Quote from: kevinof on 03/04/2019 02:34 pmNo high definition altimeter (radar/lidar) for judging when to fire the superdracos and when to shut them off.Quote from: OnWithTheShow on 03/04/2019 02:29 pmIf there is no altimeter how does it decide when to fire the chutes?That would not be needed for a splashdown. GPS + barometric altimeter would be enough for a water landing.The goal would not be to make a perfect landing with 0 damage, the goal would be to limit impact G-forces to prevent pressure vessel rupture and to give the crew a survival chance in the event of a catastrophic parachute failure.This doesnt need an exact altitude estimate, it would be enough to limit vertical speed to max 5m/s for any altitude under 50m above sea level. Well within the abilities of available sensors ( including auto-activation if the capsule is in freefall at that stage ). And engine shutdown on impact will be easy too. At those speeds the splashdown will have a clear signal to noise ratio.You would not need to certify such a contingency program, only the decision tree that makes sure it never ever gets activated under normal conditions.You would not want to rely on it, ever. But if the parachutes do fail, it might save lives.
No high definition altimeter (radar/lidar) for judging when to fire the superdracos and when to shut them off.Quote from: OnWithTheShow on 03/04/2019 02:29 pmIf there is no altimeter how does it decide when to fire the chutes?
If there is no altimeter how does it decide when to fire the chutes?
Quote from: Alexphysics on 03/04/2019 04:35 pmI only wish some reporter to ask this on the post-splashdown conference so some SpaceX official could close that damn discussion that's been going around for years even after the cancellation of propulsive landings.Not helped by articles like this.QuoteCrew Dragon will remain latched to the ISS until Thursday, when it will embark on a journey back to Earth. It's expected to land on a SpaceX drone ship in the Atlantic ocean, close to Kennedy Space Center.https://www.popularmechanics.com/space/rockets/a26625114/spacex-manned-mission-iss/
I only wish some reporter to ask this on the post-splashdown conference so some SpaceX official could close that damn discussion that's been going around for years even after the cancellation of propulsive landings.
Crew Dragon will remain latched to the ISS until Thursday, when it will embark on a journey back to Earth. It's expected to land on a SpaceX drone ship in the Atlantic ocean, close to Kennedy Space Center.
Quote from: Star One on 03/04/2019 04:49 pmQuote from: Alexphysics on 03/04/2019 04:35 pmI only wish some reporter to ask this on the post-splashdown conference so some SpaceX official could close that damn discussion that's been going around for years even after the cancellation of propulsive landings.Not helped by articles like this.QuoteCrew Dragon will remain latched to the ISS until Thursday, when it will embark on a journey back to Earth. It's expected to land on a SpaceX drone ship in the Atlantic ocean, close to Kennedy Space Center.https://www.popularmechanics.com/space/rockets/a26625114/spacex-manned-mission-iss/Precisely for that I'm sure some reporter will ask about that. You can imagine why I think that.
Crew Dragon will remain latched to the ISS until Thursday, when it will embark on a journey back to Earth. It's expected to make a splashdown landing in the Atlantic ocean, close to Kennedy Space Center.
Quote from: Alexphysics on 03/04/2019 05:52 pmQuote from: Star One on 03/04/2019 04:49 pmQuote from: Alexphysics on 03/04/2019 04:35 pmI only wish some reporter to ask this on the post-splashdown conference so some SpaceX official could close that damn discussion that's been going around for years even after the cancellation of propulsive landings.Not helped by articles like this.QuoteCrew Dragon will remain latched to the ISS until Thursday, when it will embark on a journey back to Earth. It's expected to land on a SpaceX drone ship in the Atlantic ocean, close to Kennedy Space Center.https://www.popularmechanics.com/space/rockets/a26625114/spacex-manned-mission-iss/Precisely for that I'm sure some reporter will ask about that. You can imagine why I think that. That line about landing on the ASDS has been corrected to readQuoteCrew Dragon will remain latched to the ISS until Thursday, when it will embark on a journey back to Earth. It's expected to make a splashdown landing in the Atlantic ocean, close to Kennedy Space Center.However the question about Super Draco assisted landing remains valid.
No it doesn’t. Stop trying to flog a dead horse. People come here as a resource and all this prolonged discussion does is confuse those viewers.
Quote from: Star One on 03/04/2019 06:58 pmNo it doesn’t. Stop trying to flog a dead horse. People come here as a resource and all this prolonged discussion does is confuse those viewers.Agreed. SpaceX, NASA, and even ASAP don't see a need for this. This is definitely riding a hobbyhorse needlessly.
You would not need to certify such a contingency program, only the decision tree that makes sure it never ever gets activated under normal conditions.
Quote from: CorvusCorax on 03/04/2019 03:01 pmYou would not need to certify such a contingency program, only the decision tree that makes sure it never ever gets activated under normal conditions.I'm going to speculate this has already been done and certified.
Quote from: Negan on 03/04/2019 10:53 pmQuote from: CorvusCorax on 03/04/2019 03:01 pmYou would not need to certify such a contingency program, only the decision tree that makes sure it never ever gets activated under normal conditions.I'm going to speculate this has already been done and certified. That's a radical speculation all right. Sure wish it was true but I'm not betting that way.
I too think it is a good idea to use Super Dracos if there was a parachute failure. It happened once with the Russians. Hopefully it would never happen. But if Super Dracos are not fired for launch escape, the fuel is there to land if they needed it. This would increase the survival options to better than the Russians and CTS 100 on landings.
While we don't know if they have this done and set up, I would suggest that they probably have or at least should.Hypothetical (unlikely, hopefully never going to happen) scenario:Parachutes fail, Crew Dragon hits water at high speed and the crew is lost. Superdracos are never fired because there was no option, no manual override, nothing. They were dumb pieces of metal as soon as launch escape system was disarmed.What would be the first "WTF?" question afterwards once everyone realizes that the capsule had 8 high power thrusters and a ton of propellant for them that could have slowed down that plunge and possibly saved the crew?How would NASA and SpaceX survive the fallout from the unavoidable public outcry? "Who was the bureaucrat that decided it was a great idea to not be able to even try to do emergency water landing with the thrusters if chutes fail?"You can explain away not doing certification & testing and not making the superdracos the primary landing method. You cannot explain away a decision to basically make it impossible to try in an emergency if primary (chutes) fail.So, an educated guess: They do have some kind of procedure for trying to pull of a decisively uncertified maybe-survivable emergency landing with the thrusters. Based on above hypothetical scenario alone. If they do not, they are betting the farm, literally, on parachutes never failing - because the public opinion would crucify everyone involved if it ever happened.
Quote from: spacenut on 03/04/2019 11:55 pmI too think it is a good idea to use Super Dracos if there was a parachute failure. It happened once with the Russians. Hopefully it would never happen. But if Super Dracos are not fired for launch escape, the fuel is there to land if they needed it. This would increase the survival options to better than the Russians and CTS 100 on landings. The difference is that Russians use just a single parachute (although they have an emergency parachute) while Dragon 2 has FOUR. The chance of a total parachute failiure is very very low
Thrusters would also be triggered by altimeter + sink rate monitoring and only limit sink rate to a survivable level for the last few meters.