Design and Performance Analysis of a Prototype Circulation Control Helicopter Rotor
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD AVIATION AND SURFACE EFFECTS DEPT
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A Circulation Control Rotor CCR has been designed for application to existing, conventional speed helicopters of the 5000 to 10000 pound weight class. A design methodology is shown which tends to minimize rotor induced power in hover while operating at near maximum airfoil section efficiency. The particular design was constrained by conventional disc loadings and blade tip speeds to be consistent with available helicopter enginetransmission combinations. The design is near optimum within these constraints and current available data. Circulation control airfoil and slot geometry design considerations are shown. Tip speed, solidity and disc loading were varied to show performance sensitivity to those parameters and to define the conditions of best overall rotor aerodynamic efficiency. The constrained CCR design was found to operate best at a thrust coefficientsolidity ratio around 0.12. At this condition hover Figure of Merit improved with increased disc loading, while cruise aerodynamic efficiency was relatively insensitive to disc loading changes. Overall performance exceeded or was equal to that of conventional rotor systems for the same weight class vehicle.