Quote from: simonbp on 03/01/2013 07:56 pmQuote from: Star One on 03/01/2013 07:53 pmBut isn't up to the Falcon to protect the Dragon thermally on the way up? Nope. That's true for a payload in a faring, but Dragon is on its own thermally (and IIRC, for power and comm).We do know that the solar actuators were colder than anticipated, so that might be a clue.See reply #62 from this morning; there was also a report of a low-temp indication for the flight computer. Hmm.
Quote from: Star One on 03/01/2013 07:53 pmBut isn't up to the Falcon to protect the Dragon thermally on the way up? Nope. That's true for a payload in a faring, but Dragon is on its own thermally (and IIRC, for power and comm).We do know that the solar actuators were colder than anticipated, so that might be a clue.
But isn't up to the Falcon to protect the Dragon thermally on the way up?
QuoteElon Musk @elonmuskThruster pods one through four are now operating nominally. Preparing to raise orbit. All systems green.
Elon Musk @elonmuskThruster pods one through four are now operating nominally. Preparing to raise orbit. All systems green.
Quote from: mmeijeri on 03/01/2013 07:45 pmQuote from: AJA on 03/01/2013 07:43 pmNone of this freezing oxidiser would happen if they stirred the tanks.Why would they need to stir the tank if it is well-insulated and perhaps heated? And how could it cause an explosion with storable oxidiser?I wonder if the fuel / oxidiser lines have insulation and heaters, as on the Shuttle.Towards end of presser, Elon said ox tanks are at 70F, so freezing seems unlikely. Stuck check valve(s) more likely (IMO).
Quote from: AJA on 03/01/2013 07:43 pmNone of this freezing oxidiser would happen if they stirred the tanks.Why would they need to stir the tank if it is well-insulated and perhaps heated? And how could it cause an explosion with storable oxidiser?I wonder if the fuel / oxidiser lines have insulation and heaters, as on the Shuttle.
None of this freezing oxidiser would happen if they stirred the tanks.
That was the Falcon 9 flight computer, not Dragon flight computer, I believe. Not the same.
Quote from: Kabloona on 03/01/2013 07:47 pmQuote from: mmeijeri on 03/01/2013 07:45 pmQuote from: AJA on 03/01/2013 07:43 pmNone of this freezing oxidiser would happen if they stirred the tanks.Why would they need to stir the tank if it is well-insulated and perhaps heated? And how could it cause an explosion with storable oxidiser?I wonder if the fuel / oxidiser lines have insulation and heaters, as on the Shuttle.Towards end of presser, Elon said ox tanks are at 70F, so freezing seems unlikely. Stuck check valve(s) more likely (IMO).Surely you mean 70K.
could it be humidity in the He supply?
Quote from: LegendCJS on 03/01/2013 08:10 pmQuote from: Kabloona on 03/01/2013 07:47 pmQuote from: mmeijeri on 03/01/2013 07:45 pmQuote from: AJA on 03/01/2013 07:43 pmNone of this freezing oxidiser would happen if they stirred the tanks.Why would they need to stir the tank if it is well-insulated and perhaps heated? And how could it cause an explosion with storable oxidiser?I wonder if the fuel / oxidiser lines have insulation and heaters, as on the Shuttle.Towards end of presser, Elon said ox tanks are at 70F, so freezing seems unlikely. Stuck check valve(s) more likely (IMO).Surely you mean 70K.No, MMH/NTO are not cryo. The "ox" is NTO, not LOX.
Test burn of the Draco thrusters comming up at 21:30 UTC according to capcom.
Quote from: paycom on 03/01/2013 08:29 pmTest burn of the Draco thrusters comming up at 21:30 UTC according to capcom.Any word on Dragon eye opening?
Quote from: mmeijeri on 03/01/2013 07:45 pmQuote from: AJA on 03/01/2013 07:43 pmNone of this freezing oxidiser would happen if they stirred the tanks.Why would they need to stir the tank if it is well-insulated and perhaps heated? And how could it cause an explosion with storable oxidiser?I wonder if the fuel / oxidiser lines have insulation and heaters, as on the Shuttle.Looking past the joke...The tanks are outside the pressure shell, but obviously inside the TPS blankets, which will limit the radiative cooling rate substantially. Combined with the fact they're fairly dense, even without their own insulation and heaters they're not going to cool very quickly. Lines might be more susceptible, though.Quote from: meekGee on 03/01/2013 07:43 pmcould it be humidity in the He supply? That's one of the first ideas that came to my mind.If the lines weren't fully purged, perhaps the initial pressure drop as the downstream side filled cooled things enough to form some ice crystals. Or perhaps even lines cooled enough during ascent for water contamination to freeze. I have no idea how their tanks are plumbed, but that might explain multiple tanks not pressurizing.Pure speculation on my part. Plenty of other possibilities, too.
FOD in three pipes simultaneously? IMHO, this screams a design problem with the valves, due to thermal or vibrational issues during ascent.
