This is a list of Rolls-Royce Merlin

Rolls-Royce Merlin

The Rolls-Royce Merlin is a British liquid-cooled, V-12, piston aero engine, of 27-litre capacity. Rolls-Royce Limited designed and built the engine which was initially known as the PV-12: the PV-12 became known as the Merlin following the company convention of naming its piston aero engines after...

variants. Engines of a similar power output were typically assigned different model numbers based on supercharger or propeller gear ratios, differences in cooling system or carburettors, engine block construction, starting system, or arrangement of engine controls. All Merlin engines were "right hand tractor", i.e. the propeller rotated clockwise viewed from behind, unless otherwise noted.

Variant overview

• Merlin II or III: 1,030 hp (775 kW) at 3,000 rpm at 5,500 ft (1,680 m). Merlin III fitted with "universal" propeller shaft able to be fitted with de Havilland or Rotol propellers.
  With 100 Octane fuel and increased (+12 lb/sq.in) Boost: 1,310 hp (977 kW) at 3,000 rpm at 12250 ft (3,733.8 m) (Merlin III); used in Spitfire Mk.I
  Supermarine Spitfire
  The Supermarine Spitfire is a British single-seat fighter aircraft that was used by the Royal Air Force and many other Allied countries throughout the Second World War. The Spitfire continued to be used as a front line fighter and in secondary roles into the 1950s...
  
   and Hurricane Mk.I
  Hawker Hurricane
  The Hawker Hurricane is a British single-seat fighter aircraft that was designed and predominantly built by Hawker Aircraft Ltd for the Royal Air Force...
  
   fighters, the Boulton Paul Defiant
  Boulton Paul Defiant
  The Boulton Paul Defiant was a British interceptor aircraft that served with the Royal Air Force early in the Second World War. The Defiant was designed and built by Boulton Paul Aircraft as a "turret fighter", without any forward-firing guns. It was a contemporary of the Royal Navy's Blackburn Roc...
  
  , and Fairey Battle
  Fairey Battle
  The Fairey Battle was a British single-engine light bomber built by the Fairey Aviation Company in the late 1930s for the Royal Air Force. The Battle was powered by the same Rolls-Royce Merlin piston engine that gave contemporary British fighters high performance; however, the Battle was weighed...
  
  .

• Merlin X: 1,130 hp (840 kW) at 3,000 rpm at 5,250 ft (1,525 m); used in Halifax Mk.I, Wellington Mk.II
  Vickers Wellington
  The Vickers Wellington was a British twin-engine, long range medium bomber designed in the mid-1930s at Brooklands in Weybridge, Surrey, by Vickers-Armstrongs' Chief Designer, R. K. Pierson. It was widely used as a night bomber in the early years of the Second World War, before being displaced as a...
  
  , and Whitley Mk.V bombers.
• Merlin XII: fitted to Spitfire Mk. II.
• Merlin XX: 1,480 hp (1,105 kW) at 3,000 rpm at 6,000 ft (1,830 m); used in Hurricane Mk.II and Beaufighter Mk.II
  Bristol Beaufighter
  The Bristol Type 156 Beaufighter, often referred to as simply the Beau, was a British long-range heavy fighter modification of the Bristol Aeroplane Company's earlier Beaufort torpedo bomber design...
  
   fighters, Halifax Mk.II and Lancaster Mk.I
  Avro Lancaster
  The Avro Lancaster is a British four-engined Second World War heavy bomber made initially by Avro for the Royal Air Force . It first saw active service in 1942, and together with the Handley Page Halifax it was one of the main heavy bombers of the RAF, the RCAF, and squadrons from other...
  
   bombers.
• Merlin 32: 1,645 hp (1,230 kW) at 3,000 rpm at 2,500 ft (760 m); used in Barracuda Mk.II
  Fairey Barracuda
  The Fairey Barracuda was a British carrier-borne torpedo- and dive bomber used during the Second World War, the first of its type used by the Royal Navy's Fleet Air Arm to be fabricated entirely from metal. It was introduced as a replacement for the Fairey Swordfish and Fairey Albacore biplanes...
  
   bomber.
• Merlin 45: 1,515 hp (1,130 kW) at 3,000 rpm at 11,000 ft (3,353 m); used in Spitfire Mk.V.
• Merlin 46: 1,415 hp (1,055 kW) at 3,000 rpm at 14,000 ft (4,270 m); high-altitude version used in Spitfire PR.Mk.IV and PR.Mk.VII
• Merlin 50.M: 1,585 hp (1,182 kW) at 3,000 rpm at 2,750 ft (838 m); Low altitude version with supercharger impeller "cropped" to 9.5 inches (241.3 mm) in diameter. Permitted boost was +18 lb/sq.in. instead of +16 lb/sq.in. as on a normal Merlin 50 engine. A "negative g" carburettor was fitted.
• Merlin 61: fitted with a new two-speed two-stage supercharger
  Supercharger
  A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...
  
