A focused historical reference collection devoted to the remarkable Le Rhône rotary aircraft engines and the technical literature that supported their operation, care, installation, and adjustment.

Historical overview

• First introduction: 1910 for the 7-cylinder models; 1912 for the 9-cylinder series.
• Manufacturer: Société des Moteurs Le Rhône, founded by Louis Verdet; later associated with Gnome et Rhône.
• Design origins: Evolved from a 7-cylinder rotary concept developed by Louis Verdet at Rossel Peugeot, with a design intended to avoid the dominant Gnome engine patents.
• Production: Approximately 1910 through the 1920s, with around 100,000 engines produced, including direct manufacture, licensed production, and copies.
• Key variants: Le Rhône 7A, 7B and 7B2, rated at approximately 50–60 hp; Le Rhône 9C, rated at 80 hp; Le Rhône 9J, rated at 110–130 hp; and the German Oberursel UR.II copy.

Aircraft and operational significance

Le Rhône engines powered important military aircraft including the Nieuport 11, Nieuport 17, Sopwith Pup, Sopwith Camel, Hanriot HD.1, Morane-Saulnier N, and the Fokker Dr.I through the Oberursel UR.II derivative. Civil applications included Borel monoplanes, Sommer biplanes, and early post-war utility, sporting, and training aircraft.

During the First World War, the Le Rhône became a backbone powerplant for Allied fighter scouts and was widely valued for its reliability compared with Gnome monosoupape engines. After the war, surplus aircraft using these engines found new lives in barnstorming, early mail delivery, and aviation training.

Technical specifications

• Engine type: Air-cooled rotary engine, with the cylinders and propeller rotating around a stationary crankshaft.
• Configuration: Single-row circular arrangement, with early 7-cylinder and later 9-cylinder variants.
• Displacement: Approximately 667–920 cubic inches, or 10.9–15.1 litres, depending on variant.
• Power range: Approximately 80–130 hp for the principal 9-cylinder engines in this collection.
• Bore and stroke: 105 × 140 mm for the 9C and 9J; the higher-powered 9Jb used 112 × 170 mm.
• Compression ratio: Approximately 4.5:1–4.8:1.
• Weight: Approximately 268–323 lb, or 121.5–147 kg.
• Fuel and lubrication: Straight-run gasoline with castor oil in a total-loss lubrication system.
• Notable features: A single push-pull rod system using one rocker arm for both intake and exhaust valves, plus a split master connecting rod with internal concentric grooves securing the bronze slipper shoes of the articulating rods.

Current historical status

Original airframes and modern vintage reproductions equipped with Le Rhône-type engines remain active in exceptional heritage-flight settings, including aircraft associated with The Vintage Aviator and the Shuttleworth Collection. The engines are primarily of museum and historical interest today, with no current type certificate holder or active service bulletins and airworthiness directives identified in this collection data.

Five manual groups in this collection

The collection follows the five-group Rhône manifest. The group names below preserve the archive structure, while the detailed title-page records are retained where they have been confirmed. Some groups contain more than one file, and the 80–110 hp, 110 hp English, and 110/130 hp 1918 folders should be checked for overlap before being described as separate editions.

1. Le Rhône 80 HP Engine Manuals, 1920

2. Le Rhône 80–110 HP Engine Manuals

3. Le Rhône 110 HP and 130 HP Engine Manuals, 1918

4. Le Rhône 110 HP Engine Manuals, English

5. Le Rhône CJ Engine Manuals

Confirmed title-page records

1. Instructions for 80-horsepower Le Rhone Engine
   Document number: N/A
   Date: 1919
   Type: Operator / instructional manual
   Publisher: United States Bureau of Aircraft Production / Air Service

2. Care and Maintenance Manual for the Le Rhone Type J 9 Cylinder, 110hp Aero Engine
   Document number: Part No. 8
   Date: Circa 1917–1918
   Type: Maintenance manual

3. 110 H.P. Le Rhone Engine Installation, Operation, Description
   Document number: GGLERHONE HB C
   Date: Circa 1918
   Type: Service / operator manual

This archive is intended for aviation historians, collectors, restorers, museums, and researchers of First World War aircraft technology. It preserves the five-group manifest while avoiding unsupported claims about exact edition details where the title pages still require checking.

Historical reference material only. Not a substitute for current engineering, maintenance, or airworthiness instructions.