Napier Lion VII
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The Napier Lion is a 12-cylinder,
petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
-fueled 'broad arrow' W12 configuration
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 ...
built by D. Napier & Son from 1917 until the 1930s. A number of advanced features made it the most powerful engine of its day and kept it in production long after other contemporary designs had been superseded. It is particularly well known for its use in a number of racing designs, for aircraft, boats and cars.


Design and development

Early in the First World War, Napier were contracted to build aero engines to designs from other companies, initially a
Royal Aircraft Factory Royal may refer to: People * Royal (name), a list of people with either the surname or given name * A member of a royal family Places United States * Royal, Arkansas, an unincorporated community * Royal, Illinois, a village * Royal, Iowa, a cit ...
model and then Sunbeams. Both engines proved to be unreliable and in 1916 Napier decided to design an engine with high power, light weight and low frontal area. Napier's engineers laid out the engine with its 12 cylinders in what they called a "broad arrow"—three banks of four cylinders sharing a common crankcase. This suggested the design's first name, the Triple-Four. The configuration is also known as a
W engine A W engine is a type of piston engine where three or four cylinder banks use the same crankshaft, resembling the letter W when viewed from the front. W engines with three banks of cylinders are also called "broad arrow" engines, due to their shap ...
. The engine was also advanced in form, the heads using four valves per cylinder with twin overhead
camshaft A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition systems ...
s on each bank of cylinders and a single block being milled from
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
instead of the common separate-cylinder steel construction used on almost all other designs. Under
Arthur Rowledge Arthur John Rowledge, (30 July 1876 – 11 December 1957) was an English engineer who designed the Napier Lion aero engine and was a key figure in the development of the Rolls-Royce Merlin. Career Rowledge was born in Peterborough, Northampto ...
, the design of the engine, renamed Lion, was completed in 1917; hand-built prototypes ran later that year. It was fitted to an Airco DH.9 in early 1918, and many cooling problems were observed during testing. The milled block was difficult to build with the required accuracy and the design reverted to separate aluminium cylinders. Both problems were solved by the middle of the year and the engine entered production in June 1918. The first Lion I versions delivered from their 24
litre The litre (international spelling) or liter (American English 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 metre (m3). ...
s. The power output made the Lion the most powerful Allied aircraft engine, which had previously been the
Liberty L-12 The Liberty L-12 is an American water-cooled 45° V-12 aircraft engine displacing and making designed for a high power-to-weight ratio and ease of mass production. It saw wide use in aero applications, and, once marinized Marinisation (also m ...
, producing . As the most powerful engine available (particularly after a
turbocharger In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
became an option in 1922), the Lion went on to commercial success. Through the years between the wars the Lion was ubiquitous and Napier manufactured little else. They stopped making cars in 1925 and little thought was given to replacing their world-famous product. Between the wars the Lion engine powered over 160 different aircraft types. In highly tuned racing versions, the engine could reach and it was used to break many world height, air speed and distance records in aircraft and boats, delivering in a highly tuned Lion for a water speed record of in 1933. In land speed records, Lion engines powered many of
Sir Malcolm Campbell Major Sir Malcolm Campbell (11 March 1885 – 31 December 1948) was a British racing motorist and motoring journalist. He gained the world speed record on land and on water at various times, using vehicles called ''Blue Bird'', including a 1 ...
