HOME > UNITED KINGDOM > PREVIOUS PAGE

Rolls-Royce Merlin

The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litres (1,650 cu in) capacity. Rolls-Royce designed the engine and first ran it in 1933 as a private venture. Initially known as the PV-12, it was later called Merlin following the company convention of naming its piston aero engines after birds of prey.

After several modifications, the first production variants of the PV-12 were completed in 1936. The first operational aircraft to enter service using the Merlin were the Fairey Battle, Hawker Hurricane and Supermarine Spitfire. The Merlin remains most closely associated with the Spitfire and Hurricane, although the majority of the production run was for the four-engined Avro Lancaster heavy bomber. A series of rapidly applied developments, brought about by wartime needs, markedly improved the engine's performance and durability. Starting at 1,000 hp for the first production models, most late war versions produced just under 1,800 hp, and the very latest version as used in the de Havilland Hornet over 2,000 hp.

One of the most successful aircraft engines of the World War II era, some 50 versions of the Merlin were built by Rolls-Royce in Derby, Crewe and Glasgow, as well as by Ford of Britain at their Trafford Park factory, near Manchester. A de-rated version was also the basis of the successful Rolls-Royce/Rover Meteor tank engine. Post-war, the Merlin was largely superseded by the Rolls-Royce Griffon for military use, with most Merlin variants being designed and built for airliners and military transport aircraft. Production ceased in 1956 with the fulfilment of an order for 170 Merlins for the Spanish Air Force's CASA 2.111 and Hispano Aviación HA-1112 aircraft, after 160,000 engines had been delivered. In addition, the Packard V-1650 was a version of the Merlin built in the United States, itself produced in numbers upwards of 55,000 examples, and was the principal engine used in the North American P-51 Mustang.

Design and Development
In the early 1930s, Rolls-Royce started planning its future aero-engine development programme and realised there was a need for an engine larger than their 21-litre (1,296 cu in) Kestrel which was being used with great success in a number of 1930s aircraft. Consequently, work was started on a new 1,100 hp (820 kW)-class design known as the PV-12, with PV standing for Private Venture, 12-cylinder, as the company received no government funding for work on the project. The PV-12 was first run on 15 October 1933 and first flew in a Hawker Hart biplane (serial number K3036) on 21 February 1935. The engine was originally designed to use the evaporative cooling system then in vogue. This proved unreliable and when ethylene glycol from the U.S. became available, the engine was adapted to use a conventional liquid-cooling system. The Hart was subsequently delivered to Rolls-Royce where, as a Merlin testbed, it completed over 100 hours of flying with the Merlin C and E engines.

In 1935, the Air Ministry issued a specification, F10/35, for new fighter aircraft with a minimum airspeed of 310 mph (500 km/h). Fortunately, two designs had been developed: the Supermarine Spitfire and the Hawker Hurricane; the latter designed in response to another specification, F36/34. Both were designed around the PV-12 instead of the Kestrel, and were the only contemporary British fighters to have been so developed. Production contracts for both aircraft were placed in 1936, and development of the PV-12 was given top priority as well as government funding. Following the company convention of naming its piston aero engines after birds of prey, Rolls-Royce named the engine the Merlin after a small, Northern Hemisphere falcon (Falco columbarius).

Two more Rolls-Royce engines developed just prior to the war were added to the company's range. The 885 hp (660 kW) Rolls-Royce Peregrine was an updated, supercharged development of their V-12 Kestrel design, while the 1,700 hp (1,300 kW) 42-litre (2,560 cu in) Rolls-Royce Vulture used four Kestrel-sized cylinder blocks fitted to a single crankcase and driving a common crankshaft, forming an X-24 layout. This was to be used in larger aircraft such as the Avro Manchester.

Although the Peregrine appeared to be a satisfactory design, it was never allowed to mature since Rolls-Royce's priority was refining the Merlin. As a result, the Peregrine saw use in only two aircraft: the Westland Whirlwind fighter and one of the Gloster F.9/37 prototypes. The Vulture was fitted to the Avro Manchester bomber, but proved unreliable in service and the planned fighter using it – the Hawker Tornado – was cancelled as a result. With the Merlin itself soon pushing into the 1,500 hp (1,100 kW) range, the Peregrine and Vulture were both cancelled in 1943, and by mid-1943 the Merlin was supplemented in service by the larger Griffon. The Griffon incorporated several design improvements and ultimately superseded the Merlin.

