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Le Rhône 7

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. First run in 1910, 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 horsepower (97 kW)), they were dependable rotary engines. The Le Rhône 9 was a development of the Le Rhône 7, a seven-cylinder design.

The copper induction tubes had their crankcase ends located in different places on the 80 and 110 horsepower (60 and 82 kW) 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 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 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 value. 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 functioned but it did prevent the incorporation of valve overlap which limits power output. Due to the structural and cooling limitations of the overall engine design the Le Rhône engines produced as much power as they were capable of, regardless.

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), 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.



Le Rhône Type 7A
(1910) 50 hp (37 kW), seven-cylinder rotary engine - twenty built for use on Borel Monoplanes and Sommer Biplanes.

Le Rhône Type 7B
(1911) 50 hp (37 kW), seven-cylinder rotary engine - Thirty-five prototype engines built.

Le Rhône Type 7B2
(1912) 60 hp (44.7 kW), seven-cylinder rotary engine - 350 built at Societe Moteurs le Rhône.


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Avro 504
Bristol M.1
Bristol Scout
Caudron G.3
Caudron G.4
Hanriot HD.1
Fokker Dr.I
La Cierva C-6, autogyro, 1924
Macchi M.14
Morane-Saulnier N
Mosca MB 2 bis
Nieuport 11 "Bebe"
Nieuport 17
Nieuport 27
Sopwith Camel
Sopwith Pup
Standard E-1
Texas-Temple prototype
Thomas-Morse S-4C





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