Emergency Unpowered Descent

[Ed88888888]

Hi Steve - It's been done with other brands, successfully, but I can't find any documentation with relation to Yuneec's products. Additionally, Yuneec turns off the motor (at least when at a hovering idle) if the device is tipped more than 90 degrees (or flips over). The DJI (at least from a year's old firmware) does not.

Here's a video of a DJI flyer arresting motors at around 5000ft and then restarting - you'll note that the craft seems to maintain an upright (although terrifyingly unstable) position, allowing him to restart motors. (Fast forward to 12:20)

There is a neat video showing a guy in the USA doing same with his Mavic Pro... insane

 

[Joeman434]

I'm coming in a bit late on this...a few years ago I tried shutting down the motors on a 350 about 2,000 feet, let it free fall to about 400 feet and re-started the motors. Worked great so when I just thought i had it under control, after about 3 times, and letting it get lower each time, it over stressed a prop and about 50 feet one let go and a crash resulted. Luckily, less than $100 and it was back flying. Since then, I have done it with a Typhoon and a Chroma, but only let them free fall about 50 feet.

 

[Ro19]

Hey All - question for anyone who either has experience with this - I can't seem to find an answer or video.

Barring any violation or concern of regulations/laws, if an individual were to take their TH up to 1500ft+ altitude but needed to rapidly descend, it would seem the fastest way would be to cut power to the motors; allowing the device to begin a free-fall.

In the simulation software, when you fly the Q, you can restart the motors and the craft will correct itself and respond to throttle commands, however, I am wondering if this is a situation that would happen in reality?

I've seen posts on the DJI boards that "people have done this" but when pressed for videos or proof, they simply reply with "just google for a video on YouTube" - I have, and I can't find anything. I've tried 14 different keywords but the closest is a CSC video from about 20' where the individual was testing whether the system would actually shut off if it knew it was mid-air. It did. The next closest are simple wreck videos of drones failing mid-flight... etc. None that pose an intentional power cut mid-flight with attempted power restore and in-descent stabilization.

On my DJI, I would suspect this wouldn't work because the IMU doesn't show interactive function once you land and power down. However, when I've hooked directly to my TH, I notice that nearly all of the sensors remain live/active and appear to be functional.

If I were rich and carefree I'd be tempted to try it out myself. This isn't a question to challenge legality or rationale of such a maneuver, more just curiosity around the general physics and capability of the craft itself.

I saw a video of aexactly this yesterday on YouTube with. MAVIC Pro

 

[Eyeup]

Look at the shape and weight distribution on the TH. The weight is below the props which I would assume would act like the feathers on a badminton shuttlecock. Given the stability of the Phantom, which is a less exaggerated version of the shuttlecock then I'm not sure why there is such an assumption that the TH would flip mid-air.

 

[Ralphy]

I'm coming in a bit late on this...a few years ago I tried shutting down the motors on a 350 about 2,000 feet, let it free fall to about 400 feet and re-started the motors. Worked great so when I just thought i had it under control, after about 3 times, and letting it get lower each time, it over stressed a prop and about 50 feet one let go and a crash resulted. Luckily, less than $100 and it was back flying. Since then, I have done it with a Typhoon and a Chroma, but only let then free fall about 50 feet.

We want to drop it from 400' with Dji carbon fiber props...

Sounds like a job for Myth busters

 

[skrubol]

I think even if you had done this successfully on a particular craft, it would be a roll of the dice every time you did it. These things aren't particularly stable in freefall, and can flip in a very short time. Once it's inverted, most likely the firmware won't know how to deal with the situation (accellerometer values won't make sense, etc.) and it'll just throttle down into the ground. Even if it does know how to deal with being inverted, it may take it several hundred feet to stabilize.

 

[Omar Dairky]

THIS IS WHAT PISSES ME OFF U ARE NOT ALLOWED TO DO IT END OF STORY....THIS IS WHY PEOPLE HATE DRONES WHY ACCIDENTS HAPPEN AND WHY FAA REGULATIONS WILL GET TIGHTER AND TIGHTER...400 IS PLENTY WHERE YOUR DRONE WILL BE THE SIZE OF A CHEESE BURGER ALL THESE WHAT IFS HOW ABOUTS CAN I PEOPLE SHOULD NOT HAVE A DRONE...CAN YOY CUT YOUR MOTORS SURE DO IT AND HOPEFULLY YOU DONT KILL ANYONE

 

[prathbun]

Take a breath, Omar.

Discussing legitimate possible emergency-recovery scenarios isn't a crime. I suppose we shouldn't talk about fly-aways, signal-loss or ESC failures, either...