Turn props off in mid-air for fast descent (and on again :-)

sar104 · Mar 14, 2019

Camino Ken said:
The deceleration at the air mass to land mass interface would however result in fairly high stress values. ha ha

That would test the accelerometers.

mariachi76 · Mar 14, 2019

Thanks a lot for you input, the data is really shows a lot about its behaviour - also in the other thread sar104 linked. I estimate that under normal atmospheric conditions the m2p would most of time be able to stabilize itself and position itself upright, however the time to do so might vary, depending on its position when props are turned on again, and wind conditions. The point of potentially different behaviour of firmware versions is a factor too - we dont know it.

I guess I will also not try it with mine - but it is good to know that it is an option for a fast descent in any case of emergency situation, with a good chance of recovering the drone.

best regards
mariachi76

blackomega · Mar 15, 2019

Why would DJI even include this option?
I would not even A small chance that I would accidentally shut off my motors mid flight

crlmjohnson · Mar 15, 2019

mariachi76 said:
Hello,
a rather theoretical question:
The Mavic 2 props can be turned off by pulling both sticks down/inside. With the same function they can be turned on again.
Can that be used in mid-air for a fast descent?

When flying up to 500m, the descent takes very long because the descent rate is rather slow (~2-3 m/s). So what would happen if I just turn off the props at 500m above ground, and turn them on ~200m above ground? Would the Mavic 2 stabilize again, or crash?
Anyoney ever tried?

best regards
mariachi76

Why? would you want to do this?

Vader869 · Mar 15, 2019

mariachi76 said:
Hello,
a rather theoretical question:
The Mavic 2 props can be turned off by pulling both sticks down/inside. With the same function they can be turned on again.
Can that be used in mid-air for a fast descent?

When flying up to 500m, the descent takes very long because the descent rate is rather slow (~2-3 m/s). So what would happen if I just turn off the props at 500m above ground, and turn them on ~200m above ground? Would the Mavic 2 stabilize again, or crash?
Anyoney ever tried?

best regards
mariachi76

No need to do this, Do the software hack and use DJI assistant program via your PC and change the vertical
accent /deccent speed to 10m/s and Max speed value to 10.
Change Max tilt angle from 30 degrees to 50 degrees.
You'll then decend and accend at 10m/s and you top horizontal speed will also jump from 70km/hr to 82-85km/hr.

In my opinion it's a must, only being able to decend at 3m/s is frigging boardereing on dangerous because if you need to get down and fast to avoid a bird or something then you are a sitting duck, a bird will run circles around a Mavic 2 descending that slow.
Also falling at 10m/s is like woww..... Wait till u try it... You won't go back.

I only modified mine in sports mode, I left the normal mode as is as it's good for more docile flying and battery optimisation

Inspirephil · Mar 15, 2019

sar104 said:
Are you incapable of reading a simple graph?

There’s no need to be rude about it. Quite possibly they can’t read a graph as well as you.

Inspirephil · Mar 15, 2019

Vader869 said:
No need to do this, Do the software hack and use DJI assistant program via your PC and change the vertical
accent /deccent speed to 10m/s and Max speed value to 10.
Change Max tilt angle from 30 degrees to 50 degrees.
You'll then decend and accend at 10m/s and you top horizontal speed will also jump from 70km/hr to 82-85km/hr.

In my opinion it's a must, only being able to decend at 3m/s is frigging boardereing on dangerous because if you need to get down and fast to avoid a bird or something then you are a sitting duck, a bird will run circles around a Mavic 2 descending that slow.
Also falling at 10m/s is like woww..... Wait till u try it... You won't go back.

I only modified mine in sports mode, I left the normal mode as is as it's good for more docile flying and battery optimisation

No thanks! Sounds dangerous to me.

offtheback · Mar 15, 2019

Vader869 said:
No need to do this, Do the software hack and use DJI assistant program via your PC and change the vertical
accent /deccent speed to 10m/s and Max speed value to 10.
Change Max tilt angle from 30 degrees to 50 degrees.
You'll then decend and accend at 10m/s and you top horizontal speed will also jump from 70km/hr to 82-85km/hr.

In my opinion it's a must, only being able to decend at 3m/s is frigging boardereing on dangerous because if you need to get down and fast to avoid a bird or something then you are a sitting duck, a bird will run circles around a Mavic 2 descending that slow.
Also falling at 10m/s is like woww..... Wait till u try it... You won't go back.