   providing 1,565 hp (1,170 kW) at 3,000 rpm at 12,250 ft (3,740 m), and 1,390 hp (1,035 kW) at 3,000 rpm 23,500 ft (7,170 m); high-altitude version used in Spitfire Mk.IX, and PR.Mk.XI
• Merlin 76 & 77: 1,233 hp (920 kW); used in the Westland Welkin
  Westland Welkin
  |-See also:-Bibliography:* Buttler, Tony. British Secret Projects: Fighters and Bombers 1935–1950. Hinckley, UK: Midland, 2004. ISBN 1-85780-179-2....
  
   high-altitude fighter and some later Spitfire and Mosquito
  De Havilland Mosquito
  The de Havilland DH.98 Mosquito was a British multi-role combat aircraft that served during the Second World War and the postwar era. It was known affectionately as the "Mossie" to its crews and was also nicknamed "The Wooden Wonder"...
  
   variants. Fitted with a two-speed, two-stage supercharger and a Bendix-Stromberg carburettor. The odd-numbered mark drove a blower for pressurising
  Cabin pressurization
  Cabin pressurization is the pumping of compressed air into an aircraft cabin to maintain a safe and comfortable environment for crew and passengers when flying at altitude.-Need for cabin pressurization:...
  
   the cockpit.
• Merlin 130 & 131: 2,070 hp (1,543 kW); redesigned "slimline" versions made for the de Havilland Hornet
  De Havilland Hornet
  The de Havilland DH.103 Hornet was a piston engine fighter that further exploited the wooden construction techniques pioneered by de Havilland's classic Mosquito. Entering service at the end of the Second World War, the Hornet equipped postwar RAF Fighter Command day fighter units in the UK and was...
  
  . Engine modified to decrease frontal area to minimum and was 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 SU injection carburettor. Maximum Boost was 25 lb (2,053mm Hg). The Merlin 131 had an additional idler gear in the reduction gear casing allowing "reverse" (left hand tractor) rotation. Merlin 130 was fitted in starboard nacelle, Merlin 131 in port on production Hornets.
• Merlin 133 & 134: 2,030 hp (1,514 kW); derated variants of 130/131 used in Sea Hornet
  De Havilland Hornet
  The de Havilland DH.103 Hornet was a piston engine fighter that further exploited the wooden construction techniques pioneered by de Havilland's classic Mosquito. Entering service at the end of the Second World War, the Hornet equipped postwar RAF Fighter Command day fighter units in the UK and was...
  
   F. Mk. 20, N.F. Mk. 21 and P.R. Mk. 22. Maximum Boost was lowered to 18 lb (1,691 Hg).
• Merlin 266: the prefix 2 indicates built by Packard
  Packard
  Packard was an American luxury-type automobile marque built by the Packard Motor Car Company of Detroit, Michigan, and later by the Studebaker-Packard Corporation of South Bend, Indiana...
  
  , otherwise as Merlin 66, optimised for low-altitude operation. Fitted to the Spitfire Mk. XVI.