Initially the new engine was plagued with problems, such as failure of the accessory gear trains and coolant jackets, and several different construction methods were tried before the basic design of the Merlin was set. Early production Merlins were also unreliable: Common problems were cylinder head cracking, coolant leaks, and excessive wear to the camshafts and crankshaft main bearings.

Early engines
The prototype, developmental, and early production engine types were the:

• PV-12 The initial design using an evaporative cooling system. Two built, passed bench type testing in July 1934, generating 740 horsepower (552 kW) at 12,000-foot (3,700 m) equivalent. First flown 21 February 1935.
• Merlin B Two built, ethylene glycol liquid cooling system introduced. "Ramp" cylinder heads (inlet valves were at a 45-degree angle to the cylinder). Passed Type Testing February 1935, generating 950 horsepower (708 kW) at 11,000-foot (3,400 m) equivalent.
• Merlin C Development of Merlin B; crankcase and cylinder blocks became three separate castings with bolt-on cylinder heads. First flight in Hawker Horsley 21 December 1935, 950 horsepower (708 kW) at 11,000-foot (3,400 m).
• Merlin E Similar to C with minor design changes. Passed 50-hour civil test in December 1935 generating a constant 955 horsepower (712 kW) and a maximum rating of 1,045 horsepower (779 kW). Failed military 100-hour test in March 1936. Powered the Supermarine Spitfire prototype.
• Merlin F (Merlin I) Similar to C and E. First flight in Horsley 16 July 1936. This became the first production engine, and was designated as the Merlin I. The Merlin continued with the "ramp" head, but this was not a success and only 172 were made. The Fairey Battle I was the first production aircraft to be powered by the Merlin I and first flew on 10 March 1936.
• Merlin G (Merlin II) Replaced "ramp" cylinder heads with parallel pattern heads (valve stems parallel to the cylinder bore axis) scaled up from the Kestrel engine. 400-hour flight endurance tests carried out at RAE July 1937; acceptance test 22 September 1937. It was first widely delivered as the 1,030-horsepower (770 kW) Merlin II in 1938, and production was quickly stepped up for Fairey Battle II.
• Merlin III Merlin II with standardised de Havilland/Rotol SBAC propeller shaft, and dual accessory-drive. 1,030-horsepower (770 kW) at 3,000 rpm at 10,250 feet at +6.5 lb boost. Formed basis for the Rolls-Royce/Rover Meteor tank engine
• "Racing" Merlin Racing engine for 1937/38 "Speed Spitfire" world speed record attempt. Merlin III with strengthened pistons, connecting rods, and gudgeon-pins, running on increased octane fuel, developed 2,160-horsepower (1,610 kW) at 3,200 rpm and +27 lb boost, a power/weight ratio of 0.621 lb per horsepower. Completed 15 hour endurance run at 1,800-horsepower (1,342 kW), 3,200 rpm at +22 lb boost.
• Merlin IV Merlin with pressure-water cooling for Armstrong Whitworth Whitley IV.
• Merlin V Merlin for Fairey Battle V.
• Merlin VIII Medium-supercharged Merlin developed for Fairey Fulmar I, rated 1,010-horsepower (754 kW) at 2,850 rpm at 6,750 feet, 1,080-horsepower (805 kW) at 3,000 rpm for take-off using 100 octane fuel.
Merlin X First Merlin with two-speed supercharger, 1,145-horsepower (853 kW) in low gear at 5,250 feet, 1,010-horsepower (754 kW) in high gear at 17,750 feet. First of Rolls-Royce unitised "Power Plant" installation designs for this engine in 1937 and used in Handley Page Halifax I, Vickers Wellington II, and Armstrong Whitworth Whitley V and VII.
• Merlin XII Merlin fitted with 0.477:1 reduction gear installed in some Spitfire II's with three-bladed Rotol constant-speed propeller. Rated at 1,150-horsepower (857 kW) at 3,000 rpm at 14,000 feet.
• Merlin XX Merlin X with Stanley Hooker re-designed supercharger incorporating re-designed inlet and improved guide vanes on impeller with revised blower gear ratios; 8:15:1 for low gear, 9:49:1 for high gear. New larger SU twin choke updraught carburettor. Engine interchangeable with Merlin X. Rated at 1,240-horsepower (924 kW) at 2,850 rpm in low gear at 10,000 feet and +9 lb boost; 1,175-horsepower (876 kW) at 2,850 rpm in high gear at 17,500 feet at +9 lb boost. Revised Rolls-Royce unitised "Power Plant" installation design. Engine used in Bristol Beaufighter II, Boulton Paul Defiant II, Handley Page Halifax II and V, Hawker Hurricane II and IV, and Avro Lancaster I and III. First Merlin produced by Packard Motor Car Company as V-1650-1 and designated by Rolls-Royce as Merlin 28.

