VTOL Tricopter not taking off

ArduPlane VTOL Plane
1

Hello,

I have recently been constructing and tuning my own vtol tricopter. Here is a picture:

1174×714 163 KB

It is 2m wide, has a AUW of 3kg, uses 3x 5010 360kv flycat motors with 15x5.5 inch props and a 6s 8400mah lion battery.

The issue I have been running into is that the vtol is not able to takeoff. The autopilot seems to not give it enough power. The maximum power I have obtained at full throttle was 22A. All it does is hover in ground effect and do little hops over the ground.

I am sure the esc (which is a 4 in 1 45A esc) is functionnal because I have individually tested each motor with it using a flysky receiver to give the full 2000 pwm. Here I found that the max power of each motor was about 20A.

I have been testing it mostly in QSTABILISE. I have tried QHOVER but the tune isnt good so it becomes uncontrolable.

When starting to throttle up, the front motors combined push harder than the back motor, so it tilts back. I believe this may make the two front motors not create sufficient thrust and the back motor too much thrust, which contrains the autopilot and makes it unable to give a lot more throttle to the motors.

How could I fix this issue if this was actually the cause?

Here is the logs of the Roll, Pitch and Yaw outputs:

Roll

Roll
Roll1526×520 87.3 KB

Pitch

Pitch
Pitch1533×530 75.1 KB

Yaw:

image
image1530×527 57.4 KB

Here is the logs of the motor outputs.

image
image1532×523 104 KB

Here are the outputs

image
image539×494 26 KB

Ardupilot bin file, google drive link

Thank you for your time!

2

The rear motor is commanded to max so I don’t think that’s what’s happening. Based on the components, weight and battery power it’s overweight/underpowered. Or in any case unbalanced power.

RCout
RCout1711×509 79.6 KB

3

Yes I believe It is simply unbalanced, I will try to put the center of gravity much forward and that will probably resolve the issue.

4

That might work. But in Plane mode the CG needs to be close to right.

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5

Looks clean, what is the weight by chance?

6

Yeah it work, just 14A in total for hover now, so It got even more efficient. I moved the CG but more importantly slid the booms back so the front motors are closer.

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7

about 2.9 kg, with 850g battery

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8

:+1: Let’s see a log of that at hover.

9

(Ardupilot bin file - Google Drive)

I have added it, .bin 100

I was not able to get much flight since there was a lot of wind yesterday and rain today, but we can still see that the RC output 4 is a lot less than before.

10

That’s a significant improvement. Hopefully that shift in CG will be OK for fixed wing forward flight.

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