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The Gnome 7 Lambda was a French designed, seven-cylinder, air-cooled rotary aero engine that was produced under license in Britain and Germany. Powering several World War I era aircraft types it was claimed to produce 80 horsepower (60 kW) from its capacity of 12 litres (720 cubic inches) although recorded figures are lower.[1]

Gnome Lambda - Moteurs Gnome October 1913.png
Gnome 7 Lambda as shown in a 1913 Gnome catalog
Type Rotary aero engine
Manufacturer Gnome et Rhone
First run c.1911
Major applications Avro 504
Bristol Boxkite
Bristol Scout
Number built 979 (British production)

Just under 1,000 units were produced in Britain, the majority (967) by the Daimler Company of Coventry. A 14-cylinder variant was known as the Gnome 14 Lambda-Lambda.

In Germany Motorenfabrik Oberursel license-built the seven-cylinder engine as the Oberursel U.0 and later copied the 14-cylinder design and designated it as the Oberursel U.III.



Gnome 7 Lambda
Seven-cylinder, single-row rotary engine.
Gnome 7 Lambda (long stroke)
Increased stroke of 145 mm (5.7 in) to raise the compression ratio to 3.87:1, and total displacement to 12.26 litres.
Gnome 14 Double Lambda
14-cylinder, two-row rotary engine using Lambda cylinders. 160 hp (120 kW).
Motorenfabrik Oberursel U.0
German production of the Gnome 7 Lambda – had a 124mm cylinder bore and 140mm piston stroke for a total displacement of 11.52 litres, external diameter of 1.020 meters.[2]
Motorenfabrik Oberursel U.III
:German production of the Gnome 14 Double Lambda



An original Gnome 7 Lambda engine is installed in the Sopwith Tabloid replica aircraft on display in the Grahame-White hall of the Royal Air Force Museum London.[4]

Specifications (Gnome 7 Lambda)Edit

Oberursel U.III, a copy of the 14-cylinder Gnome Lambda-Lambda

Data from Lumsden.[1]

General characteristics

  • Type: 7-cylinder, single-row, rotary engine
  • Bore: 124 mm (4.9 in)
  • Stroke: 140 mm (5.5 in)
  • Displacement: 11.8 L (721.2 cu in)
  • Length: 112 cm (44 in)
  • Diameter: 93 cm (36.6 in)
  • Dry weight: 96 kg (212 lb)


  • Valvetrain: Automatic centre-piston inlet valve, overhead exhaust valve (one each per cylinder)
  • Cooling system: Air-cooled
  • Reduction gear: Direct drive, right-hand tractor, left-hand pusher


  • Power output: 50.3 kW (67.5 hp) at 1,250 rpm (maximum power)
  • Compression ratio: 3.75:1

See alsoEdit

Comparable engines

Related lists



  1. ^ a b Lumsden 2003, p. 151.
  2. ^ "Obsah fóra :: Zbraně a vybavení :: Výzbroj, zbraňové systémy, vybavení a příslušenství :: Motory :: Letecké motory :: Pístové :: Německo (DEU) :: Oberursel U.0". (in Czech). Retrieved July 19, 2013.
  3. ^ "The Borel Hydro-Monoplane". Flight: 450. 19 July 1913.
  4. ^ RAF Museum – Sopwith Tabloid replica history[permanent dead link] Retrieved: 11 November 2010.


  • Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.