Henson and Stringfellow’s remarkable influence on modern design
STRINGFELLOW’S MODEL OF 1848, which is now in the Science Museum, South Kensington, had a wing span of 10 feet; the length of the tail was 3 ft 6-in, giving a total supporting surface of about 14 square feet. The engine drove two screw propellers, which made three revolutions to one stroke of the engine. The model, less than nine pounds in weight, is shown slung on the launching apparatus. It was held back until the airscrews were revolving at full speed and then released; it then travelled along the wire until it encountered a block which released the model.
A MANUFACTURER of lace machinery was destined to become famous as the inventor of the first aeroplane to fly under its own power. The lace machinery manufacturer was John Stringfellow.
One day in 1820 Stringfellow came to the little Somerset town of Chard, where he met a young engineer named William Samuel Henson. For years Henson had been ambitious to solve the great problem of flight. Henson and Stringfellow, with their common engineering interests, soon became firm friends, and Henson confided in Stringfellow his secret ambition. Stringfellow was sympathetic and actively helpful at a time when it did not seem possible that anything except a balloon could sustain itself in the air.
Shortly after the two friends had discussed their “flying machine” in detail, and had planned much of its construction, Henson had to go to London, but they kept up a regular correspondence. Stringfellow turned his attention to building a small, light steam engine - this was many years before the petrol engine had been thought of - while Henson considered the design of the aeroplane itself.
By 1840 Henson was ready to begin his experiments with gliders and a light steam engine which he was building under the advice of Stringfellow. Towards the end of 1841 Stringfellow paid a visit to Henson and arranged to build an engine. In 1842 Henson took out his remarkable patent No. 9478 for “Certain Improvements in Locomotive Apparatus and Machinery for Conveying Letters, Goods and Passengers from Place to Place through the Air, part of which Improvements are applicable to Locomotive and other Machinery to be used on Water and on Land”. He specified among other things a steam engine which incorporated Stringfellow’s suggestions. Henson formed a company to exploit his inventions, and in March 1843 J. A. Roebuck, M.P., brought in a Bill in Parliament for an Act of Incorporation for the Aerial Steam Transit Company. Henson’s patent and the Bill in Parliament attracted wide attention. The papers of the day published pictures of Henson’s Steam Carriage flying over Hyde Park, the Thames at London Bridge, the English Channel, the Pyramids and other places. Scientists vied with one another in writing articles for or against the possibility of flight.
It is not possible to give here Henson’s patent in full, but the following extract may be made.
“The first part of my invention consists of an apparatus so constructed as to offer a very extended surface or plane of a light yet strong construction, which will have the same relation to the general machine which the extended wings of a bird have to the body when a bird is skimming in the air; but in place of the movement or power for onward progress being obtained by movement of the extended surface or plane, as is the case with the wings of birds, I apply suitable paddle wheels or other mechanical propellers worked by a steam or other sufficiently light engine, and thus obtain the requisite power for onward movement to the plane or extended surface; and in order to give control as to the upward and downward direction of such a machine I apply a tail to the extended surface which is capable of being inclined or raised, so that when the power is acting to propel the machine, by inclining the tail upwards the resistance offered by the air will cause the machine to rise on the air; and, on the contrary, when the inclination of the tail is reversed, the machine will immediately be propelled downwards and pass through a plane more or less inclined to the horizon as the inclination of the tail is greater or less; and in order to guide the machine as to the lateral direction which it shall take, I apply a vertical rudder or second tail, and according as the same is inclined in one direction or the other, so will be the direction of the machine.”
JOHN STRINGFELLOW was born in Sheffield in 1799 and became a manufacturer of lace-making machinery. In 1820 he moved to Chard, in Somerset, and there met another engineer, William Samuel Henson. They collaborated in aeronautical research and in 1842 Henson took out patents for an “aerial steam carriage”. Stringfellow persevered in his experiments and produced models which flew under their own power.