I only modified mine in sports mode, I left the normal mode as is as it's good for more docile flying and battery optimisation

Sounds like it's safe and can you do something in between normal and the max hack?

Cmick1972 · Mar 15, 2019

I don’t know about you guys, I wish this “feature” could just be turned off. What if I did it by accident, and then in the ensuing panic attack, I watch the glorious fall while I puke brains out after.

Pontoon-pilot · Mar 15, 2019

The graph shows the motors speed negative during the fall, the propellers started to autorotate. Quad rotors + CG being below the props would it not stabilize the drone?

m0j0 · Mar 15, 2019

Cmick1972 said:
I don’t know about you guys, I wish this “feature” could just be turned off. What if I did it by accident, and then in the ensuing panic attack, I watch the glorious fall while I puke brains out after.

Pretty unlikely to do it by accident. The stick commands are extreme

cochitiman · Mar 15, 2019

It's been a long cold winter here in Albuquerque too.

wes93j · Mar 15, 2019

Yeah.. Ahhh.. No. Not a good idea. It's not going to float down enough for you to try to restart again. In fact, it's going to plummet to the ground and you'll be minus that drone. I know you've probably seen helicopters that are in de-stress and decending. They will rotate too the ground (in some cases). Definitely not the case with your mavic. It's going into free fall and even if you were fast enough to restart, it's very unlikely that you'll recover.

cochitiman · Mar 15, 2019

sar104 said:
OK - apologies for my impatience there but the thread was getting cluttered with bad information. Personally I don't think I would try this with any of mine either. I'd be worried about the restart and would feel very foolish if I crashed trying. But - it's clear that it does work and that the motors are easily able to arrest the resulting descent.

Cmick1972 · Mar 15, 2019

m0j0 said:
Pretty unlikely to do it by accident. The stick commands are extreme

Thanks

Ken K · Mar 15, 2019

Reminds me of the guy that jumped off a ten story building.
As he passed by the fifth floor he was thinking "Well, so so far so good!".
Remember, it's not the fall that hurts; it's the sudden stop landing.

sar104 · Mar 15, 2019

Pontoon-pilot said:
The graph shows the motors speed negative during the fall, the propellers started to autorotate. Quad rotors + CG being below the props would it not stabilize the drone?

No - you are looking at the wrong axis. The motor speed axis is on the right and the recorded motor speed goes to zero because the motors are off. The props are undoubtedly autorotating, but that's not recorded.

It clearly is stabilizing the drone to some extent - the aircraft is wobbling and spinning but not tumbling.

sar104 · Mar 15, 2019

Pontoon-pilot said:
The graph shows the motors speed negative during the fall, the propellers started to autorotate. Quad rotors + CG being below the props would it not stabilize the drone?

The wobble, as opposed to tumble, is easier to see in unwrapped attitude:

JakeRobinson · Mar 15, 2019

Vader869 said:
No need to do this, Do the software hack and use DJI assistant program via your PC and change the vertical
accent /deccent speed to 10m/s and Max speed value to 10.
Change Max tilt angle from 30 degrees to 50 degrees.
You'll then decend and accend at 10m/s and you top horizontal speed will also jump from 70km/hr to 82-85km/hr.

In my opinion it's a must, only being able to decend at 3m/s is frigging boardereing on dangerous because if you need to get down and fast to avoid a bird or something then you are a sitting duck, a bird will run circles around a Mavic 2 descending that slow.
Also falling at 10m/s is like woww..... Wait till u try it... You won't go back.

I only modified mine in sports mode, I left the normal mode as is as it's good for more docile flying and battery optimisation

Where can ine learn more about the "hack" and you reference?

Cheers

sar104 · Mar 15, 2019

wes93j said:
Yeah.. Ahhh.. No. Not a good idea. It's not going to float down enough for you to try to restart again. In fact, it's going to plummet to the ground and you'll be minus that drone. I know you've probably seen helicopters that are in de-stress and decending. They will rotate too the ground (in some cases). Definitely not the case with your mavic. It's going into free fall and even if you were fast enough to restart, it's very unlikely that you'll recover.

Presumably you haven't actually read this thread - it includes flight records showing exactly this maneuver working just fine.