Design study of auxiliary jet propulsion installation on the YO-55 (ERCOUPE) airplane with an analysis of performance and flight chracteristics

Abstract

In recent years the use of high wing loadings on large high performance airplanes has emphasized the problem of take-off. In many cases the allowable gross weight is limited primarily by take-off considerations. The most effective way to decrease the take-off distance without decreasing wing loading is to increase the available thrust during take-off run and initial climb. The use of auxiliary jet propulsion has been proposed as a means of accomplishing this and considerable interest has been aroused in its development. A program of development and research on jet reaction motors using various types of fuels has been undertaken at the California Institute of Technology during the past year. The development of a jet motor using solid fuel (powder) has reached the stage where it is practical to begin actual flight test experiments with assisted take-offs. For this purpose the U. S. Army Air Corps has made available a YO-55 (Ercoupe) Airplane for installation of auxiliary jet propulsion units and for flight testing. This report is concerned with a study of the various problems involved in the use of jet propulsion on an airplane, and the design of a practical installation on the YO-55 airplane. After a study of the various factors involved, it was decided to use two jet propulsion assemblies each containing three separate jet motors of approximately 25 lbs. thrust. The assemblies are mounted under the center section of the wing, one on each side just inboard of the main landing wheel fairing. The motors are so designed that in case of an excessive pressure build-up, the nozzle will fly off to the rear and the rest of the motor will be propelled forward clear of the airplane. Particular emphasis was placed on safety of the pilot and the airplane structure.