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 Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...

and ease of mass production. It saw wide use in aero applications, and, once marinized, in marine use both in racing and runabout boats. A single bank 6-cylinder version, the

Liberty L-6 The Liberty L-6 was a six-cylinder water-cooled inline aircraft engine developed in the United States during World War I. Design and development The Liberty L-6, which developed 200–215 hp, was built by the Thomas-Morse Aircraft Corp. ...

, and V-8, the

Liberty L-8 The Liberty L-8 (also known as the Packard 1A-1100) was a prototype of the Liberty L-12 engine designed by Jesse Vincent and Elbert Hall. Fifteen L-8 prototypes were manufactured by several companies including Buick, Ford, Lincoln, Marmon, and ...

, were derived from the Liberty L-12. It was succeeded by the Packard 1A-2500.

Development

In May 1917, a month after the United States had declared war on

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

, a federal task force known as the

Aircraft Production Board The Aircraft Board was a United States federal government organization created from the Aircraft Production Board on October 1, 1917, by Act of Congress to provide statutory authority to the APB, which had been created by a resolution of the Counci ...

summoned two top engine designers, Jesse G. Vincent (of the

Packard Packard or Packard Motor Car Company was an American luxury automobile company located in Detroit, Michigan. The first Packard automobiles were produced in 1899, and the last Packards were built in South Bend, Indiana in 1958. One of the "Th ...

Motor Car Company of Detroit) and Elbert J. Hall (of the

Hall-Scott Hall-Scott Motor Car Company was an American manufacturing company based in Berkeley, California. It was among the most significant builders of water-cooled aircraft engines before World War I. History 1910–21 The company was founded in 1910 ...

Motor Co. in

Berkeley, California Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and E ...

), to Washington, D.C. They were given the task of designing as rapidly as possible an aircraft engine that would rival if not surpass those of

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, and Germany. The Board specified that the engine would have a high power-to-weight ratio and be adaptable to mass production. The Board brought Vincent and Hall together on 29 May 1917 at the Willard Hotel in Washington, where the two were asked to stay until they produced a set of basic drawings. After just five days, Vincent and Hall left the Willard with a completed design for the new engine, which had adopted, almost unchanged, the single overhead camshaft and rocker arm valvetrain design of the later Mercedes D.IIIa engines of 1917–18. In July 1917, an eight-cylinder prototype assembled by Packard's Detroit plant arrived in Washington for testing, and in August, the 12-cylinder version was tested and approved.

Production

In the fall of 1917, the War Department placed an order for 22,500 Liberty engines, dividing the contract among the automobile and engine manufacturers

Buick Buick () is a division of the American automobile manufacturer General Motors (GM). Started by automotive pioneer David Dunbar Buick in 1899, it was among the first American marques of automobiles, and was the company that established General ...

, Ford,

Cadillac The Cadillac Motor Car Division () is a division of the American automobile manufacturer General Motors (GM) that designs and builds luxury vehicles. Its major markets are the United States, Canada, and China. Cadillac models are distributed ...

, Lincoln, Marmon, and

in California was considered too small to receive a production order. Manufacturing by multiple factories was facilitated by its modular design. Ford was asked to supply cylinders for the new engine and rapidly developed an improved technique for cutting and pressing steel, which resulted in cylinder production rising from 151 per day to over 2,000; the company eventually manufactured all 433,826 cylinders produced, as well as 3,950 complete engines. Lincoln constructed a new plant in record time, devoted entirely to Liberty engine production, and assembled 2,000 engines in 12 months. By the time of the

Armistice with Germany The Armistice of 11 November 1918 was the armistice signed at Le Francport near Compiègne that ended fighting on land, sea, and air in World War I between the Entente and their last remaining opponent, Germany. Previous armistices ...

, the various companies had produced 13,574 Liberty engines, attaining a production rate of 150 engines per day. Production continued after the war, for a total of 20,478 engines built between July 4, 1917 and 1919. Although it is widely reported otherwise, a few Liberty engines did see action in France as power for the American version of the British Airco DH.4.

