Dual heli(tandem helicopter) pitch control question

ArduCopter Traditional Helicopter
1

Hi everyone, I have a question about pitch control.
I’m using 8 servo to control swash now…(4 servo front swash, 4 servo rear swash)
If i move forward with dual heli parameter, front swash down and rear swash up moving.

But i want swash to move like cyclic swash… it will move like

servo1(down) servo2(down)
(front swash)
servo3(up) servo4(up)

servo5(down) servo6(down)
(rear swash)
servo7(up) servo8(up)

When i connect my servo with Y cable (servo1,5 servo2,6, servo3,7 servo 4,8)
In this case, I can’t use rudder…
How can i using cyclic swash when i move elevator, Now i want your idea

2

https://ardupilot.org/copter/docs/dual-helicopter.html

Have you read that? I don’t think a y-cable is a good idea because the swashplate servos need to move independently.

1 Like
3

The code in the tandem heli motors class would need to be changed. What exactly do you want to use the cyclic pitch for?

4

Hello Bill,

Why you say that the tandem code need to be changed ?

There is an issue with the code?

Have you seen my last post ?

Thanks again for your help.

Have a good weekend.

5

Well, if @vodrnls2659 wants to have individual cyclic pitch control of the swashplate then the code will need changed. Pitch for a tandem rotor heli is controlled using differential collective pitch. So cyclic pitch control is not needed.

There is no issue with the code.

6

Sorry for late see,
I’m making large scale tandem with engine… (One engine for two swash with shaft)
If I use your machanism, The shaft(connection with two mast) could be broken by twist(Because there different load).
That’s why i want cyclic pitch for.

7

Yes i already read this page…
This page have no information what i need,
I’m already searching other machanism too (like coaxial, traditialnal heli etc…) but almost machnism is for battery vehicle, not a engine vehicle.
I’m trying not to move fuel in fuel tank when i move foward

8

All full scale tandem helicopters use differential collective pitch to control the pitch axis, not longitudinal cyclic. Differential collective pitch is the most effective way to control pitch axis on tandem rotor helicopters. you need to build the cross shaft that can withstand the torque difference.

But if you want to use longitudinal cyclic pitch, you can change the code to do this. i’m sorry but I will not change the code for the released version. So you will have to compile your own version with this change.

1 Like
9

Ok… I’ll change my own code😓

10

Some full size tandems do you different pitch and different rotor head angles between the front and rear rottor head. Having some adjustable longitudinal cyclic pitch control would be a welcome knob to be able tune for tandems.

If you read up on the CH47 they use different rotor head angles and some different longitudinal cyclic mixing to help the heli fly faster with the body more level.

11

Yes that is true. But that is not what @vodrnls2659 wanted. They wanted to control the pitch motion with only longitudinal cyclic. There are plans in the future to provide longitudinal cyclic to do as you have said but this requires some control law development to make it work well.

3 Likes
12

Oooo where is that work being discussed? I’m not even sure what to search. I have a twinn rexx under construction that if I ever finish it I might be able to test with. At the very least id love to see whats being done there to apply it to my tandem someday when it actually flies.

1 Like