The Rolls-Royce Eagle Mk XXII is a British 24-cylinder,

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 tru ...

, H-block aero engine of 46

litre The litre ( Commonwealth spelling) or liter ( American spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metres (m3). A ...

(2,807

cubic inch The cubic inch (symbol in3) is a unit of volume in the Imperial units and United States customary units systems. It is the volume of a cube with each of its three dimensions (length, width, and height) being one inch long which is equivalent ...

es)

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 ...

. It was designed and built in the early-1940s by

Rolls-Royce Limited Rolls-Royce Limited 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 Crane ( ...

and first ran in 1944. It was liquid-cooled, of flat H configuration with two

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

s and was capable of 3,200

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are t ...

(2,387 kW) at 18

psi Psi, PSI or Ψ may refer to: Alphabetic letters * Psi (Greek) (Ψ or ψ), the twenty-third letter of the Greek alphabet * Psi (Cyrillic), letter of the early Cyrillic alphabet, adopted from Greek Arts and entertainment * "Psi" as an abbreviat ...

boost.

Design and development

The Rolls-Royce design team realised that producing a scaled-up version of their Griffon

V-12 engine A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft. V12 engines are more common than V10 engines. However, they are less common than V8 engines. The f ...

would lead to excessively large

combustion chamber A combustion chamber is part of an internal combustion engine in which the air–fuel ratio, fuel/air mix is burned. For steam engines, the term has also been used for an extension of the Firebox (steam engine), firebox which is used to allow a mo ...

s and problems with

detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...

.Rubbra 1990, p. 91. The team concluded that a larger number of small cylinders would be the answer and considered an X-24 design. This layout had previously caused unreliability with the

Rolls-Royce Vulture The Rolls-Royce Vulture was a British Aircraft engine, aero engine developed shortly before World War II that was designed and built by Rolls-Royce Limited. The Vulture used the unusual "X-24 engine, X-24" configuration, whereby four cylinder ...

due to the need to fasten four

connecting rod A connecting rod, also called a 'con rod', is the part of a reciprocating engine, piston engine which connects the piston to the crankshaft. Together with the crank (mechanism), crank, the connecting rod converts the reciprocating motion of the p ...

s in a complicated arrangement to a common big end bearing. The designers finally settled on an 'H' layout with two crankshafts and 'blade and fork' connecting rod attachments, the crankshafts being connected through the

propeller speed reduction unit A propeller speed reduction unit is a Transmission (mechanics), gearbox or a belt and pulley device used to reduce the output revolutions per minute (rpm) from the higher input rpm of the powerplant.Gunston 2006, p. 82. This allows the use of sm ...

. The new engine followed the layout of the

Napier Sabre The Napier Sabre is a British H engine, H-24-cylinder, coolant, liquid-cooled, sleeve valve, piston aircraft engine, aero engine, designed by Frank Halford, Major Frank Halford and built by D. Napier & Son during World War II. The engine evolv ...

and similarly used

s but with a simplified drive system. A two-speed, two-stage

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 (engine), displacement. It is a form of forced induction that is mechanically ...

and

intercooler An intercooler is a heat exchanger used to cool a gas after compression. Often found in turbocharged engines, intercoolers are also used in air compressors, air conditioners, refrigeration and gas turbines. Internal combustion engines Mo ...

were used to compress then cool the air-fuel mixture, following Griffon and

Merlin The Multi-Element Radio Linked Interferometer Network (MERLIN) is an interferometer array of radio telescopes spread across England. The array is run from Jodrell Bank Observatory in Cheshire by the University of Manchester on behalf of UK Re ...

practice. Starting was by Coffman starter. An auxiliary shaft driven by the lower crankshaft operated the main coolant pump, intercooler coolant pump, pressure and scavenge oil pumps and a

fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of a fuel injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All c ...

pump.

Piston ring A piston ring is a metallic split ring that is attached to the outer diameter of a piston in an internal combustion engine or steam engine. The main functions of piston rings in engines are: # Sealing the combustion chamber so that there is mini ...

failures and

cylinder head In a piston engine, the cylinder head sits above the cylinders, forming the roof of the combustion chamber. In sidevalve engines the head is a simple plate of metal containing the spark plugs and possibly heat dissipation fins. In more modern ...

sealing problems were experienced during early flight testing.

Applications

The Eagle was never fitted to a production front-line fighter, as it was overshadowed by a new wave of

turbojet engine The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, an ...

s, such as the Rolls-Royce Derwent and

turboprop A turboprop is a Gas turbine, gas turbine engine that drives an aircraft Propeller (aeronautics), propeller. A turboprop consists of an intake, reduction drive, reduction gearbox, gas compressor, compressor, combustor, turbine, and a propellin ...

s such as the Dart and Armstrong Siddeley Python. Fifteen Eagle 22s were produced to power prototypes of the Westland Wyvern fighter/torpedo bomber because of delay in the development of the Python. Supermarine specified the Eagle in their 1944 proposal for a single-engined Naval fighter, the Type 391, but the proposal was not followed up.

Variants

46H Eagle I :(1944) -

Compression ratio The compression ratio is the ratio between the maximum and minimum volume during the compression stage of the power cycle in a piston or Wankel engine. A fundamental specification for such engines, it can be measured in two different ways. Th ...

6.5:1. 46H Eagle II :(1944) - Modified Eagle I. 46H Eagle (20 srs) 22 :(1946-1949) - Increased compression ratio (7:1), 3,500 hp at 3,500 rpm and 28 lb boost. Fifteen engines produced at the

Derby Derby ( ) is a City status in the United Kingdom, city and Unitary authorities of England, unitary authority area on the River Derwent, Derbyshire, River Derwent in Derbyshire, England. Derbyshire is named after Derby, which was its original co ...

Rolls-Royce factory. First flown in a Westland Wyvern on 16 December 1946.

Engines on display

*An Eagle 22 with some of the cowling panels removed to display the engine can be seen fitted to Westland Wyvern TF1, ''VR137'', at the

Fleet Air Arm Museum The Fleet Air Arm Museum is devoted to the history of British naval aviation. It has an extensive collection of military and civilian aircraft, aero engines, models of aircraft and Royal Navy ships (especially aircraft carriers), and paintings ...

RNAS Yeovilton Royal Naval Air Station Yeovilton, commonly referred to as WAFU central, (HMS ''Heron'') is an airbase of the Royal Navy, sited a few miles north of Yeovil, in the English county of Somerset. It is one of two active Fleet Air Arm bases, the ...

. This pre-production aircraft never flew.Fleet Air Arm Museum - Westland Wyvern TF1
www.fleetairarm.com Retrieved: 25 March 2010.

Specifications (Eagle 22)

References

Notes

Bibliography

* Gunston, Bill. ''World Encyclopedia of Aero Engines (5th Edition)''. Phoenix Mill, Gloucestershire, UK: Sutton Publishing Limited, 2006. * Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. . * Rubbra, A.A. ''Rolls-Royce Piston Aero Engines - a designer remembers: Historical Series no 16'' :Rolls-Royce Heritage Trust, 1990.

External links

A working Rolls-Royce Eagle 22 model engineAdditional pictures of the same model enginePhoto of a Rolls-Royce Eagle 22
a 1947 ''Flight'' article {{RRaeroengines Eagle 22 Sleeve valve engines 1940s aircraft piston engines