Contrarotating Propellers-Design Theory and Application

This paper sets forth recent developments in the design theory for contrarotating propellers. The analysis includes a more accurate solution for the optimum circulation distribution than has been previously formulated, it includes prediction of slipstream contraction for the first time, and it includes faster and more accurate methods of computing the mutual interactions between the forward and aft propeller. The addition, the theory has been extended to allow for finite loading at the blade roots and takes into account the effect of the hub boundary. The paper provides numerical predictions of efficiency as a function of thrust loading, advance coefficient, and comparisons between single and contrarotating propellers. Calculations and measurements are also presented for the forces and flow field velocities of a contrarotating propeller designed for uniform flow.