Le Rhône 9C


The 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 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.

Design and development

First marketed in 1912, the 80 horsepower 9C was the first of the Rhône series rotary engines to have nine cylinders. 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.
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 flight from Paris to Gdańsk with a single refuelling stop in Berlin. The 9C also powered the 1913 world altitude record of set by the aviator Georges Legagneux in a Nieuport.
The 9C was selected early on for use in military aircraft with the first of many applications being the 1912 Voisin Type 1.
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.
The German Fliegertruppen fitted captured 9Cs in their Fokker Eindekkers in place of engines built by Oberursel. Eindekkers fitted with the Le Rhône 9C were found to be superior particularly in relation to climb and maximum altitude.

Super Rhone (radial conversion)

In the mid‑1920s, the Texas firm Tips and Smith purchased a large quantity of surplus American‑built Le Rhône 9C rotary engines and converted them into air‑cooled radial engines. During the conversion, balance weights were added to the crankshaft, and a new mounting arrangement was fitted that reversed the engine’s orientation so that the induction pipes were positioned opposite the propeller. The new mounting system also incorporated a revised induction arrangement in which the carburettor was supplied with air drawn in from the crankcase. This design cooled and scavenged the crankcase while heating the inlet air to the carburetor which helped to vaporise the fuel.
The conversion to a radial configuration increased the engine’s output from at 1,200 rpm to at 1,400 rpm. The engine’s weight was. During World War I, the Rhône 9C engines had been purchased by the US War Department for US$4,250 dollars each. In 1926, the Super Rhone engines were on sale for just US$750, and around 400 had been sold by May of that year.

Applications

Super Rhone radial conversion

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 are each powered by 80 hp Le Rhône 9C rotary engines, and fly regularly throughout the summer months.
An operative Le Rhone 9C is shown at the Museo Nacional de Aeronautica in Buenos Aires Argentina.

Engines on display