Better performance margin if you fly to depletion for the first stage... Otherwise, you're leaving some margin behind when you stage.
All of which I thought was irrelevant: doesn't the Falcon just have one (redundant) control system on the 2nd stage controlling the whole vehicle?
Would 7 @ 112.5% be worth trying if there was reason to believe the engines could probably hack those conditions *once* and stay close enough to profile to prevent loss of mission? Think in terms of red lining a racing engine. You can probably get away with exceeding the red line once, but don't try it on a regular basis. All of this is modulo the question of how much can they overboost and what does the failure probability look like when doing so.
At the very least we know they have a computer per stage in F9 v1.1.
Quote from: mlindner on 03/23/2013 01:44 amAt the very least we know they have a computer per stage in F9 v1.1.We know this from where?
Quote from: baldusi on 03/22/2013 08:11 pmQuote from: 2552 on 03/22/2013 04:40 pm8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?What if the way to increase the thrust is to change the O/F ratio?Not good if you are going to throttle a lot - you want oxidizer and fuel to be depleted at the same time.
Quote from: 2552 on 03/22/2013 04:40 pm8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?What if the way to increase the thrust is to change the O/F ratio?
8 1Ds at 112.5% thrust should be the same total thrust and propellant flow rate as 9 at 100%, so immediately throttling the remaining 8 up, if possible, after an engine out should avoid any performance loss. Or is this wrong?
For the restart tests, yes, they'll need guidance for the first stage, but it doesn't follow from that that every v1.1 has/will have 2 sets of computers. Certainly not 2 complete sets of triple string computers as mlindner is asserting. I would be surprised if the restart tests use anything more than single string on the 1st stage.
That's like saying they put parachutes in the first F9 so why not keep putting them in all other vehicles as well, to avoid multiple configurations. Recovery systems had logic as well. 1st stage guidance and 2nd stage guidance shouldn't really be linked in a way that it counts as an integration problem if you *remove* 1st stage guidance when you don't need it. It's supposed to kick in only after staging and be completely inactive until then. At least that's what the customers would like, I'd think.
So we had a trade-off: SpaceX wants to experiment with reentry, customers want a stable configuration.
Quote from: Prober on 03/17/2013 04:45 pmQuote from: oldAtlas_Eguy on 03/16/2013 01:46 pmThank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing. Maybe a possible 1E will come out of the long wait of the 1D?Even the "Is Falcon 1E dead?" thread is dead. (No, he's just resting. Dead! Dead, I tell you!)There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets. I was disappointed. They "built it" but "they did not come". The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.
Quote from: oldAtlas_Eguy on 03/16/2013 01:46 pmThank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing. Maybe a possible 1E will come out of the long wait of the 1D?
Thank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing.
Quote from: Comga on 03/17/2013 06:53 pmQuote from: Prober on 03/17/2013 04:45 pmQuote from: oldAtlas_Eguy on 03/16/2013 01:46 pmThank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing. Maybe a possible 1E will come out of the long wait of the 1D?Even the "Is Falcon 1E dead?" thread is dead. (No, he's just resting. Dead! Dead, I tell you!)There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets. I was disappointed. They "built it" but "they did not come". The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.F1 programme Merlin-1C's were transferred to the F9 programme quite a while ago, so the answer to the beginning of post is a confirmed no.
Has a Merlin 1D ever failed (exploded) in testing?If one did would SpaceX disclose it?
Quote from: russianhalo117 on 03/24/2013 12:47 amQuote from: Comga on 03/17/2013 06:53 pmQuote from: Prober on 03/17/2013 04:45 pmQuote from: oldAtlas_Eguy on 03/16/2013 01:46 pmThank you Chris for oversight on the thread. I lost my reading glasses a few days ago and am having difficulties with reading and writing. Maybe a possible 1E will come out of the long wait of the 1D?Even the "Is Falcon 1E dead?" thread is dead. (No, he's just resting. Dead! Dead, I tell you!)There must be a bunch of Merlin 1C's around and they have the F1 launch erector and pad available from Kwaj which they could set up at CCAFS or VAFB, but SpaceX said they would not sell any Falcon 1 rockets. I was disappointed. They "built it" but "they did not come". The Merlin 1D just makes it less likely. SpaceX is not going to the effort of creating a whole new rocket that is not on their main path.F1 programme Merlin-1C's were transferred to the F9 programme quite a while ago, so the answer to the beginning of post is a confirmed no.I don't think the question was about the Falcon 1E, but about about a possible Merlin 1E, a hypothetical follow-on to the Merlin 1D.I don't know if they're going to be happy with that engine and make it mainstream for a while, or if they have a continuous development program going on with it.
"If engines are not exploding, you are not testing hard enough" ?