side by side helicopter model is needed

Dear all
I need a side by side helicopter of twin rotor model.I want to use it doing SITL with heli_dual firmware in ardupilot. currently,I had built a model of twin rotor,but its roll stability is not good, such as oscillation and divergence.I do not know whether my model or my PID param has some questions?
As the follow picture shows its hovering.
1640761249489.png
the follow picture show as fps
1640761672409.png
the attachment is my model.
 

Attachments

legoman

Well-known member
I flew the plane with manual controls not ardupilot and rubbed my two brain cells together. And it seems like the gyroscopic force from the spinning rotors seem to be reducing the effect of control inputs. smack the stick to left roll and the heli accelerates, stops then accelerates very fast.
 
I flew the plane with manual controls not ardupilot and rubbed my two brain cells together. And it seems like the gyroscopic force from the spinning rotors seem to be reducing the effect of control inputs. smack the stick to left roll and the heli accelerates, stops then accelerates very fast.
thanks for your reply.if you do not use ardupilot, what is your control input and electronics?I have a flightaxis plugin which can read realflight's data,which will can analysis relative between radio transmitter and roll rate or roll angle by using matlab. then,by the result of RF's data analysis,I will check whether the gyroscopic force from the spinning rotors reducing the effect of control inputs. now,I do not know what is potential mistake in my model.

1640939273399.png
 

legoman

Well-known member
I have not fully settled the percentages in the mix. I noticed some (a lot) control coupling where the yaw input requires a lot of aileron input to cancel roll which can be reduced with some "toe-in" in the swash plate phase adjustment of 25-35 degrees.

I dont think the oscillation you are experiencing is your PID. you may have better luck with adding paddles (flybar paddles). when tuned properly they might help. I am a heli newbie and have only a base knowledge to make it work.

 
I have not fully settled the percentages in the mix. I noticed some (a lot) control coupling where the yaw input requires a lot of aileron input to cancel roll which can be reduced with some "toe-in" in the swash plate phase adjustment of 25-35 degrees.

I dont think the oscillation you are experiencing is your PID. you may have better luck with adding paddles (flybar paddles). when tuned properly they might help. I am a heli newbie and have only a base knowledge to make it work.

yes,there exists control coupling phenomenon for yaw input when I fly it by ardupilot or no ardupilot.
I want to consult a question whether the swash plate phase adjustment changes servo position similar to real helicopter's servo of non rotating ring(general helicopter is three servo which distribute to 0,120,240deg ) .
BTW,whether 3ds max rotor system model effect realflights' servos position of swash plate.In RF,main rotor only has collective,roll,pitch,three servos. I do not understand what is difference between them and general helicopter.
 

legoman

Well-known member
yes,there exists control coupling phenomenon for yaw input when I fly it by ardupilot or no ardupilot.
I want to consult a question whether the swash plate phase adjustment changes servo position similar to real helicopter's servo of non rotating ring(general helicopter is three servo which distribute to 0,120,240deg ) .
BTW,whether 3ds max rotor system model effect realflights' servos position of swash plate.In RF,main rotor only has collective,roll,pitch,three servos. I do not understand what is difference between them and general helicopter.


yes and no it rotates the whole ring, servos and all, a number of degrees. the servo distribution is not important to rf in that you tell RF the inputs roll, pitch, and collective (the three servos) and rf adjusts the rotor to make the input into outputs. swash plate phase adjustment is where you want the zero defection points for the roll and pitch axis in the rotor's rotation
 
yes and no it rotates the whole ring, servos and all, a number of degrees. the servo distribution is not important to rf in that you tell RF the inputs roll, pitch, and collective (the three servos) and rf adjusts the rotor to make the input into outputs. swash plate phase adjustment is where you want the zero defection points for the roll and pitch axis in the rotor's rotation
I want to consult a question, swash plate phase of the right and left rotor should be different direction,such as the right rotor is -25 degrees and the left rotor is +25 degrees.I do not know whether my understand is right. could you give me some suggestions? thanks
 

legoman

Well-known member
I want to consult a question, swash plate phase of the right and left rotor should be different direction,such as the right rotor is -25 degrees and the left rotor is +25 degrees.I do not know whether my understand is right. could you give me some suggestions? thanks
it is weird. The best way to describe it is positive is in the direction the blade is rotating and negative is opposite the blade rotation. So, both positive
 
Top