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 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 (81 kW) rotary designs, while another 75,000 were produced by various licen ...

. They powered a number of military aircraft types of the

First World War World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

. Le Rhône engines were also produced under license worldwide. Although not powerful (the largest wartime version produced ), they were dependable rotary engines.Le Rhone Rotary Engine
Retrieved on 18 February 2009. The Le Rhône 9 was a development of the Le Rhône 7, a seven-cylinder design. Examples of nine-cylinder Le Rhône rotary engines are on public display in

aviation museum An aviation museum, air museum, or air and space museum is a museum exhibiting the history and cultural artifacts, artifacts of aviation. In addition to actual, replica or accurate reproduction aircraft, exhibits can include photographs, maps, P ...

s with several remaining airworthy, powering vintage aircraft types.

Operation

In most respects the Le Rhône engines were typical rotary engines, so that the

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

remained stationary in operation, with the entire

crankcase In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/a ...

and its attached cylinders rotating around it as a unit. The copper induction tubes had their crankcase ends located in different places on the versions; the 80 hp versions had them entering the crankcase in a location ''forward'' of the vertical center-line of each cylinder, while the 110 hp version had them located behind the cylinder's center-line. 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 engine. The master rod was of a split-type, which permitted assembly of the connecting rods. It also employed three concentric grooves, designed to accept slipper bearings from the other cylinders. The other connecting rods used inner-end bronze shoes, which were shaped to fit in the grooves. The master rod was numbered as number one and the shoes of numbers two, five and eight rode in the outer groove, the shoes of three, six and nine in the middle groove and four and seven in the inner groove. Although this system was complex, the Le Rhône engines worked very well. The Le Rhône engines used an unconventional valve actuation system, with a single centrally-pivoting

rocker arm In the context of an internal combustion engine, a rocker arm is a valvetrain component that typically transfers the motion of a pushrod to the corresponding intake/exhaust valve. Rocker arms in automobiles are typically made from stamped steel ...

moving the exhaust valve and the intake valve. When the arm moved down it opened the intake valve and when it moved up it opened the exhaust valve. To make this system work a two-way push-pull rod was fitted, instead of the more conventional one-way pushrod. This feature required the cam followers to incorporate a positive action, a function designed in by using a combination of links and levers. This design prevented valve overlap and so limited power output, but as the engine structure and cooling arrangements would not have been adequate at a higher power output, this should not be considered a significant design fault.

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 Oberursel Motorenfabrik Oberursel A.G. was a German manufacturer of automobile, locomotive and aircraft engines situated in Oberursel (Taunus), near Frankfurt (Main), Germany. During World War I it supplied a major 100 hp-class rotary engine that was u ...

), Austria, the United Kingdom (by Daimler), Russian Empire and Sweden. le Rhône engines were made under license in the United States by Union Switch and Signal of

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

, and the Oberursel Ur.II rotary engine used by Germany in World War I, in such famous fighters such as the

Fokker Dr.I The Fokker Dr.I (''Dreidecker'', "triplane" in German), often known simply as the Fokker Triplane, was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918. It became famous as the ...

triplane, was a close copy of the

le Rhône 9J The Le Rhône 9J is a nine-cylinder rotary aircraft engine produced in France by Gnome et Rhône. Also known as the Le Rhône 110 hp in a reference to its nominal power rating, the engine was fitted to a number of military aircraf ...

version.

Variants

''Data from'' : Oberursel-UR-2-engine

;Le Rhône Type 7A :(1910) , seven-cylinder rotary engine — twenty built for use on Borel Monoplanes and Sommer Biplanes. ;Le Rhône Type 7B :(1911) , seven-cylinder rotary engine — Thirty-five prototype engines built. ;Le Rhône Type 7B2 :(1912) , seven-cylinder rotary engine — 350 built at Societe Moteurs le Rhône. ;Le Rhône Type 7Z :40hp ;Le Rhône Type 9C :(1916) , nine-cylinder rotary engine. ;Le Rhône Type 9J :(1913) , nine-cylinder rotary engine. ;Le Rhône Type 9Ja :(1915) , nine-cylinder rotary engine. ;Le Rhône Type 9Jb :(1916) , nine-cylinder rotary engine. ;Le Rhône Type 9Jby :(1916) , nine-cylinder rotary engine. Le Rhône 9R - Paris 1919 050220 p147

