Maximum rotor speed reached...

[erkme73]

I finally had enough me-time to load my DAT files into @budwalkers program. The flight with the overspeed warning looked virtually identical @kingkrule's graph above. I had one slightly cracked prop (may 1/4" crack on the leading edge), and one that was missing two of the three locking tabs.

Oddly enough, both rear motor speeds tracked nearly identically - much in the way the graph above shows. So I think when one prop is sufficiently damaged to require max speed, depending on the maneuver (i.e. full forward/throttle), the opposite motor providing the same thrust will ramp up to the same overspeed.

In any case, what caused my damaged props was a flight from the previous day where I landed on a flat rocky surface, without the downward positioning sensor enabled. It slammed down hard, and made a horrible smacking sound.

The DAT for that flight revealed a very brief moment where the left rear motor went from about 5000 RPM to 0 RPM and then back to 5000 RPM. I guess the props don't like when that happens.

 

[Alex ROV]

Hey guys!

I had this MAX SPEED WARNING today... But I was flying the SIMULATOR!!! How could that be possible? Motors dont spin when using simulator... Could it be internal problems in Mavic´s hardware?
And Mavic landed without any command or way to control it...

Scary... Very scary...

Thanks,
Alex

 

[ChosenMavic]

This message is just a warning and can be ignored. The only time it has real relevance is if you are flying near the altitude limits, like over 16,000 feet. It would alert you that there is no more elevator force to be had. It there is not enough lift, you'll get no more as the Motor is already at max RPM.

Edit: Well there is one exception to my statement. If you have prop damage, the message could be displayed prematurely. The mavic will fly even if you cut the props in half. The prop would have to spin at a much higher RPM to induce lift. This could make that max Motor speed message come up, even for mild elevator, roll, and pitch changes.

Ignoring the warning is bad advice, at least in the case of the Mavic Air. The drone may force you to land when they (motors) begin to overheat, so you'll want to make sure you find somewhere safe to do that immediately. I just ran into this.

 

[ChosenMavic]

That's exactly what it is, and it's telling you it engaged i.e. you're pushing it too much.

I think what they mean is a limit so this warning isn't required, which would be an actual limit rather than one suggested.

 

[Kilrah]

I had this MAX SPEED WARNING today... But I was flying the SIMULATOR!!! How could that be possible?

The simulator simulates everything, including the motor speeds your aircraft would see if it was flying and the related behavior.

 

[TomMcC]

Hello all. I've had a Mavic Pro for some years now, but also fly FPV. I decided to combine the 2 and build an 8inch quad using Mavic pro motors and props, a 4200mah 3s1p li-ion battery and using inav firmware. All went well except at 54% throttle the props become increasingly unstable with incredible amount of vibration. This 54% throttle on 3s (12.6v) equates to around 9500rpm so the limiting factor and the reason I believe for the max motor rpm warning is the operating window of the props. It also means that the Mavic utilizes throttle limiting/scaling. I will be using 3 blade carbon fiber props to attempt to push past this threshold on my build but unfortunately these props will have no advantage on the Mavic die to the throttle limiting/scaling.