Rolls-Royce Buzzard / H Srs



The Rolls-Royce Buzzard (also referred to as the H engine) was a British piston aero engine of 36.7 litres (2,240 cubic inch) capacity that produced about 800 horsepower (600 kW). The Buzzard was developed by scaling-up the Kestrel engine in the ratio of 5:6. Designed and built by Rolls-Royce Limited it featured 12 cylinders in a 'V' configuration of 6 inch bore and 6.6 inch stroke, and the engine was supplied as standard with a medium supercharger capable of being used to its fullest extent on the ground, so as to give the maximum possible take-off power, first run in June 1928.

The Series I, II and III engines had reduction gear ratios of 0.632, 0.553 and 0.477 respectively, and the normal power was 825 h.p. at 2,000 r.p.m. at sea level. At 2,300 r.p.m., 955 h.p. was available at sea level. The dry weight was 1,540 lb.

Buzzards were installed in the Blackburn Iris V and VI (Perth), MA/30 and MA/30A, Handley Page H.P.46 (MA/30), Hawker Horsley, Short Singapore I, K.F.I and Sarafand, and Vickers M.1/30.

The total production of Buzzard engines 100.

It was manufactured in the late 1920s, but only 100 were sold. A further development was the Rolls-Royce R Schneider Trophy engine.


Buzzard IMS, (H.XIMS)
(1927), Maximum power 955 hp (712 kW), nine engines produced at Derby.

Buzzard IIMS, (H.XIIMS)
(1932-33), Maximum power 955 hp (712 kW), reduced propeller drive ratio (0.553:1), 69 engines produced at Derby.

Buzzard IIIMS, (H.XIVMS)
(1931-33), Maximum power 937 hp (699 kW), further reduced propeller drive ratio (0.477:1), 22 engines produced at Derby.


Blackburn Iris
Blackburn M.1/30
Blackburn Perth
Handley Page H.P.46
Hawker Horsley
Kawanishi H3K
Short Sarafand
Vickers Type 207


Buzzard IMS
Type: 12-cylinder liquid-cooled Vee aircraft piston engine
Bore: 6 in (152.4 mm)
Stroke: 6.6 in (167.6 mm)
Displacement: 2,239.3 in³ (36.7 L)
Length: 75.7 in (1,923 mm)
Width: 30.6 in (777 mm)
Height: 44.4 in (1,128 mm)
Dry weight: 1,140 lb (517 kg)
Valvetrain: Overhead camshaft
Supercharger: Single-stage supercharger
Fuel type: 73-77 octane petrol
Cooling system: Liquid-cooled
Power output: 800 hp (600 kW)
Specific power: 0.36 hp/in³ (16.3 kW/L)
Compression ratio: 5.5:1
Power-to-weight ratio: 0.7 hp/lb