HELICOPTERS AND AUTOGYROS
550 450 350 Retreating blades 50 150 250
F I G U R E 8 .1 5
250 150
Advancing blades
Relative airspeeds for a forward speed of 150 mi/h.
trailing edge to the leading edge of the rotor blade. This is the region of reverse flow, shown in Figure 8.16, and it changes in size and distance from the hub with changes in forward speed. The region of reverse flow does have one small advantage: It puts a force on the rotor in the direction of rotation and helps it to spin.
Direction of travel Region of reverse flow
F I G U R E 8 .1 6
Region of reverse flow.
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