Bristol had originally intended to use the Aquila and Perseus as two of its major product lines in the 1930s, but the rapid increase in size and speed of aircraft in the 1930s demanded much larger engines than either of these. The mechanicals from both of these designs were then put into two-row configurations to develop much larger engines, the Aquila becoming the Taurus, and the Perseus becoming the Hercules.
The Taurus was a 14-cylinder two-row radial sleeve valve design, resulting in an extraordinarily uncluttered exterior and very low mechanical noise. It offered high power with a relatively low weight, starting from 1,015 hp (760 kW) in the earliest versions. It was also compact, with a diameter of 46 inches (1170 mm) which made it attractive to fighter designers. Unfortunately, the engine has also been described as "notoriously troublesome", with protracted development and a slow growth in rated power. After several years of development, power had been increased from 1,015 hp (760 kW) to only 1,130 hp (840 kW). As the most important applications of this engine were in aircraft that flew at low altitude, engine development efforts focussed on low-altitude performance.
Bristol Taurus 11 14-Cylinder sleeve-valve double bank air-cooled radial engine of 1938 provided 1,065 h.p. at 5,000ft, and was fitted to the Beaufort Mk 1 as well as the Fairey Battle and Fairey Albacore.
The first Taurus engines were delivered just before World War II began and found some use primarily in the Fairey Albacore and Bristol's own Beaufort torpedo bomber. Starting from April 1940, it was suggested to replace the Taurus engines of the latter by the famous Pratt & Whitney R-1830 Twin Wasp, but this change was postponed to the autumn of 1941 while attempts were made to cure the reliability problems of the Taurus, and later had to be temporarily reversed because of shortages of Twin Wasp engines. The Twin Wasp was, however, strongly preferred, especially for overseas postings, because of its much greater reliability. In later models of the Taurus engine the reliability problems were mostly cured by a change in the cylinder manufacturing process, although the engine kept a poor reputation, and in the Albacore the Taurus engine was retained until the end of that aircraft's production in 1943.
There were no other operational applications of the Taurus engine, because its initial reliability problems discouraged the development of Taurus-powered aircraft, and because later-war combat aircraft demanded more powerful engines. Its production lines were closed down in favour of the Hercules engine.
1940 1,060 hp.
1940 985 hp. Supercharger ratio decreased, impeller diameter increased.
1940 985 hp.
Trials engine only, one built.
Bristol Type 148
Fairey Battle testbed only
Type: 14-cylinder, two-row, supercharged, air-cooled radial engine with dual ignition
Bore: 5 in (127 mm)
Stroke: 5.625 in (143 mm)
Displacement: 1,550 in³ (25.4 L)
Length: 49.2 in (1,250 mm)
Diameter: 46.25 in (1,175 mm)
Dry weight: 1,301 lb (590 kg)
Valvetrain: Sleeve valve
Supercharger: Single-speed centrifugal type supercharger
Fuel system: Claudel-Hobson carburettor
Fuel type: 87 Octane petrol
Cooling system: Air-cooled
Reduction gear: Farman epicyclic gearing, 0.444:1
996 hp (743 kW) at 3,225 rpm for takeoff
1,050 hp (783 kW) at 3,225 rpm at 5,000 ft (1,520 m)
Specific power: 0.68 hp/in³ (30.83 kW/l)
Compression ratio: 7.2:1
Specific fuel consumption: 0.43 lb/(hp·h) (261 g/(kW·h))
Power-to-weight ratio: 0.81 hp/lb (1.33 kW/kg)