Editing Napier Lion

{{Short description|British piston aircraft engine family}}
{{Use dmy dates|date=October 2019}}
{{Use British English|date=September 2023}}
<!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. -->
{{Use British English|date=December 2017}}
{|{{Infobox aircraft begin
 |name=Lion
 |image= File:CASM - Napier Lion II - 030906.jpg
 |caption= Napier Lion II at [[Canada Aviation Museum]]
}}{{Infobox Aircraft Engine
 |type=[[Piston]] [[Aircraft engine|aero-engine]]
 |manufacturer=[[D. Napier & Son]]
 |first run=1917
 |major applications=[[Handley Page Hyderabad]]<br />[[Vickers Vernon]]
}}
|}

The '''Napier Lion''' is a 12-cylinder, [[petrol]]-fueled 'broad arrow' [[W12 engine|W12]] configuration [[aircraft engine]] 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made it the most powerful engine of its day and kept it in production long after other contemporary designs had been superseded.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==
{{More citations needed section|date=December 2013}}
Early in the First World War, Napier were contracted to build aero engines to designs from other companies, initially a [[Royal Aircraft Establishment|Royal Aircraft Factory]] model and then [[Sunbeam Motor Car Company#Sunbeam-Coatalen engines|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#In characterisation of internal combustion engines|"broad arrow"]]—three banks of four cylinders sharing a common crankshaft. The configuration is also known as a [[W engine]].<ref name="Wiley1936">{{cite book |last1=Domonoske |first1=Arthur Boquer |last2=Finch |first2=Volney Cecil |year=1936 |title=Aircraft Engines: Theory, Analysis, Design and Operation |url=https://books.google.com/books?id=qrc7AAAAMAAJ|type=Engineering textbook |publisher= J. Wiley & Sons |page=7 |quote=The W, or broad arrow engine, has three rows of cylinders of which the central row is vertical with the other two rows forming equal angles with the vertical.}}</ref> The engine was also advanced in form, the heads using four valves per cylinder with twin overhead [[camshaft]]s on each bank of cylinders and a single block being milled from [[aluminium]] instead of the common separate-cylinder steel construction used on almost all other designs. In contrast to the long stroke small bore engine designs typical of the period, the Lion engine was also well ahead of its time in being [[oversquare]], the cylinder bore diameter being larger than the crankshaft stroke, this allowing higher engine speeds and greater efficiency. 

[[File:Napier Lion cambox.jpg|thumb|left|Cutaway view showing the [[Overhead camshaft|double overhead camshaft]] arrangement]]

Under [[Arthur Rowledge]], 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 {{convert|450|hp|kW}} from their 24 [[litre]]s. The power output made the Lion the most powerful Allied aircraft engine, which had previously been the [[Liberty L-12]], producing {{convert|400|hp|kW}}.

As the most powerful engine available (particularly after a [[turbocharger]] 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.

[[File:Napier-Railton Engine Bay.jpg|thumb|The Napier Lion installed in the [[Napier-Railton]] car]]
In [[engine tuning|highly tuned]] racing versions, the engine could reach {{convert|1300|hp|kW|abbr=on}} and it was used to break many world height, air speed and distance records in aircraft and boats, delivering {{convert|1375|hp|kW|abbr=on}} in a highly tuned Lion for a water speed record of {{convert|100|mph|abbr=on}} in 1933. In land speed records, Lion engines powered many of [[Sir Malcolm Campbell]]'s [[:Category:Bluebird record-breaking vehicles|record breakers]] including a record of over {{convert|250|mph|abbr=on}} in 1932 and [[John Cobb (motorist)|John Cobb]]'s {{convert|394|mph|abbr=on}} ''[[Railton Mobil Special]]'' 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]], in 1922 and 1927 but were dropped by [[Supermarine]] in favour of a new engine, the [[Rolls-Royce 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]] and the [[Rolls-Royce Merlin]] 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]]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]] and Navy.

Turning away from the broad arrow layout, Napier designed new engines using the more compact [[H engine]] layout. The 16-cylinder [[Napier Rapier]] produced {{convert|400|hp|kW|abbr=on}} and the 24-cylinder [[Napier Dagger]] delivered just under {{convert|1000|hp|kW|abbr=on}}. The engines were smaller than contemporary designs from other companies and Napier started afresh with a new [[sleeve valve]] design, which evolved into the [[Napier Sabre]].