Production engines
The Merlin II and III series were the first main production versions of the engine. The Merlin III was the first version to incorporate a "universal" propeller shaft, allowing either de Havilland or Rotol manufactured propellers to be used.

The first major version to incorporate changes brought about through experience in operational service was the XX, which was designed to run on 100 octane fuel. This fuel allowed higher manifold pressures, which were achieved by increasing the boost from the centrifugal supercharger. The Merlin XX also utilised the two-speed superchargers designed by Rolls-Royce, resulting in increased power at higher altitudes than previous versions. Another improvement, introduced with the Merlin X, was the use of a 70%–30% water-glycol coolant mix rather than the 100% glycol of the earlier versions. This substantially improved engine life and reliability, removed the fire hazard of the flammable ethylene glycol, and reduced the oil leaks that had been a problem with the early Merlin I, II and III series.

The process of improvement continued, with later versions running on higher octane ratings, delivering more power. Fundamental design changes were also made to all key components, again increasing the engine's life and reliability. By the end of the war the "little" engine was delivering over 1,600 horsepower (1,200 kW) in common versions, and as much as 2,030 horsepower (1,540 kW) in the Merlin 130/131 versions specifically designed for the de Havilland Hornet. Ultimately, during tests conducted by Rolls-Royce at Derby, an RM.17.SM (the high altitude version of the Merlin 100-Series) achieved 2,640 horsepower (1,969 kW) at 36 lb boost (103"Hg) on 150 octane fuel with water injection.

With the end of the war, work on improving Merlin power output was halted and the development effort was concentrated on civil derivatives of the Merlin. Development of what became the "Transport Merlin" (TML) commenced with the Merlin 102 (the first Merlin to complete the new civil type-test requirements) and was aimed at improving reliability and service overhaul periods for airline operators using airliner and transport aircraft such as the Avro Lancastrian, Avro York (Merlin 500-series), Avro Tudor II & IV (Merlin 621), Tudor IVB & V (Merlin 623), TCA Canadair North Star (Merlin 724) and BOAC Argonaut (Merlin 724-IC). By 1951 the time between overhauls (TBO) was typically 650–800 hours depending on use. By then single-stage engines had accumulated 2,615,000 engine hours in civil operation, and two-stage engines 1,169,000.

In addition, an exhaust system to reduce noise levels to below those from ejector exhausts was devised for the North Star/Argonaut. This "cross-over" system took the exhaust flow from the inboard bank of cylinders up-and-over the engine before discharging the exhaust stream on the outboard side of the UPP nacelle. As a result, sound levels were reduced by between 5 and 8 decibels. The modified exhaust also conferred an increase in horsepower over the unmodified system of 38 hp (28 kW), resulting in a 5 knot improvement in true air speed. Still-air range of the aircraft was also improved by around 4 per cent. The modified engine was designated the "TMO" and the modified exhaust system was supplied as kit that could be installed on existing engines either by the operator or by Rolls-Royce.

Power ratings for the civil Merlin 600, 620, and 621-series was 1,160 hp (870 kW) continuous cruising at 23,500 feet (7,200 m), and 1,725 hp (1,286 kW) for take-off. Merlins 622–626 were rated at 1,420 hp (1,060 kW) continuous cruising at 18,700 feet (5,700 m), and 1,760 hp (1,310 kW) for take-off. Engines were available with single-stage, two-speed supercharging (500-series), two-stage, two-speed supercharging (600-series), and with full intercooling, or with half intercooling/charge heating, charge heating being employed for cold area use such as in Canada. Civil Merlin engines in airline service flew 7,818,000 air miles in 1946, 17,455,000 in 1947, and 24,850,000 miles in 1948.

