My motors are C9, C10, C11 and C12. Is C9 motor 1 (top right) and C10 (bottom left)?

My C9 and C10 seems to always be spinning faster. If they are motors 1 and 2 as on the ardupilot diagram then I just don’t know why this is happening. It can’t be wind because it is standing still largely even in Althold. It does move slightly, but not much

Motor layout

I swapped a prop on motor 2 just to see if there is a difference. I don’t see any difference.

Before changing prop on motor 2 00000090.BIN

Before changing prop on motor 2 00000091

After changing prop on motor 2 00000094

After checking balance 00000094 on a scale
Seems even worst now

I balanced it on a 16mm rod
16mm rod close up

[Dropbox - IMG_20210928_224837.jpg - Simplify your life](https://16mm rod wide angle)

After balancing on a 16mm rod 00000094

I don’t know if this will help but this is the tlogs

tlog 1

tlog 2

How are your motor mountings, maybe they are slightly off or loose.
In some cases the frame also flex a bit during flight, so on the ground all seems fine but once in the air it might not be perfectly straight and level anymore.

This is due to a mechanical yaw bias, very common particularly on craft with round arms. Arms twisted or not level, frame distortion, etc.

I will rebuild the arms this week and see what that does. I hit a pole on the rugby field today again. I can’t seem to estimate the distance 100m away between the drone and objects and FPV is illegal here so I need to get a FPV LCD screen it seems and probably stop flying myself and just use auto mode.

I soft mounted the motors.
Soft mounted motor on a scale

I will also remove the rubber and see if it makes a difference. Two motors sit on a single solid carbon square tube and the other two each have a carbon square tube. So that might also be part of the issue. I tried to glue the carbon together, but I can’t find the right glue it seems.
One long carbon tube and two short tubes

I will also add more nuts and bolts to hold the legs to the base. I tried to re-use the stack nuts and bolts to hold the legs in place but I am thinking I can’t tighten that enough because I might break the PCB’s of the stack.

I can’t get new carbon square tubing quickly enough (I have a job 15 October with the drone) so changing over to 12.7mm x 12.7mm x 1.5mm aluminum tubing for now. The glue might work on the aluminium so hopefully the cross (X) will be stiffer. I can’t go to someone this week to get the frame welded together.

Dont soft-mount the motors, it’s usually worse. Secure any loose wiring.
You’ll need a base plate underneath those arms, like the top plate. That will add a lot of stiffness.

2 x 530KV and 2 x 260KV motors log

I don’t have a base plate at the moment. I will order more carbon from HobbyKing. There seem to be issues getting things in from HobbyKing at the moment. Their Australian warehouse is in Singapore.

I rebuilt the drone to use aluminium legs (10mm U shape). I will try 25mm U shaped aluminium next and see if it gives me different results. The 10mm I can twist with the motor on the end. That can’t be good. The 10mm square carbon had the same issue.

I ran out of 260KV motors because with every crash the motor mounts break and the motor that hits the ground first rips its wires off so I am using 2 of my old 530KV motors on Motor position 1 and 3 so C9 and C11 and 2 of the 260KV motors on 2 and 4 so C10 and C12.

I didn’t autotune this setup yet because the wind is strong today. Gusts up to 38km/h.

This is a very interesting graph. RCOU C9 has a flat base. That is a 530KV motor. I would think the C11 would look about the same because it is also a 530KV motor.

I didn’t expect it to fly so I was surprised. It does have a hickup sometimes where it starts to sway forward and back uncontrollably then I need to take it out of loiter and put it in althold and back into loiter. You will see that in the graph. It did the same before when I had all 260KV motors. So it gets confused about something.

Hopefully my new motors will arrive soon. With the 25mm aluminium legs I will move away from motor mounts and just make holes in the legs to mount the motors directly onto the leg. That should guarantee a flat motor mount.

Looks like I will be over 2kg if I want something big and stable so I see a ±$1300 license in my future.