==Variants==

{| class="wikitable"
|-
|+ Lion models<ref>Vessey 1997</ref><ref name="Flight, 27 June 1958, Napier Lion" >{{cite journal
  |journal=[[Flight (magazine)|Flight]]
  |title=Napier Aero-Engines
  |url=http://www.flightglobal.com/pdfarchive/view/1958/1958%20-%200877.html
  |date=27 June 1958
  |volume=73
  |number=2579
  |page=893
  |ref=Flight, 27 June 1958, Napier Lion
}}</ref>
|-
! Model !! Date !! Works No. !! Power !! Notes !! Notable uses
|-
| I || 1918 || || {{convert|450|bhp|kW|abbr=on}} at 1,950 rpm || geared, also related IA and 1AY ||
|-
| II || 1919 || E64 || {{convert|480|bhp|kW|abbr=on}} at 2,200 rpm || ||
|-
| III || || ||geared high compression||||[[Vickers Vernon]] Mk.III
|-
| IV || || ||experimental geared||||[[Gloster Gorcock]]
|-
| V || || || {{convert|470|bhp|kW|abbr=on}} at 2,000 rpm<br /> {{convert|500|bhp|kW|abbr=on}} at 2,250 rpm || VA had increased CR to 5.8  || Mainstay engine of the RAF in the late 1920s, replaced by Lion XI
|-
| VS || || E79 || || Turbocharged, intercooled
|-
| VIS || 1927 || || || Turbocharged || [[Gloster Guan]]
|-
| VII || 1925 || || {{convert|700|bhp|kW|abbr=on}} (racing) || || [[Gloster III]] (Schneider Trophy entrant)<br />[[Supermarine S.4]]
|-
| VIIA || 1927 || E86 || {{convert|900|bhp|kW|abbr=on}} (racing)|| || [[Golden Arrow (land speed racer)|Golden Arrow]] <br />[[Napier-Campbell Blue Bird|Blue Bird (1927)]] <br />[[Miss England I]] <br />[[Supermarine S.5]]<br />[[Gloster IV]]
|-
| VIIB || 1927 || || {{convert|875|bhp|kW|abbr=on}} (racing) || geared || [[Supermarine S.5]]<br />[[Gloster IV]]
|-
| VIID || 1929 || E91 || {{convert|1350|bhp|kW|abbr=on}} at 3,600 rpm (racing) ||Supercharged, about 6–8 built  || [[Campbell-Napier-Railton Blue Bird|Blue Bird (1931)]] <br />[[Fred H Stewart]]'s ''Enterprise''  <br />[[Betty Carstairs]]' ''Estelle V'' powerboat <br />[[Miss Britain III]] <br />[[Gloster VI]] (Schneider Trophy entrant)<br />[[Railton Special]] (John Cobb's land speed record car)
|-
| VIII ||1927 ||  || || direct drive || [[Gloster Gorcock]]
|-
| XIA || 1928 || || {{convert|580|bhp|kW|abbr=on}} at 2,585 rpm, 6:1 CR || RAF production model || [[Napier-Railton]]
|-
| Lioness || || E71 || || Inverted layout, for better visibility. At least some were built turbocharged, for racing. ||
|-
| Sea Lion ||1933 ||  || {{convert|500|and|600|bhp|kW|abbr=on}} || Marine version of Lion XI || [[British Power Boat Company Type Two 63 ft HSL]]
|}

==Applications==

===Aircraft===
[[File:Napier Lion W12 @ Brooklands Museum.JPG|thumb|Napier Lion at [[Brooklands|Brooklands Motor Museum]]]]
{{Div col|colwidth=22em}}
*[[Alliance P.2 Seabird]]
*[[Avro Bison]]
*[[Blackburn Blackburn]]
*[[Blackburn Dart]]
*[[Blackburn Pellet]]
*[[Blackburn Ripon]]
*[[Blackburn Velos]]
*[[Boulton Paul Atlantic]]
*[[Boulton Paul Bodmin]]
*[[Boulton Paul Bolton]]
*[[Bristol Ten-seater]]
*[[English Electric Kingston]] (prototype)
*[[Fairey III]]
*[[Fairey Fawn]]
*[[Felixstowe F.5]] – (N4839)<ref name='Ransom'>{{cite web|last1=Ransom and Fairclough|first1=S and R|title=English Electric Aircraft and their Predecessors|url=http://flyingmachines.ru/Site2/Crafts/Craft25646.htm|website=Their Fighting Machines|publisher=Putnam|access-date=7 January 2017|date=1987}}</ref>
*[[Fokker C.IV-W]]
*[[Fokker C.V]]
*[[Fokker D.C.I]]
*[[Fokker D.XIII]]
*[[Gloster Gorcock]]
*[[Gloster Guan]]
*[[Handley Page H.P.31 Harrow]]
*[[Handley Page Hyderabad]]
*[[Handley Page Type W#W.10|Handley Page W.10]]
*[[Letov Š-8]]
*[[Mitsubishi B1M]]
*[[Parnall Pike]]
*[[Parnall Possum]]
*[[Parnall Puffin]]
*[[Supermarine S.4]]
*[[Supermarine S.5]]
*[[Supermarine Seagull (1921)|Supermarine Seagull]]
*[[Supermarine Southampton]]
*[[Tarrant Tabor]]
*[[Vickers Vernon]]
*[[Vickers Valparaiso]]
*[[Vickers Victoria]]
*[[Vickers Virginia]]
*[[Vickers Vixen]]
*[[Westland Walrus]]
{{Div col end}}