Structure (Merlin 61)

• Cylinders: Twelve cylinders consisting of high-carbon steel liners set in two, two-piece cylinder blocks of cast "R.R.50" aluminium alloy having separate heads and skirts. Wet liners, ie. coolant in direct contact with external face of liners. Cylinder heads fitted with cast-iron inlet valve guides, phosphor bronze exhaust valve guides, and renewable "Silchrome" steel-alloy valve seats. Two diametrically opposed spark plugs protrude into each combustion chamber.
• Pistons: Machined from "R.R.59" alloy forgings. Fully floating hollow gudgeon pins of hardened nickel-chrome steel. Three compression and one oil-control ring above the gudgeon pin, and one oil-control ring below.
• Connecting rods: H-section machined nickel-steel forgings, each pair consisting of a plain and a forked rod. The forked rod carries a nickel-steel bearing block which accommodates steel-backed lead-bronze-alloy bearing shells. The "small-end" of each rod houses a floating phosphor bronze bush.
• Crankshaft: One-piece, machined from a nitrogen-hardened nickel-chrome molybdenum steel forging. Statically and dynamically balanced. Seven main bearings and six throws.
• Crankcase: Two aluminium-alloy castings joined together on the horizontal centreline. The upper portion bears the wheelcase, supercharger and accessories; and carries the cylinder blocks, crankshaft main bearings (split mild-steel shells lined with lead bronze alloy), and part of the housing for the airscrew reduction gear. The lower half forms an oil sump and carries the oil pumps and filters.
• Wheelcase: Aluminium casting fitted to rear of crankcase. Houses drives to the camshafts, magnetos, coolant and oil pumps, supercharger, hand and electric starters, and the electric generator.
• Valve gear: Two inlet and two exhaust poppet valves of "K.E.965" steel per cylinder. Both the inlet and exhaust valves have hardened "stellited" ends; while the exhaust valves also have sodium-cooled stems, and heads protected with a "Brightray" (nickel-chromium) coating. Each valve is kept closed by a pair of concentric coil-springs. A single, seven-bearing camshaft, located on the top of each cylinder head operates 24 individual steel rockers; 12 pivoting from a rocker shaft on the inner, intake side of the head to actuate the exhaust valves, the others pivoting from a shaft on the exhaust side of the head to actuate the inlet valves.

Variants:
This is a list of representative Merlin variants, describing some of the mechanical changes made during development of the Merlin. Engines of the same power output were typically assigned different model numbers based on supercharger or propeller gear ratios, differences in cooling system or carburettors, engine block construction, or arrangement of engine controls. Power ratings quoted are usually maximum "military" power. All but the Merlin 131 and 134 engines were "right-hand tractor", i.e. the propeller rotated clockwise when viewed from the rear. In addition to the mark numbers, Merlin engines were allocated experimental numbers by the Ministry of Supply (MoS) – e.g.: RM 8SM for the Merlin 61 and some variants – while under development; these numbers are noted where possible. Merlin engines used in Spitfires, apart from the Merlin 61, used a propeller reduction ratio of .477:1. Merlins used in bombers and other fighters used a ratio of .42:1.

