A Experimental Study Concerning Mutual Interference between Propeller and Rudder

Abstract

This report pertains to the experimental results obtained relative to the reciprocal interference resulting from the combination of the Troost B.4-40 type or other propellers, and the reaction rudder as described in the theoretical report which was read in the spring meeting in 1961.A comparison of the present experimental results with the theoretical conclusion reached in the said report has clarified the following matters : (1) It is supporsed that the propeller is affected by tne rudder largely due to the potential wake-of the rudder and its lifting line, while the deformation of the propeller free vortices under the influence of the rudder, on the other hand, does not practically affect the performance of the propeller.(2) Of the influences by the propeller exerted on the rudder, nonstationary effect is most serious. In case the pitch ratio of the propeller is minor, the effect is so large that it nearly overwhelms any thrust gain due to the rotatory flow of the propeller. Accordingly, the theoretically calculated thrust gain does not necessarily conform to the experimental value in quantitative way, but, in regard to the comparative superiority or inferiority of each of the rudders, the theoretical and experimental results coincide with each other.(3) The pitch distribution of the propeller to be combined with the reaction rudder should preferably be the decreasing distribution (with increased pitch at the blade root), which was suggested by the theoretical study.