[1][2] Louis Coatalen, Sunbeam engine designer, started work on a diesel powered aero-engine, that would be suitable for use in airships, in 1928.
[2] Using his experience with both aero-engines and auto-mobile diesel engines, the result, given the company designation P.1, was based on the Dyak.
[2] Given the name Pathan, a prototype engine was displayed at the 1929 Olympia Aero Show, but attracted no orders.
[2] Using the same bore and stroke of the Dyak (120mm x 130mm - 4.72in x 5.12in ), the Pathan was a water-cooled six-cylinder in-line diesel engine with a cubic capacity of 8.8l (537cu in).
Rated to give 100 hp (74.6 kW) @ 1,500rpm the engine was fitted with a new type of fuel injection system allowing cold starts without other assistance.