WITH the increasing use of fully automatic carburetors, it was found to be more and more important to make sure that all elements of the installation were carefully worked out so as to insure accurate metering of the carburetor under all operating conditions. Experimental flight investigations demonstrated that this was particularly true of the carburetor airscoop, which admits the air to the carburetor and can therefore cause flow disturbances which may seriously affect carburetor metering.
Test laboratory investigations were made of a considerable number of airscoops in an effort to determine what factors contributed to the proper or improper functioning of the scoop. It was found that the shape and size of the scoop passages and
also the location of the hot air valves were important factors, and a number of general design criteria were formulated, and these are discussed in detail. A discussion of the ram characteristics under various conditions of flight and for various sizes of scoop is also included.
An actual production model of airscoop was designed in which these various features were included. The aerodynamic and structural features of this airscoop are discussed and explained in detail.
Five simple rules are given to assist the designer in laying out an airscoop which will incorporate the design features which were found to be desirable.