's
record breakers ''Record Breakers'' was a British children's TV show, themed around world records and produced by the BBC. It was broadcast on BBC1 from 15 December 1972 to 21 December 2001. It was originally presented by Roy Castle with Guinness World Record ...
including a record of over in 1932 and John Cobb's ''
Railton Mobil Special Railton may refer to: * Railton (surname) * Railton (car), a former marque of British automobiles * Railton, Kentucky, a place in the US; see List of tornadoes in the Super Outbreak * Railton, Tasmania, a town in Tasmania, Australia See also * Cam ...
'' in 1947—a record that came well after the Lion had passed its prime and stood until the 1960s. The record had been held by British drivers for 32 years. Lions powered successful entrants in the most prestigious event in air racing, the
Schneider Trophy The Coupe d'Aviation Maritime Jacques Schneider, also known as the Schneider Trophy, Schneider Prize or (incorrectly) the Schneider Cup is a trophy that was awarded annually (and later, biennially) to the winner of a race for seaplanes and flying ...
, in 1922 and 1927 but were dropped by
Supermarine Supermarine was a British aircraft manufacturer that is most famous for producing the Supermarine Spitfire, Spitfire fighter plane during World War II as well as a range of seaplanes and flying boats, and a series of Jet engine, jet-powered figh ...
in favour of a new engine, the
Rolls-Royce R The Rolls-Royce R is a British aero engine that was designed and built specifically for air racing purposes by Rolls-Royce Limited. Nineteen R engines were assembled in a limited production run between 1929 and 1931. Developed from the Rolls-R ...
, which had been designed for racing. During the 1930s a new generation of much larger and more powerful engines appeared and the Lion became uncompetitive. By the time 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 ...
and the
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 ...
arrived in the late 1930s, the Lion was obsolete. The Sea Lion, a marine version of the Lion, was used to power high speed
RAF Rescue Launch The Marine Branch (1918-1986) was a branch of the Royal Air Force (RAF) which operated watercraft in support of RAF operations. Just days after the creation of the RAF itself, the Marine Craft Section (MCS) was created with the transfer of Roy ...
es. The Lion aero engine was also adapted to power propeller-driven motor sleighs, which were used for high-speed transport and SAR duties on sea ice by the
Finnish Air Force The Finnish Air Force (FAF or FiAF; fi, Ilmavoimat, , Air forces; sv, Flygvapnet, , Air weapon) is one of the branches of the Finnish Defence Forces. Its peacetime tasks are airspace surveillance, identification flights, and production of Finnis ...
and Navy. Turning away from the broad arrow layout, Napier designed new engines using the more compact
H engine An H engine is a piston engine comprising two separate flat engines (complete with separate crankshafts), most often geared to a common output shaft. The name "H engine" is due to the engine blocks resembling a letter "H" when viewed from the fr ...
layout. The 16-cylinder
Napier Rapier The Napier Rapier was a British 16-cylinder H pattern air-cooled aero engine designed by Frank Halford and built by Napier & Son shortly before World War II. Design and development The Rapier was the first of Napier's H cylinder engines. The ...
produced and the 24-cylinder
Napier Dagger The Napier Dagger was a 24-cylinder H-pattern ''(or H-Block)'' air-cooled engine designed by Frank Halford and built by Napier before World War II. It was a development of the earlier Napier Rapier. Design and development The H-Block has a ...
delivered just under . The engines were smaller than contemporary designs from other companies and Napier started afresh with a new
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. ...
design, which evolved into the
Napier Sabre The Napier Sabre is a British H-24-cylinder, liquid-cooled, sleeve valve, piston aero engine, designed by Major Frank Halford and built by D. Napier & Son during World War II. The engine evolved to become one of the most powerful inline ...
.


