necessary to achieve certification.