I believe we can now reconstruct the last moments of #Ingenuity's #Flight72 with some certainty. The actual trajectory may be a little more complicated, e.g. turning while hopping, but we'll never know.
EDIT: there is a new theory about Flight 71, see comments.
Animation
Processed MCZ_RIGHT, FL: 110mm
looking NNE (16°) from RMC 52.0000
Sol 1130, LMST: 16:19:24
@65dBnoise I'm not sure that this kind of bounce is possible. I was told by one of the Ingenuity engineers that the shock absorbers are so effective even on hard ground that a bounce on much more absorbent sand could never reach this high.
There is a new theory that these imprints on the backside of the sandripple are actually from Flight 71. The official landing location was apparently just a rough estimate and there don't seem to be any imprints at that location anyways.
@stim3on
So, if the new theory is correct, then the heli wasn't flying sideways or at an angle, or we'll have to assume it went much farther horizontally and was coming back at an angle, which is a stretch for a flight meant to be just up-hover-down.
The fact that there isn't any image from the last two flights seems to confirm that radio coverage was indeed really poor or non existent, something that was already noticeable around the time 71 & 72 took place. https://mastodon.social/@65dBnoise/111788436672301562
@65dBnoise As far as I know, only partial telemetry (the output from the kalman filter) is transmitted during a flight, individual sensor data and images are only sent after landing.
These data are stored in RAM during flight, and I believe there is a mechanism that reboots the system after an aborted flight. That's why there are no images and why there is almost no telemetry data to analyze from these flights, which makes it so hard to reconstruct.
@stim3on
I don't mean live images.
Rebooting sounds to me like the wrong thing to do, but there may be reasons that necessitate it, given the hardware limitations, especially the lack of redundancy, AFAICT. Otherwise, keeping the data captured during a malfunction would be of paramount importance for analyzing the causes and taking corrective action. Stating the obvious here, of course.
But Ingenuity wasn't designed to take that hard a beating, so reboot might have been the best one could get.
@65dBnoise if #72 was indeed just a popup flight without lateral drift, a fast vertical landing on the slope would induce quite a bit of roll. This could introduce significant gyroscopic precession effects on the blades which the team believes could have bent the rotors beyond their limits until they snapped off.
Here are two animations I made about how gyroscopic precession would bend the blades. I thought it might have bent them until contact but they are most likely too stiff for that.
@stim3on
Nice animations! Although I too doubt the heli could bounce that high under just gravity. I thought that would only be possible under powered flight, where a disoriented navigation system tried to correct things.
@65dBnoise I made these animations almost two months ago, long before we knew about the new footprints.
I got the same feedback about the bounce height back then.
I never thought about an impact while the rotors were still generating lift, that could explain a larger bounce, but I doubt the heli could have traversed the sand ripple crest like that without any additional marks.
@stim3on
One would expect the top to be marked too, true. The new theory sounds much more plausible. If there can be substantiation of some kind, then that location for flight71 would probably answer many questions cleanly.
@stim3on
The team said the heli was flying at an angle. Presumably that meant flying under power, not just dropping under gravity. So, being powered, flying at an angle and hitting the ground at high velocity, is about as chaotic as it could get.
But the new theory sounds much more interesting, and also explains why we can't find the marks from the #Flight71 landing. My previous hypothesis for FLight 71 has it 50m to the east, while this one is just 1~2m to the west.
I like it a lot.
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