Variants


Applications


Aircraft

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Alliance P.2 Seabird __NOTOC__ The Alliance P.2 Seabird was a British single-engined long-range biplane designed by J.A. Peters to enter the Daily Mail £10,000 Atlantic Flight Prize. In the end it did not compete but became the first aircraft to fly from London (Ac ...
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Avro Bison The Avro 555 Bison was a British single-engined fleet spotter/reconnaissance aircraft built by Avro. Development and design The Bison was designed to meet British Specification 3/21 for a carrier-based fleet spotter and reconnaissance aircraf ...
*
Blackburn Blackburn The Blackburn R-1 Blackburn was a 1920s British single-engine fleet spotter/reconnaissance aircraft built by Blackburn Aircraft. History The Blackburn was developed to meet a naval requirement ( Specification 3/21) for a carrier-based reconnai ...
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Blackburn Dart The Blackburn Dart was a carrier-based torpedo bomber biplane designed and manufactured by the British aviation company Blackburn Aircraft. It was the standard single-seat torpedo bomber operated by the Fleet Air Arm (FAA) between 1923 and 19 ...
*
Blackburn Pellet The Blackburn Pellet was a single-engined, single-seater biplane flying boat designed as a contender for the 1923 Schneider Trophy competition. It was destroyed while taking off for the trials of the contest. Development The 1923 Schneider T ...
*
Blackburn Ripon The Blackburn T.5 Ripon was a carrier-based torpedo bomber and reconnaissance biplane designed and produced by the British aircraft manufacturer Blackburn Aircraft. It was the basis for both the license-produced Mitsubishi B2M and the improved ...
*
Blackburn Velos The Blackburn T.3 Velos was a 1920s British two-seat coastal defence seaplane built by Blackburn Aeroplane & Motor Company Limited, Brough Aerodrome and the Greek National Aircraft Factory. Design and development The basic design of the Blac ...
*
Boulton Paul Atlantic The Boulton & Paul P.8 Atlantic was Boulton & Paul's attempt to adapt their well-performing Bourges bomber into an airliner. They hoped to gain publicity for it by winning the outstanding prize for the first non-stop Atlantic crossing but a f ...
* Boulton Paul Bodmin *
Boulton Paul Bolton The Boulton & Paul P.15 Bolton was a one-off experimental twin-engined reconnaissance biplane ordered by the Air Ministry to sustain Boulton & Paul's development of steel-framed aircraft early in the 1920s. It was the RAF's first metal-framed ...
*
Bristol Ten-seater The Bristol Ten-seater and Bristol Brandon were British single-engine biplane transport aircraft built by the Bristol Aeroplane Company in the early 1920s. Only three were built, two of which were used as civil transports and one of which (th ...
*
English Electric Kingston The English Electric P.5 Kingston was a British twin-engined biplane flying boat built by English Electric. When the English Electric Company was formed in 1918 from several companies, the Phoenix Dynamo Manufacturing Company brought with it ...
(prototype) *
Fairey III The Fairey Aviation Company Fairey III was a family of British reconnaissance biplanes that enjoyed a very long production and service history in both landplane and seaplane variants. First flying on 14 September 1917, examples were still in us ...
*
Fairey Fawn The Fairey Fawn was a British single-engine light bomber of the 1920s. It was designed as a replacement for the Airco DH.9A and served with the Royal Air Force between 1924 and 1929. Development The Fairey Fawn was designed by F Duncanson ...
*
Felixstowe F.5 The Felixstowe F.5 was a British First World War flying boat designed by Lieutenant Commander John Cyril Porte RN of the Seaplane Experimental Station, Felixstowe. Design and development Porte designed a better hull for the larger Curtiss H-12 ...
– (N4839) *
Fokker C.IV-W The Fokker C.IV was a 1920s Dutch two-seat reconnaissance aircraft designed and built by Fokker. Design and development The C.IV was developed from the earlier C.I but it was a larger and more robust aircraft. The C.IV was designed as a recon ...
*
Fokker C.V The Fokker C.V was a Dutch light reconnaissance and bomber biplane aircraft manufactured by Fokker. It was designed by Anthony Fokker and the series manufacture began in 1924 at Fokker in Amsterdam. Development The C.V was constructed in the earl ...
*
Fokker D.C.I The Fokker DC.I was an aircraft produced in the Netherlands in the early 1920s to fulfill a role of combined fighter and reconnaissance aircraft. The company designation chosen by Fokker, "DC" reflected this, with "D" being the ''Idflieg'' design ...
*
Fokker D.XIII The Fokker D.XIII was a fighter aircraft produced in the Netherlands in the mid-1920s. It was a development of the Fokker D.XI with a new powerplant and considerably refined aerodynamics, and had been designed to meet the requirements of the cl ...
*
