In the UK, the old-established company D Napier Ltd., was developing a licence-built version of the Junkers Jumo IV opposed-piston engine, and called it the 'Culverin'. The engine had cylinders of 4¾" X 8¼" with a swept volume of 14247 cc or 877 cu ins. From this, the engine produced 720 bhp at 1700 rpm, for a weight of 1785 lbs. Mechanical details are very similar to the Junkers engine, and of course this all came to an abrupt halt with the outbreak of WW2. A smaller version of the same engine named the 'Cutlass' was under development at the same time. Dimensions of the Culverin were: 7 ft long, 2 ft wide and nearly 6ft high.
Napier Culverin In-line Opposed-Piston Diesel Aero Engine
Another European engine was designed by L.Coatalen, and in 1936 was shown at the Paris Aero Show. This diesel was a 60° V diesel with twelve cylinders of 150 mm X 170 mm, giving 36 litres. This engine is very close to the petrol engines Rolls-Royce Merlin engine, except that it has twin overhead camshafts against the Merlin's single cams. Output power was 550 bhp at 2000 at a dry weight of 1210 lbs. The injection equipment was mounted on the back of the engine, and comprised two 6-cylinder pumps mounted in a V formation as per the engine. A centrigugal supercharger was fitted underneath the fuel pumps and was driven off the crankshaft at ten times crank speed. Dimensions were: 68" length 31" width 39" height.
Coatalen Diesel Aero Engine