;Le Rhône Type 9R :(1916) / 9-cylinder rotary. ;Le Rhône 9Z :(1920) A 9-cylinder rotary. ;Le Rhône 11F :(1913) A 11-cylinder rotary. ;Le Rhône 14D :(1912) A two-row rotary, consisting of two seven-cylinder rows rotating round a single two-throw crankshaft. ;Le Rhône 18E (1912) :(1912) A two-row rotary, consisting of two nine-cylinder rows rotating round a single two-throw crankshaft. ;Le Rhône 18E (1917) :(1917) A two-row rotary, consisting of two 9R rows rotating round a single two-throw crankshaft. ;Le Rhône 28E :(1918) A four-row rotary, consisting of four seven-cylinder rows rotating round a single four-throw crankshaft. ;Le Rhône K :(1916) A 9-cylinder rotary prototype engine. ;Le Rhône L :(1916) A 9-cylinder rotary prototype engine. ;Le Rhône M :(1917) A 9-cylinder rotary engine produced in small quantities. ;Le Rhône P :(1917) A 9-cylinder rotary prototype engine. ;Le Rhône R :(1917) A 9-cylinder rotary prototype engine. ;Oberursel Ur.II :A clone of the Le Rhône 9J ;Oberursel Ur.III :An 11 cylinder German development of the Ur.II (Le Rhône 9J).

Oberursel licence production

Oberursel Oberursel (Taunus) () is a town in Germany and part of the Frankfurt Rhein-Main urban area. It is located to the north west of Frankfurt, in the Hochtaunuskreis county. It is the 13th largest town in Hesse. In 2011, the town hosted the 51st Hes ...

produced the 110 hp model, supposedly without authorization in Germany. The Oberursel Ur.II was a licensed copy of the Le Rhône, but imported or captured Le Rhônes were preferred over the Oberursel due to tighter manufacturing tolerances with the French product. However, by July 1918 there was a shortage in Germany of

castor oil Castor oil is a vegetable oil pressed from castor beans. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about ...

, a plant-based lubricant that the rotaries required, as it didn't dissolve easily into the fuel and because its heat tolerance and lubrication qualities were superior to available mineral oils.Gnome Monosoupape Type N Rotary
Retrieved on 18 February 2009. A new Voltol-based lubricant, derived from mineral oil, was substituted and was blamed for engine failures on German fighters such as the

Fokker E.V The Fokker E.V was a German parasol wing, parasol-monoplane fighter aircraft designed by Reinhold Platz and built by Fokker, Fokker-Flugzeugwerke. The E.V was the last Fokker design to become operational with the ''Luftstreitkräfte,'' entering se ...

, which used the Oberursel Ur.II. It has been claimed that without castor oil, the Le Rhône rotary would have been equally failure-prone. An Oberursel reproduction was manufactured by The Vintage Aviator Company in New Zealand in limited numbers by reverse engineering an original Oberursal engine, for their own project aircraft.

Le Rhônes still flying today

Several enthusiasts are using original Le Rhône engines for World War I replica aircraft today. A flying example can be seen at the Pioneer Flight Museum, Kingsbury Texas in a replica Fokker Dr 1. pioneerflightmuseum.org The engine had previously been flown in an original Thomas Morse Scout, which is now under restoration with another Le Rhône 80 hp engine planned for that flying aircraft. There are other reproductions of Dr 1's flying original Le Rhône engines, as well as the restored Thomas Morse Scouts in the United States.

Applications

* Adamoli-Cattani fighter *

Airco DH.5 The Airco DH.5 was a British First World War single-seat biplane fighter aircraft. It was designed and manufactured at British aviation company Airco. Development was led by aircraft designer Geoffrey de Havilland as a replacement for the obs ...

Avro 504 The Avro 504 was a First World War 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 tha ...

Beardmore W.B.III The Beardmore WB.III was a British carrier-based fighter biplane of World War I. It was a development of the Sopwith Pup that William Beardmore and Company, Beardmore was then building under licence, but was specially adapted for shipboard use. ...

Bristol M.1 The Bristol M.1 Monoplane Scout was a British monoplane Fighter aircraft, fighter of the World War I, First World War. It holds the distinction of being the only British monoplane fighter to reach production during the conflict. During mid-191 ...

Bristol Scout The Bristol Scout was a single-seat rotary-engined biplane originally designed as a racing aircraft. Like similar fast, light aircraft of the period it was used by the RNAS and the RFC as a " scout", or fast reconnaissance type. It was one o ...

* Caudron C.27 *

Caudron G.3 The Caudron G.3 was a single-engined French sesquiplane built by Caudron, widely used in World War I as a reconnaissance aircraft and trainer. Development The Caudron G.3 was designed by René and Gaston Caudron as a development of their earli ...

* Caudron G.4 *

Cierva C.6 The Cierva C.6 was the sixth autogyro designed by engineer Juan de la Cierva, and the first one to travel a "major" distance. Juan de la Cierva, 1st Count of la Cierva, Cierva, the engineer responsible for the invention of the autogyro, had spe ...

, (

autogyro An autogyro (from Greek and , "self-turning"), also known as a ''gyroplane'', is a type of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. Forward thrust is provided independently, by an engine-driven propeller. Whi ...

