I did leave the lawyering to the lawyers. I asked my patent attorney for his opinion prior to posting.
Quote from: HMXHMX on 07/24/2014 05:39 amI did leave the lawyering to the lawyers. I asked my patent attorney for his opinion prior to posting.Heh, did he give you that horrible attempt at prior art too? How much did he charge you to read the patent?
Nothing. He used to work for me and wrote the book.
Why the fax machine is nothing but a waffle iron with a phone attached!
Repairing the CRS-3 landing was restoring a painting that had been put through a shredder. Repairing this video would be trying to restore a painting where the painter was constantly being interrupted by a toddler drawing all over their canvas as they were working.
One tidbit I just noticed. If you replay the landing video and take the timestamps just before and after the middle fadeout (between the retro burn and the landing burn), you see 15:24:17 and 15:25:39, or only one minute and 22 seconds. That's a mighty short time period, which implies that the retro burn is occurring at a much lower altitude than I (at least) would expect. Even if the rocket were still descending at 1000mph after completion of the retro burn, and averaged around 700 mph during the descent (faster at higher altitudes, slower near the end due to thickening air), that works out to only about 15 miles or so.I am not a rocket scientist, nor an aeronautical engineer. If my napkin calculation is wrong, please explain.
Quote from: rpapo on 07/24/2014 11:21 amOne tidbit I just noticed. If you replay the landing video and take the timestamps just before and after the middle fadeout (between the retro burn and the landing burn), you see 15:24:17 and 15:25:39, or only one minute and 22 seconds. That's a mighty short time period, which implies that the retro burn is occurring at a much lower altitude than I (at least) would expect. Even if the rocket were still descending at 1000mph after completion of the retro burn, and averaged around 700 mph during the descent (faster at higher altitudes, slower near the end due to thickening air), that works out to only about 15 miles or so.I am not a rocket scientist, nor an aeronautical engineer. If my napkin calculation is wrong, please explain.I think the real question is: what was the timestamp of stage separation? We know there was some RCS maneuvering immediately after sep. Did the retro burn immediately follow that, or did they allow themselves to "drift" downrange? (And if they were targetting RTLS, would they have drifted, or done the burn right away?)
Quote from: QuantumG on 07/24/2014 05:46 amQuote from: HMXHMX on 07/24/2014 05:39 amI did leave the lawyering to the lawyers. I asked my patent attorney for his opinion prior to posting.Heh, did he give you that horrible attempt at prior art too? How much did he charge you to read the patent?Nothing. He used to work for me and wrote the book. There are numerous other examples of prior art, none of which are quoted by the patent. It is utterly indefensible on several grounds – and I do know something about the prior art here.But we are straying too far off topic.
1. So, no external video? <Groan>. What about the video from the NASA plane which filmed the hypersonic “re-entry”?
Come to think of it, you don't even need a surface ship in order to get video. [...] Get a few quad-copters on a submarine
2. Did they do any boost-back on this flight? Anyone know the co-ordinates of the splashdown?
Wouldn't they want to demonstrate that they could fly the F9 S1, precisely, and using the same mass-vs-time profile as an S1 that had to carry prop reserve for boost-back?
That suggests to me that that the next one will travel a significant distance cross-range (instead of boost-back), and that perhaps there's some uninhabited area (as opposed to the relatively densely populated Space Coast?) that SpaceX can touch down on.
3. Plus, I think they'd have to demonstrate more than pin-point landing accuracy.
(EDIT: Couldn't all three S1 cores separate at the same time? [...])
4. I don't understand why a floating platform would be uneconomical.
Quote from: cscott on 07/24/2014 12:56 pmQuote from: rpapo on 07/24/2014 11:21 amOne tidbit I just noticed. If you replay the landing video and take the timestamps just before and after the middle fadeout (between the retro burn and the landing burn), you see 15:24:17 and 15:25:39, or only one minute and 22 seconds. That's a mighty short time period, which implies that the retro burn is occurring at a much lower altitude than I (at least) would expect. Even if the rocket were still descending at 1000mph after completion of the retro burn, and averaged around 700 mph during the descent (faster at higher altitudes, slower near the end due to thickening air), that works out to only about 15 miles or so.I am not a rocket scientist, nor an aeronautical engineer. If my napkin calculation is wrong, please explain.I think the real question is: what was the timestamp of stage separation? We know there was some RCS maneuvering immediately after sep. Did the retro burn immediately follow that, or did they allow themselves to "drift" downrange? (And if they were targetting RTLS, would they have drifted, or done the burn right away?)I think (I don't know) that they skipped the boostback burn altogether on this flight. So the stage separation and reorientation would have occurred at about the three minute mark, followed by a controlled drift (keeping the stage orientation steady with RCS) for twelve whole minutes, arcing up, and then down. The reentry burn would have occurred soon after atmospheric drag started to make itself felt.Looking back at the launch videos (presumably the same clock and same camera), the timer at stage separation was approximately 15:17:50. So retro burn was about 6:30 afterwards.Both readings are approximate, since the timer at stage separation was hard to read (white on white), and when we see the retro burn, it had already started.
Wasn't this a more lofted trajectory than normal? Is it possible they didn't need a large boost-back because the first stage went higher and less downrange than previous?
1 minute and 22 seconds at terminal velocity is not much at all.
The flight radar track shows that F900 was 336 km downrange from the pad. [...] I'll have to run the numbers, but that seems pretty close to a ballistic trajectory.
time alt speed range note km mps kmlaunch video15:14:30 0 0 0 +1:00 13 450 2.5 +2:20 54 1400 21 +2:25 40 sep +2:40 112 1700 51 MVAC +4:30 240 1800 130 NewHampshire +5:30 334 2200 209 +6:30 420 2700 305 +7:30 511 3600 460 +8:45 600 5700 150??? +9:30 620 7200 1000 2ndStage cutoff landing video +9:13 start of music +9:23 ? ? ? retro burn +9:49 ice +11:09 ? ? ? oceanvisible +11:12 ? ? ? landing RCS +11:20 ? ? ? roll stopped +11:27 ? ? ? legs +11:33 ? ? ? full plume +11:36 ? 0 330 engine out +11:39 ? 0 330 splash subsides +11:41 ? 0 330 start tipover +11:43 ? 0 330 kaboom
+11:12 landing RCS
On the video this is titled "landing burn".
We knew the boost-back burn uses 3 (from the video, and it's clear you need to turn back as fast as possible, and the stage is still heavy) and we knew the landing burn uses 1 (empty stage, hover-slam) but the secret-sauce burn is a little less secret now. We know when it occurs, and we know it uses 3 engines.
A reddit user TheVehicleDestroyer ran the numbers more than a week ago. The best fit for the available data is a ballistic trajectory from separation. No boostback.