The Sunbeam Arab was a British First World War-era aero engine.

Design and development

By 1916 the demand for aero-engines was placing huge demands on manufacturing. To help ease the pressure, the War Office standardised on engines of about 200 hp; one of these was a V-8 water-cooled engine from Sunbeam known as the Arab. Using cast aluminium alloy cylinder blocks and heads with die-cast aluminium alloy pistons, the Arab had a bore of 120 mm and stroke of 130 mm for a capacity of 11.762 L, developing 208 - 212 hp at 2,000 rpm. First bench-run in 1916, the Arab was obviously inspired by the Hispano-Suiza V-8 engines but with very little in common when examined in detail. After submission to the Internal Combustion Engine Committee of the Advisory Committee on Aeronautics Sunbeam received an order for 1,000 in March 1917. The order formed part of the strategy of Sir William Weir to bypass the skilled engineering workforce needed to build Rolls-Royce Eagle and Falcon engines, through the use of cast aluminium cylinder blocks that minimised the need for machining. However, the Arab was ordered before flight testing, and when the engine went into the air, chronic vibration problems emerged which were never cured. The initial order was increased to 2,000 in June 1917 as well as another 2,160 to be built by Austin Motors (1,000), Lanchester Motor Company (300), Napier & Son (300), and Willys Overland (560) in the United States of America. Despite this massive manufacturing effort, the Arab proved largely useless, and nearly half of the production run of the Bristol Fighter, Britain’s best two-seat fighter of the First World War, went into storage because plans to power the aircraft with the Arab were abandoned due to the engine’s failings. Service use of the Arab was limited because of poor reliability and persistent vibration problems, causing some 2,350 orders to be cancelled and remaining orders 'settled', compensating manufacturers for costs incurred. Developed from the Arab were the inverted V-8 Sunbeam Bedouin, straight-six Sunbeam Dyak, W-12 Sunbeam Kaffir, and 20-cylinder radial Sunbeam Malay.

Variants

Applications

Data from Brew.

Specifications (Arab I)