) *

Fokker D.VI The Fokker D.VI was a German fighter aircraft built in limited numbers at the end of World War I. The D.VI served in the German and Austro-Hungarian air services. Design and development In late 1917, Fokker-Flugzeugwerke built two small biplane ...

Fokker D.VIII The Fokker E.V was a German parasol-monoplane fighter aircraft designed by Reinhold Platz and built by Fokker-Flugzeugwerke. The E.V was the last Fokker design to become operational with the ''Luftstreitkräfte,'' entering service in the last mon ...

* Hanriot HD.1 * Hanriot HD.14 *

Macchi M.14 The Macchi M.14 was an Italian fighter of 1918 designed and manufactured by Macchi. The M.14 was the first non-seaplane fighter Macchi produced, its previous fighter production having focused on flying boat fighters. Design and development A ...

Morane-Saulnier N The Morane-Saulnier N, also known as the Morane-Saulnier Type N, was a French monoplane fighter aircraft of the First World War. Designed and manufactured by Morane-Saulnier, the Type N entered service in April 1915 with the ''Aéronautique Mili ...

Morane-Saulnier BB The Morane-Saulnier BB was a military observation aircraft produced in France during World War I for use by Britain's Royal Flying Corps.Taylor 1989, 684"The Illustrated Encyclopedia of Aircraft", 2538 It was a conventional single-bay biplane ...

Morane-Saulnier AI The Morane-Saulnier AI (also Type AI) was a French parasol-wing fighter aircraft produced by Morane-Saulnier during World War I. Development and design The AI was developed as a refinement of the Morane-Saulnier Type N concept, and was intended ...

(trainers) * Mosca MB 2 bis * Nielsen & Winther Type AA *

Nieuport 10 The Nieuport 10 (or Nieuport XB in contemporary sources) was a French First World War sesquiplane that filled a wide variety of roles, including reconnaissance, fighter and trainer. Design and development In January 1914, designer Gustave Delag ...

Nieuport 11 The Nieuport 11 (or Nieuport XI C.1 in contemporary sources), nicknamed the ''Bébé'', was a French World War I single seat sesquiplane fighter aircraft, designed by Gustave Delage. It was the primary aircraft that ended the Fokker Scourge in ...

and 16 *

Nieuport 17 The Nieuport 17 C.1 (or Nieuport XVII C.1 in contemporary sources) was a French sesquiplane fighter designed and manufactured by the Nieuport company during World War I. An improvement over the Nieuport 11, it was a little larger than earlier N ...

, 21 & 23 *

Nieuport 24 The Nieuport 24 (or Nieuport XXIV C.1 in contemporary sources) was a World War I French sesquiplane fighter aircraft designed by Gustave Delage as a development of the successful Nieuport 17. The Nieuport 24 had the misfortune to be the penul ...

, 24bis and 27 *

Nieuport 31 The Nieuport Nie 31 or Nieuport 31 was a single-engine, single-seat monoplane or sesquiplane fighter aircraft designed and built in France in 1919. Design and development Though the Nie 31 (it had been flown and subsequently abandoned before ...

* Nieuport 80, 81 and 83 * Sikorsky S-16 *

Sopwith Camel The Sopwith Camel is a British First World War single-seat biplane fighter aircraft that was introduced on the Western Front in 1917. It was developed by the Sopwith Aviation Company as a successor to the Sopwith Pup and became one of the b ...

Sopwith Pup The Sopwith Pup is a British single-seater biplane fighter aircraft built by the Sopwith Aviation Company. It entered service with the Royal Naval Air Service and the Royal Flying Corps in the autumn of 1916. With pleasant flying characteristi ...

SPAD S.A The SPAD S.A (also called S.A.L.) was a French two-seat tractor biplane first flown in 1915. It was used by France and Russia in the early stages of the First World War in the fighter and reconnaissance roles. It was a unique aircraft that carrie ...

.2 & 4 * Spijker V.1 *

Spijker V.2 The Spijker V.2, sometimes anglicized to Spyker V.2 or Spyker-Trompenburg V.2, was a low powered, tandem seat biplane designed and built for the Dutch government for pilot training towards the end of World War I. More than seventy were built. ...

* Standard E-1 *

Thomas-Morse S-4 The Thomas-Morse S-4 Scout was an American biplane advanced trainer, operated by the United States Army and the United States Navy. Dubbed the "Tommy" by pilots who flew it, the aircraft became the favorite single-seat training airplane produced ...

C * Thulin E * TNCA Serie E ''Sonora'', ''Tololoche'', and ''México''

References

Notes

Bibliography

* * Gunston, Bill. ''World Encyclopedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989.

External links

Oberursel UR-II Rotary Engine
{{DEFAULTSORT:Le Rhone Air-cooled aircraft piston engines 1910s aircraft piston engines Gnome-Rhône aircraft engines Rotary aircraft piston engines