Saving battery by shuting off engines midflight

[trelliz]

Hello! I was wondering if you could save battery by switching the engines off at an altitude of 2.5km, wait for the drone to fall to 500m and then turn the engines on again.
Is it feasible?

 

[Plawa]

Suuuuuure.....

Well, actually it has been done but you're on your own if you try it.

Normally I would tell you it's stupid but you're already at 2500m so we're past that point anyway... please, go ahead and try it, make sure you report back how it went.

 

[trelliz]

Suuuuuure.....

Well, actually it has been done but you're on your own if you try it.

Wow! Thank you for such a quick reply. I wonder how often do mavic pros break when they fall on the grass with the engines off.

 

[Plawa]

Wow! Thank you for such a quick reply. I wonder how often do mavic pros break when they fall on the grass with the engines off.

My guess is "very often".

 

[RayOZ]

You also need to wonder what would happen if it falls on someone's head and crack their skull. Or collide with an aircraft being 2.5km up in the air.
And if the free fall flips the mavic upside down, you can't restart.

 

[RayOZ]

or if you flew right above yourself, 2.5km up, turn off motor, then busy looking at your screen and monitoring the height, then only to find you didn't restart the motors quick enough and crack your own skull as it lands on your head. so many possible scenarios.

 

[trelliz]

You also need to wonder what would happen if it falls on someone's head and crack their skull. Or collide with an aircraft being 2.5km up in the air.
And if the free fall flips the mavic upside down, you can't restart.

Really? What stops it from restarting when its upside down?
I was planning on doing that in an open field and from a safe distance

 

[RayOZ]

it's a safety feature that shuts motors when it's tipped beyond a certain angle. a spinning propeller provides lift, unless its upside down, which that case might make it fall faster.

 

[Simmo]

When the AC tilts over past 70' the motors shut down. So one could reasonably assume that if it weren't relatively level, the motors wouldn't start?
Its a fairly easy test though, take your props off and try it!

 

[Just_nick]

You can do it, but don't expect your drone to survive. Falling 2,000 meters means you're going to be reaching terminal velocity, which may rip the propellers apart in the descent itself, let alone when you restart your motors. What I expect will happen is your drone will attempt to right itself at 160+ mph, fail miserably at slowing itself down, and hit the ground and destroy itself.

 

[lolo780]

Set g_cfg_debug_motor_no_start_motor_check
And the other motor start parameter to 1 and you'll be able to csc start the motors in any orientation.

 

[Porto]

You can do it, but don't expect your drone to survive. Falling 2,000 meters means you're going to be reaching terminal velocity, which may rip the propellers apart in the descent itself, let alone when you restart your motors. What I expect will happen is your drone will attempt to right itself at 160+ mph, fail miserably at slowing itself down, and hit the ground and destroy itself.

Probably due to drag, the actual terminal velocity of a free falling Mavic is "only" about 70kph.

 

[lolo780]

Terminal velocity at sea level is 55-60km/h.

 

[Just_nick]

Probably due to drag, the actual terminal velocity of a free falling Mavic is "only" about 70kph.

I highly doubt that, not with the motors off. With them off, it's a free-falling object with a tiny surface area. If I hit over 120mph while skydiving, it's going to hit similar speeds.

 

[trelliz]

Terminal velocity at sea level is 55-60km/h.

Thats about the speed it flyes in sport+ mode.
Would it really just accelerate the descend if I switch on the engines when its falling upside down?

 

[Plawa]

Terminal velocity at sea level is 55-60km/h.

Horizontal, not vertical when it becomes a piece of rock tumbling down...

 

[Porto]

Terminal velocity at sea level is 55-60km/h.

Thanks for the correction

 

[Porto]

I highly doubt that, not with the motors off. With them off, it's a free-falling object with a tiny surface area. If I hit over 120mph while skydiving, it's going to hit similar speeds.

Just look for the video(s) on YT

 

[Tofino]

It is not a plane,it is not aerodynamic, it will not glide down. It will just drop, reach terminal velocity of 120 mph then smack into the ground..

 

[Porto]

It is not a plane,it is not aerodynamic, it will not glide down. It will just drop, reach terminal velocity of 120 mph then smack into the ground..

Initially that's what I thought too. But apparently not.