===Other applications===
* [[British Power Boat Company Type Two 63 ft HSL]]
* [[British Power Boat Company 60 ft 4 in]]<ref>[http://www.mwadui.com/HonKong/The 2nd MTB Flotilla.pdf]{{Dead link|date=April 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
* [[Napier-Railton]] race car, [[Brooklands]] lap record holder
* [[Napier-Bentley]], a 1968 special in the vintage tradition
* [[Golden Arrow (car)|Golden Arrow]] world land speed record holder
* [[Railton Special]] world land speed record holder

==Engines on display==
[[File:Napier Lion duxford.JPG|thumb|right|Napier Lion on display at Imperial War Museum Duxford]]
Preserved Napier Lion engines are on static display at
* [[Brooklands Museum]]
* [[Canada Aviation Museum]]
* [[Imperial War Museum Duxford]]
* [[National Maritime Museum]]<ref>{{cite web|url=http://collections.rmg.co.uk/collections/objects/11429.html |title=Miss Britain III – National Maritime Museum |publisher=Collections.rmg.co.uk |access-date=6 March 2013}}</ref>
* [[Solent Sky]]

==Specifications (Lion II)==
{{pistonspecs
|<!-- If you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] -->
<!-- Please include units where appropriate (main comes first, alt in parentheses). If data are missing, leave the parameter blank (do not delete it). For additional lines, end your alt units with </li> and start a new, fully-formatted line with <li> -->
|type=12-cylinder water-cooled [[W engine|W-block]] 60° (3 banks of 4 cylinders) aircraft piston engine
|ref=Lumsden<ref>Lumsden 2003, p.166.</ref>
|bore=5.5 in (139.7 mm)
|stroke=5.125 in (130.17 mm)
|displacement=1,461.6 in<sup>3</sup> (23.944 L)
|length=57.5 in (1460 mm)
|diameter=
|width=42.0 in (1067 mm)
|height=43.5 in (1105 mm)
|weight=960 lb (435 kg)
|valvetrain=Two intake and two exhaust valves per cylinder actuated via double [[overhead camshaft]]s per cylinder block.
|supercharger=
|turbocharger=
|fuelsystem=
|fueltype=
|oilsystem=
|coolingsystem=Water-cooled
|power=480 hp (358 kW) at 2,200 rpm at 5,000 ft
|specpower=0.32 hp/in<sup>3</sup> (15.0 kW/L)
|compression=5.8:1
|fuelcon=
|specfuelcon=
|oilcon=
|power/weight=0.5 hp/lb (0.82 kW/kg)
}}

==See also==
{{aircontent
|see also=
* [[Napier-Bentley]]
* [[:Category:Vehicles powered by Napier Lion engines|Vehicles powered by Napier Lion engines]]
|related=
|similar aircraft=
|lists=
* [[List of aircraft engines]]
|similar engines=
* [[Farman 12We]]
* [[Hispano-Suiza 18R]]
* [[Lorraine 12E Courlis]]
}}

== References ==

===Notes===
{{reflist}}

===Bibliography===
{{refbegin}}
* Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. {{ISBN|1-85310-294-6}}.
* Vessey, Alan. ''Napier Powered''. Stroud: Tempus (''Images of England'' series), 1997. {{ISBN|0-7524-0766-X}}.
{{refend}}

==External links==
{{commons category}}
* {{cite journal |date=27 March 1919 |title=The Napier Lion Aeromotor |journal=[[Flight (magazine)|Flight]] |volume=XI |issue=13 |id=No. 535 |pages=397–402 |url=http://www.flightglobal.com/pdfarchive/view/1919/1919%20-%200397.html |access-date=12 January 2011 }} Contemporary technical description of the Lion with photographs and drawings.

{{Napierengines}}

[[Category:Napier Lion| ]]
[[Category:Napier aircraft engines|Lion]]
[[Category:1910s aircraft piston engines]]
[[Category:W engines]]