Airplane engine

“ In the average airplane engine from 1500 to 2000 explosions or revolutions occur per minute.
The combustion cylinder of an aircraft engine is usually built of steel, and the piston of cast iron or aluminum, which furnishes a very smooth gliding surface. The piston rod transmits the power to the crankshaft, a long rotating piece of steel. Every time the piston rod is thrust down by the explosion in the cylinder, its motion serves to turn the crankshaft and thus the vertical motion of the piston is transformed into the rotary motion which sends the propeller whirling through [158] the air. ”

“ 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. ”

“ The main difficulty for air navigation is in the precarious progress of the engines. Frankly, the current engine has not yet reached what it should be. The airplane itself has developed faster than the engine.
I think, however, that soon the airplane engine will be so perfected that it will have no more imperfections than those of the best and most perfect automobiles made today.
Nowadays, an airplane engine needs to be relatively light and, at the same time, withstand a lot of continuous work. ”

“ At the word “contact” the mechanics swing the propeller, and, sometimes only after several trials, the motor starts, with a roar and a rush of wind in the passenger's face. After a moment's slow running it is speeded up, the intermittent roar becomes a continuous note, the plane shakes and strains, while the mechanics hold down the tail to prevent a premature take-off. When the engine is properly 26warmed up it is throttled to a low speed, the chocks under the wheels are removed, the mechanics hold one end of the lower wing so that the plane swings around toward the field. ”

“ 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. ”

“ This is all that need be said about why the air supports an airplane; all you have to remember is that as long as you have the forward sweeping movement, you will have the lift.
The forward movement is absolutely essential, however, and to maintain it requires a lot of horsepower and gasoline. For it is by means of the engine and propeller that this forward movement is maintained. The engine is a device for creating forward movement—the propeller drives the machine ahead in exactly the same way as is the case in a torpedo, or steamboat. ”

“ There are certain technical details which distinguish an airplane motor from an automobile motor, but a man who knows automobile engines can master the airplane motor in short order. Generally speaking, the airplane motor differs from the automobile motor in shape. The Liberty type of engine is V-shaped, with both sets of cylinders driving toward a common center, the crankshaft. Most airplane motors have special carbureters, and their oiling systems are extremely finely adjusted to take up any friction at their high speed. ”

“ 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. ”

“ Coming next to the wind motors, these possess one very great merit: they utilize a motive power that is always present as long as the plane is in motion through the air. 147On the other hand, the process of using the main propeller of the plane to pull another smaller propeller through the air appears a roundabout way to utilize the driving power of the airplane engine. ”

“ Airplanes require about one third more power during the take-off than in flight. In diesel-engined airplanes the size of the engine could be reduced by 25 percent by feeding oxygen into the intake air during the takeoff. Applying the results of the experiments to a transport plane, Fig. 31 shows the possible weight saving with various oxygen boosts. The curves are based on 6000 cruising horsepower and an estimated engine weight of 2 lb per hp. ”

“ Each of these types of motors has its peculiar advantages. The least “head resistance” is caused by a straight line engine, and this type also uses less fuel and oil. But it is usually heavier in weight, owing to the larger cooling system necessary and the longer crankshaft, and it takes up more room in the airplane fuselage than a motor of the compact radial type. The radial engine is very light in weight,—a big item in the airplane—but it consumes a large quantity of fuel and oil and besides produces a maximum “head resistance.” ”

“ The regular big biplane of the bomber type carries two propellers with an engine for each propeller. If one motor fails them when flying, about all the other is good for is to make a landing with. By reason of the great lightness of our airplane one good 400 horse-power motor is all we need for pulling purposes. ”

“ Those relating to the balancing and steering of the machine after it is actually in flight. Of these difficulties two are already to a certain extent solved. Men already know how to construct wings or aeroplanes which, when driven through air at sufficient speed, will not only sustain the weight of the wings themselves, but also that of the engine, and of the engineer as well. ”

“ 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. ”

“ 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. ”

“ We Americans love to take hold of a machine and turn it out in big quantities. Our allies were sure that we could turn out first-class airplanes, and many of them, if we tried.
Congress made an appropriation of six hundred and forty million dollars for aëronautics, and then things began to hum.
A BIRTHDAY PRESENT TO THE NATION
The heart of an airplane is its engine. We know a great deal about gasolene-engines, especially automobile engines; but an airplane engine is a very different thing. It must be tremendously powerful, and at the same time extremely light. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ In the stoppage of its motor, when a craft is in flight, several factors need consideration; but one should clearly be understood: even if his engine does fail while he is passing through the air, a pilot is not helpless, nor does his machine fall to the ground. As he flies, of course, it is the thrust of his motor, acting through the medium of the propeller, that keeps his craft moving forward; and so long as this thrust is there, forcing his planes against the air and causing them to lift their load, the machine will fly ahead. ”

“ A gas-containing envelope, made of a light, strong, varnished fabric, is kept taut by the pressure of the gas within; the car, constructed of wood or metal tubing, is suspended by ropes from the envelope, and contains engine and crew, with a two-bladed propeller revolving astern. Such a machine, in its control, had an elevating-plane and rudder, upon the same principle as those of the aeroplane. One of the difficulties to be overcome was the expansion and contraction of gas in the envelope owing to differences in altitude and temperature. ”

“ With regard to the flying-boat type of machine, a favourite practice is to mount the motor on the four struts supporting the centre section of the upper plane, which is braced by struts and wires from different points on the hull or body.
Although the modern aircraft engine is of greatly increased power, compared with the engine of the period 1912–1914, one does not find any great difference in the structural features of the mounting employed, and in view of the very diverse arrangements for mounting the same type of engine which now exist, there is need for greater uniformity. ”

“ 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. ”

“ But, in any case, the starting of the engine means the whirling of the propellers, for they are directly connected. This is why, when once the engine stops in mid-air, it can not be started again. Or at least if it is started it is mostly a matter of chance in getting it to go under compression or by the spark. There is no chance for the aviator to get out and whirl the propellers which are, in a measure, what a flywheel is to an automobile. ”

“ Then, there were double control wires, running from the levers to the rudder and the elevating planes, so that, if one wire broke (a thing that has caused many an aviator’s death) another would take its place.
For starting the machine from the seat—without having to have some one whirl the propeller till the engine was going—there was an electrical motor, which was a sort of boy of all work. For, when it was through its work as a motor, it became a dynamo, and filled up storage-batteries which worked the big electrical search-light, for use when the machine was flying at night. ”

“ Subsequent developments have indicated that this type, with the further development from it of the double-Vee, or engine with three rows of cylinders, is likely to become the standard design of aero engine where high powers are required. The construction permits of placing every part so that it is easy of access, and the form of the engine implies very little head resistance, while it can be placed on the machine—supposing that machine to be of the single-engine type—in such a way that the view of the pilot is very little obstructed while in flight. ”

“ 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. ”