Originally Posted by
discap
once again I will prove my ignorance of all things Helicopter. Is it theoretically possible to build a 2 blade ridged rotor system. What I am envisioning is the teeter and feather replaced by the same type of plates used on a multi bladed ridged system.
I have been thinking about this for a while and cannot come up with a reason that it would not work. Is the amount of flapping in a 2 bladed system too much? Seems like it would eliminate mast bumping and tail amputations.
Please educate me.
Bill.
Do not think about it. It would be a perfect shaker.
The flapping motion of the blade induces some vertical force at the flapping hinge that directly varies with the flapping angle. If you sum the contributions of the different blades, it gives you a constant moment in the fixed frame... as soon as you have 3 blades or more.
With a two-bladed rotor, the vertical force on both blades is opposed (when one blade is up, the other is down). This makes a pure moment at the hub center, which varies cyclically, like the flapping. The only way to get rid of it is to have no flapping hinge offset. All 2-bladed rotors are see-saw rotors.