Is there any possibility the in flight abort for Dragon 2 to be the RTF mission ?The real question is will it be ready on time.If it is, it poses the least demand on the F9R booster: 1 - Its only until MaxQ 2 - It offers the maximum fuel margins for recovery 3 - It's planned to reuse the already used Dragon V2On the downside, as a partial mission, it wouldn't test F9R on a complete mission but it should increase confidence for more takers to go on the follow on mission.
e a second stage which is the part that failed, so it would not be an RTF mission. So it does not do anything for confidence building.
Quote from: Jim on 08/10/2015 11:34 ame a second stage which is the part that failed, so it would not be an RTF mission. So it does not do anything for confidence building.Aren't the same struts used on the first stage to hold the Helium bottles? I would have thought flying the new struts on the first stage would have added some confidence.
Same struts, but a very different stress profile. In the first stage, by the time the G forces get high, the bottles are no longer submerged in LOX nor fuel, and the bottles are more than half empty, and therefore lighter. In the second stage, during the same time, the bottles are completely submerged, and therefore more and more buoyant as the acceleration mounts. The stresses are much greater in the second stage, and in the opposite direction.
33:40 Elon Musk: Yeah. They were all at the same g-levels. Now the buoyancy force, once the liquid level drops below the position of the helium bottle, the buoyancy force drops dramatically, of course, but that was not the case at that point. All the helium bottles were experiencing approximately the same buoyancy force for the upper and lower stage.
Is there any possibility the in flight abort for Dragon 2 to be the RTF mission ?The real question is will it be ready on time.
Quote from: macpacheco on 08/10/2015 01:55 amIs there any possibility the in flight abort for Dragon 2 to be the RTF mission ?The real question is will it be ready on time.In addition to the technical aspects already covered, the visuals wouldn't be helpful - even with all the publicity in the world, casual observers will only see video of the "latest SpaceX launch abort".
Especially not the visual of stage 1 breaking up from aero loads after Dragon sep.
It was probably a combination of the aero loads (relatively weak at that altitude, but unbalanced) and a vastly higher G loads from the higher TWR of burning near full throttle a mostly empty first stage with no dragon and mostly empty stage 2 (no lox, rapidly leaking rp1 tank). Any guesses on what the TWR was before the first stage broke up?
Zero. The vehicle sharply throttled down at the first sign of trouble. Supposedly, that's a sign the FTS was activated,
Quote from: Kabloona on 08/11/2015 05:05 pmEspecially not the visual of stage 1 breaking up from aero loads after Dragon sep.It was probably a combination of the aero loads (relatively weak at that altitude, but unbalanced) and a vastly higher G loads from the higher TWR of burning near full throttle a mostly empty first stage with no dragon and mostly empty stage 2 (no lox, rapidly leaking rp1 tank).
Quote from: Greg Hullender on 08/12/2015 11:07 pmZero. The vehicle sharply throttled down at the first sign of trouble. Supposedly, that's a sign the FTS was activated,Neither are true. There is nothing in the vehicle that would sense the problem and issue commands to the booster. Where is the info that states that the FTS was activated? The ground command was sent more than 70 seconds after the vehicle was gone.
So how do you explain the velocity graph?
Quote from: yokem55 on 08/12/2015 05:40 pmIt was probably a combination of the aero loads (relatively weak at that altitude, but unbalanced) and a vastly higher G loads from the higher TWR of burning near full throttle a mostly empty first stage with no dragon and mostly empty stage 2 (no lox, rapidly leaking rp1 tank). Any guesses on what the TWR was before the first stage broke up? Zero. The vehicle sharply throttled down at the first sign of trouble. http://forum.nasaspaceflight.com/index.php?topic=37954.msg1401452#msg1401452Supposedly, that's a sign the FTS was activated, and I was pretty sure it was the FTS that destroyed the vehicle a few seconds later. What makes you think it had anything to do with aerodynamics?
Quote from: Jim on 08/12/2015 11:16 pmQuote from: Greg Hullender on 08/12/2015 11:07 pmZero. The vehicle sharply throttled down at the first sign of trouble. Supposedly, that's a sign the FTS was activated,Neither are true. There is nothing in the vehicle that would sense the problem and issue commands to the booster. Where is the info that states that the FTS was activated? The ground command was sent more than 70 seconds after the vehicle was gone. So how do you explain the velocity graph?
It doesn't matter for the sake of his answer; the fact which we know is that the ground command for FTS was sent 70s later, so any theory that has FTS being activated well before then is wrong (unless you want to say that the FTS system is faulty)
Kim Keller has stated here that since the S1 engines were observed to continue to fire right through the RUD of S2, that the FTS was never activated, because the first thing the FTS does is shut down the engines. Since the engines were observed to continue to fire right up to the point where S1 came apart, he concluded that the FTS never activated. Since Kim is one of the stalwart pros here, I tend to believe him.