• Merlin II (RM 1S): 1,030 hp (775 kW) at 3,000 rpm at 5,500 ft (1,676 m) using + 6 psi boost (41 kPa gauge; or an absolute pressure of 144 kPa or 1.41 atm); used 100% glycol coolant. First production Merlin II delivered 10 August 1937. Merlin II used in the Boulton Paul Defiant, Hawker Hurricane Mk.I, Supermarine Spitfire Mk.I fighters, and Fairey Battle light bomber.
• Merlin III (RM 1S): Merlin III fitted with "universal" propeller shaft able to mount either de Havilland or Rotol propellers. From late 1939, using 100 octane fuel and +12 psi boost (83 kPa gauge; or an absolute pressure of 184 kPa or 1.82 atm), the Merlin III developed 1,310 hp (977 kW) at 3,000 rpm at 9,000 ft (2,700 m); using 87 octane fuel the power ratings were the same as the Merlin II. Used in the Defiant, Hurricane Mk.I, Spitfire Mk.I fighters, and Battle light bomber. First production Merlin III delivered 1 July 1938.
• Merlin X (RM 1SM): 1,130 hp (840 kW) at 3,000 rpm at 5,250 ft (1,600 m); maximum boost pressure +10 psi; this was the first production Merlin to use a two-speed supercharger; Used in Halifax Mk.I, Wellington Mk.II, and Whitley Mk.V bombers. First production Merlin X, 5 December 1938.
• Merlin XII (RM 3S): 1,150 hp (860 kW); fitted with Coffman engine starter; first version to use 70/30% water/glycol coolant rather than 100% glycol. Reinforced construction, able to use constant boost pressure of up to +12 psi using 100 octane fuel; Used in Spitfire Mk.II. First production Merlin XII, 2 September 1939.
• Merlin XX (RM 3SM): 1,480 hp (1,105 kW) at 3,000 rpm at 6,000 ft (1,829 m); two-speed supercharger; boost pressure of up to +14 psi; Used in Hurricane Mk.II, Beaufighter Mk.II, Halifax Mk.II and Lancaster Mk.I bombers, and in the Spitfire Mk.III prototypes (N3297 & W3237). First production Merlin XX, 4 July 1940.
• Merlin 32 (RM 5M): 1,645 hp (1,230 kW) at 3,000 rpm at 2,500 ft (762 m); a "low altitude" version of Merlin with cropped supercharger impellers for increased power at lower altitudes and a maximum boost pressure of +18 psi; fitted with Coffman engine starter; used mainly in Fleet Air Arm aircraft, mainly the Fairey Barracuda Mk.II torpedo bomber and Supermarine Seafire F. Mk.IIc fighters. Also Hurricane Mk.V and Spitfire P.R Mk.XIII. First production Merlin 32, 17 June 1942.
• Merlin 45 (RM 5S): 1,515 hp (1,130 kW) at 3,000 rpm at 11,000 ft (3,353 m); used in Spitfire Mk.V, PR.Mk.IV and PR.Mk.VII, Seafire Ib and IIc. Maximum boost pressure of +16 psi. First production Merlin 45, 13 January 1941.
• Merlin 47 (RM 6S): 1,415 hp (1,055 kW) at 3,000 rpm at 14,000 ft (4,267 m); high-altitude version used in Spitfire H.F.Mk.VI. Adapted with a Marshall compressor (often called a "blower") to pressurise the cockpit. First production Merlin 47, 2 December 1941.
• Merlin 50.M (RM 5S): 1,585 hp (1,182 kW) at 3,000 rpm at 3,800 ft (1,158 m); low-altitude version with supercharger impeller "cropped" to 9.5 in (241 mm) in diameter. Permitted boost was +18 psi (125 kPa gauge; or an absolute pressure of 225 kPa or 2.2 atm) instead of +16 psi (110 kPa gauge; or an absolute pressure of 210 kPa or 2.08 atm) on a normal Merlin 50 engine. Merlin 50 series was first to use the Bendix-Stromberg "negative-g" carburettor.
• Merlin 61 (RM 8SM): 1,565 hp (1,170 kW) at 3,000 rpm at 12,250 ft (3,734 m), 1,390 hp (1,035 kW) at 3,000 rpm at 23,500 ft (7,163 m); fitted with a new two-speed two-stage supercharger providing increased power at medium to high altitudes; +15 psi boost; used in Spitfire F Mk.IX, and P.R Mk.XI. First British production variant to incorporate two-piece cylinder blocks designed by Rolls-Royce for the Packard Merlin. Reduction gear ratio .42:1, with gears for pressurisation pump. First production Merlin 61, 2 March 1942.
• Merlin 63 & 63A: 1,710 hp (1,275 kW) at 3,000 rpm at 8,500 ft (2,591 m), 1,505 hp (1,122 kW) at 3,000 rpm at 21,000 ft (6,401 m); strengthened two-speed two-stage development of Merlin 61; +18 psi boost; Reduction gear ratio .477:1; Merlin 63A did not have extra gears for pressurisation and incorporated a strengthened supercharger drive quill shaft. Used in Spitfire F Mk.VIII and F. Mk. IX.
• Merlin 66 (RM 10SM): 1,720 hp (1,283 kW) at 5,790 ft (1,765 m) using +18 psi boost (124 kPa gauge; or an absolute pressure of 225 kPa or 2.2 atm); low-altitude version of Merlin 63A. Fitted with a Bendix-Stromberg anti-g carburettor; intercooler used a separate header tank. Used in Spitfire L.F Mk.VIII and L.F Mk.IX.
• Merlin 76/77 (RM 16SM): 1,233 hp (920 kW) at 35,000 ft (10,668 m); Fitted with a two-speed, two-stage supercharger and a Bendix-Stromberg carburettor. Dedicated "high altitude" version used in the Westland Welkin high-altitude fighter and some later Spitfire and de Havilland Mosquito variants. The odd-numbered mark drove a blower for pressurising the cockpit.
• Merlin 130/131: 2,060 hp (1,536 kW); redesigned "slimline" versions for the de Havilland Hornet. Engine design modified to decrease frontal area to a minimum and was the first Merlin series to use down-draught induction systems. Coolant pump moved from the bottom of the engine to the starboard side. Two-speed, two-stage supercharger and S.U. injection carburettor. Corliss throttle. Maximum boost was 25 psi (170 kPa gauge; or an absolute pressure of 270 kPa or 2.7 atm). On the Hornet the Merlin 130 was fitted in the port nacelle: the Merlin 131, fitted in the starboard nacelle, was converted to a "reverse" or left-hand tractor engine using an additional idler gear in the reduction gear casing.
• Merlin 133/134: 2,030 hp (1,514 kW); derated for use at low altitude 130/131 variants used in Sea Hornet F. Mk. 20, N.F. Mk. 21 and P.R. Mk. 22. Maximum boost was lowered to +18 psi gauge (230 kPa or 2.2 atm absolute).
• Merlin 266 (RM 10SM): The prefix "2" indicates engines built by Packard, otherwise as Merlin 66, optimised for low-altitude operation. Fitted to the Spitfire Mk.XVI.
• Merlin 620: 1,175 hp (876 kW) continuous cruising using 2,650 rpm at +9 psi boost (62 kPa gauge; or an absolute pressure of 165 kPa or 1.6 atm); capable of emergency rating of 1,795 hp (1,338 kW) at 3,000 rpm using +20 psi boost (138 kPa gauge; or an absolute pressure of 241 kPa or 2.4 atm) ; civilian engine developed from Merlin 102; two-stage supercharger optimised for medium altitudes, and used an S.U. injection carburettor. "Universal Power Plant" (UPP) standardised annular radiator installation development of that used on Lancaster VI and Avro Lincoln. The Merlin 620–621 series was designed to operate in the severe climatic conditions encountered on Canadian and long-range North Atlantic air routes. Used in Avro Tudor, Avro York, and the Canadair North Star.

