Originally Posted by
Ascend Charlie
You might find that the lift is constant all the way around. If you suddenly got more lift when the blades are fore/aft, the vertical vibration would be awful.
The retreating blade tries its hardest to create enough lift, battling the wind from behind.. The advancing blade has to throw away all that beautiful lift it gets from moving into the extra airflow. The only place where the fight is equal is fore/aft.
Robinson is now working on a multi-blade model
The only downside to having more blades is cost.
More blades means you can make the blades with reduced chord and shorter and at reduced RPM.
Noise is generally lower with more blades.
The Osprey for example really could use more blades as increasing the blade chord would make the already bad vibration worse! Engineers have compensated by increasing the tip speed.. on the Osprey it's 559 mph!
In forward flight every time the blade passes in front of the wing the whole aircraft jumps!