Aeronautics

AERONAUTICS. The record of man's attempts to fly goes back into the remote past. The story of Icarus is a myth founded perhaps on some early failure to imitate the birds. Leonardo da Vinci thought and wrote about it, and there are some references to the subject in the works of Francis Bacon. In 1617, Fleyder of Tubingen lectured on flying; while in Italy, again, in his book De Motu Animalium (168o), G. A. Borelli discussed the question in connection with the strength of man's muscles and came to the conclusion that such flight was impossible.

Early History of Artificial Flight.

We are here concerned mainly with the flight of bodies heavier than air; for the early history of airships, see BALLOON and AIRSHIP. The first attempts, limited in all cases to the flight of models, were generally based on the endeavour to imitate the action of a bird's wings. Sir George Cayley, however, in 1796, constructed a tiny helicopter in which two windmills made of gull feathers were caused to revolve about a vertical axis. Figs. I and 2 illustrate two models due to Penaud, constructed in the early '7os of last .century; in the first of these the motive power is obtained from a screw driven by the torsion of an india rubber cord; in the second an attempt is made to imitate the action of a bird's wings. Stringfellow in 1842 had already constructed a model in which the supporting force was obtained from the wings while the motive power came from a screw, and from that time on some of the fundamental principles underlying flight began to be more generally recognized.

Principles of Flight.

A bird's wings have two functions to perform ; they support the bird in the air and they propel it f or ward. For an account of how this is done reference may be made to the article on FLIGHT, NATURAL. It would appear that support is given by the portions of the wing nearer the body, while the propulsive power comes from the more rapidly moving tips.

Imagine a flat surface in the form of a long rectangle, with its long edge horizontal and its surface inclined downwards from front to back, to be moved forward in a horizontal direction at right angles to its length. The pressure of the air on the under surface exceeds that on the upper; the plane thus experiences a force directed upwards and backwards. This can be resolved into one force, the "lift," acting vertically upwards, in a direction, that is, opposite to the weight of the plane, and into one directed backwards, the "drag," tending to stop the motion.

Measurement would show that approximately these forces are proportionate to the area of the plane and the square of the speed with which it is moved.

Now support on the plane an engine driving a screw propeller. If the motion thus produced be sufficiently rapid, the lift will exceed the weight of plane and engine, and, omitting for the moment considerations of balance, the plane will fly.

Early Mechanical Machines.

It was on principles such as these that machines were constructed by Henson in 1842 and Stringfellow in 1848. Stringfellow, in 1868, exhibited at the Crystal Palace a model for which he received a prize of £roo. Langley, of the Smithsonian institute of Washington, worked on similar lines. It had been realized by this time that greater lifting power could be obtained by shaping the supporting surfaces cor rectly, i.e., by giving them a convex shape on the upper side and a concave on the lower. A steam-driven model flew, in 1896, for a distance of about along the Potomac river near Washington. At a later date, Langley built a large machine which was intended for passengers. It was fitted with a remarkably light steam engine designed by Manley and driven by two propellers; this was launched into the air from a vessel in the river. On each of the two occasions in 1903 on which it was tried, something went wrong with the launching arrangements and the machine was wrecked. Another early machine was that of Sir Hiram Maxim; this too was damaged in a trial in Gliders.—Meanwhile, it had been realized that before success was reached more knowledge as to the conditions of balance in the air was necessary and, further, that much could be learned by the aid of gliders depending for their support on natural air currents.

The experimenters, suspended from their wings, jumped from natural or artificial heights and allowed the wind to carry them through the air. Lilienthal in Germany, who first showed the advantage of curved over flat surfaces, was killed after making over 2,000 safe flights; he endeavoured in these to maintain his balance by shifting his position relative to the wings. Chanute, in America, made the surfaces of the aeroplane movable; he con structed a number of machines.

The Modern Era.

Wilbur and Orville Wright, of Dayton in Ohio, began their epoch-making work in 1900 with gliders. They introduced two great improvements: the elevator, or horizontal rudder for steering the machine in the vertical plane, which they placed in front of the main planes (in nearly all modern machines it is attached to the tail) ; and the flexing of the rear edge of the main planes so as to vary the lift on either or both at will and thus maintain the balance in the air. A petrol motor driving a screw was added in 1903. In 5905 they made 45 flights, in the longest of which they remained in the air for half an hour and travelled 241 miles. A little later, 1906, Santos Dumont constructed a machine in which he flew a distance of about 25oyd. in 21 seconds.

In 1908, Henry Farman, at Issy-les-Molineaux, made a circular flight of 'km. and on Sept. 29 he covered 241-m. in 42min. Meanwhile the Wrights had continued their work at Dayton. On Sept. 12, 1908, Orville made a flight of 45m. in 'hr. 142min.; but a few days later he had an accident in which he was seriously injured and his passenger was killed. Wilbur Wright, on Sept. 21, 1908, at Le Mans, beat all previous records by a flight of 56m.

in 'hr. 3imin. 251sec. On Dec. 31 he remained in the air for 2hr. 2omin. 23sec.

These great advances had been rendered possible by the im provement of the petrol engine.

In 1909, a number of notable flights were made, several of them in monoplanes. On July 25 Bleriot crossed the Channel from Calais to Dover, and later Latham nearly achieved the same feat.

In November, Farman covered a distance of about 1344m. in 4hr. 17min. 53sec.

Next year Paulhan, at Los Angeles, in a biplane, reached a height of 1,383yd. and on April 27-28, 191o, the same pilot won the Daily Mail prize of f io,000 by flying within 24 hours from London to Manchester with one stop.

Table I., printed herewith, gives some details, approximately correct, of the principal experiments made with flying machines from 1879 to Wilbur Wright's flight in France.

Since that day the advance has been enormous. In place of the toy models of Henson and Stringfellow we have machines weigh ing as much as fifteen tons with a wing span up to ioo feet and speeds from i5o to 200 m.p.h. or, in a machine such as that which won the Schneider trophy in 1929, 35o m.p.h., driven by triple or quadruple engines aggregating well over 2000 h.p.

For details of British aircraft see Table II. on page See also TRANS-OCEANIC AND TRANS-CONTINENTAL FLIGHTS.