Henson’s machine was a huge monoplane. For lightness, it was to be built of bamboo and hollow wooden spars braced with wires. The planes were to measure 4,500 square feet, with a triangular shaped tail giving an additional supporting surface of 1,500 square feet. It was to be driven by two six-bladed propellers, the steam engine being about 25-30 horse-power.
Henson’s machine, patented in 1812, bears a remarkable resemblance to many machines flying today. His was an amazing forecast when it is remembered that no one at that time had any real idea of what an aeroplane would look like.
The real genius of Henson is clear from a study of the patent he took out. His aircraft had the moving tail of modern aeroplanes, the moving rudder for turning, and a similar form of construction of the main plane which can be seen today - the main spar, the strengthened leading edge, the doubly curved surface and the curved ribs are all common in one form or another at the present day. Henson was right not only in his general conception, but also in many of the details of his design.
The great difference was that his machine was a pusher aeroplane - that is, the propellers were behind the wings instead of in front, as in most modern aeroplanes. Even here Henson cannot be held to have been in error, for it later became known that there are many advantages in putting the propellers behind the wings instead of in front.
Stringfellow’s Persistence Rewarded
Stringfellow’s part in the great work was to undertake the construction of the monoplane, but Henson, like so many inventors whose ideas are ahead of their time, found that, though many people were enthusiastic enough, few were prepared to risk their money. Funds were not forthcoming, and the great project slowly faded away. Henson went back to Chard and the two inventors began to build a small model to confirm their theories.
By 1847 the model was ready for experiments, but they were not as favourable as expected. Every time the model was launched it slowly descended. The failure was not so much in the machine but in its construction, which proved too frail. Henson grew discouraged by the failures and refused to continue. In a short time he married and went to America. Stringfellow refused to acknowledge defeat. He set to work on the model which was to make his name famous in aeronautical history as the first engine-driven aeroplane of any kind to fly. This historic machine was 10 feet in span and 2 feet across in its widest part. The tail was 3½ feet in length and the total supporting surface was 14 square feet. The two propellers, turning in opposite directions, had four blades each. The model, with its little steam engine, fuel and water, weighed only 8½ lb. The cylinder of the engine was of ¾-in. diameter, with a two-inch stroke, and a bevel gear to the crankshaft giving three revolutions of the propellers to one stroke of the engine. The wings had a slightly curved front edge, specially strengthened, as in modern practice, with a flexible trailing edge, and it was due to this form of construction that the aeroplane was so successful.
MODEL TRIPLANE exhibited at the first Aeronautical Exhibition, held at the Crystal Palace, London, in 1868. The model had three rectangular superposed planes, decreasing progressively in span. The supporting surface amounted to about 28 square feet, including the tail. The weight of the model, including the engine (which developed about one-third horse-power), boiler and fuel, was less than 12 lb.
Stringfellow’s model was completed early in 1848, and in June of that year it was tested in a long room in a disused lace factory. The model was slung from a wire running about half the length of the room for starting, the other half of the room being left for the free flight of the model. At one end of the room was a canvas screen to take the shock of the machine without damaging it. To quote the account of his son, “Steam was 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.”
A large number of people had assembled to watch the great and, as it turned out, highly successful experiment. For the first time in the history of the world an engine had driven an aeroplane through the air. Stringfellow afterwards repeated his successful
experiment at Cremorne Gardens, Chelsea; the model flew for a distance of 40 yards on that occasion. There is little doubt that, because of Stringfellow’s efforts, if the petrol engine had then been available, man would have been flying fifty years before he did and the credit for the first successful man-carrying aeroplane would have been an Englishman’s. As it was, the world had to wait until 1903 when the Wright brothers built their aeroplane.
In 1849 Stringfellow paid a visit to America, and it was many years before he once more began to study the problem of flight. The engine of his model he gave to Heathcote & Co, of Tiverton (Devonshire), to drive a small lace machine, and the relics of his great experiment were almost forgotten.
