The first world war would see the first widespread use of airplanes in armed conflict. At the time, the French aero-engine industry included both specialized firms and major auto manufacturers such as Darracq, Peugeot and Hispano-Suiza. Gnome and Le Rhône merged, becoming a world leader.

Gnome et Rhône takes shape

After several years of fierce competition, Gnome and Le Rhône finally decided to merge. On January 12, 1915, Gnome bought out Louis Verdet's Le Rhône company to form "Société des Moteurs Gnome et Rhône".

From 1914 to 1918, Gnome et Rhône would produce some 25,000 engines in France. Nearly 100,000 French-designed engines were built during this period, either in France or abroad under license. It was not an uncommon sight to see French, English or American fighter pilots in a dogfight against their German or Austrian counterparts flying airplanes also powered by French engines! For example, the Le Rhône 9C would power the Fokker triplane flown by German WWI ace Manfred von Richthoffen - "the Red Baron".

Gnome et Rhône rotary engines powered both French and foreign WWI aircraft. Produced in both 1 and 2-row configurations, these engines developed from 50 to 150 horsepower, and could be used for a wide range of applications. The 110-hp Rhône 9J was the best-seller of the time, powering renowned aircraft such as the Caudron, Nieuport, Morane and Hanriot (France), the Bristol (UK) and the Fokker (Germany).

Emergence of Hispano-Suiza

The power output of rotary engines quickly reached its limit, however, because the increase in rotating mass created a gyroscopic torque that made it impossible to control the aircraft. As early as 1915, the situation would be changed irrevocably by the advent of a new in-line engine, designed by Hispano-Suiza. Although with mixed Swiss-Spanish origins, as the name indicates, the Société Hispano-Suiza was founded in France in 1911 by Swiss engineer Marc Birkigt and Damian Mateù. Renault and Lorraine would also opt for the production of non-rotary engines.

Starting in 1916-17, Hispano-Suiza engines accounted for the majority of French production, forcing Gnome et Rhône to share their previous virtual monopoly on aerial victories. The fixed configuration of these in-line engines enabled them to reach unprecedented levels of power, increasing from 150 hp in 1916 to over 300 hp by 1918.

Hispano-Suiza engines would power a number of different fighters, including the Spad made famous by French ace Georges Guynemer. Their 1918 engine developed some 345 horsepower, with power density exceeding that of the rotaries which were unable to develop more than 240 horsepower. By the end of the war, Hispano-Suiza had produced nearly 50,000 engines.

The quest for ever-more power would be facilitated by the advent of superchargers and turbochargers, invented by Auguste Rateau. Some 20 years later, this type of engine would still be in service.

The first world war clearly energized the aviation industry, which advanced by leaps and bounds. In the aero-engine market, conventional in-line and V engines were winning market share from the original rotary engines, very few of which were produced in Great Britain and the United States. The aero-engine was largely split between Hispano-Suiza and Gnome et Rhône.

But with the end of the war, thousands of airplanes, pilots and mechanics were out of a job. A few weeks after the armistice, Latécoère opened the first airmail line between Toulouse and Barcelona. By 1919, several dozen air transport companies had been created in France, and had started service on European routes. Despite the precipitous drop in military orders, airplanes had to fly faster, higher and farther to meet the demand from emerging civil operators...

Gnome et Rhône copes with the crisis: introduction of the Jupiter

With the end of the war, Gnome et Rhône had to cope with a several major problems: military orders were drying up. The company responded by diversifying. It launched the construction of chassis and engines for the Rolland Pilain and Ricard-Pictet cars, along with Ansaldo diesel engines, refrigerators, sewing machines and even jackhammers! At the same time, Gnome et Rhône entered the motorcycle market, a market Snecma would continue to supply until 1963.

In 1921 the company purchased a license for the Bristol Aeroplane Company Jupiter, a radial engine that would be sold worldwide. Developing up to 480 horsepower, the Jupiter would power a hundred different civil and military aircraft types, including the Spad, Dewoitine, Bréguet, Potez and others in France, the Dutch Fokker, the Junkers, Dornier and Heinkel in Germany, Piaggio in Italy and the Soviet Polikarpov. The engine's power and dependability also made it suitable for the specific needs of seaplanes and commercial transports.

In 1922, Paul-Louis Weiller, a WWI ace and member of an illustrious businessmen family, succeeded Laurent and Amédée Seguin at the head of Gnome et Rhône. He refocused the company on aircraft engines, while still maintaining significant production capacity for the emerging motorcycle market.

Encouraged by the success of the Jupiter (which came with a 200 hour warranty), in 1923 Weiller purchased another license from Bristol, this time for the Titan, a 230-hp 5-cylinder radial engine. The Titan was also a huge success. In 1930, Gnome et Rhône delivered more than 6,000 Titan and Jupiter engines, making it the largest French exporter of aircraft engines. The Titan and Jupiter would power some 100 different aircraft types in their career, including seaplanes.

Meanwhile, both Renault and Hispano-Suiza were continuing the development of liquid-cooled in-line engines.