(1) I think that is a "hard" landing ;) I say it it the mark.
(2) The Question: I ain't no rocket scientist, but even if the engine failure had turned on, did the engines all just turn on quite late?
Just trying here some crazy college physics so not sure if this checks out but, here goes. Again, just for fun. If it takes X: (summation of thrust) to fly that high over x seconds, then it would take the X + some at the very last 4 seconds I saw engines turn on for soft landing.
Are we capable of having enough thrust in the last 4 seconds? Maybe try earlier so there can be more lead way in case of failure?
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Freefall: 11:06 (all estimates)
12:45 (still free fall, engines off and preparing for vertical)
12:48 (engine on, flipping for vertical)
12:50 (vertical) (4 seconds left to apply thrust)
12:54 (crash landing)
I have about 104 seconds of free fall, and 4 seconds left when engine turned on.
Is 4 seconds enough? Just intuition and genuinely wondering ...
Just for fun - does my physics checkout (at freefall)?
vf = 0 + (1/2) * at^2
vf = 9.8m/s^2 (108s^2) = 57153.6 m/s = 127848.9621 mi/hr (yea, ignoring at moment drag/terminal, physics ;)
Nice analysis. I can answer your question by illuminating two major points you missed.
1. The StarShip reaches a terminal velocity (in "the bellyflop") of about 200 km/h downwards and remains at that velocity until the "flip maneuver" at the end.
That's essentially a free force vector upwards due to drag which is free thrust on descent.
2. The weight of fuel reduces drastically on ascent which is why less engines are required as the StarShip soars higher into the air (they shut down when one reaches the 40% min thrust)
You'll see during the hover at the top that StarShip balanced on one engine for some time without moving. So that is the thrust required for station keeping. What we saw here was a combination of reaching a target location and burning excess fuel.
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So, landing burn is (supposed to be) done with two fully throttled raptors, which is essentially 4x the hover thrust. Here with SN9 you see what happens when only one of those raptors is actually working.
Here is an Excellent SN8 (not SN9) video with carefully reconstructed telemetry (based on pixel counting video references) and you can see the velocities on descent. Rewind the video for full detail:
I think they are doing it the most efficient way (similar to the Falcon 9) - that is with 0 hover.
The timing doesn't mean much because an entire engine didn't light... so it would have flipped up right faster and slowed down faster. Timing on a failure case doesn't really work.
Also it was only 1 engine compared with two, they could gimbal independently and have one course correcting while the other decelerates
(2) The Question: I ain't no rocket scientist, but even if the engine failure had turned on, did the engines all just turn on quite late?
Just trying here some crazy college physics so not sure if this checks out but, here goes. Again, just for fun. If it takes X: (summation of thrust) to fly that high over x seconds, then it would take the X + some at the very last 4 seconds I saw engines turn on for soft landing.
Are we capable of having enough thrust in the last 4 seconds? Maybe try earlier so there can be more lead way in case of failure?
===
Freefall: 11:06 (all estimates) 12:45 (still free fall, engines off and preparing for vertical) 12:48 (engine on, flipping for vertical) 12:50 (vertical) (4 seconds left to apply thrust) 12:54 (crash landing)
I have about 104 seconds of free fall, and 4 seconds left when engine turned on.
Is 4 seconds enough? Just intuition and genuinely wondering ...
Just for fun - does my physics checkout (at freefall)?
vf = 0 + (1/2) * at^2 vf = 9.8m/s^2 (108s^2) = 57153.6 m/s = 127848.9621 mi/hr (yea, ignoring at moment drag/terminal, physics ;)
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vf = (1/2) (F/m)t^2, F=ma (vf2m) / t^2 = F (Thrust required)
Again, just for fun. Don't kill me. Physics, it been a long time. If it's right, Elon, are you hiring?
EDIT: SpaceX, Tesla to the -moon- mars!