For nearly twenty years Stringfellow’s interest in aviation languished, but it was revived when the Aeronautical Society of Great Britain - now the Royal Aeronautical Society, the oldest aeronautical society in the world - was founded by the Duke of Argyll, in 1866.
A paper by F. H. Wenham on aerial locomotion was read before this Society, and, having learnt that the Society was to hold an Aeronautical Exhibition at the Crystal Palace, London, in 1868, Stringfellow began his experiments afresh.
He built a three-winged or triplane model, and a light aero engine. The triplane ran suspended from a wire in the nave of the Crystal Palace. The model had a total surface of 28 square feet without the tail, and weighed, including engine, boiler, fuel and water, a little under 12 lb.
THE AEROPLANE PROPOSED BY HENSON in his patent of 1842. Power was to be obtained from a light steam engine to drive paddle wheels or other propellers. The design was for a huge monoplane built of bamboo and hollow wooden spars braced with wires. This illustration shows the completed machine as seen from below, and the framework of the machine as seen from above. There are three spars running the whole length of the wings. The centre spar is of rectangular section; the outer two are of oval section and taper towards their ends. Sections at the centres and ends of the tapering spars are shown in the inset. This inset also shows plan and side views of a turnbuckle used to tighten the bracing wires.
The engine worked two propellers, each 21 inches in diameter, at about 600 revolutions a minute and got up steam to 100 lb. pressure in about five minutes. To guard against danger from fire no free flight was allowed, but the triplane lifted considerably when running along the wire.
“It was a grand day for Uncle,” wrote his niece Rosa. “The Prince and Princess of Wales [afterwards King Edward VII and Queen Alexandra] and Prince Alfred and several of the Princesses were there. The Prince was so charmed with the model that he sent the Duke of Sutherland for Uncle to go to the Royal Box.”
The steam engine shown by Stringfellow was awarded the prize of £100 offered for “the lightest steam engine in proportion to its power”. The engine developed a little over one horse-power and, with its boiler, weighed only 13 lb; it was the lightest steam engine yet built.
It is worth while quoting from the Society’s Report on the model at the Exhibition. “The cylinder is 2-in in diameter, stroke 3-in, and works with a boiler pressure of 100 lb. per square inch; the engine making 300 revolutions per minute. The time of getting up steam was noted; in three minutes after lighting the fire the pressure was 30 lb, in five minutes 50 lb, and in seven minutes there was a full working pressure of 100 lb.
“When started, the engine had a fair amount of duty to perform in driving the four-bladed screw propellers 3 feet in diameter at 300 revolutions per minute.
“The 2-in cylinder is of very thin brass tube; the covers, flanges and glands are also as light as they can be made consistently with strength; the ports and passages are in one separate piece, screwed on; one piston rod passes through each end of the cylinder, and by means of long connecting rods, works in opposite directions two cranks fitted to the axes of two four-bladed screws three feet in diameter. The boiler consists of a number of inverted cones made of very thin sheet copper; each cone is closed with a hemispherical cap.”
After this fresh triumph Stringfellow became a member of the Aeronautical Society. He continued for some time to experiment, and with the £100 awarded to him he erected a building over 70 feet long in which to conduct his experiments.
Failing eyesight forced him to desist, and he died in 1883 at the age of 84.
The Henson-Stringfellow model and the Stringfellow model of 1848 were later restored and presented to the Science Museum, South Kensington, where they are now preserved as a monument to the genius of the men born fifty years too soon. The light engine exhibited at the Crystal Palace in 1868 was bought by the United States and is now in the National Museum, Washington, with a reproduction of the model triplane.
STRINGFELLOW’S MODEL TRIPLANE suspended from a wire at the Aeronautical Exhibition in 1868. Because of the danger from fire, the model was not allowed to demonstrate its capabilities of free flight, but its overhead wire was seen to slacken when the model was working. In the right centre is a model aeroplane built by J. M. Kaufmann, with flapping wings, but this proved to be a failure.