Le Rhône
Encyclopedia
Le Rhône was the name given to a series of popular rotary aircraft engines
produced in France by Société des Moteurs Le Rhône and the successor company of Gnome et Rhône
. They powered a number of military aircraft types of the First World War
. Le Rhône engines were also produced under license worldwide.
Although not powerful (the largest wartime version produced 130 hp), they were dependable rotary engines. The Le Rhône 9 was a development of the Le Rhône 7, a seven-cylinder design. Examples of Le Rhône engines are on public display in aviation museum
s with several remaining airworthy, powering vintage aircraft types.
to the master rod. In the Le Rhône, the fuel–air mixture went first to an annular chamber at the back of the crankcase and thence, via polished copper pipes, to conventional intake ports and cam
-operated valves
in the cylinder heads. The copper induction tubes had their crankcase ends located in different places on the 80 hp versions – the 80 hp versions had them entering the crankcase in a location forward of the vertical centerline of each cylinder, while the 110 hp version had them located behind the cylinder's centerline. This resulted in the 80 hp version's intake plumbing being "fully visible" from the front, while the 110 hp version had the lower ends of its intake tubes seemingly "hidden" behind the cylinders.
A complicated slipper bearing system was used in the Le Rhône. Its master rod was a split-type to allow assembly of the connecting rods, and had three concentric grooves to take slipper bearings from all the other cylinders. The remaining rods carried bronze shoes, shaped to fit in the grooves, at their inner ends. Counting the master rod as no. 1, the shoes of nos. 2, 5, and 8 rode in the outer groove, those of 3, 6, and 9 in the middle groove, and 4 and 7 in the innermost one. Although complex, Le Rhônes worked very well.
The Le Rhônes employed an unusual method of valve actuation. A single rocker arm
, pivoted near its center, was made to operate both the exhaust valve and the intake valve. Pulled down, it opened the intake valve; pushed up, it opened the exhaust. To do this, the rocker had to be actuated by a push-pull rod instead of by the usual pushrod. This, in turn, meant that the cam followers had to have a positive action, which was accomplished by a system of links and levers. This system works well enough – some makers used it up to the late 'twenties – but its use makes overlap of valve openings impossible. In an engine designed for high- power and speed, the intake valve begins to open before the exhaust valve is quite closed, but on the Le Rhône, the rocker arm must clear the exhaust valve before it can contact that of the intake. While this put a limit on power output, most Le Rhône models produced all the power that their structural strength and cooling arrangements could cope with.
), Austria, the United Kingdom (by Daimler
), Russian Empire and Sweden.
Le Rhône 80 hp (60 kW) engines were made under license in the United States by Union Switch and Signal of Pennsylvania
, and the 110 hp (82 kW) Oberursel UR.II rotary engine used by Germany in World War I, in such famous fighters such as the Fokker Dr.I
triplane, was a close copy of the 110 hp 9J version.
Le Rhône Type 7A 50 hp (37 kW), seven-cylinder rotary engine - twenty built for use on Borel Monoplanes and Sommer Biplanes.
Le Rhône Type 7B 50 hp (37 kW), seven-cylinder rotary engine - Thirty-five prototype engines built.
Le Rhône Type 7B2 60 hp (44.7 kW), seven-cylinder rotary engine - 350 built at Societe Moteurs le Rhône.
Le Rhône Type 9C
80 hp (60 kW), nine-cylinder rotary engine.
Le Rhône Type 9J
110 hp (82 kW), nine-cylinder rotary engine.
Le Rhône Type 9Ja
110 hp (82 kW), nine-cylinder rotary engine.
Le Rhône Type 9Jb
120 hp (89.5 kW), nine-cylinder rotary engine.
Le Rhône Type 9Jby
130 hp (97 kW), nine-cylinder rotary engine.
Le Rhône Type 9R 170 hp (127 kW), nine-cylinder rotary engine.
Le Rhône 14D A two row rotary, consisting of two seven cylinder banks rotating round a single two throw crankshaft.
Le Rhône 18E A two row rotary, consisting of two nine cylinder banks rotating round a single two throw crankshaft.
Le Rhône 28E A four row rotary, consisting of four seven cylinder banks rotating round a single four throw crankshaft.
Le Rhône 11F An 11 cylinder rotary.
Le Rhône 9Z A 9 cylinder rotary.
