- Albert F. Zahm, "Conspectus of Early Powerplane Development". Records of the Columbia Historical Society, Washington D.C., Vol. 46/46, 1944/1945.
Available online at JSTOR.
As outlined in the first sentence: "Of the nineteenth-century contributions to aviation art three are especially noteworthy: (1) invention of the airplane, (2) addition of three-torque control, (3) first man-flights with ample power." Three engineers, he writes, accomplished these developments before 1900. These were, respectively, William Samuel Henson, Alexandre Goupil, and Clément Ader.
Goupil invented the aileron, thus adding torque control in a third dimension and completing Henson's invention. However Zahm credits Matthew Piers Watt Boulton with 'explaining the principle' in Patent GB-1868-392.
Ader was the "first to take off in sustained flight".
In 1891 Clement Ader, seated in his tractor steam monoplane, taxied and took off many times in straightaway sustained flight, in hops of 50 to 100 meters over level ground. His engine developed 30 horsepower and with accessories weighed 6.6 pounds per horsepower. Stringfellow's best engine, with boiler, weighed but 13 pounds per horsepower; Langley's steam engine still less. In 1894 Maxim carried over 10,000 pounds off a level track in a steam multiplane having ample power but defective control. It flew some 300 feet with a crew of 3 men. With all accessories (boilers, pumps, generators, condensers, cooling water) his engines weighed but 8 pounds per horsepower. Had he copied Goupil's version of Henson's transport plane, he might have inaugurated the grand sport of exhibition stunts before the gasoline engine was well developed by the automotive industry. (p. 330)
Author of Aerial Navigation, Appleton, 1911; constructed first modern wind tunnel at Brookland, D.C.; former Chief Research Engineer, Curtiss Aeroplane Co.; former Director Aerodynamical Laboratory of U.S. Navy; now holds Guggenheim Chair of Aeronautics, Library of Congress; member of this Society since 1936. This paper, offered as a communication to the Records, represents a revision for this purpose of a former publication by Dr. Zahm, privately printed. In the preface to that publication, acknowledgment was made to the Journal of the Franklin Institute (Vol. 236, no. 3, September 1943) and to The Journal of the Maryland Academy of Sciences (Vol. II, no. 2, April, 1931) through whose courtesy part of the material was reprinted.
The article hs a clear subtext in assigning priority to the three individuals credited. Zahm writes: "one hopes this limited commentary may prove helpful to earnest students, and acceptable to fair-minded readers. Its object is truth rather than controversy or light entertainment." (p. 326)