The Rolls-Royce Eagle XVI was a British experimental 16 cylinder aero engine designed and developed by

Rolls-Royce Limited Rolls-Royce was a British luxury car and later an aero-engine manufacturing business established in 1904 in Manchester by the partnership of Charles Rolls and Henry Royce. Building on Royce's good reputation established with his cranes, they ...

in 1925. The engine was test run but did not fly, the project, together with the planned larger variant, the Eagle XX, was cancelled in favour of the

Rolls-Royce Kestrel The Kestrel or type F is a 21 litre (1,300 in³) 700 horsepower (520 kW) class V-12 aircraft engine from Rolls-Royce, their first cast-block engine and the pattern for most of their future piston-engine designs. Used during the interwar pe ...

, that was being developed concurrently.

Background

The appearance of the

Curtiss D-12 The Curtiss D-12, sometimes identified with the military designation Curtiss V-1150, was an aircraft engine of 18.8 liter displacement. It was a water-cooled V12, producing 443 hp (330 kW) and weighing 693 lb (314 kg). It was ...

, and its importation under license to Britain by Fairey prompted the

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

to ask Rolls-Royce to develop a new aero engine for fighter aircraft, the ministry felt that there were too many engine manufacturers and did not support or encourage the Fairey company to continue. Rolls-Royce developed two distinct types of engine to meet the requirement, 'a modernised V-12' - the F engine, which became the Kestrel, and the Eagle XVI

Design and development

Henry Royce Sir Frederick Henry Royce, 1st Baronet, (27 March 1863 – 22 April 1933) was an English engineer famous for his designs of car and aeroplane engines with a reputation for reliability and longevity. With Charles Rolls (1877–1910) and Claude ...

, the Eagle XVI was a completely new design and unrelated to the earlier

Eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...

. The engine featured four banks of fore and aft staggered cylinder blocks with the banks arranged at 90 degrees to each other to form a perfect 'X'. The valve gear was operated by a single

overhead camshaft An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion c ...

and used four valves per cylinder. The crankcases and cylinder blocks were cast from

aluminium alloy An aluminium alloy (or aluminum alloy; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal ...

. Normal engine bearers could not be used so the unit was held in the test stand by two conical mounts that attached to the crankcase. Initial test running was carried out without a

supercharger In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. The current categorisation is that a supercharger is a form of forced induct ...

fitted and an improvised

carburettor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meterin ...

and induction system. The engine did not run well with this arrangement due to poor fuel distribution, however when a supercharger and matched carburettor were fitted (borrowed from the Kestrel development unit) the engine ran and performed well, producing 500 hp (373 kW) on the

dynamometer A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed (RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the ...

. Despite this the engine was not received well by the aircraft industry where it was felt that the unusual layout would block the pilot's forward view in a typical fighter aircraft installation. The project was dropped and development efforts then concentrated on the Kestrel.Rubbra 1990, p.24. Like the Crecy the Eagle XVI was one of the few Rolls-Royce projects that did not fly, it is of note that the 'X' engine layout was reused in the later

Vulture A vulture is a bird of prey that scavenges on carrion. There are 23 extant species of vulture (including Condors). Old World vultures include 16 living species native to Europe, Africa, and Asia; New World vultures are restricted to North and ...

and

Exe Exe or EXE may refer to: * .exe, a file extension * exe., abbreviation for executive Places * River Exe, in England * Exe Estuary, in England * Exe Island, in Exeter, England Transportation and vehicles * Exe (locomotive), a British locomotive ...

designs.

Specifications (Eagle XVI)

References

Notes

Bibliography