I have been doing some testing (outside the US) that involve very high altitudes - 1800 meters or more. The climb takes no more power than coming down. Even though going up takes more power per minute, coming down is slower, so the total power consumed when coming down is easily equal to the power going up.
I was thinking that it would be more energy-efficient to shut off the motors at the highest point, and letting the quad free-fall and then turning the motors on again at 30 meters or so to right itself and slow down for landing. Has anyone tried this? I have been told that dji can do this.
I'm using APM and PixHawk controllers.
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As I mentioned, I was outside the US (on a British Caribbean Island). Maybe the same rules apply there, but when I asked a local policeman, he said he knew of no limitations, so I did what I always wanted to do in the US, but could not do because of regulations.
There is a new APM flight mode called "Throw Mode" being developed. When/if released, it may do what you need, but I'm not sure. You can see a video demonstrating it here.
I set up one of my radio spring switches for that, it can be useful for more than just descending quickly. I was practicing maneuvering around trees, and getting very close to them, and of course my blades started getting into the leaves and then getting non-horizontal. I switched the motors off, my Iris+ descended out of the leaves and righted itself, then I released the switch, motors came back on out of danger and Iris+ stabilized.
It's also good after a crash when it seems you never can get the motors to stop fast enough, or when you're landing and a little kid starts running up to it.
This looks like it would probably do what I want. Is there any code on GitHub? I looked around and didn't see any.
Who told you that...
A friend who says he has a friend....
I know that it might not be true. Nonetheless,I was wondering if anyone has tried it with an APM.
I have a small quad with a KK2 controller. I pushed the throttle all the way up and it climbed so fast it scared me (I was new to the sport at the time), so at approximately 200' in altitude, I pulled the throttle all the way down. Inertia kept it going up for a short time, then it started falling - motors off. It did not stay upright, it was tumbling. It took me a short time to regain my composure and push the throttle up again. At a height of about 50', the little quad caught itself and kept on flying. I did NOT have the "motors spin when armed option ON", so they actually stopped.
So a KK2 can do it.
I am reluctant to try the same thing with any of my newer, bigger aircraft. The cost of failure is too high.
Hi, yes it works suprisingly well, I've tried it several times while getting familiar with 'edge of the envelope' scenarios. It will of course tumble on the way down but when you apply throttle it should right itself even when inverted. I would certainly restart before 30 meters though! More like a 100 meters at least, preferably higher, as it will essentially be falling at terminal velocity from that height. Also I haven't tried it since DCM (3.2 firmware) days, it may be that if you're tumbling that high and that long that the EKF in the recent firmware (3.3/3.4) takes a little longer to recover or may get very upset and throw a hissy fit.
Coming down in a straight line is very slow because you're descending through prop wash and it's very aerodynamically unstable. You can descend very quickly if you add an angle to the descent so it no longer comes down through it's own wash. You could try and zig-zag downards like a skier down a mountain, it would get you down much faster, or in a spiral. There's no flight mode that will do that, but you could use guided mode and code something or possibly even use auto mode and code a mission to do similar.
Very interesting task, please let us know how you get on :)
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