Servers by jDrones

Modifying Traditional Heli

Hello everyone,

I want to create a new airframe on apm 2.6. I have two tail motors, one swashplate pitch and roll 90 degree and one main motor.

How to do this?

Best regards,

First, I would recommend using the last stable software version for the APM 2.6 which was Copter 3.2.1. As far as your question on how to create a new airframe, this is not a simple request, especially in this version of software. Even if you were well versed with C++, this will take some time. I created a compound heli frame in version 3.3 and that took me the better part of a week in the evenings to get that working. Granted I’m not a seasoned C++ programmer. So I have two options to offer up:

  1. Use the commits of another user that did something similar. I had followed fhedberg’s modifications to the code to produce the compound frame and adjusted them slightly for my application. you can look at his repo or my compound heli repo for AC 3.3.3 here
  2. Or buy a pixhawk or other flight controller capable of hosting AC 3.5.5. Making new frames in this version is much easier. I converted my compound frame from AC 3.3.3 to AC 3.5.5 in one night.


Hello Bill,
Thank you for your kind reply. But in this way, I have to compile it and upload onto APM then in Mission planner selecting heli frame, How about the connections or wiring? looking in RC Channel file is enough?

Best regards,

If you don’t want to change the code and you are happy with using the trad heli code, then you could use Y cables to send the same signal to the two motors however there are many other details like whether they will be fixed pitch or variable pitch? As for the swashplate, you only mention pitch and roll. Is this a standard swashplate or different? You need to explain. Does the main motor have an ESC that has a governor or not?
What is your helicopter configuration going to look like if you have two tail rotors?

Hello Bill,
Many many thanks for your help.
I have a spherical mini helicopter;

There are two tail motors with ESC near the sphere.
One main motor at the center of sphere.(with ESC)
Two servos pitch and roll for main motor.These servos controlled with like a gimbal mechanism. also they are 5 Volt.

Best regards,

Is the main rotor held at a constant speed? How are you controlling the vertical axis (i.e. Climb and descent)
The trad heli code can be set up so it does an old style swashplate where pitch and roll are independent servos. You would set this using the parameter H_SWASH_TYPE

I’m not sure what you mean by spherical helicopter. You still didn’t answer whether the tail rotors are fixed pitch or variable pitch.

It has vertical take off. and also tail rotors are fixed pitch.Changing the main rotor speed provide climbing

Very interesting set up. we can make this work for the using the TradHeli software but it won’t be ideal for the vertical axis. The tradheli code is set up for a constant speed variable pitch main rotor control in the vertical axis. So I would recommend using mode 3 which I’m not sure how well that works in AC 3.2.1. I think it is just a V-curve but you could set it up so it outputs a proportional output to your collective stick. I would not recommend just hooking up the ESC to the collective output. Then you lose the safety protections for the esc’s. I’m not even sure how well the Direct Drive Fixed Pitch (DDFP) system works for the tailrotors in this version of the code. This is slightly before my time of working on the code.

Be careful when setting this up and make sure you remove the props.

Servers by jDrones