QuoteMany people aren't going to like me for this, but given the now-confirmed improper Orbcomm orbit result, my methodology requires me to categorize this as a launch vehicle failure. Those familiar with my system know that I list launches as successes if proper orbits are achieved, and failures if not, without compromise. I show three Space Shuttle failures and one Atlas 5 failure, for example. I list SA-502/Apollo 6 as a failure. I think it's fairly obvious to the casual observer that this launch succeeded at its primary objective (deploy Dragon such that it can berth with the ISS) and failed at it's secondary objective (deploy OrbComm in it's proper orbit).I understand the desire for a black and white pass/fail criteria, but saying this launch is a complete failure seems a bit much. Did you mark down Falcon 9 Flight 1 as a failure since it failed to achieve a restart burn?
Many people aren't going to like me for this, but given the now-confirmed improper Orbcomm orbit result, my methodology requires me to categorize this as a launch vehicle failure. Those familiar with my system know that I list launches as successes if proper orbits are achieved, and failures if not, without compromise. I show three Space Shuttle failures and one Atlas 5 failure, for example. I list SA-502/Apollo 6 as a failure.
Quote from: dunderwood on 10/09/2012 04:22 amQuoteMany people aren't going to like me for this, but given the now-confirmed improper Orbcomm orbit result, my methodology requires me to categorize this as a launch vehicle failure. Those familiar with my system know that I list launches as successes if proper orbits are achieved, and failures if not, without compromise. I show three Space Shuttle failures and one Atlas 5 failure, for example. I list SA-502/Apollo 6 as a failure. I think it's fairly obvious to the casual observer that this launch succeeded at its primary objective (deploy Dragon such that it can berth with the ISS) and failed at it's secondary objective (deploy OrbComm in it's proper orbit).I understand the desire for a black and white pass/fail criteria, but saying this launch is a complete failure seems a bit much. Did you mark down Falcon 9 Flight 1 as a failure since it failed to achieve a restart burn?I don't know how you can come to that conclusion as well. It was not the second stages fault that the command was not given to raise Orbcomm's satellite to it's proper orbit. NASA's parameters did not allow for it. I would classify the mission as a partial success and that is only if and when Dragon fulfills it's intended flight plan.
I'd call it "head end" or "top end" not back end. It's part of the combustion chamber/throat/nozzle assembly which is called a TCA ("thrust chamber assembly") in most publications.The pressure inside the TCA, exhausted via the throat and through the nozzle, is what creates thrust. Any opening or venting outside of the nozzle will lower combustion pressure, and that will be sensed as fault by the engine controller. Presumably if that happened, the engine would command itself to shut down.I don't have any details about the engine but the walls are likely fairly thin, perhaps only a few millimeters thick. There are many failure modes, from burn-though, stress cracking, etc., that generally require analysis of the post-failure hardware to determine. That may not be possible in this case.But since there is only one (?) flight of Merlin 1C left, and then SpaceX transitions to the very different Merlin 1D, the failure has come at about the worst time in that version's manufacturing cycle. SpaceX has a few hard decisions to make going forward (in my view). While unlikely, they might wish to transition earlier to the F9v1.1 than they had planned...but that creates it own set of problems. Tough call and I wish them the best.
Quote from: sdsds on 10/08/2012 08:48 pmFor modemeagle: in your simulations if F9v1 loses thrust from two engines at T+1:20 does the payload reach any orbit at all?Yes, according to my simulation.
For modemeagle: in your simulations if F9v1 loses thrust from two engines at T+1:20 does the payload reach any orbit at all?
It was not the second stages fault that the command was not given to raise Orbcomm's satellite to it's proper orbit. NASA's parameters did not allow for it. I would classify the mission as a partial success and that is only if and when Dragon fulfills it's intended flight plan.
The pressure inside the TCA, exhausted via the throat and through the nozzle, is what creates thrust. Any opening or venting outside of the nozzle will lower combustion pressure, and that will be sensed as fault by the engine controller. Presumably if that happened, the engine would command itself to shut down.
So do I understand correctly that it is the back-end of the combustion chamber, and so a rupture there would cause the outflow to be mixed and basically already ignited.
So, could this be a turbopump running too fast and causing the fuel dome to overpressure and rupture? Or, an overpressure caused by a blockage down the line? It's a pintle engine, so only one injector to block.
It also occurs to me, it worth asking: if this had occurred on a manned flight would it have triggered activation of the LAS on dragon or would the flight have continued on the other 8 (considering the apparent violence of the failure, brief though it was)?
Quote from: FinalFrontier on 10/09/2012 07:57 amIt also occurs to me, it worth asking: if this had occurred on a manned flight would it have triggered activation of the LAS on dragon or would the flight have continued on the other 8 (considering the apparent violence of the failure, brief though it was)? Excellent question. My guess is no, not unless the GNC computed that they could not reach the desired orbit. An abort is almost as dangerous as staying on a deranged-but-intact rocket, so you don't want to trigger it if you don't have to.
Quote from: Kabloona on 10/09/2012 03:15 amhttp://www.popularmechanics.com/science/space/rockets/why-the-engine-failure-could-be-good-news-for-spacex-13520351?src=rssWho is this Rand Simberg, and why is he claiming absolute knowledge of what failed, in apparent contradiction to Chris' article stating that SpaceX says the fuel dome ruptured ? Rand is a highly experienced "recovering" aerospace engineer who published a blog called Transterrestrial Musings (www.transterrestrial.com). He is a thirty-plus year veteran of the industry. Nothing he said in that article seem to me to contradict what Chris wrote.
http://www.popularmechanics.com/science/space/rockets/why-the-engine-failure-could-be-good-news-for-spacex-13520351?src=rssWho is this Rand Simberg, and why is he claiming absolute knowledge of what failed, in apparent contradiction to Chris' article stating that SpaceX says the fuel dome ruptured ?