Variant table

Variant	Take-off Power	Combat Power	Application	Notes
Merlin I	890 hp at 2,850 rpm		Battle I	First production Merlin; 172 built. Merlin I through III used 100% glycol coolant.
Merlin II	880 hp at 3,000 rpm	1,310 hp at 3,000 rpm, +12 lb/sq.in boost, 9,000 ft	Spitfire I, Defiant I, Hurricane I, Sea Hurricane I, Battle I
Merlin III	880 hp at 3,000 rpm	1,310 hp at 3,000 rpm, +12 lb/sq.in boost, 9,000 ft	Spitfire I, Defiant I, Hurricane I, Sea Hurricane I, Battle I	1,310 hp at 9,000 ft, +12 lb/sq.in, with 100 octane fuel (5-minute limit) . 1,440 hp at 3,000 rpm, +16 lb/sq.in boost, 5,500 ft in Sea Hurricane .
Merlin VIII	1,080 hp at 3,000 rpm	1,275 hp at 3,000 rpm, +9 lb/sq.in boost, sea level	Fulmar I Fairey Fulmar The Fairey Fulmar was a British carrier-borne fighter aircraft that served with the Fleet Air Arm during the Second World War. A total of 600 were built by Fairey Aviation at its Stockport factory between January 1940 and December 1942...	1,275 hp 100 octane
Merlin X	1,280 hp at 3,000 rpm	1,280 hp at 3,000 rpm, +10 lb/sq.in boost, sea level	Halifax I, Wellington II, Whitley V and VII
Merlin XII	1,175 hp at 3,000 rpm	1,280 hp at 3,000 rpm, +12 lb/sq.in boost, 10,500 ft	Spitfire II	Coffman cartridge starter. First version of Merlin to use 30/70% glycol/water coolant.
Merlin XX	1,280 hp at 3,000 rpm	1,490 hp at 3,000 rpm, +16 lb/sq.in boost, 12,500 ft	Beaufighter II, Defiant II, Halifax II and V, Hurricane II and IV, Lancaster I and III, Spitfire III	First production version with two speed supercharger. Used 100-octane petrol (avgas)
Merlin 21	1,280 hp at 3,000 rpm	1,490 hp at 3,000 rpm, +16 lb/sq.in boost, 12,500 ft	Mosquito I, II, III, IV and VI
Merlin 22	1,390 hp at 3,000 rpm	1,435 hp at 3,000 rpm, +16 lb/sq.in boost, 11,000 ft	Lancaster I, York I
Merlin 23	1,390 hp at 3,000 rpm	1,435 hp at 3,000 rpm, +16 lb/sq.in boost, 11,000 ft	Mosquito I, II, IV, VI, XII and XIII
Merlin 24	1,610 hp at 3,000 rpm	1,510 hp at 3,000 rpm, +18 lb/sq.in boost, 9,250 ft	Lancaster I and VII, York I, Handley Page Halifax II
Merlin 25	1,610 hp at 3,000 rpm	1,510 hp at 3,000 rpm, +18 lb/sq.in boost, 9,250 ft	Mosquito VI and XIX
Merlin 27	1,610 hp at 3,000 rpm	1,510 hp at 3,000 rpm, +18 lb/sq.in boost, 9,250 ft	Hurricane IV
Merlin 28	1,300 hp at 3,000 rpm	1,240 hp at 3,000 rpm, +9 lb/sq.in boost, 11,500 ft	Lancaster III, Kittyhawk II (P-40F)	Built by Packard as the V-1650-1
Merlin 29	1,300 hp at 3,000 rpm	1,240 hp at 3,000 rpm, +9 lb/sq.in boost, 11,500 ft	Hurricane (Canadian-built), Kittyhawk II (P-40F)	Built by Packard as the V-1650-1, splined airscrew shaft
Merlin 30	1,300 hp at 3,000 rpm	1,360 hp at 3,000 rpm, +12 lb/sq.in boost, 6,000 ft	Barracuda I, Fulmar II
Merlin 31	1,300 hp at 3,000 rpm	1,240 hp at 3,000 rpm, +9 lb/sq.in boost, 11,500 ft	Mosquito XX (Canadian), Mosquito 40 (Australia), Kitthawk II (P-40F and L)	Built by Packard as the V-1650-1
Merlin 32	1,625 hp at 3,000 rpm	1,640 hp at 3,000 rpm, +18 lb/sq.in boost, 2,000 ft	Barracuda II, Seafire II, Hurricane V, Spitfire PR Mk. XIII
Merlin 33	1,400 hp at 3,000 rpm	1,240 hp at 3,000 rpm, +9 lb/sq.in boost, 11,500 ft	Mosquito XX (Canadian), Mosquito 40 (Australia)	Packard-built Merlin 23
Merlin 38	1,400 hp at 3,000 rpm	1,240 hp at 3,000 rpm, +9 lb/sq.in boost, 11,500 ft	Lancaster I and II	Packard-built Merlin 24
Merlin 45	1,185 hp at 3,000 rpm	1,515 hp at 3,000 rpm, +16 lb/sq.in boost, 11,000 ft	Spitfire V, PR Mk. IG (later redesignated PR.VII), PR Mk IV, Seafire IB, IIC
