Bristol Aquila

The Aquila was developed two years after the larger Perseus, both being sleeve valve designs. The primary difference was in size, the Perseus was based on the 5.75 by 6.5 in (146 by 170 mm) cylinder used in the Mercury engine, while the Aquila used a new and smaller 5 by 5.375 in (130 by 136.5 mm) sized cylinder. The result was a reduction in displacement from 1520 to 950 cubic inches (24.9 to 15.6 L).

First run in 1934, the first Aquila engine delivered 365 horsepower (272 kW) but soon developed into more powerful versions as improvements were worked into the line  and by 1936 it had improved to 500 hp (370 kW). This would have made it an excellent replacement for the Bristol Jupiter, which ended production at 590 hp (440 kW) three years earlier, but by this time almost all interest was on ever-larger engines. The Aquila was never used in production, but further developments led to the Bristol Hercules, Bristol Taurus, and Bristol Centaurus.

Applications:
Bristol Bulldog
Bristol Bullpup
Bristol Type 143
Vickers Venom

Aquila I
Type: Nine-cylinder single-row naturally aspirated air-cooled radial engine
Bore: 5 in (130 mm)
Stroke: 5.375 in (136.5 mm)
Displacement: 950 cu in (15.6 L)
Length: 41 in (1,000 mm)
Diameter: 46 in (1,200 mm)
Dry weight: 776 pounds (352 kg)
Valvetrain: Sleeve valve
Supercharger: Medium supercharged
Fuel system: Claudel-Hobson carburettor
Fuel type: 73 octane rating petrol
Cooling system: Air-cooled
Reduction gear: 0.5:1 turning a Hamilton Standard variable pitch propeller
Power output: 493 hp (368 kW) at 2,600 rpm for takeoff
Specific power: 0.52 hp/in³ (23.59 kW/l)
Compression ratio: 7.3:1
Specific fuel consumption: 0.46 lb/(hp•h) (282 g/(kW•h))
Oil consumption: 0.21 oz/(hp•h) (8g /(kW•h))
Power-to-weight ratio: 0.64 hp/lb (1.05 kW/kg)