Radial Engine - Diesel Radials

Diesel Radials

While most radial engines have been produced for gasoline, there have been Diesel radial engines. Two major advantages favour Diesel engines — lower fuel consumption and reduced fire risk.

Packard designed and built a 9-cylinder 980 cubic inch displacement Diesel radial aircraft engine, the 225 horsepower (168 kW) DR-980, in 1928. On 28 May 1931, a DR-980 powered Bellanca CH-300 piloted by Walter Edwin Lees and Frederick Brossy set a record for staying aloft for 84 hours and 32 minutes without being refueled. This record stood for 55 years until broken by the Rutan Voyager.

The experimental Bristol Phoenix of 1928–1932 was successfully flight tested in a Westland Wapiti and set altitude records in 1934 that lasted until World War II.

In 1932 the French company Clerget developed the 14D, a 14-cylinder two-stroke Diesel radial engine. After a series of improvements, in 1938 the 14F2 model produced 520 hp (390 kW) at 1910 rpm cruise power, with a power-to-weight ratio near that of contemporary gasoline engines and a specific fuel consumption of roughly 80% that for an equivalent gasoline engine. During WWII the research continued, but no mass-production occurred because of the Nazi occupation. By 1943 the engine had grown to produce over 1,000 hp (750 kW) with a turbocharger. After the war, the Clerget company was integrated in the SNECMA company and had plans for a 32-cylinder Diesel engine of 4,000 hp (3,000 kW), but in 1947 the company abandoned piston engine development in favour of the emerging turbine engines.

The Nordberg Manufacturing Company of the United States developed and produced a series of large two-stroke radial Diesel engines from the late 1940s for electrical production, primarily at aluminium smelters and for pumping water. They differed from most radials in that they had an even number of cylinders in a single bank (or row), thanks to an unusual double master connecting rod that allowed the engine to be timed so the cylinders fired in consecutive order. Variants were built that could be run on either Diesel oil or gasoline or mixtures of both. A number of powerhouse installations utilising large numbers of these engines were made in the U.S.