The Potez 8D is the largest member of the Potez D series of air-cooled piston aircraft engines which share several common features. It is a superchargedeight cylinder inverted engine with a take-off power of 373 kW (500 hp).
Design and development
In the 1930s Potez planned a series of new engines to replace their Anzani-derived radial engines. The Potez 4D, a four-cylinder inverted inline engine ran before World War II but did not reach production until the late 1940s, when it was joined by another inverted inline, the six cylinder Potez 6D, and the eight cylinder inverted-V 8D. The D-series engines had much in common, most obviously sharing pistons and cylinders, with the same stroke, bore and valve gear. The larger 8D required an enhanced though similar lubrication system and different connecting rods because of its 90° V layout.[1]
A 8D.32 powered the first prototype of the Potez 75 ground attack aircraft but budget cuts in 1957 led to the cancellation of an order for 15 pre-series and 100 series machines.[2]
Pistons, connecting rods and crankshaft: Y-alloy pistons with two compression and two scraper rings. Fork and blade type nitrided Ni-Cr-Mo steel connecting rods, with split big-ends and lead -bronze bearings. Four throw, forged nitrided Ni-Cr-Mo steel balanced crankshaft, its rear end driving the supercharger via flexible drive. Five lead-bronze plated bearings. Cast aluminium-alloy crankcase.
Performance
Power output: Normal at 1,900 m (6,200 ft), 321 kW (430 hp) at 2,500 rpm; take-off, 373 kW (500 hp) at 2,530 rpm.