Freefall of a Mavic Pro

[JanB]

Excellent point. The blades will be turning, and pretty fast in the airflow as it goes down. Just their spinning would give stability to the aircraft. I just took my drone out and blew on a blade to confirm to myself that the blades, however, are going backward. So when the start command is issued that must be quite a strain on the motors to suddenly have to change direction while spinning. I really think you have a good point that illustrates how the drone could be stable. I wonder if it turned upside down a moment if the center of balance would get it back over before the blades started spinning. It may be that it never does turn sideways or upside down because the blades would start spinning backward as soon as the motors stopped.

You are not right in presuming that the drone never turns sideways or upside down, this -and before all the sideways turn- will happen quite often as I can assure you from my own experience. Therefore you have to exactly monitor the fall to put on the motos the right moment! It really tumbles falling down.

 

[sar104]

You are not right in presuming that the drone never turns sideways or upside down, this -and before all the sideways turn- will happen quite often as I can assure you from my own experiance. Therefore you have to exactly monitor the fall to put the motos on the right moment! It really tumbles falling down.

During that tumbling motion, if you put the sticks in the CSC position will it start the motors when it becomes upright, or do you have to wait to apply the CSC until it is upright?

 

[_KG]

Why would anyone want to purposley put their expensive drone in a situation like that for excitement. Kind of like sticking your head in a alligator's mouth to get a cool pic.

Because no other (home made) quad for about €800 could fly this long/far/high, so with some simple tweaks it is just the ultimate longrange rig, and it also makes nice pictures and high quality video

 

[JanB]

During that tumbling motion, if you put the sticks in the CSC position will it start the motors when it becomes upright, or do you have to wait to apply the CSC until it is upright?

This is a good question I never tried. I always waited that the drone lies quite horizontal in the air to restart the motors and sometimes I had to try it for several times because the drone did not respond at once...

 

[JanB]

During that tumbling motion, if you put the sticks in the CSC position will it start the motors when it becomes upright, or do you have to wait to apply the CSC until it is upright?

Wait till tomorrow, I will show you a clip which will give a good example of this tumbling...
Today it is too late for me, mom said I had to go to bed...

 

[sar104]

Wait till tomorrow, I will show you a clip which will give a good example of this tumbling...
Today it is too late for me, mom said I had to go to bed...

What would really be interesting would be the mobile device DAT file for that event - that would put all of these questions to bed.

 

[JanB]

What would really be interesting would be the mobile device DAT file for that event - that would put all of these questions to bed.

Yeah, I think so, but this would show where I fly. I would not like this and I think that is quite comprehensible... Sorry...

 

[sar104]

Yeah, I think so, but this would show where I fly. I would not like this and I think that is quite comprehensible... Sorry...

Understandable. But if you feel like extracting the data yourself and removing the location information then the aircraft velocity, attitude and motor performance data would still be interesting.

 

[wombat]

I am no expert but IMHO a mavic will not start upside down, cos the fuel would not flow in the correct direction

 

[netfolks2000]

This is a good question I never tried. I always waited that the drone lies quite horizontal in the air to restart the motors and sometimes I had to try it for several times because the drone did not respond at once...

Up that high how could you have a visual to know when a fast falling drone would be in an upright position? Until there is data I'm going to guess, even suppose, that holding the sticks in the start position will work once the drone turns in an upright position. It is a short time from motors off to "impact" on the ground. Those who've succeeded in re-starting and soft landing must've hit that sweet spot when it was upright in the tumbling process.

 

[JanB]

Understandable. But if you feel like extracting the data yourself and removing the location information then the aircraft velocity, attitude and motor performance data would still be interesting.

Voilà, a short clip I cut from a longer one to show the tumbling and fast rotating drone in free fall:

I made this clip quite short not to show too much of the region. Sorry, I don't keep the data files... but you can see a lot of the aircraft velocity, attitude and motor performance in the picture in the picture.

 

[JanB]

Up that high how could you have a visual to know when a fast falling drone would be in an upright position? Until there is data I'm going to guess, even suppose, that holding the sticks in the start position will work once the drone turns in an upright position. It is a short time from motors off to "impact" on the ground. Those who've succeeded in re-starting and soft landing must've hit that sweet spot when it was upright in the tumbling process.

Normally I don't throw the RC and the cell phone away after having cut the motors. So I still have the opportunity to look on the still established visual connection to the drone. Marvellous world of electronic ...

 

[Nile Mcmillion]

I replayed the second video at 1/4 speed (click the gear icon) and you can see that the drone was ~40 degrees when it restarted. I've started my MP from some pretty crazy angles but the motors won't start at anything more than 90 degrees on mine. I think what also may have been happening was that he was holding the sticks together to restart and when the drone was within its limits it restarted. Just my thoughts.

 

[sar104]

I am no expert but IMHO a mavic will not start upside down, cos the fuel would not flow in the correct direction

Voilà, a short clip I cut from a longer one to show the tumbling and fast rotating drone in free fall:

I made this clip quite short not to show too much of the region. Sorry, I don't keep the data files... but you can see a lot of the aircraft velocity, attitude and motor performance in the picture in the picture.

That's fascinating behavior. I'd be really interested to see the telemetry. I'm just not willing to take any of my aircraft high enough to try to replicate that.

 

[Perran]

A bit off topic . . . .

I entered into a coconut crown with my MP.
At a height something 25+ meters.
I heard a smattering sound and saw how the drone was falling down, in small pieces !
However, it was pieces of the palm leaves that were cut off by the propellers.
The drone fell down, moving sidewise in an arc, left to right.
The maximum tilt angle was say 60 degrees.
After a few "arcs", the drone levelled out and hovered after say 6 meter fall.

Learnt something !
Happy that the drone managed this accident so elegantly !
Thanks DJI !

 

[netfolks2000]

I replayed the second video at 1/4 speed (click the gear icon) and you can see that the drone was ~40 degrees when it restarted. I've started my MP from some pretty crazy angles but the motors won't start at anything more than 90 degrees on mine. I think what also may have been happening was that he was holding the sticks together to restart and when the drone was within its limits it restarted. Just my thoughts.

Need to hold the drone at about 60 to 70 degrees and try to start it, or better, hold it past 90 while someone holds the sticks for a start and see if it starts when pulled in less than 90 on up to level.

 

[Nile Mcmillion]

Need to hold the drone at about 60 to 70 degrees and try to start it, or better, hold it past 90 while someone holds the sticks for a start and see if it starts when pulled in less than 90 on up to level.

Although I'll never try killing the motors in-flight, I'll give that a try next time I can and let you know what I find out.

 

[JanB]

That's fascinating behavior. I'd be really interested to see the telemetry. I'm just not willing to take any of my aircraft high enough to try to replicate that.

Next time I do this again I will keep the datas, promise! ...But that can last some months because I don't do it very often because I know the material is near it's limits and I love my drone ...

 

[Simmo]

Hey @JanB, if you were to send your files to @sar104 personally, I would guarantee that he would remove any location data, so you dont need to worry.
His analasys (sic) of the flight characteristics data though, would be extremely valuable to the whole community!
Please consider his request?!

 

[JanB]

I am no expert but IMHO a mavic will not start upside down, cos the fuel would not flow in the correct direction

You are wrong! Of course all drones and planes in Aussie land have to start upside down to compensate the fact that the whole country is upside down...