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Aviation History
1919
1919 - 0853.PDF
JUNE 26, 1919 PROGRESS OF AVIATION IN THE WAR PERIOD* )orae Items of Scientific and Technical Interest By LEONARD BAIRSTOW, C.B.E., F.R.S., D.Sc. IT was with great pleasure that the lecturer received an invitation from the Council of the Royal Aeronautical Society to deliver the lecture of 1919 to the memory of Wilbur Wright. Most of us remember the appearance of their aero plane in Europe about ten years ago and the revolution brought about by their method of lateral control. The effect on European flying was immediate, for the periods of flight began to extend from minutes to hours. I have par ticular pleasure in adding my tribute to their skill because of the scientific and painstaking way in which they approached the problem of aviation, and successively removed one after another of the outstanding difficulties. Their unhurried attack on a difficult problem contrasts strongly with the present irrational worship of the immediately practical. They were preceded by another distinguished American, Processor Langley, who with equal patience and little reward laid the foundations of aerodynamics on which calculations as to the possibility of flight were first made with any reason able, approach to accuracy. That Langley was correct in his estimates of weight and horse-power has been shown during the War period by the flight of the man-carrying aeroplane which he designed and made. It is true that the original steam-engine was replaced by a modern aero-motor, but the power unit troubled all early workers. Maxim, in a remark able effort, succeeded in producing a steam-engine in which each horse-power involved a weight of only half a pound, but aviation had to wait for the petrol motor l>efore flight was achieved. Both Maxim's and Langley's efforts at flight came to an early end. The latter launched a pilotless aeroplane from the top of a houseboat on the Potomac River, but, probably owing to lack of stability, it dived into the water and was wrecked. Maxim endeavoured to avoid the problems of stability by making his aeroplane captive, but the bending of an axle led to disaster when the wings were taking a lift of 10,000 lbs. It was in their progress from this point that the Wright brothers made history. Their early flight experiments were directed to the development of controls by means of which the sense* of the pilot were introduced into the mechanics of the aeroplane motion. In their aeroplane it was for the first time possible to raise or lower the nose by elevator, turn to right or left by rudder and maintain an even keel by wirg warping. At the present time no other controls are used or appear to be required. Of the three controls mentioned, that of wing warping for maintenance of an even keel had not previously been suggested, and the ailerons of modern design are mechanical improvements and not changes of principle. The problems of inherent stability were at that time un touched in practice, although Bryan was then working out the mathematical theory which has now been adopted as the best statement and solution of the problem of the disturbed motion of an aeroplane. I propose to skip the period 1908-14 and to proceed to some of the relatively highly developed forms of aircraft as they existed at the outbreak of hostilities. At that time a speed of 85 to 90 m.p.h. was considered good, with the possibility of climbing to a height of 10,000 ft. Military training pro ceeded on the hypothesis that flying for reconnaissance and photography would take* place at 3,000 ft., whilst fighting in the air was not adequately provided for. Two types of aeroplane of the early period will be referred to ; both have survived on their merits to the present time, ;dthough long since past the standard required on active service. The " Avro " aeroplane has to its credit one of the earliest of the many daring and spectacular feats of our flying men, for it was in aeroplanes of this type that two aviators, now Col. F. Briggs and Major Sippe, flew over the Zeppelin sheds at Friedriehshafen and dropped bombs on their objective. In those days machine guns were extremely rare as part of the equipment of an aeroplane, and the various ingenious devices for firing between the blades of an airscrew making 20 to 30 r.p.s. had not even been contem plated. The horse-power of the engine was 70, as contrasted with the 1,500 h.p. of the largest modern aeroplane flown. In the later periods of the War the " Avro " became the standard elementary training aeroplane, and has an excellent * Paper read before the Royal Aeronautical Society at the Royal Society of Arts, John Street, Adelphi, Strand, W.C., on Wednesday, June 18, 1919. record of good service. It appears to be peculiarly free from undesirable characteristics. The second aeroplane which will be referred to as a good early type is the B.E.2C, which has just been declared obsolete. Much controversy has ranged round this aero plane, perhaps more than any other, and I can imagine mixed feelings amongst members of the audience at hearing \t described as a good aeroplane. Probably most of them will agree, however, that its record as a straightforward flying machine is good, and will focus their criticisms on that peculiar feature of the aeroplane which can be best described by saying that it had a strong will of its own. The develop ment of the fighting scout has brought out very clearly the pilot's desire for an aeroplane which is wholly obedient to him, even for extraordinary and dangerous manoeuvres. Designers have admitted this view, and have done their best to meet it. It is not difficult to see that in aerial fighting a balance must be struck between danger from enemy action and danger inherent to the aeroplane. The B.E.2C. was deliberately designed to have a will of its own and a desire to stay right side up. The late Mr. Busk spent much of his energy in producing this effect, and I believe that General Seely took the aeroplane from Farn- borough to Salisbury Plain without using any other control than the rudder. It was strong and for those days reasonably fast, whilst fighting in the air had not begun to show promi nently that its excessive stability was a defect. I want to make it quite clear at this point that, on the other hand, instability is not a desirable characteristic in any aeroplane, and certainly not for civil uses ; instability leads to accidents. The B.E.2C. was unpopular because it was too stable, and called for considerable muscular effort in the rapidly re curring emergencies of a fight with a mortal enemy. It is now obsolete mainly because of the insufficiency of its engine power to meet modem needs. Scientifically and technically the B.E.2C. is one of the most interesting aeroplanes ever built. It showed con clusively that the line of argument developed mathematic ally by Bryan could be used to calculate the degree of stability of an aeroplane, and so paved the way for the design of aeroplanes with the desired characteristics of in difference or stability as required for fighting or bombing. It showed that the will of an aeroplane is not a fortuitous characteristic, but is one of those quantities over which the designer has a large measure of control. Stability and instability in an aeroplane are easily measured, and at Martlesham Heath a camera has been designed and used to produce records, some of which I propose to show you at a later stage. It appears that many of our aeroplanes are stable. The B.E.2C. had an engine of 90 h.p., carried pilot and passenger, and reached a top speed of over 85 m.p.h. On these points it may be contrasted with the Bristol Fighter, which took one of the favourite places in the later phases of aerial fighting. The engine power was 275 and the top speed over no m.p.h. at 10,000 ft., whilst it was able to climb to nearly 20,000 ft. Using such aeroplanes our fighting pilots waited for considerable periods of time at heights of 15,000 ft. ready to swoop on an enemy seen at a lower level. With the barometer at 17 ins. and the ther mometer showing 60 degrees of frost, prolonged effort was no small call on their physical and mental powers. Fitted with two guns firing through the airscrew and a third gun which could be trained in any direction by an observer, this aeroplane was a formidable antagonist. The usual fighting scout was, however, a single-seater with its two fixed guns firing through the airscrew and trained by the motion of the aeroplane. Speeds up to 130 m.p.h. have been reached and the ceiling pushed up to 25,000 ft. This increase of speed and ceiling are accounted for chiefly by the fact that it has been found possible to instal an engine of 210 h.p. in an aeroplane weighing less than 2,000 lbs., a figure which means 1 h.p. for each 10 lbs. of load carried. The large aeroplane, as we now know it, had no repre sentative until the middle period of the War, when the first large type of Handley Page aeroplane began to operate from Dunkirk. With a total weight of 11,000 lbs. and a horse-power of 550, the aeroplane will be seen to compare on weight per horse-power with the "Avro" and B.E.2C, *53
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