Aircraft engine

“ THE HORIZONTALLY-OPPOSED ENGINE Among the first internal combustion engines to be taken into use with aircraft were those of the horizontally-opposed four-stroke cycle type, and, in every case in which these engines were used, their excellent balance and extremely even torque rendered them ideal—until the tremendous increase in power requirements rendered the type too long and bulky for placing in the fuselage of an aeroplane. ”

“ Here one sees how dissimilar [93] the aviation engine is from the car engine. It is almost impossible, without having actually witnessed it, to picture to oneself a 12-cylinder engine running at 2,200 R. P. M. against a brake test. As the exhaust ports are on either side of the engine, the cylinders being placed in the form of a V, it is possible, by passing on either side, to look into the combustion-chamber and see the valves rising and the spit of the exhaust, and, what is almost incredible, that the exhaust valves are actually red-hot and run in this condition for hours. ”

“ About 0.55 pint per brake horse-power per hour was the usual fuel consumption necessary to full load running, and the engine was also economical as regards the consumption of lubricating oil, the lubricating system being ‘forced’ for all parts, including the cam-shaft. The shape of these engines was very well suited for work with aircraft, being narrow enough to admit of a stream-line form being obtained, while all the accessories could be so mounted as to produce little or no wind resistance, and very little obstruction to the pilot’s view. ”

“ To meet these requirements the aviation motor must be especially designed, and since the vibration of the propeller shakes the frail frame on which the engine is mounted, the materials must have the greatest strength and resistance. ”

“ With this type of engine the breakage of air-screws was of frequent occurrence, and an engine having a more regular rotation was sought, both for this and to avoid the excessive vibration often experienced with the four-cylinder type. Another, point that forced itself on engine builders was that the increased power which was becoming necessary for the propulsion of aircraft made an increase in the number of cylinders essential, in order to obtain a light engine. ”

“ The evolution of the heavier-than-air flying-machine, like that of the lighter-than-air, covers a long period of time, and was fraught with many difficulties and dangers. For ages many scientific men played with the idea, but owing to the lack of motive power light enough to be mounted on a glider yet supplying sufficient strength to drive a set of planes through the air at 45 miles an hour, very little progress was made until the perfection of the steam-engine and the development of the gasoline motor. ”

“ Most of us manufacturers, sold on our own doctrine, had now moved into the design and production of new transport aircraft intended to replace the war-weary war surplus. In United Aircraft, for instance, we had undertaken to expand the power output and increase the dependability of our current commercial engines and had at the same time inaugurated a wholly new engine, a twenty-eight-cylinder Wasp Major with a capacity of 4,360 cubic inches and an initial rating of 3,000 horsepower. ”

“ To begin with he was able to use a new and efficient form of motor destined to become popular, and capable, as the automobile manufacturers later showed, of almost illimitable development in the direction of power and lightness. Except for the gasoline engine, developed by the makers of motor cars, aviation to-day would be where it was a quarter of a century ago. ”

“ Therefore, before we attempt to demonstrate how this fastest engine of [172] flight can be made to do man’s will as easily and comfortably as the powerful steam-engine, the mysterious electric dynamo, and the subtle gasoline motor, let us first examine in detail what has already been accomplished in aeroplane transportation. ”

“ No doubt airplane-engine practice of the last four years and the advance that it has made will be reflected in a very marked degree in the automobile, not necessarily by fitting large airplane engines in cars, but by applying to car practice the knowledge that has been gained in manufacture. ”

“ In short distance, high-speed machines it works well, but in the larger planes the vertical or V-type motor has been found to give greater satisfaction.
When we read of the enormous trouble the pioneers of aviation went to, in order to find an engine suitable to drive the propeller of the airplane, we cannot help wondering just how the revolving of the propeller sends the whole machine flying forward through the air. ”

“ It is true that you can regulate the aeroplane engine by the throttle to run from as low as three hundred revolutions a minute to as high as sixteen hundred; but except when testing the motor there is rarely any reason for slowing it up while in the air. ”

“ Now the wings and fuselage of our airplane are ready, and the rudder, the elevating surfaces and the ailerons are in course of production. They are made in the same manner as the wings, with a wooden framework over which fabric is stretched and “doped.” We begin to think our big bird is almost ready to be put together, but we have forgotten two important items: the engine and the propeller.
The airplane manufacturer usually does not attempt to build his own engines or propellers. ”

“ A slight knowledge of motors such as would be obtained from familiarity with automobiles was a marked advantage at the start, for the first task of the novice was to make himself familiar with every type of airplane engine. The army pilot in all the armies was the aristocrat of the service. Mechanics kept his motor in shape, and helpers housed, cleaned, and brought forth his machine for action. ”

“ For these reasons aircraft require special kinds of motors. The V type is so called because the cylinders are set in the form of that letter; the rotary motor has the cylinders arranged in a circle like the spokes of a wheel, and it revolves on its shaft like the propeller. The rotary motor is used in scouting machines because it is light. The revolving engine also revolves on its shaft, but it has a great many more cylinders arranged side by side like the cylinders of an automobile engine. ”

“ It may be said that the development of the Mercedes engine contributed very largely to such success as was achieved in the war period by German aircraft, and, in developing the engine, the builders were careful to make alterations in such a way as to effect the least possible change in the design of aeroplane to which they were to be fitted. ”

“ Considerable development of the compression ignition type of engine for aircraft will be required before it is commonly available. It is believed that the weight per horsepower must be equal to, or less than, that of the present type of engines, in order to interest the public, since rapid take-off, rate of climb, and speed are desired, rather than low fuel consumption or high mileage. ”

