How many channels do you need to control a heli and why?
You need five channels to control a heli. You need one each to control pitch, roll, and yaw. You need one to control throttle, and you need one to control collective. You might think that one servo could control both throttle and collective, since they are related. There are several reasons this wouldn’t work, however. The main rotor disk of a heli is huge and generates a correspondingly huge amount of drag compared to an airplane prop. (If you think of the heli rotor disk as a big propeller, its actually pretty amazing that a tiny little .32 engine can turn it at all. There’s about a 10:1 gear down from the engine to the main rotor, which makes it possible for the engine to turn the main rotor.) So, you have to have fairly fine control over the relationship between the collective pitch (and corresponding drag) and the throttle setting. If you get it wrong, the engine bogs badly or races wildly. Also, auto-rotation is an important maneuver, and this entails control of collective pitch
You need five channels to control a heli. You need one each to control pitch, roll, and yaw. You need one to control throttle, and you need one to control collective. You might think that one servo could control both throttle and collective, since they are related. There are several reasons this wouldn’t work, however. The main rotor disk of a heli is huge and generates a correspondingly huge amount of drag compared to an airplane prop. (If you think of the heli rotor disk as a big propellor, its actually pretty amazing that a tiny little .32 engine can turn it at all. There’s about a 10:1 gear down from the engine to the main rotor, which makes it possible for the engine to turn the main rotor.) So, you have to have fairly fine control over the relationship between the collective pitch (and corresponding drag) and the throttle setting. If you get it wrong, the engine bogs badly or races wildly. Also, auto-rotation is an important maneuver, and this entails control of collective pitch