Gloster Gorcock The Gloster Gorcock was a single-engined single-seat biplane fighter aircraft produced to a United Kingdom Air Ministry contract completed in 1927. Only three were built. Development In May 1924 Glosters received an Air Ministry contract for th ...
*
Gloster Guan The Gloster Guan was a single-engined single-seat experimental biplane fighter built in the United Kingdom to test the performance of fighters using supercharged engines at high altitudes. Three were planned but only two constructed. Developme ...
*
Handley Page H.P.31 Harrow The Handley Page H.P.31 was a two-seat single-engined biplane built to a British specification for a carrier-based torpedo bomber and reconnaissance aircraft. After trials, the Blackburn Ripon was preferred, though the Harrow played a significa ...
*
Handley Page Hyderabad The Handley Page H.P.24 Hyderabad was a twin-engine biplane heavy bomber designed and produced by the United Kingdom, British aircraft manufacturer Handley Page. It holds the distinction of being the last wooden heavy bomber to be operated by ...
* Handley Page W.10 *
Letov Š-8 The Letov Š-8 was a Czech racing aircraft designed by Alois Šmolik. The aircraft was wooden-built, mostly fabric covered, with tail-skid undercarriage and was powered by a Napier Lion The Napier Lion is a 12-cylinder, petrol-fueled 'broad ...
*
Mitsubishi B1M The Mitsubishi B1M was a Japanese torpedo bomber of the 1920s, also known as the Navy Type 13 Carrier-Borne Attack Aircraft. It was designed and built by Mitsubishi and used in combat against China. The aircraft was used by the air services of th ...
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Parnall Pike The Parnall Pike was a 2/3-seat biplane Surveillance aircraft, reconnaissance aircraft, capable of operating off carrier decks or from water, built to an Air Ministry specification in 1927. Only one was constructed. Design and development The ...
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Parnall Possum The Parnall Possum was an experimental triplane, with a single, central engine driving wing-mounted propellers via shafts and gears. Two of these British aircraft were built in the mid-1920s. Design and development The Parnall Possum was one ...
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Parnall Puffin The Parnall Puffin was an experimental amphibious fighter-reconnaissance biplane produced in the United Kingdom just after World War I. It had several unusual features, principally a single central float and an inverted vertical stabilizer and ...
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Supermarine S.4 The Supermarine S.4 was a 1920s British single-engined monoplane built by Supermarine. Designed by a team led by the company's chief designer, R. J. Mitchell, it was built to race in the 1925 Schneider Trophy contest. Mitchell's design ...
* Supermarine S.5 * Supermarine Seagull *
Supermarine Southampton The Supermarine Southampton was a flying boat of the interwar period designed and produced by the British aircraft manufacturer Supermarine. It was one of the most successful flying boats of the era. The Southampton was derived from the experime ...
*
Tarrant Tabor The Tarrant Tabor was a British triplane bomber designed towards the end of the First World War and was briefly the world's largest aircraft. It crashed, with fatalities, on its first flight. Development The Tabor was the first and only aircraft ...
*
Vickers Vernon The Vickers Vernon was a British biplane troop carrier used by the Royal Air Force. It entered service in 1921, and was the first dedicated troop transport of the RAF. The Vernon was a development of the Vickers Vimy Commercial, a passenger v ...
*
Vickers Valparaiso The Vickers Valparaiso was a British light bomber biplane of the 1920s. It was designed by Vickers as a development of its Vickers Vixen, Vixen for export, being sold to Portugal and Chile. Development and design The Vickers Valparaiso was a d ...
*
Vickers Victoria The Vickers Type 56 Victoria was a British biplane Cargo aircraft, freighter and troop transport aircraft used by the Royal Air Force. The Victoria flew for the first time in 1922 and was selected for production over the Armstrong Whitworth Awan ...
*
Vickers Virginia The Vickers Virginia was a biplane heavy bomber of the British Royal Air Force, developed from the Vickers Vimy. Design and development Work on the Virginia was started in 1920, as a replacement for the Vimy. Two prototypes were ordered on 13 ...
*
Vickers Vixen The Vickers Vixen was a British general-purpose biplane of the 1920s. Designed and developed by Vickers in a number of variants, with 18 Vixen Mark V sold to Chile. A prototype of a version with metal wings was built as the Vickers Vivid. The V ...
*
Westland Walrus The Westland Walrus was a British spotter/reconnaissance aircraft built by Westland Aircraft. Design and development In 1919 the Royal Navy had an urgent need for a three-seat spotter/reconnaissance aircraft. To save money, the Airco DH.9A was ...