Lincoln production

As the United States entered

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

, the

division of General Motors was asked to produce the new Liberty aircraft engine, but William C. Durant was a

pacifist Pacifism is the opposition or resistance to war, militarism (including conscription and mandatory military service) or violence. Pacifists generally reject theories of Just War. The word ''pacifism'' was coined by the French peace campai ...

who did not want General Motors or Cadillac facilities to be used for producing war material. This led to Henry Leland leaving Cadillac to form the Lincoln Motor Company to make Liberty engines. He quickly gained a $10,000,000 government contract to build 6,000 engines. Subsequently, the order was increased to 9,000 units, with an option for 8,000 more if the government needed them. (Durant later changed his mind and both Cadillac and Buick produced the engines.) More than 16,000 Liberty engines were produced during the calendar year 1918. To November 11, 1918, more than 14,000 Liberty engines were produced. Lincoln had delivered 6,500 of the V-12 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 ...

engines when production ceased in January 1919.

Design

The Liberty engine was a modular design where four or six cylinders could be used in one or two banks, allowing for inline fours, V-8s, inline sixes, or the V-12. The design was held together by a two-part cast aluminium

crankcase In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, resulting in the fuel ...

. The two pieces formed the upper and lower halves of the completed assembly and were held together with a series of bolts running around the outside perimeter. As was common for the era, the cylinders were separately formed from forged steel tubes with thin metal jackets surrounding them to provide cooling water flow. A single overhead camshaft for each cylinder bank operated two valves per cylinder, in an almost identical manner to the inline six-cylinder German Mercedes D.III and BMW III engines. Each camshaft was driven by a vertical driveshaft that was placed at the back of each cylinder bank, again identical to the Mercedes and BMW straight-six powerplants. Delco Electronics provided the

ignition system An ignition system generates a spark or heats an electrode to a high temperature to ignite a fuel-air mixture in spark ignition internal combustion engines, oil-fired and gas-fired boilers, rocket engines, etc. The widest application for spark i ...

and

Zenith The zenith (, ) is an imaginary point directly "above" a particular location, on the celestial sphere. "Above" means in the vertical direction ( plumb line) opposite to the gravity direction at that location ( nadir). The zenith is the "high ...

the

carburetor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...

. Dry weight was 844 lb (383 kg). Fifty-two examples of a six-cylinder version, the

, which very closely resembled the Mercedes and BMW powerplants in overall appearance, were produced but not procured by the Army. A pair of the 52 engines produced were destroyed by William Christmas testing his so-called " Christmas Bullet" fighter.

Variants

;V-1650: An inverted Liberty 12-A referred to as the V-1650 was produced up to 1926 by Packard. The same designation was later applied to the

Packard V-1650 Merlin The Packard V-1650 Merlin is a version of the Rolls-Royce Merlin aircraft engine, produced under license in the United States by the Packard Motor Car Company.Gunston 1995, p. 144. The engine was licensed to expand production of the Rolls-Ro ...

, an engine with nearly identical

engine displacement Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the ...

. This was a

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

Packard produced version of 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 late ...

, and is not to be confused with the earlier Liberty-based version. ;Allison VG-1410: The Allison VG-1410 was an air-cooled inverted Liberty L-12, with a geared super-charger, Allison epicyclic propeller reduction gear, and bore reduced to , giving a lower displacement of . ;Liberty L-6: A 6-cylinder version of the Liberty L-12, nicknamed the "Liberty Six", consisted of a single bank of cylinders, with the resulting engine bearing a strong external resemblance to both the Mercedes D.III and BMW III straight-six German aviation engines of World War I. ;Liberty L-8: An 8-cylinder V engine using Liberty cylinders in banks of four at 45°. ;Mikulin M-5:License production (or copies) produced in the USSR. ;Nuffield Liberty: Crusader tank III

The Nuffield Liberty tank engine was licensed and produced in World War II by the UK car manufacturer Nuffield. It was used in early

cruiser tank The cruiser tank (sometimes called cavalry tank or fast tank) was a British tank concept of the interwar period for tanks designed as modernised armoured and mechanised cavalry, as distinguished from infantry tanks. Cruiser tanks were developed ...

s, the Crusader, the

Cavalier The term Cavalier () was first used by Roundheads as a term of abuse for the wealthier royalist supporters of King Charles I and his son Charles II of England during the English Civil War, the Interregnum, and the Restoration (1642 – ). ...

