![]() ![]() If you push down on one blade, the other one goes up like a teeter-totter. It is easy to visualize this because of the Bell/Textron insistance on the semi-rigid, underslung, see/saw type rotor system. In a two-bladed system, like the Bell Huey, Kinda spooky, huh? Anyway, it all balances out and the lift is equal across the disk. ![]() This INDUCED FLOW through the rotors system changes the angle of attack on the blades and causes the upward-flapping advancing blade to produce less lift, and the downward-flapping retreating blade to produce a corresponding lift increase. Increased airspeed (and corresponding lift increase) on the advancing blade, it flaps upward.ĭecreasing speed and lift on the retreating blade causes it to flap downward. This has to be compensated for in some way, or the helicopter would corkscrew through theĪir doing faster and faster snap rolls as airspeed increased.ĭissymetry of lift is compensated for by BLADE FLAPPING. Your blades at a hover move at 300 knots and you fly forward at 100 knots, your advancingīlade is now moving at a relative speed of 400 knots and your retreating blade is moving at 200). As the helicopter gainsĪirspeed, the advancing blade develops greater lift because of the increased airspeed (for example, if ![]() All rotor systems are subject to Dissymetry of lift in forward flight.Īt a hover, the lift is equal across the entire rotor disk.
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