T-Motor MN2806 KV650 with Arducopter 4.2.x

Anyone having success experience with MN2806 KV650 motor to share? MOT_THST_EXPO = 0.66 - 0.72, MOT_THST_HOVER = 0.2 - 0.25, still can’t hover (stabilize, Alt-hold).

Using initial parameters from mission planner.

Propeller tested, 11x10x3-blades, 11x07x3-blades, 11x4.5x2-blades.

What ESCS ?
The motors themselves won’t make much difference to those params.
Can you fly in AltHold mode for a while and the hover thrust value adjusts itself?

Actually a .bin log and a description of the copter would be useful

11x4.5x2 manage to, but obviously, no propulsion holding the height. Learn until the hover thrust = 0.37, from 0.25

11x7x3, took off for a few seconds, struggling to take-off
11x10x3-blades, totally cannot take-off at 80% throttle stabilizes flight mode
We need three blades to have a longer flight duration.

Hobbywing digital ESC

Quad-X, 1.6kg

log 1 11x7x3 and log 2 11x4.5x2

MN2806 KV650 data really bad with the motor parameters calculation. I think instead of increase MOT_THST_EXPO, tomorrow I try reduce it instead.

I looked at the log with the 11X4.5X2. Your amp draw is not high at all, assuming that the sensor measures correctly and the motors are never commanded to go higher than about 1600pwm on average (1500 being 50%). So maybe a bit under powered/overweight for that propeller. But not much and it should fly/hover quite well.

Your motor is also tested by t-motor to use 12 or 13 inch propellers (2 blade). Why use 11?

Have you done the initial setup for the aircraft/initial parameters?

Some more info about the aircraft would be great as well.

Although @xfacta knows quite a bit more than me so wait for his answer too

In BLHELI32 settings have you disabled Low RPM Power Protect ?

Normal thrust expo should be OK, as calculated by the Initial Parameters. You can adjust it later as per:

  • set too high you can see instability at low throttle
  • set too low you can see instability at high throttle

to gather data for setting up the Harmonic Notch Filter.

Best if you can get the ESC Telemetry wire to a serial port RX pin and set (serial or telem 2 used in this example)
You will then have RPM, voltage and temperature data

And the Harmonic Notch Filter can be pre-set to use that ESC data
INS_HNTCH_ENABLE,1 ← set this then refresh params to see the rest

Also check out the Master Airscrew MR series props, I can vouch for the 12inch for exceeding expectations in flight time and lifting ability. Only 2 blades too, so usually considered more efficient in this application.

additional things:
Check your Arming Checks, usually a value of 1 is OK
There was no GPS data in the log I looked at, even though it’s configured
to allow the CAN GPS unit time to boot up before the flight controller
you wont be able to arm in any mode until there’s valid GPS data and Home can be set
This will take time but you get used to it, but safety is important and it helps prevent fly-aways

Also configure Loiter as a flight mode, if you are after flight time and efficiency this will be your main selection once tuning is done. Keep Stabilise and AltHold handy.
Later you’ll be able to check in logs for the most efficient speed and set that as your Loiter speed, WPNAV speed ( * and RTL speed)

You can easily swap in Autotune instead of Loiter in the flight mode list for the purposes of tuning.

Bingo, 11x7x3 and 11x10x3 are from Master Airscrew, very expensive products.

To answer all why 11 inch and not 12 or 13, we have size of the drone constraint and to get the longest best flight duration.

I am not sure how to do it. Is there manual or guide on the internet? So obviously no.

I am suspecting this now.

Noted, will try.

That’s why we use this motor. It is expensive, but for the collaborator required flight duration, good to explore.

Dont change thrust expo until after you’ve turned off Low RPM Power Protect and got some relatively normal flight going on.

Download and install the BLHeliSuite32 and it should be able to connect to the ESCs using flight controller pass-through

There’s a whole section on this stuff at

Indoor flying before doing suntanning

How do I get the connection to serial 2 or telemetry 2? Is there such signal in Hobbywing Digital ESC?

  1. Low RPM Power Protection: Power limiting for low RPMs can be enabled or disabled. Disabling it can be necessary in order to achieve full power on some low KV motors running on a low supply voltage. However, disabling it increases the risk of sync loss, with the possibility of toasting motor or ESC.

Well that sucks, no telemetry output on these ESCs according to the manual

You will need to disable Low RPM Power Protect regardless of the dire warnings or the ESC will never operate with anything but quad-racer style high kv motors. Doing this is very common, and in fact required for all but small racing style quads.

Instead use these HNTOCH settings for now, and they can be adjusted after test flights
INS_HNTCH_ENABLE,1 ← set this then refresh params to see the rest

Cube Orange right?
You should be able to use the bidirection DShot firmware and get the ESC RPM data.
No other changes would be required, except we can simplify some of the HNOTCH settings and tesing to:
INS_HNTCH_ENABLE,1 ← set this then refresh params to see the rest
(as I listed earlier)
Also keep
So we can check pre-filter data
then later you can set
to see post-filter data

Yes, I am using Cube Orange. Sorry, this morning I was busy in a meeting.

safety switch ensures it is pushed
done. turned off Low RPM Power Protect

done for 11x4.5x2 log, indoor
INS_LOG_BAT_OPT, 0 and the rest of INS_HNTCH_xx settings.
disable Low RPM Power Protect
MOT_THST_EXPO = 0.66 (initial parameters)
MOT_THST_HOVER = 0.25 (start)
MOT_THST_HOVER = 0.3494199 (learn)

INS_LOG_BAT_OPT, 2 flight log also done.

logs for 11x7x3, indoor

ignore the INS_LOG_BAT_OPT values as I changed first then reboot and prepare for the next flight. go by filename is correct.

You will need these unless you changed to the bi-directional DShot firmware

For some reason the FFT graphs dont show any data for those flights
until this is all nailed down a bit more

Noted, will repeat the flights and also include 11x10x3

do you mean this? I think FFT_ENABLE is = 0, I have enabled it now for next flight test.

The FFT_ENABLE parameter is for the flight controller to run the FFT analysis live and use that for a souce of HNOTCH filtering.
I couldnt get MissionPlanner to display any of the INS_LOG_BAT data as it normally does, where MissionPlanner runs the FFT analysis post-fight.

okay, I put it back to 0 then.

Hmm, interesting. I have put in all values already.

log for 11x7x3, uploaded into same folder
log for 11x4.5x2, uploaded into same folder
log for 11x10x3, uploaded into same folder