ORIGINAL: tippy
02nelsc:: ... actully can someone spread some light as to why our helis have flybars and paddles, what purpose do they serve?
Physics ...
Two reasons ... stability and controllability.
Stability: The weighted paddles act as a gyro. When the paddles are 0 pitch and spinning, they tend to want to stay on that plane ... they don't want to teeter. So it keeps your cyclic stable when the cyclic is centered. If your heli happens to take a little gust of wind, the heli will move relative to the spinning paddles which induces a pitch change on the main rotors (remember that it is the flybar teetering that changes the pitch on the mains ... not the paddle angles). This induces a pitch change which will help stabilize the heli. There are some full scale helis that have a stabilizer bar and used for the same reason.
Controllability: We have to change the collective pitch and the cyclic pitch to maintain control of the heli. This requires a tremendous amount (relative to RC helis anyway) of force to make those pitch changes because you are working against the forces of physics ...
The problem is ... our standard size servos (even the top dollar high torque kind) simple don't have the muscle to do the job unless you want to fly around in scale mode all the time (not that there is anything wrong with that).
So how do we fly then if our servos are not up to the task? We harness the energy of physics. We create a flybar system where minute changes in paddle pitch produces a huge amount of teetering force (again, it is the teetering that changes the pitch of the main rotor blades). We connect/mix this teetering leverage to the main rotor blade pitch control and bingo ... we cycle the main blades with the leverage of the flybar.
Ever notice helis that use mCCPM (ala TT Raptor) that they have a long lever that the pitch servo operates. The servo needs the mechanical advantage of the long lever to over come the force needed to push the pitch through its paces. eCCPM helis don't have this lever but they are also combine the force of 3 servos to produce collective pitch changes.
Are there servos that can handle the force? Sure but you can't fit a 1/4 scale (or bigger) servos in our helis and they don't make servos in standard size that can produce the force necessary ... yet.
Until then, we use the flybar systems.