page_title: Aviation in the pioneer era
section_title: Engine development
hierarchical_section_title: Aviation in the pioneer era / Technical development / Engine development
caption_attribution_description: English: Gnome 7 Omega rotary aero engine on display at the Royal Air Force Museum, London.
context_page_description: The pioneer era of aviation refers to the period of aviation history between the first successful powered flight, generally accepted to have been made by the Wright Brothers on 17 December 1903, and the outbreak of the First World War in August 1914.
  Once the principles of powered controlled flight had been established there was a period in which many different aircraft configurations were experimented with. By 1914 the tractor configuration biplane had become the most popular form of aircraft design, and would remain so until the end of the 1920s. The development of the internal combustion engine—primarily from their use in early automobiles even before the start of the 20th century—which enabled successful heavier-than-air flight also produced rapid advances in lighter-than-air flight, particularly in Germany where the Zeppelin company rapidly became the world leader in the field of airship construction.
context_section_description: Early aircraft development was heavily reliant on the development of the internal combustion engine, and the problem of staying in the air was largely a matter of having an engine which was not only sufficiently powerful but was also lightweight and reliable. Most early engines were neither powerful nor reliable enough for practical use, and the development of improved engines went hand-in-hand with improvements in the airframes themselves.
  The Wright Brothers had been unable to find a satisfactory engine and, with the help of their mechanic, had manufactured their own. They used a single flight engine, a 12 hp water-cooled four-cylinder inline type with five main bearings and fuel injection.
  The first internal combustion piston engine design to be widely used for powering aircraft was the Antoinette water-cooled V8 engine, believed to be the very first V-form eight-cylinder internal combustion engine ever placed in production, designed by the Frenchman Léon Levavasseur. The Antoinette 8V incorporated direct fuel injection, evaporative water cooling and other advanced features, weighed 95 kg (209 lb) and produced 37 kW (50 hp). Introduced in 1906, these engines were used by, among others, Santos Dumont, the early Voisin aircraft and Samuel Cody. American aviation engine designers quickly picked up on the V-8 engine concept from 1906 onwards as the era progressed, with both Glenn Curtiss' firm designing a series of liquid-cooled V-8 aviation engines culminating in the Curtiss OX-5 by the early years of World War I—another major American engine manufacturer, Hall-Scott, had their A-2 and A-3 overhead valve, liquid-cooled V-8s in production as early as 1908.
  The British Green C.4 of 1908 followed the Wright's pattern of a four-cylinder inline water-cooled design but produced 52 hp (38 kW). It powered many successful pioneer aircraft including those of A.V. Roe.
  Horizontally opposed designs were also used with some success. Santos-Dumont's Santos-Dumont Demoiselle No. 20 monoplane used first the 18 kW (24-hp output Dutheil et Chalmers liquid-cooled opposed twin engine, later replaced by a 22 kW (30 hp) Darracq-built engine of the same layout. The four-cylinder water-cooled de Havilland Iris achieved 45 hp but was little used, while the successful two-cylinder Nieuport design achieved 28 hp (21 kW) in 1910.
  1909 saw radial engine forms rise to significance. The air-cooled Anzani 3-cylinder semi-radial or fan engine of 1909 (also built in a true, 120° cylinder angle radial form) developed only 25 hp (16 kW) but was much lighter than the liquid-cooled  Antoinette, and was chosen by Louis Blériot for his cross-Channel flight. A major advance came with the introduction of the Seguin brothers' Gnome Omega seven-cylinder, air-cooled rotary engine, exhibited at the Paris Aero Salon 1n 1908 and first fitted to an aircraft in 1909.  This radial-configuration engine was constructed in such a way that the entire crankcase and cylinder assembly rotated around a stationary crankshaft, itself fastened securely through the engine's rear attachment to the airframe, ensuring an adequate flow of cooling air over the cylinders even when the aircraft was not moving.  Although this type had been introduced as long ago as 1887 by Lawrence Hargrave and built two years later by Hargrave for compressed-air power—with an experimental five-cylinder internal combustion rotary engine used by French inventor Félix Millet that same year to power an early motorcycle design — improvements made to the Seguin brothers' Gnome series of engine designs created a robust, relatively reliable and lightweight design which revolutionised aviation and would see continuous development over the next ten years. Fuel was introduced into each cylinder direct from the crankcase meaning that only an exhaust valve was required.  Producing 37 kW (50 hp) for a dry weight of 75 kg (165 lb), this engine soon became one of the most widely used powerplants; the company went on to produce a number of similar engines producing more power, first by increasing the engine capacity and al
caption: The Gnome Omega
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