Motor speed error. To me!!!

[AndreaBB]

I think it was just matter of time.
Today, following a forum mate example (silverdragon), I went to the meadow next to my house to learn how my Mini flies into the wind.
I do not have lots of experience, just 19 takeoffs (and luckily 19 landings) so far.
Never used the fly more combo bag (that I own), never bent the blades, never had any problem so far.
While the Mini was hovering 20 meters over my head, after a few minutes of flight I’ve got the well known error.
Close to panicking, I landed.
Switched off the drone, switched it on again ready for another flight.
Well, 25 minutes in a row in a windy meadow without any further error. Same drone, same blades.
Back to home I was willing to check if everything was good, and I took these 2 pictures.
Do you see anything strange? I’m not gonna tell you which esc was in error mode, yet.

 

[timinator]

1. Don't panic when flying, ever. Panic is the enemy of a successful resolution to the problem at hand.
2. You've got a few choices available - download the flight data and post it for interpretation by some of the experts here, maybe downgrade the FW back to 0400 and see how that goes, keep existing FW and fly more to see if the error recurs, or if it makes you feel better, change the props.

 

[AndreaBB]

Here's the files: on both the back left blade was spinning faster than the right one, but on one I've got the error, on the second one, after a couple of minutes, I didn't.

 

[Ajkari]

I cant see anything strange from looking at the props. Lets see what information the experts can read from your files.

 

[sar104]

The difference is subtle. Looking at comparable periods in the two flights, the maximum left rear motor speeds are similar, but in the case where an error flag occurred the duration of the highest peak was 1.5 seconds, as opposed to under 0.5 seconds in the flight with no error.





So possibly the error is trigger by a combination of overspeed (e.g. > 16 krpm) and duration (e.g. > 1 s).

 

[AndreaBB]

Thanks sar104, just refreshed the fw, changed the blades and charged the batteries.
I will go out early tomorrow to test this configuration.
Does anyone know if the AC does automatically land after some time while showing the error?

 

[wickedflyah]

From what I've read it's been the same motor (rear left) for everyone that's had this issue. I just got my Mavic Mini earlier this week and on the second day I got the same error message. I immediately changed the propellers on the indicated motor and haven't had the error message pop up since. I'm hoping it's just a software issue, if it wasn't though I still replaced the props so we'll see.

 

[sar104]

Thanks sar104, just refreshed the fw, changed the blades and charged the batteries.
I will go out early tomorrow to test this configuration.
Does anyone know if the AC does automatically land after some time while showing the error?

No - it doesn't land - it's just a warning message. You can ignore it.

 

[RogerDH]

I think it was just matter of time.
Today, following a forum mate example (silverdragon), I went to the meadow next to my house to learn how my Mini flies into the wind.
I do not have lots of experience, just 19 takeoffs (and luckily 19 landings) so far.
Never used the fly more combo bag (that I own), never bent the blades, never had any problem so far.
While the Mini was hovering 20 meters over my head, after a few minutes of flight I’ve got the well known error.
Close to panicking, I landed.
Switched off the drone, switched it on again ready for another flight.
Well, 25 minutes in a row in a windy meadow without any further error. Same drone, same blades.
Back to home I was willing to check if everything was good, and I took these 2 pictures.
Do you see anything strange? I’m not gonna tell you which esc was in error mode, yet.

View attachment 100216View attachment 100217

It appears to me that the tip of at least one of your left rear blades is so close to having a negative angle of attack (which would create downward force at the tip instead of lift) that it might happen if the blade twists just a bit. I think the blade is flimsy enough that, when that starts to happen, the downward force could become large enough to bend the blade and twist it even more, increasing the downward force. I have a theory that this is also what causes the front props to bend down enough to strike the body. Maybe it's my imagination, but I think I'm seeing the same thing on my Mini's blades, although I haven't flown it enough to have either problem. Yet.

 

[scro]

Looking at the photos it does appear to have a negative angle of attack at the tip. Especially left blade in the 1st photo!

Just curious - how do you store your drone?

 

[AndreaBB]

So let's start from your first post: you are right, the problem seemed to be related to the rear left blade. But... the blade didn't have a negative pitch itself, it just had a screw end play (I think this is the correct English way to explain it). Unfortunately the screw was tided enough but pushing the blade upwards with a finger was enough to see both blades having the same pitch.

My MM come inside the FMC bag, that I have never used afterword. Since I was aware about the potential problem I bought the STARTRC Mavic Mini Shoulder Bag:



So when I'm at home it sits on my desk with the legs opened, when I'm out to fly it's in that bag on in the air.
I had 16 flights without any problem before the well known motor error occurred.
Anyway, yesterday night I did re-upgrade the firmware and changed the rear left blades. This morning I went into a meadow next to my house and flown 3 batteries.
While the hovering stability doesn't seem as good as it was before, the motors do RPMs look much better:





Summary: I'm not sure how the blades got damaged, but there was something odd according to the DAT files.
As per today's experience, I didn't notice any flight improvement but a worse hovering.

Should we analyse the DAT files every single fight to be sure our props are in a good condition?

 

[scro]

If I've understood you correctly the plastic blade is loose on the mounting screw, enough that gently wiggling it with your finger you can change the pitch at the top from negative to positive? The screw itself is tight, but because it has a "shoulder" it doesn't clamp the blade, rather the shoulder tightens down on the top of the motor bell housing.

My blades are loose like this too, but not to the point where the leading edge is lower than the trailing, at the tip.

(Note, I've studied airfoil design and you actually still get lift from a thin curved blade when the leading edge is just lower than the trailing. I was designing an airfoil that gave lift in both directions without a pitch change. Almost sounds counter intuitive, but proven in wind tunnel tests!)

 

[AndreaBB]

If I've understood you correctly the plastic blade is loose on the mounting screw, enough that gently wiggling it with your finger you can change the pitch at the top from negative to positive? The screw itself is tight, but because it has a "shoulder" it doesn't clamp the blade, rather the shoulder tightens down on the top of the motor bell housing.

It's clear you speak English better than I do , that's what I meant to write.

 

[scro]

It's clear you speak English better than I do , that's what I meant to write.

Haha, thanks! I have no excuse to be bad at English since it is my primary language!

 

[orb]

Wonder if it could be the same fault I had a faulty power esc module.Mini went slightly backwards on lifting and seemed to make a noise on one of the rear motors.Sent for repair and was exchanged for a new one.

 

[kidroc]

Looking at the photos it does appear to have a negative angle of attack at the tip. Especially left blade in the 1st photo!

Just curious - how do you store your drone?

Defiantly has a flat edge on the one tip...

 

[Derick]

I received this error today. Read various threads. Please closely examine the props.

 

[timinator]

That's been chewed up really well. Trash that sucker!

 

[Derick]

That's been chewed up really well. Trash that sucker!

Only new never hit anything. However landed on short grass which was a bit longer than I thought ????????

 

[timinator]

Hand catch, my friend, hand catch the landing!