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British Industrial History

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Bristol Engine Co: Taurus

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Note: This is a sub-section of Bristol Engine Co

The Taurus was a 14-cylinder two-row radial aircraft engine, produced by the Bristol Engine Co starting in 1936. The Taurus was developed by adding cylinders to the existing Aquila design, creating a design that produced just over 1,000 horsepower (750 kW) with very low weight.

Bristol had originally intended to use the Aquila and Perseus as two of its major designs 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 sleeve valve design, resulting an extraordinarily uncluttered exterior and very low noise. It offered high power with a relatively low weight, starting from 1015 hp (760 kW) in the earliest versions. It was also compact, with a diameter of 117.5 cm (46.25 in) 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 only from 1015 hp (760 kW) to 1,130 hp (840 kW). As the most important applications of this engine were in aircraft that flew at low altitude, engine development efforts focused on low-altitude performance.

The first Taurus engines were delivered just before World War II began and found some use primarily in the Fairey Albacore and Bristol 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 the autumn of 1941 while attempts where 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, 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.

General characteristics (Taurus II)

  • Type: 14-cylinder supercharged two-row radial engine with dual ignition
  • Bore: 5 in (127 mm)
  • Stroke: 5.625 in (142.9 mm)
  • Displacement: 1,546.3 in³ (25.34 l)
  • Dry weight: 1,300 lb (590 kg)

Components

  • Valve-train: Sleeve valve
  • Fuel type: 87-octane value to specification D.T.D. 230
  • Cooling system: Air-cooled

Performance

  • Power output:
    • 1,010 hp (753 kW) at 3,225 rpm for takeoff (bmep 160.4psi)
    • 1,065 hp (794 kW) at 3,225 rpm at 5,000 ft (1,520 m) war emergency power for 5 minutes
  • Specific power: 0.65 hp/in³ (29.6 kW/L)
  • Power-to-weight ratio: 0.82 hp/lb (1.35 kW/kg)

General characteristics (Taurus XII)

  • Type: 14-cylinder two-row radial engine
  • Bore: 5 in (127 mm)
  • Stroke: 5.4 in (137 mm)
  • Displacement: 1,550 in³ (25.4 L)
  • Dry weight: 1,300 lb (590 kg)

Components

  • Valve-train: Sleeve valve
  • Fuel type: 87-octane value to specification D.T.D. 230
  • Cooling system: Air-cooled

Performance

  • Power output: 1,130 hp (840 kW) at 3,100 rpm
  • Power-to-weight ratio: 0.87 hp/lb (1.42 kW/kg)

See Also

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