The Aquila was a nine-cylinder single-row

radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing f ...

aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many ...

Bristol Engine Company The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aircraft engines. Notable ...

starting in 1934. A

sleeve valve The sleeve valve is a type of valve mechanism for piston engines, distinct from the usual poppet valve. Sleeve valve engines saw use in a number of pre-World War II luxury cars and in the United States in the Willys-Knight car and light truck. ...

engine, its basic design was developed from the

Bristol Perseus The Bristol Perseus was a British nine-cylinder, single-row, air-cooled radial aircraft engine produced by the Bristol Engine Company starting in 1932. It was the first production sleeve valve aero engine. Design and development In late 1925 ...

. The Aquila was never used in production, but further developments led to the

Bristol Hercules The Bristol Hercules is a 14-cylinder two-row radial aircraft engine designed by Sir Roy Fedden and produced by the Bristol Engine Company starting in 1939. It was the most numerous of their single sleeve valve ( Burt-McCollum, or Argyll, typ ...

Bristol Taurus The Taurus is a British 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 single-row Aquila design and transforming it into a twin ...

, and

Bristol Centaurus The Centaurus was the final development of the Bristol Engine Company's series of sleeve valve radial aircraft engines. The Centaurus is an 18-cylinder, two-row design that eventually delivered over . The engine was introduced into service lat ...

Design and development

The Aquila was developed two years after the somewhat larger

Perseus In Greek mythology, Perseus (Help:IPA/English, /ˈpɜːrsiəs, -sjuːs/; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of Mycenae and of the Perseid dynasty. He was, alongside Cadmus ...

, both being

designs. The primary difference was in size, the Perseus being based on the cylinder used in the

Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...

engine, while the Aquila used a new and smaller sized cylinder. The result was a reduction in

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

from 1520 to 950 cubic inches (24.9 to 15.6 L). The first Aquila engine delivered a modest , which was unspectacular for an engine of this size. It soon developed into more powerful versions as improvements were worked into the line (as well as similar changes to the Perseus), and by 1936 it had improved to . This would have made it an excellent replacement for the

Bristol Jupiter The Bristol Jupiter was a British nine-cylinder single-row piston radial engine built by the Bristol Aeroplane Company. Originally designed late in World War I and known as the Cosmos Jupiter, a lengthy series of upgrades and developments turn ...

, which ended production at three years earlier, but by this time almost all interest was on ever-larger engines.

Applications

''Note:''List from Lumsden, the Bulldog and Bullpup were test aircraft only. *

Bristol Bulldog The Bristol Bulldog is a British Royal Air Force single-seat biplane fighter designed during the 1920s by the Bristol Aeroplane Company. More than 400 Bulldogs were produced for the RAF and overseas customers, and it was one of the most fa ...

Bristol Bullpup The Bristol Type 107 Bullpup was a British fighter aircraft built in the 1920s. It was not selected for squadron service and only the single prototype was built Background The design of the Bullpup was an outcome of a series of design studie ...

Bristol Type 143 The Bristol Type 143 was a British twin-engine monoplane aircraft designed by Frank Barnwell of the Bristol Aeroplane Company. Developed alongside the more famous Bristol Type 142, which was developed into the Blenheim light bomber, it used th ...

Vickers Venom The Vickers Type 279 Venom was a British low-wing monoplane single-seat, single-engined, eight-gun fighter aircraft. It was fast and manoeuvrable but its Bristol Aquila radial engine was underpowered. Together with other designs built to the same ...

Specifications (Aquila I)

References

Notes

Bibliography