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Nimbus 1800 vectored yaw VTOL maiden

by the way, I know this man, he is Kris.

@Eosbandi
yaw seems unstable, i think you’d better tune pid.
here are my params:
Q_A_RAT_YAW_D,0
Q_A_RAT_YAW_FF,0
Q_A_RAT_YAW_FILT,2.5
Q_A_RAT_YAW_I,0.045
Q_A_RAT_YAW_IMAX,0.5
Q_A_RAT_YAW_P,0.6

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What kind of flight times are you guys getting with what battery?

@Eosbandi

Hi Andras,

Did you have any issues eliminating the yaw wobble on your Nimbus VTOL? Did you use the RDS3115MG robot servos?

Cheers!

I would probably try a faster servo on tail rotor, if it is anything like helicopters (in wich a fast tail servo is vital) than that is your solution. On helis wich change the tail blades pitch to keep yaw stable a fast and precise servo is essential to have good performances. A slow and weak servo can induce yaw movements like in your video because it is constantly late in correction and has difficulties in keep a precise center.

Just to give you an idea, good tail rotor servos on helis can cost 100-150 Eur (120-170 USD).

Corrado

Hi Corrado,

The Nimbus 1800 VTOL does not use a tail rotor or tail servo. It uses vectored yaw on the front two rotors.

Cheers!

Ah ok, than all i said can be applied to the 2 front motors, i have a feeling it needs fast servos.

Front servos to manage yaw correctly, if understood correctly, need to fight all inertia of 2 motor + prop and fight gyroscopic effect too. So the stronger/faster the better tail will hold.

Corrado

Ok, that makes sense. I am currently using 5v BEC to power the servos so I will try using 6v as this is what FoxTechFPV uses on there servos. Fortunately, my Turnigy BEC has a jumper for 5v/6v so it should be an easy test.

Cheers!

If those servos are HV you can feed them with 2S (8,4 volts), that will make a difference for sure, butfirst check in the specs if they can run direct on a 2S lipo.

Corrado

Hi, It seems most of you are expert but I am new!
Can anyone tell me what is vectored yaw? I read the documentation but I didn’t understand.
and what happens if I don’t use it?

In tricopter configuration, as there is an odd number of rotors, there is an imbalance in the moment / torque generated by these rotors. With this yawing moment, the vehicle would rotate around the vertical axis if we did nothing about it…

In quad, hexa or octacopters, half of the rotors rotate clockwise, half rotate counterclockwise. In total, their moments cancel out.

In a helicopter (monocopter), the small horizontal tail rotor neutralizes the moment from the large vertical rotor. In a tricopter, we can either tilt the tail rotor slightly or tilt the front rotors asymmetrically off the vertical axis to counter the yawing moment. I think the community calls the second option vectored thrust.

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Thank you for your answer.

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