NASAKennedyCrew Dragon parachutes successfully deploy during latest development test that simulated a pad abort, where the vehicle is tumbling at low altitude before parachute deploy, validating SpaceX’s parachute models and margins.
The industry-wide asymmetry value of 1.1 is insufficient for accurately assessing the structural margins of highly reefed parachutes operating in a cluster
Do you know if they considered (for example) dumping the landing fuel after reaching orbit. That might have reduced weight sufficiently to stick with the three parachute setup. Be interesting to know how the trades went.
QuoteDo you know if they considered (for example) dumping the landing fuel after reaching orbit. That might have reduced weight sufficiently to stick with the three parachute setup. Be interesting to know how the trades went.I actually thought about this the other day. Of course the hypergolics are toxic, so you wouldn't want to toss the fuel when you're below the atmosphere. And then I remembered that half the point of having crew dragon is to have an abort that works *before* you've made it out of the atmosphere, and in all of those situations you cannot dump the fuel at all.
Quote from: thirtyone on 09/18/2019 11:56 pmQuoteDo you know if they considered (for example) dumping the landing fuel after reaching orbit. That might have reduced weight sufficiently to stick with the three parachute setup. Be interesting to know how the trades went.I actually thought about this the other day. Of course the hypergolics are toxic, so you wouldn't want to toss the fuel when you're below the atmosphere. And then I remembered that half the point of having crew dragon is to have an abort that works *before* you've made it out of the atmosphere, and in all of those situations you cannot dump the fuel at all.The fuel could be dumped after leaving the ISS, after the deorbit burn, before atmospheric reentry.
Are the SuperDracos connected to the same tanks as the Dracos?If so, non-propulsive ignition of a set of thrusters could quite easily burn much of it off over a short time period before it gets in range of ISS, leaving little more than required to get deorbit.
Quote And then I remembered that half the point of having crew dragon is to have an abort that works *before* you've made it out of the atmosphere, and in all of those situations you cannot dump the fuel at all.I don't understand this. Doesn't abort in the atmosphere use the fuel? Is there an in atmosphere abort mode that doesn't fire the super dracos as long and hard as they can to get away from a malfunctioning stage?
And then I remembered that half the point of having crew dragon is to have an abort that works *before* you've made it out of the atmosphere, and in all of those situations you cannot dump the fuel at all.
Great work by SpaceX parachute engineering! The Crew Dragon parachutes are way more difficult than they may seem. The Apollo program found them to be so hard that it became a notable morale problem!
Koren: Musk said this weekend that SpaceX would be ready to fly NASA astronauts within three to four months. Does that sound realistic to you?Bridenstine: No. They have redesigned their launch-abort system, and with that redesign, [the system] has to be qualified. We are lucky that the explosion happened when it exploded during a test. If that wouldn’t have happened, we would be taking a lot more risk than we would not be aware of right now. But now that we have a new design, it needs to be tested, it needs to be qualified.And that’s not the hardest problem. The hardest problem is the parachutes. We do not have the margin of safety [that NASA requires] in the parachutes, and that’s going to take probably more time to resolve than the launch-abort system.
How many parachutes does Soyuz have? How were they modeled? Oh wait...
Quote from: rockets4life97 on 10/01/2019 11:44 pmHow many parachutes does Soyuz have? How were they modeled? Oh wait...Soyuz hasn’t had a parachute failure since 1967, Crew Dragon on the other hand...I guess more isn’t always better...
Quote from: HeartofGold2030 on 10/01/2019 11:49 pmQuote from: rockets4life97 on 10/01/2019 11:44 pmHow many parachutes does Soyuz have? How were they modeled? Oh wait...Soyuz hasn’t had a parachute failure since 1967, Crew Dragon on the other hand...I guess more isn’t always better...What failure in the parachute system was there during DM-1?
Going by the mantra "the best part is no part" and the conviction of the worst error an engineer can make is "try to perfect something that is not needed" recently expressed by Mr. Musk, I believe the simplest solution is to revert to the tried and tested three chute design and dump the hipergolic fuels prior to landing to get rid of the excess mass.