, and finally

Centaur A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse. Centaurs are thought of in many Greek myths as bein ...

tanks. It was a 27 L (1,649 in³) engine with an output of , which was inadequate for the increasing vehicle weights as the war progressed and also suffered numerous problems with cooling and reliability. The Nuffield Liberty ran through multiple versions: * Mark I, US built engines modified in Britain. Modification incorporated new carburettors and a new induction system from Solex, revision of the crankcase breather, new timing gear, and revised crankshaft end thrust. This produced when governed to 1,500 rpm with the new carburettors. * Mark II, British built engines. The air compressor (for starting) was not used, and was removed on later engines * Mark III, IIIA and IIIB, made for the Crusader tank. This required a reduced height to fit in the engine bay, achieved by redesigning the oil pump and relocating the water pump. The air compressor was reinstated to enable pneumatically-operated braking and steering. Significant problems were experienced in desert use (the North African Campaign), and the Mk III went through multiple revisions. This included three different chain drive designs for the ancillary cooling fans, a revised valve adjustment mechanism, increased compression ratio, revised oil feeds, and two water pump replacements. * Mark IV, a revised design providing a shaft drive for cooling fans. This replaced the troublesome chain drive. This version also changed the air compressor to run at a lower speed. * Mark IVA, the power was increased to by increasing the governor limit to 1,700 rpm, and by fitting a new intake manifold and carburettor for the Cavalier tank. * Mark V, a redesigned engine producing the same power as the Mark IVA but for use in the Centaur tank. It revised the oil distribution in the engine, but remained governed to the higher speed of 1,700 rpm. The engine was intended for the

Cromwell tank The Cromwell tank, officially Tank, Cruiser, Mk VIII, Cromwell (A27M), was one of the series of cruiser tanks fielded by Britain in the Second World War. Named after the English Civil War-era military leader Oliver Cromwell, the Cromwell was t ...

, but the Liberty-based design was dropped in favour of the Rolls-Royce Meteor procured by the Tank Board. Those tanks fitted with Liberty were renamed Centaur, and production was split.

Applications

Aircraft

The primary use of the Liberty was in aircraft. *American-built versions of the Airco DH.4 * Airco DH.9A *

Airco DH.10 Amiens The Airco DH.10 Amiens was a twin-engined heavy bomber designed and produced by the British aircraft manufacturer Airco. It performed the first nighttime air mail service in the world on 14-15 May 1919. The DH.10 was developed in the final ye ...

* Breguet 14 B2 L *

Caproni Ca.60 The Caproni Ca.60 Transaereo, often referred to as the Noviplano (nine-wing) or Capronissimo, was the prototype of a large nine-wing flying boat intended to become a 100-passenger transatlantic airliner. It featured eight engines and three sets ...

Curtiss H-16 The Curtiss Model H was a family of classes of early long-range flying boats, the first two of which were developed directly on commission in the United States in response to the £10,000 prize challenge issued in 1913 by the London newspaper, t ...

* Curtiss HS * Curtiss NC * Curtiss Carrier Pigeon * Douglas C-1 * Douglas DT * Douglas O-2 *

Felixstowe F5L The twin-engine F5L was one of the Felixstowe F series of flying boats developed by John Cyril Porte at the Seaplane Experimental Station, Felixstowe, England, during the First World War for production in America. A civilian version of the air ...

