Object StatementAircraft engine, Dragon Fly Mk II, WWI, single-row, radial, air cooled, nine cylinder, 320 hp, 1750 rpm, steel, designed by ABC Motors Ltd, made under licence by Sheffield Simplex Motor Works Ltd, Tinsley, Sheffield, England, 1919
Physical DescriptionAircraft engine, Dragon Fly Mk II, WWI, single-row, radial, air cooled, nine cylinder, 320 hp, 1750 rpm, steel, designed by ABC Motors Ltd, made under licence by Sheffield Simplex Motor Works Ltd, Tinsley, Sheffield, England, 1919
The Dragonfly aero engine comprises a nine-cylinder, single-row, air-cooled, radial engine designed to provide 320 hp at 1750 rpm. The cylinder assemblage was fixed relative to the aircraft fuselage while the propeller rotated with the crankshaft. Cam-driven push rods protruded from the crankcase in the front of the engine and actuated the inlet and exhaust valves in the cylinder head through rocker levers. Each cylinder has one large inlet valve and two smaller exhaust valves. The spring loaded inlet valve rod passed through the mixture transfer pipes at the back of the engine. The spiral spring-loaded rocker arm for the exhaust valves acts on a cross piece which connects with the valve rods to either side of each cylinder head. Exhaust pipes joined to the ports conveyed the products of combustion through the engine cowling.
The cylinders are steel forgings with integral heads and the cooling fins are coated with copper in an attempt to improve cooling. The pistons are of aluminium alloy. Two Claudel-Hobson H.C.8 carburettors and two Thompson Binnel Magnetos (Type AK9 Nos 418/420, made in Birmingham) are fitted. The magnetos fired two spark plugs mounted on the side of each cylinder. As in all radial engines, one of the connecting rods connects with the crankshaft in a conventional manner. This rod is designated the ?master rod' and other connecting rods articulate with it.
The engine operated on the four-stroke cycle where the air was first drawn through a carburettor then through a circular manifold to the engine cylinders. Ignition occurred in alternate cylinders during each engine revolution.
Height: 1240 mm
Width: 1240 mm
Depth: 1215 mm
Cylinder diameter: 139.7 mm
Piston stroke: 165.1 mm
Weight: 299 kg
Compression ratio: 4.42:1
Engine plate details:
Type: Dragonfly Mk II
Manufactured by Sheffield Simplex Motor Works
Tinsley, Sheffield, England
Type Dragon Fly Mk II 5000
Firing Order 135792468
Sheffield Simplex Motor Works Ltd
Tinsley Sheffield England
5000 A 60150 A D D37