Well, they are referring to the FAA-report, which most of us have probably read. I think that the only mention of the trunk is:Quote from: FAAThe DragonFly RLV is the Dragon capsule with an integrated trunk (which may or may not be attached during a DragonFly operation)...My guess is that the Waco Tribune simply extrapolated "may be attached during a DragonFly operation" to meaning the whole operation including landing instead of launching with it and then detaching. The report does not differentiate between these scenarios...
The DragonFly RLV is the Dragon capsule with an integrated trunk (which may or may not be attached during a DragonFly operation)...
OK, I haven't been through all 11 pages on this thread, so someone forgive me if this has already been mentioned.Where in the report does it say the engine firing will be continuous? They can fire for 10 x 0.5 seconds for a total of 5 seconds. Since the acceleration will not be sustained for a long period of time, they can get away with higher-G's too... possibly making the development of the SuperDracos easier..?
Quote from: eriblo on 05/23/2014 03:35 pmWell, they are referring to the FAA-report, which most of us have probably read. I think that the only mention of the trunk is:Quote from: FAAThe DragonFly RLV is the Dragon capsule with an integrated trunk (which may or may not be attached during a DragonFly operation)...My guess is that the Waco Tribune simply extrapolated "may be attached during a DragonFly operation" to meaning the whole operation including landing instead of launching with it and then detaching. The report does not differentiate between these scenarios... This seems most likely to me. However the launched-then-detached trunk option makes me wonder if it would be straightforward (or even possible) to fit a small recovery chute in the trunk - for these Dragonfly tests only, of course, not for operational Dragon landings.
Has there been any analysis what would happen if Dragon(Fly) would lose a number of SDs?
It's hard to loose even 1 hypergolic engine, let alone "a number" of them.
Quote from: J-V on 05/22/2014 11:58 amHas there been any analysis what would happen if Dragon(Fly) would lose a number of SDs?It's hard to loose even 1 hypergolic engine, let alone "a number" of them. No moving parts in the power stream, just a couple of valves to open or close the 2 propellant streams, which are pressure fed. Open the valves, propellant flows and the engine self-ignites. Close the valves and the engine shuts off. Simple. That's a big reason why Apollo CSM/LM went with hypergols. Practically foolproof.
Note: 500m is still below the "Brown Pants Line" (BPL) in this pilot's opinion. I'd want to know the motors are running up around 1000m, even if they are turning on a few at a time to provide some emotional comfort and stability at low altitude.
BPL - Brown Pants Line. On descent, the altitude at which you will sh** deficate in your pants if you are still in free fall.
In this case, if there's no parachute, or they're below minimum safe altitude for a parachuted landing, the severity is loss of/serious injury to crew. There's no way they're simply going to go ahead with "Yeah, hypergolics don't fail".Also, engine control can be lost due to software glitches too.
The timely deployment of parachutes and/or airbags will require software too.
3. If the normal method for landing a Dragon2 will indeed be with the trunk attached (and this is only one possible interpretation of the FAA permit), I presume that the trunk could act as an additional crush/crumble zone, that could improve the survivability even with severely reduced engine power and very late parachute deployment. Modern cars have quite good survivability in head on collisions, even at high speeds. Of course a capsule like Dragon has added risk because of fuel leaks and other things...
Um, wouldn't that assume that no hypergolic propellent is stored in trunk? I don't believe that is and that the stores in the capsule are probably shock isolated to a reasonable extent, but wasn't there some talk of storing additional supplies in the trunk earlier in this thread.Hypergolic Tanks + crumple zone = Hollywood movie car crash.
...The Shuttle and the Dream Chaser probably wont fly well without software to control them.So this is not any different for any of the competing space craft.
Having pulled the reserve twice so far, both above the established hard deck, i would say that BPL is a mischaracterization, as your sphincter ani externus actually tends to rapidly contract.
An interesting feature of all this is that SpaceX will be flying the capsule all the way from orbit to within a km or two of the landing pad... That will be a ride! Edit: Not actually DragonFly, but the real version.
Quote from: AncientU on 05/23/2014 11:13 pmAn interesting feature of all this is that SpaceX will be flying the capsule all the way from orbit to within a km or two of the landing pad... That will be a ride! Edit: Not actually DragonFly, but the real version.I would think, they would like to nail the landing pad. But did you mean, the launch pad???