Henson, who had spent a considerable amount of money in these experimental constructions, consoled himself for failure by venturing into matrimony; in 1849 he went to America, leaving Stringfellow to continue experimenting alone. From 1846 to 1848 Stringfellow worked on what is really an epoch-making item in the history of aeronautics—the first engine-driven aeroplane which actually flew. The machine in question had a 10 foot span, and was 2 ft. across in the widest part of the wing; the length of tail was 3 ft. 6 ins., and the span of tail in the widest part 22 ins., the total sustaining area being about 14 sq. ft. The motive power consisted of an engine with a cylinder of three-quarter inch diameter and a two-inch stroke; between this and the crank shaft was a bevelled gear giving three revolutions of the propellers to every stroke of the engine; the propellers, right and left screw, were four-bladed and 16 inches in diameter. The total weight of the model with engine was 8 lbs. Its successful flight is ascribed to the fact that Stringfellow curved the wings, giving them rigid front edges and flexible trailing edges, as suggested long before both by Da Vinci and Borelli, but never before put into practice.
Mr F. J. Stringfellow, in the pamphlet quoted above, gives the best account of the flight of this model: ‘My father had constructed another small model which was finished early in 1848, and having the loan of a long room in a disused lace factory, early in June the small model was moved there for experiments. The room was about 22 yards long and from 10 to 12 ft. high.... The inclined wire for starting the machine occupied less than half the length of the room and left space at the end for the machine to clear the floor. In the first experiment the tail was set at too high an angle, and the machine rose too rapidly on leaving the wire. After going a few yards it slid back as if coming down an inclined plane, at such an angle that the point of the tail struck the ground and was broken. The tail was repaired and set at a smaller angle. The steam was again got up, and the machine started down the wire, and, upon reaching the point of self-detachment, it gradually rose until it reached the farther end of the room, striking a hole in the canvas placed to stop it. In experiments the machine flew well, when rising as much as one in seven. The late Rev. J. Riste, Esq., lace manufacturer, Northcote Spicer, Esq., J. Toms, Esq., and others witnessed experiments. Mr Marriatt, late of the San Francisco News Letter brought down from London Mr Ellis, the then lessee of Cremorne Gardens, Mr Partridge, and Lieutenant Gale, the aeronaut, to witness experiments. Mr Ellis offered to construct a covered way at Cremorne for experiments. Mr Stringfellow repaired to Cremorne, but not much better accommodations than he had at home were provided, owing to unfulfilled engagement as to room. Mr Stringfellow was preparing for departure when a party of gentlemen unconnected with the Gardens begged to see an experiment, and finding them able to appreciate his endeavours, he got up steam and started the model down the wire. When it arrived at the spot where it should leave the wire it appeared to meet with some obstruction, and threatened to come to the ground, but it soon recovered itself and darted off in as fair a flight as it was possible to make at a distance of about 40 yards, where it was stopped by the canvas.
‘Having now demonstrated the practicability of making a steam-engine fly, and finding nothing but a pecuniary loss and little honour, this experimenter rested for a long time, satisfied with what he had effected. The subject, however, had to him special charms, and he still contemplated the renewal of his experiments.’
It appears that Stringfellow’s interest did not revive sufficiently for the continuance of the experiments until the founding of the Aeronautical Society of Great Britain in 1866. Wenham’s paper on Aerial Locomotion read at the first meeting of the Society, which was held at the Society of Arts under the Presidency of the Duke of Argyll, was the means of bringing Stringfellow back into the field. It was Wenham’s suggestion, in the first place, that monoplane design should be abandoned for the superposition of planes; acting on this suggestion Stringfellow constructed a model triplane, and also designed a steam engine of slightly over one horse-power, and a one horse-power copper boiler and fire box which, although capable of sustaining a pressure of 500 lbs. to the square inch, weighed only about 40 lbs.
Both the engine and the triplane model were exhibited at the first Aeronautical Exhibition held at the Crystal Palace in 1868. The triplane had a supporting surface of 28 sq. ft.; inclusive of engine, boiler, fuel, and water its total weight was under 12 lbs. The engine worked two 21 in. propellers at 600 revolutions per minute, and developed 100 lbs. steam pressure in five minutes, yielding one-third horse-power. Since no free flight was allowed in the Exhibition, owing to danger from fire, the triplane was suspended from a wire in the nave of the building, and it was noted that, when running along the wire, the model made a perceptible lift.
A prize of £100 was awarded to the steam engine as the lightest steam engine in proportion to its power. The engine and model together may be reckoned as Stringfellow’s best achievement. He used his £100 in preparation for further experiments, but he was now an old man, and his work was practically done. Both the triplane and the engine were eventually bought for the Washington Museum; Stringfellow’s earlier models, together with those constructed by him in conjunction with Henson, remain in this country in the Victoria and Albert Museum.
John Stringfellow died on December 13th, 1883. His place in the history of aeronautics is at least equal to that of Cayley, and it may be said that he laid the foundation of such work as was subsequently accomplished by Maxim, Langley, and their fellows. It was the coming of the internal combustion engine that rendered flight practicable, and had this prime mover been available in John Stringfellow’s day the Wright brothers’ achievement might have been antedated by half a century.
V
WENHAM, LE BRIS, AND SOME OTHERS
There are few outstanding events in the development of aeronautics between Stringfellow’s final achievement and the work of such men as Lilienthal, Pilcher, Montgomery, and their kind; in spite of this, the later middle decades of the nineteenth century witnessed a considerable amount of spade work both in England and in France, the two countries which led in the way in aeronautical development until Lilienthal gave honour to Germany, and Langley and Montgomery paved the way for the Wright Brothers in America.