“ The actual manufacturing side of the work would naturally be very similar to the manufacture of a car engine, but one obtains a better perspective of what an engine is subjected to by passing from the erecting and manufacturing shops to the engine-testing shop, where the ear-splitting reports from the open exhausts of a number of engines being tested at the same time are heard. ”

“ The First Airplane Diesel Engine: Packard Model DR-980 of 1928, by Robert B. Meyer. 1964. 48 pages, 37 figures, appendix, bibliography. Price 60¢. The Liberty Engine 1918-1942, by Philip S. Dickey. 1968. 110 pages, 20 figures, appendix, bibliography. Price 75¢. Aircraft Propulsion: A Review of the Evolution of Aircraft Piston Engines, by C. Fayette Taylor. 1971 viii + 134 pages, 72 figures, appendix, bibliography of 601 items. Price $1.75. ”

“ The lungs of the machine—its engines—are the crux of man's mechanical wisdom and skill. Their marvelous reliability and intricacy are almost as awesome as the human anatomy. When both engines are going well, and synchronized to the same speed, the roar of the exhausts develops into one long-sustained and not inharmonious boom-m-m-m-m! It is a song of pleasant melody to the pilot, whose ear is ever pricked to catch the first semblance of a "sharp" or "flat" note telling him that one or more of the twelve cylinders of each busy engine is missing fire and needs a little doctoring. ”

“ Upon going into a mathematical calculation of the whole subject, I found that it would be possible to make a machine on the aeroplane system, driven by a steam engine, which would be sufficiently strong to lift itself into the air. I first made drawings of a steam engine, and a pair of these engines was afterwards made. These engines are constructed, for the most part, of a very high grade of cast steel, the cylinders being only 3/32 of an inch thick, the crank shafts hollow, and every part as strong and light as possible. ”

“ The evolution of the motor-car led to the adoption of the vertical type of internal combustion engine in preference to any other, and it followed naturally that vertical engines should be first used for aeroplane propulsion, as by taking an engine that had been developed to some extent, and adapting it to its new work, the problem of mechanical flight was rendered easier than if a totally new type had had to be evolved. ”

“ A larger motor was installed, and radiators and gasoline reservoirs of larger capacity replaced those previously used. No attempt was made to make high or long flights.
In order to show the general reader the way in which the machine operates, let us fancy ourselves ready for the start. The machine is placed upon a single-rail track facing the wind, and is securely fastened with a cable. The engine is put in motion, and the propellers in the rear whir. You take your seat at the center of the machine beside the operator. ”

“ Owing to the great range of an airship a thoroughly reliable engine is a paramount necessity. The main requirements are--firstly, that it must be capable of running for long periods without a breakdown; secondly, that it must be so arranged that minor repairs can be effected in the air; and thirdly, that economy of oil and fuel is of far greater importance to an airship than the initial weight of the engine itself. ”

“ Also that is why the aviator has to be in his seat at the controls, and have some other person start his machine for him, by turning over the propeller, or propellers until the motor fires.
Lately however, especially since the talk of the flight across the Atlantic, a means has been found to allow the aviator, or some helper with him, to start the engine once it has stalled in midair. This is accomplished by means of a sprocket chain gear and a crank connected to the engine shaft. The turning handle is within reach of the aviator. ”

“ ENGINES OF THE WAR PERIOD The principal engines of British, French, and American design used in the war period and since are briefly described under the four distinct types of aero engine; such notable examples as the Rolls-Royce, Sunbeam, and Napier engines have been given special mention, as they embodied—and still embody—all that is best in aero engine practice. So far, however, little has been said about the development of German aero engine design, apart from the early Daimler and other pioneer makes. ”

“ The propeller is driven by the engine.
The engine is usually of the gasoline type which develops high power with light weight, frequently one horse power for every three pounds of weight and in rare instances as high as one horse power for every pound of weight. These powerful little engines are marvels of mechanism and they have had much to do in the rapid modern progress of aeronautics.
The rudder, as its name indicates, guides the aeroplane in its flight. It consists in the main of small horizontal and vertical planes under the control of the pilot. ”

“ It showed a tendency to rise, but its lifting power was insufficient for the weight of the engine driving the propellers. It was evident, however, that if the power of the engine could be sufficiently increased, or, what amounts to the same thing, its weight sufficiently lightened, a machine built on the aeroplane principle could be made to fly. But at that time the lightest type of engine was a crude, heavy machine, and for the moment nothing more was attempted in producing a mechanical flying-machine propelled by steam. ”

“ The construction of the motor is possible to an expert machinist only, and the aeroplane builder will save time and money by buying his engine from a reliable maker. It is not necessary to send to France for a Darracq motor. Any good gasoline engine of equal power, and about the same weight, will serve the purpose. ”

“ The rear section, with separate leaves, like the feathers of a bird’s wing, likewise disappears, leaving only the long narrow wing which has always been the ideal speed machine.
“To drive this huge craft, whose body consists of two stories or decks with pilot house, staterooms, fuel chambers, engine room, bridges above and protective galleries, a much higher percentage of motor power than ever secured before had to be turned into propulsive energy. ”

“ An elevating rudder of two horizontal planes ten feet in front of the machine, and a rudder of two vertical planes about six feet long and one foot apart in the rear of the machine were under control by levers close to the hands of the pilot, who, prostrate on the lower large plane, directed the course up or down, to the right or left at will. But the most remarkable features of all were the gasoline engine that was to give motive power and the propellers by which that power was to move the machine in its flight through the air. ”