Fokker T.II The Fokker T.II or T.2 (Not to be confused with the Fokker T-2) was a single engine floatplane designed in the Netherlands in the early 1920s as a torpedo bomber. Three were bought by the US Navy who tested them against other aircraft from ...

* Handley Page H.P.20 * Witteman-Lewis XNBL The engine was also used in the RN-1 (Zodiac) blimp.

Automobile

Based on aircraft use the engine provided a good power-to-weight ratio. This made it ideal for use in land speed attempt vehicles. It was selected for two land speed record attempts. * ''

Babs Babs or BABS may refer to: People * Nickname of Barbara Windsor (1937-2020), British actress * Babs McMillan, Australian actress * Babs Olusanmokun, American actor * Babs Reingold, American artist * Babs Fafunwa (1923-2010), Nigerian educationis ...

'', a single engined vehicle * White Triplex, mounting three Liberty engines working in tandem Both attempts set new records. Both crashed during further attempts, resulting in the deaths of the drivers and a newsreel cameraman.

Tank

As early as 1917 the Liberty showed good potential for use in tanks as well as aircraft. The Anglo-American, or "Liberty", Mark VIII tank was designed in 1917–18. The American version used an adaptation of the Liberty V-12 engine of 300 hp (220 kW), designed to use

cast iron Cast iron is a class of iron– carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impuri ...

cylinders rather than drawn

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...

ones. One hundred tanks were manufactured at the Rock Island Arsenal in 1919–20, too late for

. They were eventually sold to Canada for training in 1940, except for two that have been preserved. Inter-war,

J. Walter Christie John Walter Christie (May 6, 1865 – January 11, 1944) was an American engineer and inventor. He is best known for developing the Christie suspension system used in a number of World War II-era tank designs, most notably the Soviet BT and T-34 ...

combined aircraft engines with new suspension design, producing a rapid and highly mobile tank. Using Christie's concept, Russian forces selected and copied the Liberty in the BT-2 & BT-5 Soviet interwar tank (at least one reconditioned Liberty was installed in a BT-5). Demonstration of this tank was witnessed by the British, and Christie's design characteristics were licensed and incorporated into the British A13 design specification. As

loomed, Nuffield, producing British

s, licensed and re-engineered the Liberty for use in the A13 (produced as the Cruiser Mk III) and later cruiser tanks, with an output of 340 hp (410 hp from the Mark IV version). In later British tanks it was replaced by the Rolls-Royce Meteor, an engine based on the

aero engine, which offered greater engine power (600 hp). Nuffield Liberty engines were used in British tanks of immediate pre-war and Second World War: * Cruiser Mk III (A13 Mark I) – Nuffield Liberty Mk I * Cruiser Mk IV (A13 Mark II) – Nuffield Liberty Mk II * Crusader tank – Nuffield Liberty Mk III, IIIA, IIIB, or IV * Cavalier tank – Nuffield Liberty Mk IVA * Centaur tank – a parallel version of the

Meteor A meteoroid () is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mi ...

-engined

Cromwell Oliver Cromwell (25 April 15993 September 1658) was an English politician and military officer who is widely regarded as one of the most important statesmen in English history. He came to prominence during the 1639 to 1651 Wars of the Three Ki ...

British World War II tank – Nuffield Liberty Mk V

Watercraft

''HD-4'' or ''Hydrodome number 4'' was an early research

hydrofoil A hydrofoil is a lifting surface, or foil, that operates in water. They are similar in appearance and purpose to aerofoils used by aeroplanes. Boats that use hydrofoil technology are also simply termed hydrofoils. As a hydrofoil craft gains s ...

watercraft developed by the scientist

Alexander Graham Bell Alexander Graham Bell (, born Alexander Bell; March 3, 1847 – August 2, 1922) was a Scottish-born inventor, scientist and engineer who is credited with patenting the first practical telephone. He also co-founded the American Telephone and T ...

