Bristol Taurus

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Bristol Taurus engine

The Taurus was a 14-cylinder two-row radial aircraft engine, produced by the Bristol Engine Company 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 configuations to develop much larger engines, the Aquila becoming the Taurus, and the Perseus becoming the Hercules.

Unlike the earlier engines, where the sleeve valve was a new and untried design, the Taurus was fairly well understood and was delivered running at almost the same power it ended with, at 1,015 hp (760 kW). After several years of development, this improved only to 1,130 hp (840 kW), a testimonial to how good the first versions were.

The first Taurus engines were delivered just before World War II began and found some use primarily in Bristol's own Beaufort torpedo bomber. When the same plane was fitted with the famous Pratt & Whitney R-1830 Twin Wasp, its performance actually fell even though the Twin Wasp was both lighter and more powerful.

Nevertheless by the time the engine was in widespread production, designs had already demanded even higher power settings. The Hercules went on to see fairly widespread use, while the Taurus ended with the Beaufort after only a few years.

[edit] Specifications (Taurus II)

General characteristics

Type: 14-cylinder supercharged two-row radial engine with dual ignition
Bore: 5 in (127 mm)
Stroke: 5.625 in (142.9 mm)
Displacement: 1,550 in³ (25.4 l)
Dry weight: 1,300 lb (590 kg)

Components

Valvetrain: 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
- 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)