Le Rhône K A 9 cylinder rotary prototype engine.
Le Rhône L An 9 cylinder rotary prototype engine.
Le Rhône M An 9 cylinder rotary prototype engine.
Le Rhône P An 9 cylinder rotary prototype engine.
Le Rhône R An 9 cylinder rotary prototype engine.
produced the 110 hp model, supposedly without authorization in Germany. The Oberursel Ur.II was a straight copy of the Le Rhône, but the Le Rhône was preferred over the Oberursel due to the superior materials used in the French product. However, by July 1918 there was a shortage in Germany of castor oil
, a plant-derived lubricant that the rotaries required as it could not be easily dissolved into the fuel, and because it possessed lubrication qualities superior to mineral oils of the day. A new Voltol-based lubricant, derived from mineral oil, was substituted and was blamed for a rash of engine failures on rotary-engined German fighters such as the Fokker E.V
which used the Oberursel Ur.II. It has been suggested that without the proper lubricants, the Le Rhône rotary would have been equally failure prone.
Rotary engine
The rotary engine was an early type of internal-combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary and the entire cylinder block rotated around it...
produced in France by Société des Moteurs Le Rhône and the successor company of Gnome et Rhône
Gnome et Rhône
Gnome et Rhône was a major French aircraft engine manufacturer. Between 1914 and 1918 they produced 25,000 of their 9-cylinder Delta and Le Rhône 110 hp rotary designs, while another 75,000 were produced by various licensees, powering the majority of aircraft in the first half of the war on...
. They powered a number of military aircraft types of the First World War
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
. Le Rhône engines were also produced under license worldwide.
Although not powerful (the largest wartime version produced 130 hp), they were dependable rotary engines. The Le Rhône 9 was a development of the Le Rhône 7, a seven-cylinder design. Examples of Le Rhône engines are on public display in aviation museum
Aviation museum
An aviation museum, air museum or aerospace museum is a museum exhibiting the history and artifacts of aviation. In addition to actual or replica aircraft, exhibits can include photographs, maps, models, dioramas, clothing and equipment used by aviators.Aviation museums vary in size from housing...
s with several remaining airworthy, powering vintage aircraft types.
Operation
The Le Rhône had a conventional induction system and an unusual method of connecting the link rodsConnecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....
to the master rod. In the Le Rhône, the fuel–air mixture went first to an annular chamber at the back of the crankcase and thence, via polished copper pipes, to conventional intake ports and cam
Cam
A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path...
-operated valves
Poppet valve
A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...
in the cylinder heads. The copper induction tubes had their crankcase ends located in different places on the 80 hp versions – the 80 hp versions had them entering the crankcase in a location forward of the vertical centerline of each cylinder, while the 110 hp version had them located behind the cylinder's centerline. This resulted in the 80 hp version's intake plumbing being "fully visible" from the front, while the 110 hp version had the lower ends of its intake tubes seemingly "hidden" behind the cylinders.
A complicated slipper bearing system was used in the Le Rhône. Its master rod was a split-type to allow assembly of the connecting rods, and had three concentric grooves to take slipper bearings from all the other cylinders. The remaining rods carried bronze shoes, shaped to fit in the grooves, at their inner ends. Counting the master rod as no. 1, the shoes of nos. 2, 5, and 8 rode in the outer groove, those of 3, 6, and 9 in the middle groove, and 4 and 7 in the innermost one. Although complex, Le Rhônes worked very well.
The Le Rhônes employed an unusual method of valve actuation. A single rocker arm
Rocker arm
Generally referred to within the internal combustion engine of automotive, marine, motorcycle and reciprocating aviation engines, the rocker arm is a reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it...
, pivoted near its center, was made to operate both the exhaust valve and the intake valve. Pulled down, it opened the intake valve; pushed up, it opened the exhaust. To do this, the rocker had to be actuated by a push-pull rod instead of by the usual pushrod. This, in turn, meant that the cam followers had to have a positive action, which was accomplished by a system of links and levers. This system works well enough – some makers used it up to the late 'twenties – but its use makes overlap of valve openings impossible. In an engine designed for high- power and speed, the intake valve begins to open before the exhaust valve is quite closed, but on the Le Rhône, the rocker arm must clear the exhaust valve before it can contact that of the intake. While this put a limit on power output, most Le Rhône models produced all the power that their structural strength and cooling arrangements could cope with.
