Author: Carl M. Harlacher

Publisher:

Published: 1941

Total Pages: 136

ISBN-13:

Power to. drive the airplane through the air is furnished by the engine, the brake horsepower of which is transformed into thrust by the propeller. The propeller may be described as a twisted airfoil of irregular plan form. In order to analyze the blade element, each blade is divided into 6-inch sections and each section is set at the proper angle to the relative air (fig. 1). The sections near the tip of the propeller travel at a higher peripheral speed than those near the hub, consequently the blade angles become less as the tip is approached. The sections from 12 to 18 inches from the hub are thick ill order to give strength to the propeller, and as a result, deliver little or no thrust. In general, each section is so designed and set at such an angle that when the propeller is being operated at a given rotative and forward speed, the best efficiency of each section will be obtained.