178 SYMPOSIUM ON AERONAUTICS. 



internal combustion service, notably kerosene and distillate, and 

 cheapest of all, crude oil which is used in engines of the Diesel 

 type. The demands of aeronautic service are, however, insistent in 

 regard to the holding of engine and machinery weights to the 

 minimum and any attempt to use fuels other than gasoline must 

 reckon with the possibility of increased weight. This limitation 

 will apparently, at least under existing design conditions, rule out 

 the Diesel engine from consideration. 



With existing conditions of design and operation there seems 

 to be nothing in sight as an immediate substitute for gasoline, and 

 we cannot well see in what direction to turn for the ultimate solu- 

 tion of this problem. It is, however, none the less real and the eco- 

 nomic extension of the aeroplane will depend in large measure upon 

 the success or failure of efiforts directed toward the development of 

 a cheaper fuel. 



Passing now to the problem of the carburetor only the briefest 

 reference can be made to the principal details of this problem. 



The primary function of the carburetor may be defined as the 

 mixing of the gasoline in a finely divided state with the air necessary 

 for combustion. Following this, on its way to the cylinder and on 

 entering the cylinder, the liquid fuel becomes rapidly vaporized and 

 ready for compression and ignition. The fundamental require- 

 ments are the following: 



1. Fine subdivision of the liquid fuel. 



2. A uniform or nearly uniform mixture by proportion of gasoline 



to air at varying motor speeds. 



For aeroplane service, there should be, in addition, some adjust- 

 ment, either automatic or manual, with reference to altitude and the 

 consequent varying density of the air. 



The function of the carburetor may be viewed under two heads. 



1. Reliability. 



2. Economy. 



For aeroplane service a carburetor giving a nearly uniform 

 mixture over a wide range of operating conditions is of special 

 importance from the standpoint of reliability. When the life of the 

 aeronaut may well depend on the degree of reliability with which the 

 carburetor furnishes a nearly uniform mixture suited for ready igni- 



