The discussion revolves around the concepts behind fixed pitch radio-controlled helicopters, focusing on their operational principles, control mechanisms, and design features. Participants explore how altitude and movement are controlled, as well as the implications of fixed pitch design on stability and maneuverability.
Participants generally agree on the basic principles of fixed pitch helicopter operation, but there are differing views on the specifics of control mechanisms and stability features, particularly regarding the role of paddles and the necessity of additional control surfaces.
Some claims about the mechanics of control and stability are based on personal experiences with specific helicopter models, which may not apply universally to all fixed pitch designs. The discussion reflects a variety of understandings and interpretations of the principles involved.
Individuals interested in radio-controlled aircraft, particularly those focused on helicopter mechanics and design, may find this discussion relevant. Hobbyists and engineers exploring control systems in fixed pitch helicopters could also benefit from the shared insights.
aresnick said:As I understand it, with a Fixed Pitch the angle of the main blades remains constant and the flyer controls altitude by using the speed of the main motor, simply creating more or less lift by choosing the attitude of the helicopter (which determines how much of the lift propels the helicopter forward, and how much upward) and the speed of rotation (which provides the lift).
-a.
thanx a ton .. it answered my question perfectly!aresnick said:I believe that the transmitter controls what's essentially an amplifier (either via op-amp or transistor), controlling the size of the voltage sent to the motor. So I believe fixed pitch helicopters can't actually roll unless they have extra ailerons; without ailerons, the torque control is used to slip (that is, yaw) the helicopter left and right.
Thanx for that info ! Really appreciated!Greg Freeman said:I just wanted to add a bit to this...
Fixed pitch helicopters will have no collective (rotors rotating equally on each side to provide more/less lift) or cyclic (rotors rotating unequally on each side to provide tilt in any direction, be it forward, backward, or left and right). The tail rotor balances the torque from the main rotors and changing the tail rotor speed gives the helicopter yaw (like aresnick said).
Now, I have a small remote controlled helicopter that has no control for collective or cyclic control. All of the control is done by speeding up the main rotors (which means I also have to increase the tail rotor speed so that it faces in the same direction). What's neat about the helicopters I have is that they aren't fixed pitch, I just can't actively change the pitch. There are 2 main blades and 2 paddles. The paddles are short and stubby and are offset by the main rotors by about 30 degrees or so. They have weights on them. What happens, is that if the helicopter tilts in any direction, the weight of the paddles resist this, and this resistance is mechanically linked to the main rotors. The paddles, in effect, cause the main rotors to tilt in a way that forces the helicopter to right itself. This is because a pure fixed-pitch helicopter will be very unstable with only 2 blades, but by adding a passive mechanical control, it can be stable.
Also, because of the paddles, I can add weight to the nose of the helicopter which will make the helicopter fly forward. It's a really simple design, and you can buy the things for about $20 or less now.