Aircraft speed

“ All at once there is a mighty swoop through the air like the drop of a bird of prey, and in no time the black flyer is immediately over the Englishman and the air is filled with the furious crackling of a machine gun, followed by the rapid ta-ta-ta of two or three more, all operated at the highest speed just as during a charge. ”

“ Therefore every pound of weight added to an aeroplane decreases its speed proportionately and requires an equivalent increase in horse-power to force it through the air. Of course, an increase of speed gives an increase in lift, so by doubling the speed of a plane you increase the lift just four times.
There are, however, a number of factors which tend to decrease the progress of a machine through the air: the head resistance of the fuselage, the motor, the struts, the wires, the landing-gear, etc. ”

“ Thirty-five miles an hour, except where the head resistance is great, is the slowest speed now made in landing a heavier-than-air machine. The invention of a device or the discovery of a means of reducing the speed to ten miles an hour when touching the ground, though still only in the realms of the probable, is by no means diametrically opposed to the inherent laws of the aeroplane. This accomplished, the danger of flying in an aeroplane will be reduced to infinitesimal proportions—at least to a degree no more precarious than riding in an automobile. ”

“ If we assume some given value for the horse-power per unit weight, then a machine may be designed either to develop the highest flight speed possible or to obtain the greatest rate of altitude increase—i.e., vertical velocity. Any actual design is of the nature of a compromise; maximum flight speed is kept as high as possible consistently with obtaining a sufficient rapidity of ascent. The independent air fleet must be, without question, the master of the service machines whose destruction it is required to encompass, both in the matter of speed and climbing capacity. ”

“ Sea completely hidden by clouds and no visibility whatsoever. Stopped forward and two aft engines, and now running on only two wing engines at 1,600 revolutions. These are giving us an air speed of 30 knots, or 33.6 miles per hour. This is the airship’s most efficient speed, as she only consumes on the two engines twenty-five gallons of petrol per hour.
Wind is east, seven miles per hour, and so we are making good forty miles per hour and resting three engines. ”

“ The airplane has never really come into its own as a sporting proposition. Of late years the tendency has been to develop a high rate of speed rather than to build machines that may be operated safely at a comparatively low speed. You see, a machine adapted to make from seventy to one hundred miles an hour cannot run at all except at a pretty rapid clip, and this means difficulty in getting down. ”

“ A serious disadvantage under which the sea-going aeroplane at present labours, whether it be of the single boat or double-float type, is that its speed is essentially limited by the fact that it has to alight and take off from the water, and this involves designing to a comparatively low minimum flight velocity. ”

“ One salient fact is at once evident; the greater the horse-power available for a given engine weight the greater the advantage in the matter of speed in favour of the aeroplane; the highest speed of flight of an aeroplane attained to-day (through, i.e., relatively to, the air) is already more than twice that of which the fastest dirigible is capable. There is every prospect that its advantage in this respect will increase rather than diminish with the march of progress. ”

“ Owing to quite wellunderstood conditions, it is necessary, before rising, to attain a speed on the ground not very much less than the normal flight-speed of the machine, and so, in the case of a machine designed for 120 miles per hour maximum flight-velocity, it would be necessary to acquire a speed round about 80 miles per hour before leaving the ground, which would necessitate a straight-line run of about 300 yards. ”

“ A form of machine which the professional airmen say has yet to be developed is the small monoplane, carrying two passengers at most, and of low speed—not more than twenty miles an hour at most. In this age of speed mania the idea of deliberately planning a conveyance or vehicle that shall not exceed a low limit seems out of accord with public desire. But the low speed airplane has the advantage of needing no extended field in which to alight. It reaches the (p. 230) ground with but little momentum to be taken up and can be brought up standing on the roof of a house or the deck of a ship. ”

“ Loss of speed—"perte de vitesse," as the French call it—is the aviator's most common peril in landing. If it occurs after his engine is cut off and he has not the time to start it again, the machine tilts and slides down sideways. If it occurs higher up a vrille is the probable result. In this the plane plunges toward the ground spinning round and round with the corner of one wing as a pivot. In either case a serious accident is almost inevitable.
In fact the land is almost as dangerous to the navigator of the air as it is to him of the sea. ”

“ The engine must be of American manufacture and capable of throttling to run at reduced speed. (8) Same as No. 7 above. This test will be made with aviator and passenger, extra weight and fuel enumerated in paragraphs 3 and 4. (9) The aeroplane must develop a speed in the air of at least forty miles an hour. This test will be made with aviator and passenger, extra weight and fuel enumerated in paragraphs 3 and 4. The maximum speed must not exceed sixty-five miles per hour. ”

“ Now when for speed the arch is made very slight, the lifting power can still be increased by increasing the area of the wing, thus adding to the upward pressure. Thus for certain war duties an airplane [97] with very large, comparatively flat wings can develop both a very good lifting power and a very high speed. ”

“ The wings of the airplane, its propeller and its whole construction have been planned so that it can support itself best in the air when flying at a certain fixed speed. Suppose this speed for a certain type of airplane to be 150 miles per hour. The airplane cannot land while traveling at that rate, yet its speed while still in the air can only be diminished to a certain point with safety, and below that point it may not be able to sustain [166] itself in flight. The pilot must be able to land his machine without accident and without throttling his engine below this danger line ”

