Robert Esnault-Pelterie was born in Paris on November 8, 1881. He was a French aviation pioneer who made important contributions to the beginnings of heavier-than-air flight in Europe. The son of a textile manufacturer, he earned science degrees at the Sorbonne in 1902 in botany, physics, and chemistry. After further studying engineering at the Sorbonne, Esnault-Pelterie attempted to build a duplicate of the Wright brothers’ glider of 1902. However, since his data was incomplete, and he did not fully understand their steering technique. he could not reproduce the Wrights’ aircraft. This led him to abandon their steering methods and in 1903, to invent the aileron (a movable airfoil at the trailing edge of the wing) as a means of steering aircraft.
Esnault-Pelterie designed and built his own gliders, then flew tests with them near Calais. When these proved successful he began making powered aircraft. On October 10, 1907, he flew one of the first monoplanes, which he had designed and built. It relied on internally braced wings, rather than a drag-producing system of external wires, and was powered by a lightweight seven-cylinder radial engine that he had also invented. This “R.E.P. monoplane” was the first metallic plane and the earliest aircraft with an enclosed fuselage of welded-steel tubing, a revolutionary means of streamlining.
Robert Esnault-Pelterie’s longest flight in this aircraft was over 2,600 feet. On June 18, 1908, however, he crashed the monoplane and was severely injured. Esnault-Pelterie never piloted a plane again, fearing his life-long injuries might cause him to make an involuntary movement while at the controls. On September 25, 1909, he was one of the co-founders of the Paris Air Show, the first exhibition to be devoted entirely to aviation and still one of the most important venues in the aviation industry.
Esnault-Pelterie soon shifted his interests into space exploration. On November 15, 1912, in a paper to the Physics Society of France, he offered an early discussion of the problems of space travel, including a proposal to use atomic energy to travel to the Moon and the planets. In 1927, Esnault-Pelterie, and banker Andre Louis-Hirsch established a 5,000-franc annual prize for the author of the most outstanding work on avionics, the Prix REP-Hirsch. In 1929, Esnault-Pelterie came up with the concept of aero-braking, using the principle of atmospheric drag to slow a spacecraft for gravitational capture by a planet.
In 1930 Esnault-Pelterie’s published his book L’Astronautique (Astronautics), in which he coined the word “astronautics.” In this volume and its 1934 supplement, L’Astronautique-Complement, he discussed virtually all that was known of rocketry and space flight at the time. He had already considered the military future of rocketry in a 1929 proposal to the French Army for the development of ballistic bombardment missiles. He believed such weapons could deliver huge payloads of explosives over hundreds of miles, a vision of the World War II V-1 and V-2 offensives by Nazi Germany.
By 1931, Esnault-Pelterie was testing rocket motors for the French government. The loss of all four of his fingers on his left hand in an explosion during one such test in October 1931 failed to deter him, and in 1934, he received more funding from the French army to research not liquid-fuel and solid-fuel rockets that could be used to accelerate conventional bombs. French rocketry, however, continued only sporadically, and without conclusive results, until the outbreak of the Second World War in 1939.
Esnault-Pelterie also invented the rocket steering concept of the gimbaled or swiveling nozzle, which is used on all space launch vehicles today. He received over 200 patents for his inventions in fields such as metallurgy, electricity, magnetism, fluid dynamics, thermodynamics, combustion turbines, automobile suspensions, tidal energy, and rocketry.
Robert Esnault-Pelterie died in November 1957 in Geneva, Switzerland. A crater on the moon is named for him.