Bristol Draco


The Bristol Draco was an air-cooled 9-cylinder radial engine from the British manufacturer Bristol Aeroplane Company. It was essentially a version of their Pegasus converted to use a fuel injection system.

The carburettor had only a simple butterfly valve, while two injection pumps supplied the cylinders with fuel, one handling four cylinders and the other, five. Injection was into the manifold before they split into the two intake valves for each cylinder. First run in 1935, the engine was flight tested in a Westland Wapiti. Since the expenditure did not bring considerable improvements the development was stopped.

Draco
Type: Nine-cylinder air-cooled radial engine.
Bore: 5.75 in (146 mm)
Stroke: 7.5 in (190 mm)
Displacement: 1,753 cu in (28.7 L)
Length: 43.5 in (1,105 mm)
Diameter: 55.5 in (1,410 mm)
Dry weight: 1,093 lb (495.8 kg)
Designer: Roy Fedden
Valvetrain: Overhead valve
Supercharger: Medium supercharged
Fuel system: Fuel injected
Cooling system: Air-cooled
Reduction gear: Geared epicyclic, reduction ratio 0.5:1, left hand tractor
Power output: 570 hp at 2,000 rpm
Compression ratio: 5.3:1
Power-to-weight ratio: 0.52 hp/lb