Clerget

The Clerget was an early rotary aircraft engine. Manufactured in both Great Britain (Gwynne Limited) and France, it was used on such aircraft as the Sopwith Camel.

What distinguished the Clerget from its rivals (Gnome and Le Rhône) was the Clerget had normal intake and exhaust valves unlike the Gnome, and the connecting rod arrangement was much simpler than the Le Rhone. A source of failure among the Clerget engines were the piston rings, called obturator rings. These were located below the wrist pin to block heat transfer from the combustion area to the lower part of the cylinder. These rings were often made from brass and only had a lifespan of a few hours. The Clerget engines were considered reliable but they cost more per unit to produce than their rivals. Unlike other contemporary rotaries which were either on or off, the Clerget featured a throttle.

The Bentley BR1 and Bentley BR2 rotaries were designed as improvements of the Clerget, while sharing some of the earlier engine's distinctive design features.

Design features

The Clerget is an air-cooled rotary engine with nine cylinders. It is fitted with a double thrust ball race, which enables it to be used either as a pusher or as a tractor.

The engine works on a four-stroke cycle. Its chief points of difference from other rotary engines are:
* The pistons are of an aluminium alloy.
* The connecting rods have a tubular section.
* The inlet and exhaust cams are mechanically operated by means of separate cams, tappets and rocker arms.

The direction of rotation is counter-clockwise as seen from the propeller end of the engine. Like many other radial engines it is made chiefly of steel, for strength and lightness. Between any two consecutive explosions, the engine turns 80 degrees.

pecifications (Clerget Type 9)

pistonspecs

type=9 cylinder air cooled rotary
bore=120mm (4.7 in)
stroke=150mm (5.9 in)
displacement=15.3 Litres (931 cu in)
length=
diameter=
width=
height=
weight=166kg (365 lb)
valvetrain=
supercharger=
turbocharger=
fuelsystem=Carburetor
fueltype=
oilsystem=
coolingsystem=air
power=110hp (82 kw) @ 1,200 RPM
specpower=
compression=
fuelcon=10 imp gal/h (45 L/h)
specfuelcon=
oilcon=2 imp gal/h (9 L/h)
power/weight=3.3 lb per rated hp (2 kg/kW)

pecifications (Clerget Type 9B)

pistonspecs

type=9 cylinder air cooled rotary
bore=120mm (4.7 in)
stroke=160mm (6.3 in)
displacement=16.3 Liters (992 cu in)
length=
diameter=
width=
height=
weight=173kg (381 lb)
valvetrain=
supercharger=
turbocharger=
fuelsystem=Carburetor
fueltype=
oilsystem=
coolingsystem=air
power=130 (96 kw) hp @ 1,250 RPM
specpower=
compression=
fuelcon=
specfuelcon=
oilcon=
power/weight=

Applications

* Caudron C.60
* Morane-Saulnier MoS-50
* Nieuport 12
* Armstrong Whitworth F.K.10
* Sopwith Baby
* Sopwith Camel
* Sopwith 1½ Strutter
* Sopwith Triplane
* Grigorovich M-5

External links

* [http://www.aviation-history.com/engines/clerget.htm Picture and Description]
* [http://www.powerhousemuseum.com/collection/database/?irn=206765 A Clerget-Blin 9Bf, Gwynnes Ltd, at Powerhouse Museum, Sydney, Australia]

References

* "Air Board" Technical Notes issued by Controller Technical Department for persons holding an official position in His Majesty's Service dated 1918
*