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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It was a one-time event, not to be repeated.
It's happen to me by accident that motors stop in the air and switching to stab I can recover and land safety but that don't warantee that a prop become spin reverse and you burn an esc and crash, take in mind that occurs too and is a risk; I prefer other suggestinos descending as slaloon or perhaps a parachute? but try to not complete stop motors.
Turning the motors during flight is dangerous, it's really possible, that they won't spin up again.
Isn't it a better way to somehow increase the descend speed?
Hi Charles,
I'm pretty sure the recovery would work fine right now in several of the flight modes.
The only thing missing is a means to tell it when to turn off the motors and then when to re-enable them.
In theory I believe you are correct, would use less power, because you would only have to counter descent from free fall speed.
I believe 30 meters might be about the minimum you would want to reengage though, still has to go through some gymnastics before it can add thrust.
Seems like you could still test this in the US just fine, just stay below 400 feet when you turn off the motors.
Now all you need is somebody to put together the crash dive mode.
I just might be able to do this myself. I normally write firmware for Microchip PICs, but I have already modified APM firmware in several areas (and it seems to work!)
Keep it under control - I have come up with a new checklist that covers all the new FAA regs. Please consider it on UASchecklist.com. It will keep all UAV/Drone users out of trouble.
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.
Cool video - Thanks!
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