Quote from: Hooperball on 10/08/2012 06:47 pmFor those who don't approve the use of the term "explosion" we may have a new acronym: EPR - Engine Pressure Release. Not to be confused with this.
For those who don't approve the use of the term "explosion" we may have a new acronym: EPR - Engine Pressure Release.
For those who don't approve the use of the term "explosion" we may have a new acronym: EPR - Engine Pressure Release. S
Quote from: SF Doug on 10/08/2012 06:27 pmQuoteOur review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure releaseCould it mean that the loss of the thrust plume from engine 1 changed the flow/pressure gradient over the fairing?Yes, a very high probability of what happened. The vehicle was still in atmosphere and there would have been a positive back pressure in the engine 1 compartment area. When engine 1 shuts down the back pressure from the plume would drop suddenly causing a rapid pressure drop, an almost explosive pressure event (here I mean a very rapid and large pressure change not an explosion) occurring on the outside of the faring as related to the pressure on the inside of the faring. All it would take is enough flexing in a a near max Q environment and the engine faring would shred.As far as engine pressure loss it only means that a pressure sensor backed by a simultaneous reading from the backup pressure sensor detected a lower pressure than the limits allowed for the engine operation. Merlin engines are highly instrumented like the Shuttle's RS-25s because they were meant to be a man rated system. The engine controllers and system responses are also designed with that end goal in mind.
QuoteOur review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure releaseCould it mean that the loss of the thrust plume from engine 1 changed the flow/pressure gradient over the fairing?
Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release
To what degree would this event be mitigated, or not, with the new engine configuration of F9 V1.1? (at least with what we know thus far)
I've been reading this thread since launch, and it was mentioned that the Orbcomm timeline was completely absent from the F9 press kit and not public (though, of course, on L2). Is there any chance that the Space Track data, facebook / forum speculation, and everything else about the supposed doom of the Orbcomm payload is once again due to lack of released information, as with the GNC door?
Official statement from SpaceX: "no explosion". They continued to receive telemetry from the engine after the event. Did you even read it?
We're going to have six pages of discussion about the definition of "explosion" now...
It didn't explode, just blew itself to bits.
battery power?
You have 9 engines. There are a few hundred of combinations of 1-2 engines out before shutdown
and a couple more out after it. [shutdown]
Well, a very quick increase in pressure that leads to structural damage of rugged components that are meant to survive supersonic airflow (the fairing) could be called an explosion according to the definition of the word. http://en.wikipedia.org/wiki/Explosion.
Quote from: rcoppola on 10/08/2012 06:52 pmTo what degree would this event be mitigated, or not, with the new engine configuration of F9 V1.1? (at least with what we know thus far)We know nothing much at this point other than:1) engine #1 experienced a rapid pressure drop and was commanded to shut down2) engine pressure release or EPR (TM), caused the fairing to blow offNow, Occam's razor would suggest that the pressure loss is in the engine is directly responsible for the fairing. i.e. that by the time the engine was commanded to shut down, the fairing was already coming off. Video shows everything happening virtually instantaneously, there is no visible engine plume decay before EPR that would suggest it was the lack of backpressure that caused the fairing to collapse. It looks to me the engine shutdown follows first visual indications of failure, not precedes it.In either case, the root cause appears to be pressure loss in the engine and I don't see why a new engine arrangement alone would alleviate that.
Just for my understanding. Does 30 seconds of extra burn roughly equate to 30 seconds of extra gravity losses, or around 300 m/s lost delta-v?