Merlin 45M	1,230 hp at 3,000 rpm	1,585 hp at 3,000 rpm, +18 lb/sq.in boost, 2,750 ft	Spitfire LF.V
Merlin 46	1,100 hp at 3,000 rpm	1,415 hp at 3,000 rpm, +16 lb/sq.in boost, 14,000 ft	Spitfire V, PR.IV and VII, Seafire IB, IIC
Merlin 47	1,100 hp at 3,000 rpm	1,415 hp at 3,000 rpm, +16 lb/sq.in boost, 14,000 ft	Spitfire HF.VI high-altitude intercepter	Fitted with a cabin pressure blower
Merlin 50	1,185 hp at 3,000 rpm	1,470 hp at 3,000 rpm, +16 lb/sq.in boost, 9,250 ft	Spitfire V
Spitfire 50M	1,230 hp at 3,000 rpm	1,585 hp at 3,000 rpm, +18 lb/sq.in boost, 2,750 ft	Spitfire LF Mk.V
Merlin 55	1,185 hp at 3,000 rpm	1,470 hp at 3,000 rpm, +16 lb/sq.in boost, 9,250 ft	Spitfire V, Seafire III
Merlin 55M	1,230 hp at 3,000 rpm	1,585 hp at 3,000 rpm, +18 lb/sq.in boost, 2,750 ft	Spitfire LF.V, Seafire III
Merlin 60	1,390 hp at 3,000 rpm	1,110 hp at 2,850 rpm, +9 lb/sq.in boost, 29,000 ft	Wellington VI
Merlin 61	1,280 hp at 3,000 rpm	1,565 hp at 3,000 rpm, +15 lb/sq.in boost, 11,250 ft	Spitfire F Mk. IX, PR Mk. XI	Two-stage supercharger fitted
Merlin 62	1,390 hp at 3,000 rpm	1,110 hp at 2,850 rpm, +9 lb/sq.in boost, 29,000 ft	Wellington VI
Merlin 63	1,280 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 8,500 ft	Spitfire VIII, IX, PR.XI	Replaced Merlin 61
Merlin 63A	1,280 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 8,500 ft	Spitfire PR.XI
Merlin 64	1,280 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 8,500 ft	Spitfire F Mk. VII	Cabin pressure blower
Merlin 66	1,315 hp at 3,000 rpm	1,705 hp at 3,000 rpm, +18 lb/sq.in boost, 5,750 ft	Spitfire LF.VIII, LF Mk.IX	Bendix-Stromberg anti-g carburettor
Merlin 67	1,315 hp at 3,000 rpm	1,705 hp at 3,000 rpm, +18 lb/sq.in boost, 5,750 ft
Merlin 68	1,670 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 6,400 ft	Mustang III (P-51B and C)	Packard-built as V-1650-3
Merlin 69	1,670 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 6,400 ft	Mustang III and IV (P-51C,D,F and K)	Packard-built as V-1650-7
Merlin 70	1,250 hp at 3,000 rpm	1,655 hp at 3,000 rpm, +18 lb/sq.in boost, 10,000 ft	Spitfire HF.VIII, HF.IX, PR.XI	Bendix-Stromberg anti-g carburettor
Merlin 71	1,250 hp at 3,000 rpm	1,655 hp at 3,000 rpm, +18 lb/sq.in boost, 10,000 ft	Spitfire HF.VII	Cabin pressure blower, Bendix-Stromberg anti-g carburettor
Merlin 72	1,280 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 8,500 ft	Mosquito PR.IX, B.IX, XVI, 30, Welkin I
Merlin 73	1,280 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 8,500 ft	Mosquito XVI, Welkin I
Merlin 76	1,250 hp at 3,000 rpm	1,655 hp at 3,000 rpm, +18 lb/sq.in boost, 10,000 ft	Mosquito XVI, 30, Welkin I	Same as Merlin 72 with a cabin pressure blower
Merlin 77	1,250 hp at 3,000 rpm	1,655 hp at 3,000 rpm, +18 lb/sq.in boost, 10,000 ft	Mosquito XVI, Welkin I, Spitfire PR.X	Same as Merlin 73 with a cabin pressure blower
Merlin 85	1,635 hp at 3,000 rpm	1,705 hp at 3,000 rpm, +18 lb/sq.in boost, 5,750 ft	Lancaster VI, Lincoln I
Merlin 130/131	2,070 hp at 3,000 rpm		Hornet F.1, P.R 2, F.3, F.R. 4.	Merlin 131 left-hand tractor.
Merlin 133/134	2,030 hp at 3,000 rpm		Sea Hornet F.20, N.F. 21 and P.R. 22
Merlin 224	1,635 hp at 3,000 rpm	1,680 hp at 3,000 rpm, +18 lb/sq.in boost, 2,500 ft	Lancaster I and III	Packard-built Merlin 24
Merlin 225	1,635 hp at 3,000 rpm	1,680 hp at 3,000 rpm, +18 lb/sq.in boost, 2,500 ft	Mosquito 25 and 26	Packard-built Merlin 25
Merlin 266	1,670 hp at 3,000 rpm	1,710 hp at 3,000 rpm, +18 lb/sq.in boost, 6,400 ft	Spitfire LF. Mk. XVI	Packard-built Merlin 66

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