Other applications

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British Power Boat Company Type Two 63 ft HSL The Type Two HSL was a 63 ft high-speed launch craft made by British Power Boat Company (BPBC). The craft were used during the Second World War for air-sea rescue operations to save Allied aircrew from the sea. The Type Two superseded the 64 ...
*
British Power Boat Company 60 ft 4 in British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...
*
Napier-Railton The Napier-Railton is an aero-engined racing car built in 1933, designed by Reid Railton to a commission by John Cobb, and built by Thomson & Taylor. It was driven by Cobb, mainly at the Brooklands race track where it holds the all-time lap ...
race car,
Brooklands Brooklands was a motor racing circuit and aerodrome built near Weybridge in Surrey, England, United Kingdom. It opened in 1907 and was the world's first purpose-built 'banked' motor racing circuit as well as one of Britain's first airfields, ...
lap record holder *
Napier-Bentley The Napier-Bentley is a vintage racing car; a one-off special built in 1972 by David Llewellyn and Peter Morley. It was based on a chassis constructed from two 4-litre Bentley sideframe members, shortened and modified to a 10 foot wheelbase. I ...
, a 1968 special in the vintage tradition * Golden Arrow world land speed record holder *
Railton Special The ''Railton Special'', later rebuilt as the ''Railton Mobil Special'', is a one-off motor vehicle designed by Reid Railton and built for John Cobb's successful attempts at the land speed record in 1938. It is currently on display at Thinkt ...
world land speed record holder


Engines on display

Preserved Napier Lion engines are on static display at *
Brooklands Museum Brooklands Museum is a motoring and aviation museum occupying part of the former Brooklands motor-racing track in Weybridge, Surrey, England. Formally opened in 1991, the museum is operated by the independent Brooklands Museum Trust Ltd, a pri ...
*
Canada Aviation Museum The Canada Aviation and Space Museum (french: link=no, Musée de l'Aviation et de l'Espace du Canada) (formerly the Canada Aviation Museum and National Aeronautical Collection) is Canada's national aviation history museum. The museum is located ...
*
Imperial War Museum Duxford Imperial War Museum Duxford is a branch of the Imperial War Museum near Duxford in Cambridgeshire, England. Britain's largest aviation museum, Duxford houses the museum's large exhibits, including nearly 200 aircraft, military vehicles, artill ...
*
National Maritime Museum The National Maritime Museum (NMM) is a maritime museum in Greenwich, London. It is part of Royal Museums Greenwich, a network of museums in the Maritime Greenwich World Heritage Site. Like other publicly funded national museums in the United ...
*
Solent Sky Solent Sky is an aviation museum in Southampton, Hampshire, previously known as Southampton Hall of Aviation. It depicts the history of aviation in Southampton, the Solent area and Hampshire. There is special focus on the Supermarine aircraft c ...


Specifications (Lion II)


See also


References


Notes


Bibliography

* Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. . * Vessey, Alan. ''Napier Powered''. Stroud: Tempus (''Images of England'' series), 1997. .


External links

* Contemporary technical description of the Lion with photographs and drawings. {{Napierengines
Lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphi ...
1910s aircraft piston engines W engines