Engineering Wonders of the World
Volume III

AERONAUTICAL ENGINES. A review of some of the most interesting of the internal combustion engines that have been designed specially for use on flying machines. THE provision of sufficient motive power and the reduction of weight to a mini- mum are two problems which have exercised the constructors of flying machines no less than that of designing efficient support- ing surfaces. The Wrights, when they first decided to apply power to their gliders, were confronted by the fact that there was not on the market an engine light enough for their particular purpose. Sir Hiram Maxim had, it is true, lifted his great experimental machine from the ground with the aid of a steam engine which developed a horse-power for every 6 lbs. of avoirdupois, boilers and all fittings included. Professor Langley subse- quently propelled a model aerodrome with a steamer that gave an output of 1| horse-power for its 7 lbs. But the difficulty of keeping these engines supplied with water and fuel, and certain other considerations, had made it evident that another form of prime mover was needed for aerial flight. The develop- ment of the internal explosion engine on the motor car prepared the way for the flying machine. Most of the aeronautical engines of to-day are, in their general principles, four- cycle motor-car engines greatly improved in the matter of weight, and modified in detail wherever modification makes for lightness. The designer has had it in his favour that aerial engines are not called upon to withstand the vibrations set up by wheels passing over rough roads, or the strains caused by clutches, gears, etc. On the other hand, he has had to be very careful not to cut weight down to danger point, as a failure of any part of the engine may have disastrous consequences. A very large proportion of aviators’ involuntary descents to earth has been due to engine failures ; and the same cause was responsible for both of M. Latham’s swoops into the Channel. If anything goes wrong with a car engine—which is a rare occurrence nowadays —the driver can stop without risk to inves- tigate. But the aerial motor must be even more reliable than the car engine. In addition, it must be extremely efficient, for if its power falls below a certain minimum the machine must come down too ; and it must be auto- matic, supplying itself regularly, and inde-