Crazy day with fly away

[AukeH]

Hi there guys,

First of all let me introduce myself. My name is Auke Halie and I am from the Netherlands. i am an occassional good weather drone flyer with a DJI Mavic Mini 1. Today I was at my in laws at their farm for a little bit of flying. in the winter i did not fly at all so I had to update severall things. After that it was flying time. I saw that i had 13 sattelites and everything was ok so it was a go, I updated the homepoint and checked for altitude for the homepoint (it is an open space) It were good flying conditions. I was hoovering for approx 2mtr and than out of the blue my drone flew away banging into a tree. Luckily it was a tree and not my nephew or niece who were also standing beside me. I shut everything down an scraped the crap out of my pants........ Now I am concerned to fly again adn harm others or myself. Can anyone help me to prevent this and tell me what i should do now? I will try to attach the data retrieved from my drone.

Thanks in advance

With kind regards, Auke

 

[slup]

This was most probably an "uncommanded descent incident" that the Mini have suffered from, from the launch of the model. The props have been deformed & can't generate enough thrust & rise the motor RPM until it reaches maximum but it isn't enough anyway so it loses height.

You had a very old version of the FLY app ... v 1.2.1, that version didn't have the warning about to fast spinning motors & the recommendation to change props ... it came in later versions.

All typical errors came up regarding "NotEnoughForce" & "Max PowerLoad Reached" already before it descended straight into the ground. That you also used prop guards didn't help out either ... the "FlyAway" was happening after it bounced from the ground & there you commanded a lot of stick inputs which enforced the bounce in a horizontal direction.

Here from the log message stream... first errors came already at 101sec into this second flight on the same power on.




And here the telemetry which shows the uncommanded descent at 141sec with the green VPS height descending into the ground + blue vertical speed rapidly going positive (descent) ... while all stick inputs (dashed graphs) was on 0 (neutral).




If you retrieve & share the mobile device stored DAT log ending with FLY091.DAT I'm sure we will discover that some of the motors are on max RPM.

If the Mini didn't suffer any damage (as you had prop guards) I recommend you to change all 4 props to new ones & update app & Mini to the latest versions ... that should to fix this.

 

[MS Coast]

Also, be careful not to store the Mini with anything pressing on the props. The straps that hold the propellers in place when the drone is folded or the case itself can press on the props and warp them.

 

[Zbip57]

Also, be careful not to store the Mini with anything pressing on the props. The straps that hold the propellers in place when the drone is folded or the case itself can press on the props and warp them.

Merely crossing the propeller blades laterally across the body can bend the blades when the Mini's arms are folded.

See this thread for illustrations:
mavicpilots.com/threads/mavic-mini-class-action-info-speed-error.103183

 

[MS Coast]

If you fly a Mini, you should have a look at @Zbip57's post about deformed props, linked in the previous message. It's probably something to be aware of for all drones.

 

[eEridani]

One might ask how the drone made it to an altitude it couldn't sustain if said props were bad. The props had to be good enough to lift the drone up; so why did the props fail mid flight? Doesn't sound like the props were the real issue.

 

[sar104]

One might ask how the drone made it to an altitude it couldn't sustain if said props were bad. The props had to be good enough to lift the drone up; so why did the props fail mid flight? Doesn't sound like the props were the real issue.

No mystery about that - it has been extensively tested and documented. For example:

Mavic Mini uncommanded descent tests

After a little experimentation I was able to replicate the uncommanded descent problem under 0400 firmware by loading the rear props for a few hours as might happen in the flymore case. The props did appear slightly flattened compared to the front props. The problem quickly manifested itself in...

mavicpilots.com

 

[eEridani]

No mystery about that - it has been extensively tested and documented. For example:

Mavic Mini uncommanded descent tests

After a little experimentation I was able to replicate the uncommanded descent problem under 0400 firmware by loading the rear props for a few hours as might happen in the flymore case. The props did appear slightly flattened compared to the front props. The problem quickly manifested itself in...

mavicpilots.com

Reasonable explanation Sar, thank you. My guess is flow separation at higher rear airfoil velocities may explain the loss of lift.

 

[sar104]

Reasonable explanation Sar, thank you. My guess is flow separation at higher rear airfoil velocities may explain the loss of lift.

Could be, although just the reduced angle of attack at higher rpms might also explain the loss of lift.

 

[Capt KO]

At first it sounded to me that op took off from a metal surface, mini got confused...and split to who knows where.