Sunbeam Maori
| Afridi | |
|---|---|
| Type | V-12 water-cooled, piston engine |
| National origin | Britain |
| Manufacturer | Sunbeam |
| Designed by | Louis Coatalen |
| First run | 1916 |
| Number built | July 1916 to June 1917 |
The Sunbeam Afridi was an aero-engine produced by Sunbeam during the First World War.
Conceived to replace the Crusader/Zulu on the production lines, Louis Coatalen designed a companion engine for the V-12 Cossack, giving it the name Afridi. The Afridi was a much smaller engine than the Cossack and also spawned a whole family of derivative engines.
The major attributes of the Afridi were a bore of 92 mm (3.62 in) and stroke of 135 mm (5.31 in) displacing 11.476 l (700.3 cu in) for a power output of 200 hp (149 kW)at 2,000rpm. The twin overhead camshafts were driven by gears, directly operating two inlet and two exhaust valves per cylinder. Two Claudel-Hobson carburettors on the outsides of the blocks fed mixture to the cylinders, where it was ignited by the dual ignition system energised by four 6-cyl magnetos.
Three hundred Afridis were ordered, of which 299 were delivered and 100 converted to Sunbeam Maoris. Service use was mainly in Curtiss R.2 tractor biplanes and various Short seaplanes.
A direct development of the Afridi, the Sunbeam Maori was far more successful. In similar fashion to Coatalens development of Sunbeam's side-valve engines he increased the bore to 100 mm (3.94 in) retaining the stroke of 135 mm (5.31 in), displacing 12.27 l (748.8 cu in) for a power output of 260 hp (194 kW)at 2,000rpm driving a geared propeller.
Production of the Maori began in April 1917, including 100 Afridis which were converted to Maoris on the production line as the Maori Mk.I, with new-build Maoris designated as Maori Mk.II. Converted Afridis, (Maori Mk.I), were rated at 250 hp (186 kW)at 2,000rpm, whilst new-build Maori Mk.IIs were rated at 260 hp (194 kW)at 2,000rpm.
Maoris found favour with Short and Fairey seaplanes as well as Handley Page O/400 bombers, with development continuing to give the Maori Mk.III and Maori Mk.IV. The Maori Mk.III introduced cylinder banks with exhaust ports on the outside rather than the inside of the Vee and the carburettors on the inside. The Mk.III was rated at 275 hp (205 kW).
The final Maori version was designed specifically for use in airships as the Maori Mk.IV, with controls mounted directly on the rear of the engine, flywheel, enlarged cooling system and water-cooled exhaust pipes. Fitted to R33 and R34, five Maori Mk.IVs were fitted to each airship in gondolas, allowing the engines to be tended by on-board mechanics.
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