The Bentley B.R.2 was a nine-cylinder British rotary

aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years ma ...

developed during the

First World War World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

by the motor car engine designer

W. O. Bentley Walter Owen Bentley, MBE (16 September 1888 – 13 August 1971) was an English engineer who founded Bentley Motors Limited in London. He was a motorcycle and car racer as a young man. After making a name for himself as a designer of aircraft a ...

from his earlier Bentley BR.1. Coming as it did near the end of the war, the BR.2 was built in smaller numbers than the earlier BR.1 – its main use being by the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

in the early 1920s.

Design and development

The initial variant of the BR.2 developed , with nine cylinders measuring for a total displacement of 1,522 cubic inches (24.9 L). It weighed , only more than the Bentley B.R.1 (A.R.1). This was the last type of rotary engine to be adopted by the RAF – later air-cooled aircraft engines such as the

Cosmos Jupiter The Bristol Jupiter was a British nine-cylinder single-row piston radial engine built by the Bristol Aeroplane Company. Originally designed late in World War I and known as the Cosmos Jupiter, a lengthy series of upgrades and developments tur ...

and

Armstrong Siddeley Jaguar The Armstrong Siddeley Jaguar was an aircraft engine developed by Armstrong Siddeley. The Jaguar was a petrol-fuelled air-cooled 14-cylinder two-row radial engine design. The Jaguar III was first used in 1923, followed in 1925 by the Jaguar ...

being almost entirely of the fixed

radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing f ...

type. With the BR.2, the rotary engine had reached a point beyond which this type of engine could not be further developed, due to its inherent limitations.

Applications

The type selected as the standard single-seat fighter of the post-war RAF, the

Sopwith Snipe The Sopwith 7F.1 Snipe was a British single-seat biplane fighter of the Royal Air Force (RAF). It was designed and built by the Sopwith Aviation Company during the First World War, and came into squadron service a few weeks before the end of th ...

, had been designed around the BR.2, as had its

ground attack In military tactics, close air support (CAS) is defined as air action such as air strikes by fixed or rotary-winged aircraft against hostile targets near friendly forces and require detailed integration of each air mission with fire and movemen ...

version, the Sopwith TF.2 Salamander. A number of other experimental and minor production types were either designed for, or otherwise fitted with this power plant during the late "war" years and into the early 1920s. Gloster Nightjar02

* Armstrong Whitworth Armadillo * Austin Osprey * Boulton Paul Bobolink * Brennan Helicopter * Gloster Grouse * Gloster Nightjar * Gloster Sparrowhawk *

Grain Griffin The Grain Griffin was a British carrier-based reconnaissance aircraft developed and built by the RNAS Marine Experimental Depot, Port Victoria, during the First World War. A development of the unsuccessful Sopwith B.1 bomber, the Grain Griffin ...

* Handley Page Type S * Nieuport Nightjar * Parnall Panther * Sopwith Buffalo * Sopwith Gnu *

Sopwith Salamander The Sopwith TF.2 Salamander was a British ground-attack aircraft of the First World War designed by the Sopwith Aviation Company which first flew in April 1918. It was a single-engined, single-seat biplane, based on the Sopwith Snipe fighter, wi ...

* Vickers Vampire

Variants

;BR.2 230 :1918, 230 hp. ;BR.2 245 :1918, 245 hp.

Engines on display

A Bentley BR.2 is on public display in the

Science Museum (London) The Science Museum is a major museum on Exhibition Road in South Kensington, London. It was founded in 1857 and is one of the city's major tourist attractions, attracting 3.3 million visitors annually in 2019. Like other publicly funded ...

, another forms part of the aero engine collection at the

Royal Air Force Museum Cosford The Royal Air Force Museum Cosford, located in Cosford in Shropshire, is a free (currently, 2022) museum dedicated to the history of aviation and the Royal Air Force in particular. The museum is part of the Royal Air Force Museum, a non-departme ...

. Another one (serial number 40543, manufactured by Gwynnes) is in the

National Military Museum, Romania The King Ferdinand I National Military Museum ( ro, Muzeul Militar Național "Regele Ferdinand I"), located at 125-127 Mircea Vulcănescu St., Bucharest, Romania, was established on 18 December 1923 by King Ferdinand I. It has been at its present ...

. The sole operational BR.2 is mounted in Fantasy of Flight's replica of the

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A ¼ scale working replica of the Bentley BR.2 World War I rotary aero engine built by Lewis Kinleside Blackmore is currently on display at the Bentley Memorial Building in Oxfordshire, UK. This was the first model built of this engine and is the subject also of a book by L K Blackmore. The Canada Aviation and Space Museum in Ottawa, Ontario, Canada has a BR.2 installed in their Sopwith 7F.1 Snipe.

Specifications (BR.2)

References

Notes

Bibliography

* * Gunston, Bill. ''World Encyclopedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. *''Jane's Fighting Aircraft of World War I''. London. Studio Editions Ltd, 1993. * Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. .

External links

National Museum of the USAF - BR.2 fact sheet
{{Bentley Rotary aircraft piston engines Air-cooled aircraft piston engines 1910s aircraft piston engines