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9C
	Le Rhône 9C engine installed in a Sopwith Pup at the Royal Air Force Museum London
Type	Rotary engine
National origin	France
Manufacturer	Société des Moteurs Le Rhône / Gnome et Rhône, Union Switch & Signal (US), Daimler Company (UK), AB Thulinverken (Sweden)
First run	1912
Major applications	Nieuport 11, Sopwith Pup
Number built	>10,000
Developed into	Le Rhône 9J

The Le Rhône 9C is a nine-cylinder rotary aircraft engine produced in France by Société des Moteurs Le Rhône / Gnome et Rhône. Also known as the Le Rhône 80 hp in a reference to its nominal power rating, the engine was fitted to many military aircraft types during the First World War. Le Rhône 9C engines were also produced under license in Great Britain, the United States and Sweden.^[1]

Design and development

First marketed in 1912, the 80 horsepower 9C was the first of the Rhône series rotary engines to have nine cylinders.^[1] In common with earlier seven cylinder Le Rhône series engines, the 9C featured copper induction pipes and used a single push-pull rod to operate its two overhead valves. Unlike the later 110 horsepower 9J, the induction pipes and push rods were located on the front of the engine.^[2]

Prior to the outbreak of World War One, aircraft powered by the Rhône 9C set numerous long distance city to city records including a highly publicised 1,400 km (870 mi) flight from Paris to Gdańsk with a single refuelling stop in Berlin. The 9C also powered the 1913 world altitude record of 6,120 m (20,080 ft) set by the aviator Georges Legagneux in a Nieuport.^[1]

The 9C was selected early on for use in military aircraft with the first of many applications being the 1912 Voisin Type 1.^[3]

During WW1 the 9C was the engine used in many single-seater scout aircraft such as the Nieuport 11 “Bebe” and the Sopwith Pup. Later in the war most 9Cs built were used in training aircraft.^[1]

The German Fliegertruppen fitted captured 9Cs in their Fokker Eindekkers in place of engines built by Oberursel (which were themselves licensed built copies of the Gnome Lambda). Eindekkers fitted with the Le Rhône 9C were found to be superior particularly in relation to climb and maximum altitude.^[4]

Applications

Surviving engines and reproductions

Examples of Le Rhône 9C engines are on view in aviation museums either installed in aircraft exhibits or as stand-alone displays. A few examples of the 9C engine remain airworthy both in Europe and North America, one powering a vintage Sopwith Pup biplane in England, and a small number of others having powered reproduction WWI-era aircraft at Old Rhinebeck Aerodrome and other American "living" aviation museums that fly their restored original engines in both similarly restored original, and airworthy reproduction period aircraft.

Both the restored Shuttleworth Collection's airworthy Sopwith Pup and the 1960s-built reproduction Pup of the Owl's Head Transportation Museum (originally from Old Rhinebeck Aerodrome) are each powered by 80 hp Le Rhône 9C rotary engines, and fly regularly throughout the summer months.^[5]^[6] An operative Le Rhone 9C is shown at the Museo Nacional de Aeronautica in Buenos Aires Argentina.

Engines on display

A Le Rhône 9C is installed in the Sopwith Pup on display at the Royal Air Force Museum London. After renovation this aircraft flew for a brief period in the 1970s and is now retired.^[7]
A Le Rhône 9C is on public display at the Aerospace Museum of California
A Le Rhône 9C is on public display at The Hangar Flight Museum

Specifications (Le Rhône 9C)

Data from Lumsden ^[8]

General characteristics

Type: Nine-cylinder, single-row rotary engine
Bore: 105 mm (4.13 in)
Stroke: 140 mm (5.51 in)
Displacement: 10.89 L (664.47 cu in)
Diameter: 94.5 cm (37.2 in)
Dry weight: 121.5 kg (268 lb)

Components

Valvetrain: Cam-operated single rocker for both inlet and exhaust valves
Oil system: Castor oil, total loss
Cooling system: Air-cooled

Performance

Power output: 92 hp (68.6 kW) at 1,300 rpm (maximum)
Compression ratio: 4.5:1

References

^ ^a ^b ^c ^d Hartmann, Gerard (2004). "Moteurs de légende : Le Rhône" [Legendary Engines: The Rhone] (PDF) (in French). Retrieved 19 March 2023.
^ "Chapter II - The 80 and 110 Horsepower Le Rhone Motor". Rotary Engines. United States: The War Department. 1919.
^ Simons, Graham M (2019). "Hydro Avions". Early French Aviation 1905-1930. Pen and Sword. ISBN 9781526758743.
^ Wilkins, Mark C (2019). "Outbreak". German Fighter Aircraft in World War I. Casemate. ISBN 9781612006208.
^ CAA G-INFO - Sopwith Pup, G-EBKY Retrieved: 17 November 2010
^ Shuttleworth Collection - Sopwith Pup Retrieved: 06 April 2017.
^ Royal Air Force Museum London - Sopwith Pup, N5182- Full history Retrieved: 17 November 2010.
^ Lumsden, Alec (2002). British Piston Engines and their Aircraft. Airlife Publishing. ISBN 1853102946.