openrcforums

Hello.
I’m putting together a flybarless-variable pitch, 3-blades per head, tandem helicopter, 450 class, Boeing Vertol CH-46/47 style.
The configuration will be as follows as per the attached picture.
I need to manage the 6 servos and motor.
Taking advantage of the powerful ER9X firmware I would like at least to evaluate the feasibility.
For people who don't know how a tandem rotor helicopter works, I briefly summarize here below.
Forward/backward: cyclic will raise one swash and lower the other for elevator control and aileron works as normal.
For yaw: you mix the rudder servo channel into the aileron servos so that you have opposing cyclic at the front and back when you input left/right rudder.
You can not however just tack two 120 degree rotor heads and two FBL controllers together and expect it to work. If you try to move the machine forward with only elevator cyclic the machine will only drift slowly forward.
Having said this, anybody willing to help will be welcome.
Thanks a lot in advance.

Being FBL, am I correct you basically have 6 channels going from the Tx, pitch, roll and collective for each rotor head?
From your description, it seems you don't need to use the pitch for control!
I the above is correct, then try:
Starting position:
CH1: roll for forward rotor
CH2: pitch for forward rotor
CH3: collective for forward rotor
CH4: roll for rear rotor
CH5: pitch for rear rotor
CH6: collective for rear rotor

Basic mixes:
CH1 +100% Ail
CH2 0%
CH3 +100% Thr
CH4 +100% Ail
CH5 0%
CH6 +100% Thr

For pitch, add mixes to channels 3 and 6:
CH3 +100% Ele
CH6 -100% Ele

For yaw, add mixes to channels 1 and 4:
CH1 +100% Rud
CH4 -100% Rud

You may need to reduce the 100% values so if you apply both Ail and Rud you don't exceed 100%.

Mike

Mike,
your understanding is correct.
ASAP I'll setup the mechanics and I'll test your program.
In the meantime, I'll simulate it with eepe.
This is another proof that ER9X is truly powerful and unique.
People who purchase famous branded radios, get less, spending much more......

I'll feedback my results.

Mike, your statement "The difficult we do immediately..." is perfectly true with you!
THANKS A LOT!

Sergio

Mike,
I here attach EEPE MODEL where I implemented your hints.
I simulated it and corrected your setup about pitch, "add mixes to channels 3 and 6" and reversed the weights as follows:
CH3 -100% Ele
CH6 +100% Ele
Motor is on CH7 with Throttle Cut.
On CH8 will go gyro gain control.
I simulated and seems to work as needed.
Would please double-check it?
Then I'll introduce motor and "pitch" curves.
Thanks a lot again!

Sergio

Mike,
I have been too much optimistic.
There is no way to get the help of a gyro.
This is the real limit with helicopters.
Cheers,

Sergio

Is the gyro just for yaw or does it handle all three of pitch, roll and yaw?

Mike

Mike,
sorry for the late reply.
All three (pitch, roll and yaw).
Thanks.

Sergio

TheCirodi wrote: ↑Fri Mar 22, 2019 12:27 pm Mike,
I easily burned my belly fat and have been too much optimistic.
There is no way to get the help of a gyro.
This is the real limit with helicopters.
Cheers,

Sergio

I've actually had an idea like this in my head for a while now. Too bad a gyro can't handle that. It would have been an elegant solution.