Among early design considerations were the layout, location and configuration of wings. Several early concepts included that of the tandem wing, including Langley’s first successful powered aircraft in 1896 (pictured, below). A tandem wing aircraft implies use of two full-sized wings mounted on each end of the fuselage. It might be considered a biplane with a great amount of “stagger” between the wings. The practical effect is to increase the stability of an aircraft. Early experimenters found that using a single or biplane wing configuration was unstable. Some tried to overcome this problem using two horizontally separated wings.
The first published account of a tandem wing design was that by Thomas Walker of England in his 1831 book, “A Treatise Upon the Art of Flying by Mechanical Means,” which had a drawing of his concept (below). One of the most important models based on this design was created by D.S. Brown in 1873. He used this model to demonstrate longitudinal stability with several models. Sir George Cayley (creator of the modern configuration of the airplane) also gave attention to the tandem wing layout.
In 1874, Thomas Moy in England completed and, in 1875, tested a large model steam engine-powered tandem wing called the Aerial Steamer, which flew in tethered flight around the fountain at London’s Crystal Palace. It is also probable that Brown’s or Moy’s work influenced S.P. Langley in the layout of his powered aircraft, the first successful powered heavier-than-air aircraft.
Samuel Pierpont Langley, a distinguished mathematician and astronomer, became, through his experiments and developments, the first major aeronautical figure in the United States. Langley, who long held an interest in the problems of flight, started serious investigations in 1887 when he constructed a whirling arm driven by a steam engine in order to test the amount of power needed to sustain a given weight in the air.
Langley then moved on and tested several rubber-driven models based on Penaud’s monoplane pusher design. In 1892-93 he moved on to four steam driven models (called Aerodromes) of the same configuration, all of which were failures. In 1895 he rebuilt his fifth model as a tandem wing monoplane. This was a much larger model with a span of 13 feet, 11 inches, and powered by a one horsepower steam engine driving twin pusher propellers. On May 6, 1896, it flew over the Potomac River in stable flight for a distance of ¾ mile. A second version, Aerodrome No. 6, flew almost a mile in November 1896.
Satisfied at last that he had proved the possibility of mechanical flight, but realizing that a full-sized man-carrying aircraft would required much time and money to build, Langley resolved not to undertake the task. That he ultimately did construct a man-carrying machine was due to the far-sightedness of President William McKinley, who was impressed by Langley’s models. The result was that in December 1898, Langley was awarded $50,000 by the War Department to develop a man-carrying machine, making the United States the second country after France to support the building of aircraft.
The full-scale Aerodrome had a wingspan of over 48 feet and a length of 52 feet. The engine was an air-cooled rotary built by Charles Manly. It was also Manly — who had never even tried to fly a glider — who was the craft’s pilot. On Oct. 7, 1903, the plane was launched by catapult from the top of a houseboat. Upon release the craft nose-dived into the Potomac River. A second attempt on Dec. 8 again ended in failure. Langley abandoned all further work in aviation and the War Department also withdrew its support, feeling that it would take thousands of dollars and years of work to develop powered flight — all this a few days before the Wrights flew at Kitty Hawk.
CAPRONI’S FLYING HOUSE BOAT
Count Caproni of Italy gained a reputation during the First World War for building the largest aircraft outside of Russia. His bombers had wing spans greater than 72 feet and gross weights in the four-ton range, with half ton bomb loads. After the war the Count had a dream of building a huge aircraft with the capability of flying to New York while carrying 100 passengers.
This triple triplane tandem wing aircraft, the Caproni CA-60, was a cross between a houseboat and an airplane. Powered by eight 400-hp American Liberty engines, the triple tandem wing plane was designed to carry 100 passengers, or 17,635 pounds of mail, or eight 1,600-lbs. torpedoes. All of this was to be supported by the three sets of triplane wings with a total area of 8,000 square feet and a wing span of 98 feet. This huge monster weighed 55,000 pounds.
Caproni’s amazing machine was launched into the water in the presence of the U.S. ambassador on Jan. 21, 1921, at Lake Maggiore in Italy. In March, after a tentative hop across the lake’s surface, the CA-60 took to the air, climbing to about 60 feet before it crashed into the water. The pilot survived, but the machine was broken up badly. There was a plan to repair it but, probably fortunately, it was destroyed by fire. Despite the demise of the project, Flight magazine reported in the April 28, 1921, issue that Signor Caproni was contemplating much larger machines.
At the other end of the tandem aircraft spectrum was the Henri Mignet design from the 1930s called the Pou-du-Ciel — literally “Sky Louse” or, as the English translated the name, “Flying Flea.”
Frenchman Henri Mignet, who designed the HM.14 Pou du Ciel in 1933, felt that spinning was a great cause of aircraft accidents and that spinning was connected with ailerons and aileron control. So when he designed the HM.14, he decided at the start that he would have no ailerons. If there were no ailerons, he argued, they could not get him into trouble.
Another problem area that he saw was stalling, which was caused by the elevators, so he eliminated them as well. For longitudinal stability he used two wings in the tandem configuration. Pitch control was obtained by changing the angle of attack of the front wing, which was mounted on a pylon above the fuselage. Directional control was by the rudder, which was operated by sideways movement of the control column.
The Flying Flea was the most popular tandem wing design, enjoying a period of intense popularity in France and England, but a series of accidents in 1935-36 blackened the airplane’s reputation. Due to the very limited flight envelope, pilots who exceeded it ended up in dives, which resulted in many deaths. Wind tunnel tests indicating the need for more angle of attack on the forward wing resolved the issue and many versions of the design continue to fly.
Even though the tandem wing design has been with us since 1831, and was the configuration for the first successful heavier-than-air powered fight, it never was a popular design feature. Given Langley’s failures and the almost instant success of the Wright Brothers and their followers, it is not surprising that the tandem-wing design should inspire few experimenters.
Dennis Parks is Curator Emeritus of Seattle’s Museum of Flight. He can be reached at firstname.lastname@example.org.