| Sikh | |
|---|---|
 A Sunbeam Sikh at the 1919 Paris Aero Salon | |
| Type | V-12 water-cooled piston engine |
| National origin | Britain |
| Manufacturer | Sunbeam[1] |
| Designer | |
| First run | 11 May 1919[1] |
| Major applications | Intended for airships[1] |
| Number built | Prototypes only[1] |
TheSunbeam Sikh was a large slow running V-12 piston engine, intended to power airships, under development at the time of theArmistice.[1]
At the end of theFirst World War there was an expectation that Britain would continue the development of airships to provide air travel throughout theBritish Empire. To power the expected airships Louis Coatalen designed the large Sikh V-12 engine delivering 800 hp (600 kW) at only 1,400 rpm, from 64.13 litre (3,913 in3) displacement in a 60-degreeV12 configuration, with six valves per cylinder operated by rockers actuated by overhead camshafts.[1]
Bench testing of this impressive engine began in 1919, passingAir Ministry acceptance tests in time for one to be displayed at the1919 Paris Aero Salon and the1920 Olympia Aero Show where it generated much interest, due to its size, but no production orders.[2] Competition to power what little airship production there was came from theRolls-Royce Condor and theNapier Cub. Development work continued till the engine produced 1,000 hp (750 kW) by 1923.[1]
To power smaller airships orBlimps, Coatalen used one cylinder bank to create theSikh II akaSemi-Sikh, a straight six-cylinder developing 400 to 425 hp (298 to 317 kW) @ 1,400 rpm.[1] As with the Sikh, the market for airship engines dried up after the war, so no production Sikh II engines were built.[1]
In the late 1920s large airships were in favour again, so Coatalen revised the Sikh and developed theSunbeam Sikh III for theR100 andR101 airship families.[2] Retaining the bore, stroke and displacement of the earlier engine, detail refinements included five valves per cylinder and enclosed valve-gear. The Sikh III was displayed at the 1929 Olympia Aero Show, generating interest due to its large size, weight and power. After theR101 disaster the large Empire airships were abandoned, and the airship market for Sunbeam engines disappeared for a second time, leaving the Sikh III with no orders.[1]
No Sikh engines of any version were sold.[1]
Data from Sunbeam Aero-Engines[1]