. In 1919, it set a world marine speed record of powered by two 350 hp Liberty L-12s. Miss America 2 1921

Inventor, entrepreneur, and boat racer Gar Wood set a new water speed record of in 1920 in a new twin Liberty V-12 powered boat called ''Miss America''. In the following twelve years, Wood built nine more Packard V-12 driven ''Miss Americas'' and broke the record five times, raising it to . He also won five straight powerboat Gold Cup races between 1917 and 1921, and the prestigious Harmsworth Trophy nine times between 1920 and 1933, at the helm of his ''Miss Americas''. Many gentlemen's runabouts, Gold Cup, and other race-winners were built with Liberty L-12 engines.

Survivors

A number of Liberty engines survive in restored operational and static display vehicles. Displays of the engine itself include: ;Australia * A Liberty 12 from a DH.9A is on display at the

Australian Aviation Heritage Centre The Darwin Aviation Museum, previously known as the Australian Aviation Heritage Centre, displays aircraft and aircraft engines of relevance to the Northern Territory and aviation in Australia generally. It is located in Darwin suburb of Winne ...

in Darwin, Northern Territory ;United Kingdom * A Nuffield Liberty is on display at The Tank Museum, Bovington ;United States * A 12A is on display at the New England Air Museum at

Bradley International Airport Bradley International Airport is a public international airport in Windsor Locks, Connecticut, United States. Owned and operated by the Connecticut Airport Authority, it is the second-largest airport in New England. The airport is about half ...

Windsor Locks Windsor Locks is a town in Hartford County, Connecticut, United States. As of the 2020 census, its population was 12,613. It is the site of Bradley International Airport, which serves the Greater Hartford-Springfield region and occupies approxim ...

, Connecticut. * An operable Liberty V-12 on a static test stand trailer is often run for demonstrations at

Old Rhinebeck Aerodrome The Old Rhinebeck Aerodrome is a living museum in Rhinebeck, New York. It owns many examples of airworthy aircraft of the Pioneer Era, World War I and the Golden Age of Aviation between the World Wars, and multiple examples of roadworthy antiqu ...

's weekend airshow events. * A Packard Liberty V-1650 Aircraft engine (cut-away)- 12 cylinder "v" type water cooled engine; 400 h.p. at 1700 r.p.m. 5" bore, 7" stroke, 8431 lbs., 45-degree angle cylinders, and aluminum pistons is on exhibit on a display stand at Carillon Historical Park in Dayton, Ohio.

Specifications

References

Notes

Bibliography

* Bradford, Francis H. Hall-Scott: The Untold Story of a Great American Engine Manufacturer * Angelucci, Enzo. ''The Rand McNally Encyclopedia of Military Aircraft, 1914–1980.'' San Diego, California: The Military Press, 1983. . * Barker, Ronald and Anthony Harding. ''Automotive Design: Twelve Great Designers and Their Work.'' SAE, 1992. . * Leland, Mrs. Wilfred C. and Minnie Dubbs Millbrook. ''Master of Precision: Henry M. Leland.'' Detroit, Michigan: Wayne State University Press, 1996. . * Lewis, David L. ''100 Years of Ford.'' Lincolnwood, Illinois: Publications International. 2005. .
"Lincolns."
''Lincoln Anonymous''. Retrieved: August 22, 2006. * Vincent, J.G. ''The Liberty Aircraft Engine.'' Washington, D.C.: Society of Automotive Engineers, 1919. * Weiss, H. Eugene. ''Chrysler, Ford, Durant and Sloan: Founding Giants of the American Automotive Industry.'' Jefferson, North Carolina: McFarland & Company, 2003. .

External links

Annals of Flight
*
Old Rhinebeck Aerodrome's operable Liberty V-12 engine run video
{{US military piston aeroengines 1910s aircraft piston engines

Liberty Liberty is the ability to do as one pleases, or a right or immunity enjoyed by prescription or by grant (i.e. privilege). It is a synonym for the word freedom. In modern politics, liberty is understood as the state of being free within society fr ...

V12 aircraft engines