Applications:

Armstrong Whitworth Whitley Avro Athena Avro Lancaster Avro Lancastrian Avro Lincoln Avro Manchester III Avro Tudor Avro York Boulton Paul Balliol and Sea Balliol Boulton Paul Defiant Bristol Beaufighter II CAC CA-18 Mark 23 Mustang Canadair North Star CASA 2.111B and D Cierva Air Horse de Havilland Mosquito de Havilland Hornet Fairey Barracuda Fairey Battle Fairey Fulmar Fairey P.4/34 Fiat G.59

Handley Page Halifax Handley Page Halton Hawker Hart (Test bed) Hawker Henley Hawker Horsley (Test bed Hawker Hotspur Hawker Hurricane Hawker Sea Hurricane Hispano Aviación HA-1112 I.Ae. 30 Ñancú Miles M.20 North American Mustang Mk X Renard R.38 Short Sturgeon Supermarine Type 322 Supermarine Seafire Supermarine Spitfire Vickers F.7/41 Vickers Wellington Mk II and Mk VI Vickers Windsor Westland Welkin

General characteristics: (Merlin 61)

• Type: 12-cylinder, supercharged, liquid-cooled, 60° "Vee", piston aircraft engine.
• Bore: 5.4 in (137 mm)
• Stroke: 6.0 in (152 mm)
• Displacement: 1,649 cu in (27 L)
• Length: 88.7 in (225 cm)
• Width: 30.8 in (78 cm)
• Height: 40 in (102 cm)
• Dry weight: 1,640 lb (744 kg)

Components

• Valvetrain: Overhead camshaft, two intake and two exhaust valves per cylinder, sodium-cooled exhaust valve stems.
• Supercharger: Two-speed, two-stage. Boost pressure automatically linked to the throttle, coolant-air aftercooler between the second stage and the engine.
• Fuel system: Twin-choke updraught Rolls-Royce/S.U. carburettor with automatic mixture control. Twin independent fuel pumps.
• Fuel type: 100/130 Octane petrol.
• Oil system: Dry sump with one pressure pump and two scavenge pumps.
• Cooling system: 70% water and 30% ethylene glycol coolant mixture, pressurised. Supercharger intercooler system entirely separate from main cooling system.
• Reduction gear: 0.42:1

Performance:

• Power output:
• 1,290 hp (962 kW) at 3,000 rpm at take-off.
• 1,565 hp (1,167 kW) at 3,000 rpm at 12,250 ft (3,740 m, MS gear)
• 1,580 hp (1,178 kW) at 3,000 rpm at 23,500 ft (7,200 m, FS gear)
• Specific power: 0.96 hp/cu in (43.6 kW/L)
• Compression ratio: 6:1
• Fuel consumption: Minimum 30 Imp gal/h (136 L/h), maximum 130 Imp gal/h (591 L/h)
• Power-to-weight ratio: 0.96 hp/lb (1.58 kW/kg) at maximum power.

HOME > UNITED KINGDOM > PREVIOUS PAGE