Sunbeam Manitou
Encyclopedia
The Sunbeam Manitou was an aero-engine produced by Sunbeam. Unsuccessful as an aero-engine, it is best known for having powered the Sunbeam 350HP racing car.
in 1917. It used aluminium blocks rather than cast iron, cast in blocks of three cylinders, a typical Sunbeam feature. Bore was increased to 110 mm, but stroke remained at 135 mm. The bank
s were at a 60° vee, with twin overhead camshafts on each bank operating four valves per cylinder. There were two Claudel-Hobson
carburettors and two BTH magneto
s. For aircraft use a reduction gear was fitted. The engine developed 300 hp at 2,000 rpm, later increased to 325 hp.
Only one engine was produced before the end of the war
, as the factory was busy with the vibration and other problems with the Arab
engine, and it was very nearly cancelled. As was not unusual for a Sunbeam engine, it was only ever fitted to a single aircraft for trials, a Short 184 seaplane, and never went into production. After the war and Sunbeam's financial problems in the war-surplus glutted aero-engine market, they were offered to the less-critical powerboat market, again not an unusual move for Sunbeam. 840 had been ordered during the war, but only 13 were delivered before cancellation of the order.
, set land speed record
s and was named to become one of Campbell's Blue Birds.
In typical Coatalen fashion, he redesigned the engine substantially even though this was just a one-off with no other likely sales. The twin-cam four-valve head was replaced by the single-cam three-valve head, possibly from the Arab
. An increase in bore to 120 mm allowed space for these larger valves.
Another change affected the stroke, also a technique from the Arab
, where it had been responsible for the engine's failure. A multi-cylinder V engine offers little length for connecting rods. Coatalen's usual solution was to use articulated connecting rods, where one rod runs on the crankshaft journal, but the other acts indirectly, through a journal on the other rod. The difficulty is that this gives a slightly different piston stroke for each bank, leading to unbalance and possible vibration problems, as for the Arab. Stroke was thus 135 mm on one bank and 142 mm on the other.
Development
The Manitou was a further development of the V-12 Maori III. Work on it began by Louis CoatalenLouis Coatalen
Louis Hervé Coatalen was a Breton automobile engineer.Coatalen was born in the Breton fishing town of Concarneau and went on to study engineering at the Ecole des Arts et Métiers at Cluny ....
in 1917. It used aluminium blocks rather than cast iron, cast in blocks of three cylinders, a typical Sunbeam feature. Bore was increased to 110 mm, but stroke remained at 135 mm. The bank
Cylinder bank
Internal combustion piston engines are usually arranged so that the cylinders are in lines parallel to the crankshaft. Where they are in a single line, this is referred to as an inline or straight engine....
s were at a 60° vee, with twin overhead camshafts on each bank operating four valves per cylinder. There were two Claudel-Hobson
Claudel-Hobson
Claudel-Hobson was a series of British carburettors manufactured by the H. M. Hobson Components Ltd..First introduced in 1908, they were widely used in British car and aircraft engines in the early 20th Century...
carburettors and two BTH magneto
Magneto
A magneto is a type of electrical generator.Magneto may also refer to:* Magneto , permanent magnetic alternating current rotary generator* ignition magneto, magnetos on internal combustion engines...
s. For aircraft use a reduction gear was fitted. The engine developed 300 hp at 2,000 rpm, later increased to 325 hp.
Only one engine was produced before the end of the war
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, as the factory was busy with the vibration and other problems with the Arab
Sunbeam Arab
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.* Brew, Alec. Sunbeam Aero-Engines. Airlife Publishing. Shrewsbury. ISBN 1 84037 023 8...
engine, and it was very nearly cancelled. As was not unusual for a Sunbeam engine, it was only ever fitted to a single aircraft for trials, a Short 184 seaplane, and never went into production. After the war and Sunbeam's financial problems in the war-surplus glutted aero-engine market, they were offered to the less-critical powerboat market, again not an unusual move for Sunbeam. 840 had been ordered during the war, but only 13 were delivered before cancellation of the order.
Maple Leaf
Sunbeam saw the market in racing powerboats as a solution to the post-war glut and weak market. Four were fitted to the boat 'Maple Leaf V' .Specifications (Manitou)
Sunbeam 350HP
The engine's only noteworthiness came when it was fitted to Sunbeam 350HP racing car in 1920. This car was later bought by Malcolm CampbellMalcolm Campbell
Sir Malcolm Campbell was an English racing motorist and motoring journalist. He gained the world speed record on land and on water at various times during the 1920s and 1930s using vehicles called Blue Bird...
, set land speed record
Land speed record
The land speed record is the highest speed achieved by a wheeled vehicle on land. There is no single body for validation and regulation; in practice the Category C flying start regulations are used, officiated by regional or national organizations under the auspices of the Fédération...
s and was named to become one of Campbell's Blue Birds.
In typical Coatalen fashion, he redesigned the engine substantially even though this was just a one-off with no other likely sales. The twin-cam four-valve head was replaced by the single-cam three-valve head, possibly from the Arab
Sunbeam Arab
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.* Brew, Alec. Sunbeam Aero-Engines. Airlife Publishing. Shrewsbury. ISBN 1 84037 023 8...
. An increase in bore to 120 mm allowed space for these larger valves.
Another change affected the stroke, also a technique from the Arab
Sunbeam Arab
|-See also:-Bibliography:* Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.* Brew, Alec. Sunbeam Aero-Engines. Airlife Publishing. Shrewsbury. ISBN 1 84037 023 8...
, where it had been responsible for the engine's failure. A multi-cylinder V engine offers little length for connecting rods. Coatalen's usual solution was to use articulated connecting rods, where one rod runs on the crankshaft journal, but the other acts indirectly, through a journal on the other rod. The difficulty is that this gives a slightly different piston stroke for each bank, leading to unbalance and possible vibration problems, as for the Arab. Stroke was thus 135 mm on one bank and 142 mm on the other.