“ So if a gale is blowing 20 miles an hour the aeroplane may be lifted off the ground when moving no faster than 15 miles an hour with respect to the earth. Likewise unless a machine is moving 35 miles an hour it will lose flying speed and fall to the ground.
Machines do not all land at the same speed. The famous Morane monoplane skimmed along the ground at anywhere from 45 to 90 miles an hour. It is manifestly impossible to do more than suggest the fundamental principles of aeroplane flight here. To be sure, the type of aircraft has, as we have indicated, much to do with why and how it flies. ”

“ On a clear night, however, with flambeaux, search-light flares, etc., a pilot has little trouble in landing, for [152] the straightaway can be as illuminated as it is in broad daylight. Nevertheless, when the aircraft is high in the sky, owing to the vast distances of infinite space, the speed at which an aeroplane moves, and the drift out of its regular course, due to the wind, it is often difficult for the flier to keep his bearings. ”

“ To bring an airplane to earth while it is traveling at a speed of 75 miles an hour is no mean accomplishment. It must not bump down heavily upon the ground, or its landing chassis will be broken, even if no more serious accident occurs. It must settle slowly until its wheels just touch, while all the time it is moving forward at the rate of a fast express train. This is an art that requires infinite practise to acquire, but it is one of the most important feats [241] the student airman has to learn. ”

“ Beyond the above, the speed of the aeroplane is approximately double that of the airship, whereas the speed of a fast destroyer is not more than 25 or 30 per cent, superior to that of a fast and heavily-armoured cruiser or battleship of modern type, and even this advantage is lost in heavy weather. ”

“ Our high-speed airplanes are already more aimed than flown, and less and less seen and seen from. Mach-3 aircraft are on the drawing boards now, aircraft that will fly at three times the 182speed of sound or about 2,000 miles per hour. ”

“ A wing gains lifting power from two sources: the upward pressure of the air current underneath it, and the force of the vacuum above it which is created by the arch of the wing. If a wing is only slightly arched it can move forward through the air more swiftly, but it will not have the lifting power of the high arched wing. This is the reason that an airplane which must be a weight carrier cannot be as fast in flight as the “speed scout,” which has only its pilot and a machine gun to carry. ”

“ To shut off the engine at precisely the right moment, (p. 114) to choose an angle of descent that will secure the greatest speed and at the same moment bring you to your landing place, to change at the most favourable time from this angle to one that will bring you to the ground at the most gentle of obtuse angles, and to let your machine, weighing perhaps a ton, drop as lightly as a bird and run along the earth for several hundred feet before coming to a full stop, are all features of making a landing which the aviator has to master. ”

“ At each lesson he has mastered some new problem. He knows how to leave the earth at the proper angle after the first short run over the ground, and how to come down again, how to turn in the air, when to cut off the power in alighting and when to apply the brakes. He learns to listen for the rhythmic sound of the engine and to know when anything has gone wrong with it.
By far the most difficult of his problems is the art of landing. As we have already seen the speed of an airplane cannot be reduced below a certain danger line if its wings are to continue to support it in the air. ”

“ Before actual airplane engines had been designed there was nothing to do but to use the type of engine which had been designed for the automobile, with as much reduction in weight as could be secured. But the automobile engine was never intended to run at top speed continuously and for long periods, as the airplane engine necessarily must do. In a car the motor has little stops and rests, as it is throttled down for a moment or changes in speed are made, and these breathing spells help it very much indeed in the “cooling off” process. ”

“ But with all the wonderful things the aeroplane has accomplished and with all the stupendous advance it has made as a carrier of man and his chattels, even though it does travel the shortest distance between any two points on this planet with the greatest speed, nevertheless, much must yet be done to make the aeroplane a safe, comfortable, popular, and inexpensive means of aerial transportation. ”

“ The large airship, until recently in contemplation for this duty, provides, in the author's opinion, a doubtful solution, without recapitulation of its other deficiencies, it is too slow; the key-note in matters of military or naval advancement is mobility, the measure of which is flight speed. ”

“ When the airplane was descending, the flying pilot would normally have reset the altitude selector to the next (lower) altitude target and moved the VERT SPEED (vertical speed) wheel to position the airplane in about a 1,000-feet-per-minute rate of descent to reach the next crossing altitude. The FD pitch command bars would move up and down to provide guidance to maintain the desired rate of descent. (In a precision approach, the command bars would provide guidance to maintain the glideslope; in nonprecision approaches, they provide guidance to maintain the desired vertical speed.) ”

“ Whether or no the inventor’s exact arrangements may prove on trial to be successful is a matter on which decisive opinion cannot be given; but the principle of expanding and diminishing surface is thoroughly sound, and is worthy of lavish expenditure and experiment. Other ways of attaining variable speed machines have been suggested, though the method of a variable surface would seem likely to carry the regulation of speed to a greater nicety than do the other plans. One of these projects is to alter the angle of the incidence of the planes while the machine is in flight ”

“ It must be remembered that an advantage in altitude can be always turned to account to give a temporary advantage in speed, as in the swoop of a bird of prey. We may look confidently to the wide employment of such swooping tactics in the future of aerial warfare. The advantage possessed by an air fleet having its base at high altitude, sometimes even some 6,000 ft, or 8,000 ft, above sea-level, will be very great ”

“ This need for superiority in the matter of speed means evidently that the air-fleet type must suffer in some degree in the matter of armament; alternatively it must be a heavier type machine for machine. Closely allied to the question of speed is that of climbing power. Other things being equal, whether for increased speed or for increased climbing power, a greater horse-power per unit weight is necessary. ”