Production
As well as production by Société des Moteurs Gnome et Rhône, which had bought out Société des Moteurs Le Rhône in 1914, the Le Rhône was produced in Germany (by Motorenfabrik OberurselMotorenfabrik Oberursel
Motorenfabrik Oberursel A.G. was a German manufacturer of automobile, locomotive and aircraft engines situated in Oberursel , near Frankfurt , Germany. During World War I it supplied a major 100 hp-class rotary engine that was used in a number of early-war fighter aircraft designs...
), Austria, the United Kingdom (by Daimler
Daimler Motor Company
The Daimler Motor Company Limited was an independent British motor vehicle manufacturer founded in London by H J Lawson in 1896, which set up its manufacturing base in Coventry. The right to the use of the name Daimler had been purchased simultaneously from Gottlieb Daimler and Daimler Motoren...
), Russian Empire and Sweden.
Le Rhône 80 hp (60 kW) engines were made under license in the United States by Union Switch and Signal of Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, and the 110 hp (82 kW) Oberursel UR.II rotary engine used by Germany in World War I, in such famous fighters such as the Fokker Dr.I
Fokker Dr.I
The Fokker Dr.I Dreidecker was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918...
triplane, was a close copy of the 110 hp 9J version.
Variants
data from : Moteurs de Légende by Gustave Hartmann.Le Rhône Type 7B 50 hp (37 kW), seven-cylinder rotary engine - Thirty-five prototype engines built.
Le Rhône Type 7B2 60 hp (44.7 kW), seven-cylinder rotary engine - 350 built at Societe Moteurs le Rhône.
Le Rhône Type 9C
80 hp (60 kW), nine-cylinder rotary engine.
Le Rhône Type 9J
110 hp (82 kW), nine-cylinder rotary engine.
Le Rhône Type 9Ja
110 hp (82 kW), nine-cylinder rotary engine.
Le Rhône Type 9Jb
120 hp (89.5 kW), nine-cylinder rotary engine.
Le Rhône Type 9Jby
130 hp (97 kW), nine-cylinder rotary engine.
Le Rhône Type 9R 170 hp (127 kW), nine-cylinder rotary engine.
Le Rhône 14D A two row rotary, consisting of two seven cylinder banks rotating round a single two throw crankshaft.
Le Rhône 18E A two row rotary, consisting of two nine cylinder banks rotating round a single two throw crankshaft.
Le Rhône 28E A four row rotary, consisting of four seven cylinder banks rotating round a single four throw crankshaft.
Le Rhône 11F An 11 cylinder rotary.
Le Rhône 9Z A 9 cylinder rotary.
Le Rhône K A 9 cylinder rotary prototype engine.
Le Rhône L An 9 cylinder rotary prototype engine.
Le Rhône M An 9 cylinder rotary prototype engine.
Le Rhône P An 9 cylinder rotary prototype engine.
Le Rhône R An 9 cylinder rotary prototype engine.
Oberursel copy
OberurselMotorenfabrik Oberursel
Motorenfabrik Oberursel A.G. was a German manufacturer of automobile, locomotive and aircraft engines situated in Oberursel , near Frankfurt , Germany. During World War I it supplied a major 100 hp-class rotary engine that was used in a number of early-war fighter aircraft designs...
produced the 110 hp model, supposedly without authorization in Germany. The Oberursel Ur.II was a straight copy of the Le Rhône, but the Le Rhône was preferred over the Oberursel due to the superior materials used in the French product. However, by July 1918 there was a shortage in Germany of castor oil
Castor oil
Castor oil is a vegetable oil obtained from the castor bean . Castor oil is a colorless to very pale yellow liquid with mild or no odor or taste. Its boiling point is and its density is 961 kg/m3...
, a plant-derived lubricant that the rotaries required as it could not be easily dissolved into the fuel, and because it possessed lubrication qualities superior to mineral oils of the day. A new Voltol-based lubricant, derived from mineral oil, was substituted and was blamed for a rash of engine failures on rotary-engined German fighters such as the Fokker E.V
Fokker D.VIII
-See also:-References:* Weyl, A.R. Fokker: The Creative Years. 1988. ISBN 0-851778-17-8....
which used the Oberursel Ur.II. It has been suggested that without the proper lubricants, the Le Rhône rotary would have been equally failure prone.
