Theoretical Performance of a Pure Jet Flap Rotor at High Advance Ratios
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD AVIATION AND SURFACE EFFECTS DEPT
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The theoretical performance of a jet flap rotor at advance ratios greater than 1.0 is examined. The rotor is four bladed with purely elliptical airfoils of fifteen percent thickness ratio. Each airfoil has two plenum chambers which supply air to slots located beneath the leading and trailing edges, respectively. The rotor operates in cruise at advance ratios greater than unity so that the retreating blade is immersed in reverse flow. The lift and moments are controlled by ejecting a jet sheet out of the trailing edge on the advancing side of the azimuth and both the leading and trailing edge on the retreating side of the azimuth. Standard blade element theory is used to calculate jet flap rotor performance thrust coefficients representative of actual full-scale rotor operation. It is shown that good performance can be obtained using the jet flap and that substantially better performance can be achieved using a circulation control airfoil.