Williams Brothers 30260 80 HP Le Rhône 9C Rotary Aircraft Engine — 1/6 Scale

Manufacturer: Williams Brothers

Kit number: 30260

Manufacturer/product number: 0040-30260-01

Subject: Le Rhône 9C / 80 HP rotary aircraft engine

Scale: 1/6

Type: Injection-moulded plastic engine model

Colour of moulded parts: Black plastic

Status: Discontinued

Kit contents: Engine components and instruction sheet

Approximate finished dimensions: 6.25 in / 159 mm diameter and 7.25 in / 184 mm long.
Williams Brothers

Williams Brothers became particularly well known among enthusiasts for producing unusual aircraft subjects, aircraft engines and accessories in scales that were sometimes poorly represented by the major manufacturers.

The company's engine kits are especially interesting because they allow the modeller to display the mechanical heart of an aircraft rather than simply the exterior.

The Williams Brothers Le Rhône is one of the company's best-known engine subjects.

A contemporary modeller discussion specifically identifies the Williams Brothers engine range as including the Wright Whirlwind, Pratt & Whitney Wasp Jr. and Le Rhône, with the Le Rhône being one of the company's reissued engine kits.

The 30260 is therefore part of a distinctive Williams Brothers product family rather than a conventional aircraft-kit range.
Kit contents

The kit is moulded in black plastic and is intended to reproduce the principal components of the nine-cylinder rotary engine.

The documented contents include black plastic parts trees containing:

nine cylinders;

crankcase components;

pushrods;

rocker arms;

associated valve-train components;

other engine fittings;

instruction sheet.

The large 1/6 scale makes the engine particularly impressive as a display model.

At approximately 159 mm across, the completed engine is substantially larger than a conventional 1/32 or 1/48 aircraft-engine accessory.

The model is intended to be assembled and painted by the modeller, with conventional polystyrene cement and modelling paints required.
What makes this kit unusual

The Le Rhône was a rotary engine, meaning that the cylinders and crankcase rotated around a stationary crankshaft during operation.

That makes it quite different visually from a conventional fixed-cylinder radial engine.

A good model therefore has considerable display value because the exposed nine-cylinder arrangement, rocker arms and pushrods are immediately recognisable.
The real engine — Le Rhône 9C

The Le Rhône 9C, commonly referred to simply as the Le Rhône 80 HP, was a French nine-cylinder rotary aircraft engine that became one of the most important powerplants of the early First World War.

The engine was developed by French engineer Louis Verdet.

Safran's historical account records that Verdet developed an 80 hp nine-cylinder rotary engine in the early 1910s and subsequently founded the Société des Moteurs Le Rhône on 29 September 1912.

The 9C became an important development in rotary-engine technology at a time when aircraft engines needed to provide greater power without becoming excessively heavy.
Technical specifications

The 9C was a remarkably compact engine for its output.

Typical specifications include:

Configuration: 9-cylinder rotary

Cooling: Air cooled

Displacement: approximately 10.9 litres

Bore: 105 mm

Stroke: 140 mm

Power: 80 hp

Rated speed: 1,200 rpm

Weight: approximately 110–112 kg

Diameter: approximately 940 mm.

The Australian War Memorial has a complete Le Rhône 9C in its collection and records the engine as producing 80 horsepower at 1,200 rpm, with an approximately 11-litre capacity and a diameter of 940 mm.
How a rotary engine worked

The term rotary can be confusing because the engine is not simply a conventional radial engine.

In a normal radial engine, the cylinders are fixed around a stationary crankcase while the crankshaft rotates.

In the Le Rhône, the cylinders and crankcase rotate, while the crankshaft remains comparatively stationary.

The propeller is attached to the rotating engine assembly.

This arrangement had several advantages in early aviation.
Low weight

The rotary engine eliminated some of the heavy components required by conventional engines.
Good cooling

The complete cylinder assembly rotated rapidly through the airflow, providing excellent cooling.
Smooth operation

The rotating mass also helped produce a relatively smooth-running engine.
Major disadvantage — fuel and oil consumption

The engine's design had a significant disadvantage: lubrication and fuel systems were primitive compared with later engines.

Castor oil was used as lubricant and much of it was expelled overboard.

This is one reason early rotary-powered aircraft were associated with the distinctive oily residue that covered the pilot and airframe.
Valve arrangement

The Le Rhône's valve system was particularly distinctive.

Each cylinder used a single push-pull valve rod and rocker arrangement.

The Australian War Memorial describes the engine as having poppet valves, rocker arms and a distinctive connecting-rod arrangement.

The nine connecting rods were arranged around a central master crank arrangement.

The design was mechanically ingenious but quite different from later conventional radial engines.

This is one reason the Williams Brothers model is interesting: the relatively large 1/6 scale gives the modeller enough space to reproduce these mechanical features.
Development and production

The Le Rhône 9C first appeared in the early 1910s.

Safran's historical material traces the development to Louis Verdet's work on rotary engines around 1911, followed by the establishment of Société des Moteurs Le Rhône in 1912.

The engine became sufficiently successful that production expanded beyond the original French manufacturer.

The 9C was manufactured in:

France;

Britain;

the United States;

Sweden;

Italy and other licensed-production locations.

The Australian War Memorial notes French, British, Italian and American production, while historical engine references also document licensed manufacture in Sweden and other countries.

The American version was manufactured by Union Switch & Signal Company in Pennsylvania during 1917–1918.

More than 10,000 Le Rhône 9C engines were produced, making it one of the major early rotary engines.
Gnome and Le Rhône

The history of the company is closely connected with Gnome.

Competition between the Gnome and Le Rhône companies was intense before the First World War.

Eventually, the two companies were brought together.

Safran's corporate history explains that the relationship developed into an acquisition, eventually leading to the later Gnome et Rhône company.

Gnome et Rhône subsequently became one of Europe's most important aircraft-engine manufacturers.

The company ultimately became part of the industrial lineage that leads to modern Safran Aircraft Engines.
Aircraft powered by the Le Rhône 9C

The engine was used in a remarkably wide variety of aircraft.

Documented applications include:

The propeller is attached to the rotating engine assembly.
Low weight
Good cooling
Smooth operation
Major disadvantage — fuel and oil consumption

Nieuport 10

Nieuport 11

Nieuport 21

Sopwith Pup

Bristol Scout

Caudron G.III

Morane-Saulnier L

Morane-Saulnier N

Morane-Saulnier P

Royal Aircraft Factory S.E.4

Vickers F.B.12

Thomas-Morse S-4

Farman HF.20

Bleriot aircraft

Sopwith Dove

numerous other early aircraft.

This means the Williams Brothers engine can be displayed with a surprisingly large range of WWI aircraft models.