Applications
- Airco DH.5Airco DH.5-Bibliography:* Bruce, J.M. Warplanes of the First World War, Vol. 1. London: MacDonald, 1965, pp. 128–132.* Jackson, A.J. De Havilland Aircraft since 1915. London: Putnam, 1962....
- Avro 504Avro 504The Avro 504 was a World War I biplane aircraft made by the Avro aircraft company and under licence by others. Production during the War totalled 8,970 and continued for almost 20 years, making it the most-produced aircraft of any kind that served in World War I, in any military capacity, during...
- Bristol M.1Bristol M.1|-See also:-External links:* * * * *...
- Bristol ScoutBristol ScoutThe Bristol Scout was a simple, single seat, rotary-engined biplane originally intended as a civilian racing aircraft. Like other similar fast, light aircraft of the period - it was acquired by the RNAS and the RFC as a "scout", or fast reconnaissance type...
- Caudron G.3Caudron G.3The Caudron G.3 was a single-engined French biplane built by Caudron, widely used in World War I as a reconnaissance aircraft and trainer. In comparison to its competitors, it had a better rate of climb and it was considered especially suitable in mountainous terrain.-Development:The Caudron G.3...
- Caudron G.4Caudron G.4|-References:*Donald, David . The Encyclopedia of World Aircraft. Leicester, UK: Blitz Editions, 1997. ISBN 1-85605-375-X.* Kalevi Keskinen, Kyösti Partonen, Kari Stenman: Suomen Ilmavoimat I 1918-27, 2005. ISBN 952-99432-2-9....
- Hanriot HD.1Hanriot HD.1|-References:* Bruce, J.M. The Hanriot HD 1 Leatherhead: Profile Publications* Cheesman E.F. Fighter Aircraft of the 1914-1918 War Letchworth, Harletford Publications, 1960 pp. 82-83- External links :*...
- La Cierva C-6, autogyroAutogyroAn autogyro , also known as gyroplane, gyrocopter, or rotaplane, is a type of rotorcraft which uses an unpowered rotor in autorotation to develop lift, and an engine-powered propeller, similar to that of a fixed-wing aircraft, to provide thrust...
, 1924 - Macchi M.14Macchi M.14-References:*Green, William, and Gordon Swanborough. The Complete Book of Fighters: An Illustrated Encyclopedia of Every Fighter Aircraft Built and Flown. New York: SMITHMARK Publishers, 1994. ISBN 0-8317-3939-8....
- Morane-Saulnier N
- Nieuport 11Nieuport 11|-See also:-References:NotesBibliography* Angelucci, Enzio, ed. The Rand McNally Encyclopedia of Military Aircraft. New York: The Military Press, 1983. ISBN 0-517-41021-4....
"Bebe" - Nieuport 17Nieuport 17|-Specifications :-See also:-Bibliography:* Bruce, Jack. "Those Classic Nieuports". Air Enthusiast Quarterly. Number Two, 1976. Bromley, UK:Pilot Press. pp. 137–153....
- Nieuport 27
- Sopwith CamelSopwith CamelThe Sopwith Camel was a British First World War single-seat biplane fighter introduced on the Western Front in 1917. Manufactured by Sopwith Aviation Company, it had a short-coupled fuselage, heavy, powerful rotary engine, and concentrated fire from twin synchronized machine guns. Though difficult...
- Sopwith PupSopwith PupThe Sopwith Pup was a British single seater biplane fighter aircraft built by the Sopwith Aviation Company. It entered service with the Royal Flying Corps and the Royal Naval Air Service in the autumn of 1916. With pleasant flying characteristics and good maneuverability, the aircraft proved very...
- Standard E-1Standard E-1|-See also:-References:* Donald, David, ed. Encyclopedia of World Aircraft, p. 854, "Standard aircraft". Etobicoke, Ontario: Prospero Books, 1997.* -External links:*...
- Thomas-Morse S-4CThomas-Morse S-4|-See also:-Bibliography:* Donald, David, ed. Encyclopedia of World Aircraft, p. 875, "Thomas Brothers and Thomas-Morse aircraft". Etobicoke, Ontario: Prospero Books, 1997....
- Fokker Dr.IFokker Dr.IThe Fokker Dr.I Dreidecker was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918...
- Mosca MB 2 bis