Thursday, February 25, 2016
Le Rhone Type 9C
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 horsepower (97 kW)), 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 museums with several remaining airworthy, powering vintage aircraft types.
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 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.
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.
80 hp (60 kW) le Rhône 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 (82 kW) le Rhône 9J version.
The Le Rhône 9C is a nine-cylinder rotary aircraft engine produced in France by Gnome et Rhône. Also known as the Le Rhône 80 hp in a reference to its nominal power rating, the engine was fitted to a number of military aircraft types of the First World War. Le Rhône 9C engines were also produced under license in Great Britain by several companies, and in the United States.
In common with other Le Rhône series engines, the 9C featured highly visible telescopic copper induction pipes and used a single push-pull rod to operate its two overhead valves.
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 WW I-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.