The Liberty L-12 is an American

water-cooled Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and no ...

45°

V-12 engine A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft. V12 engines are more common than V10 engines. However, they are less common than V8 engines. The f ...

, 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 measurement ...

and ease of

mass production Mass production, also known as mass production, series production, series manufacture, or continuous production, is the production of substantial amounts of standardized products in a constant flow, including and especially on assembly lines ...

. It was designed principally as an

aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either piston engines or gas turbin ...

and saw wide use in aero applications. It also saw marine use (both in racing and in runabout boats) once it was

marinized Marinisation (also marinization) is design, redesign, or testing of products for use in a marine environment. Most commonly, it refers to use and long-term survival in harsh, highly corrosive salt water conditions. Marinisation is done by many man ...

; it was used in various military tanks; and in some race cars. A single bank 6-cylinder version, the Liberty L-6, and V-8, the Liberty L-8, were derived from the Liberty L-12. It was succeeded by the

Packard 1A-2500 The Packard 1A-2500 is an American V-12 liquid-cooled aircraft engine designed by Packard in 1924 as a successor to the World War I-era Liberty L-12. Five aero variants were produced, of which the 3A-2500 was the most numerous. Three marine v ...

Development

In May 1917, a month after the United States had declared war on Germany, a federal task force known as the Aircraft Production Board summoned two top engine designers, Jesse G. Vincent (of the

Packard Packard (formerly the 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 ...

Motor Car Company) 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 Company), to

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

. They were given the task of designing as rapidly as possible an aircraft engine that would rival if not surpass those of Great Britain, France, 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 The Willard InterContinental Washington, commonly known as the Willard Hotel, is a historic luxury Beaux-Arts hotel located at 1401 Pennsylvania Avenue NW in Downtown Washington, D.C. It is currently a member of Historic Hotels of America, th ...

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 An overhead camshaft (OHC) engine is a piston engine in which the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combusti ...

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 (business), division of the Automotive industry in the United States, American automobile manufacturer General Motors (GM). Started by automotive pioneer David Dunbar Buick in 1899, it was among the first American automobil ...

, Ford,

Cadillac Cadillac Motor Car Division, or simply Cadillac (), is the luxury vehicle division (business), division of the American automobile manufacturer General Motors (GM). Its major markets are the United States, Canada and China; Cadillac models are ...

, 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 {{Short description, none This is a list of armistices signed by the German Empire (1871–1918) or Nazi Germany (1933–1945). An armistice is a temporary agreement to cease hostilities. The period of an armistice may be used to negotiate a peace t ...

, 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 The Airco DH.4 is a British two-seat biplane day bomber of the First World War. It was designed by Geoffrey de Havilland (hence "DH") for Airco, and was the first British two-seat light day-bomber capable of defending itself. It was desig ...

Lincoln production

As the United States entered

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, 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 to war or violence. The word ''pacifism'' was coined by the French peace campaigner Émile Arnaud and adopted by other peace activists at the tenth Universal Peace Congress in Glasgow in 1901. A related term is ''a ...

who did not want General Motors or Cadillac facilities to be used for producing war material. This led to

Henry Leland Henry Martyn Leland (February 16, 1843 – March 26, 1932) was an American machinist, inventor, engineer, and automotive entrepreneur. He founded the two premier American luxury automotive marques, Cadillac and Lincoln. Early years Henry M. Le ...

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 syst ...

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 A crankcase is the housing in a reciprocating engine, piston engine 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, res ...

. 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

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 Delco Electronics Corporation was the automotive electronics design and manufacturing subsidiary of General Motors based in Kokomo, Indiana, that manufactured ''Delco'' Automobile radios and other electric products found in GM cars. In 1972, Gen ...

provided the

ignition system Ignition systems are used by heat engines to initiate combustion by igniting the fuel-air mixture. In a spark ignition versions of the internal combustion engine (such as petrol engines), the ignition system creates a spark to ignite the fuel-ai ...

and

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

the

carburetor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline 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 Ventu ...

. Dry weight was 844 lb (383 kg). Fifty-two examples of a six-cylinder version, the Liberty L-6, 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 an indicator of the ...

. This was a

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

Packard produced version of the

Rolls-Royce Merlin The Rolls-Royce Merlin is a British Coolant#Liquids, liquid-cooled V12 engine, V-12 Reciprocating engine, piston aero engine of 27-litre (1,650 cu in) Engine displacement, capacity. Rolls-Royce Limited, Rolls-Royce designed the engine an ...

, 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. Used in the Grigorovich I-2 and early variants of the BT tank. ;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 develop ...

s, the Crusader, the

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

, and finally

Centaur A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...

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 The North African campaign of World War II took place in North Africa from 10 June 1940 to 13 May 1943, fought between the Allies and the Axis Powers. It included campaigns in the Libyan and Egyptian deserts (Western Desert campaign, Desert Wa ...

), 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 ...

, but the Liberty-based design was dropped in favour of the

Rolls-Royce Meteor The Rolls-Royce Meteor later renamed the Rover Meteor is a British tank engine that was developed during the Second World War. It was used in British tanks up to 1964. It was a result of co-operation between Leyland Motors and Rolls-Royce who bet ...

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.9A The Airco DH.9A is a British single-engined light bomber that was designed and first used shortly before the end of the First World War. It was a development of the unsuccessful Airco DH.9 bomber, featuring a strengthened structure and, cruciall ...

* Airco DH.10 Amiens *

Breguet 14 The Breguet XIV (in contemporary practice) or Breguet 14 is a French biplane bomber and reconnaissance aircraft of World War I. It was built in very large numbers and production continued for many years after the end of the war. The Breguet 14 w ...

B2 L * Caproni Ca.60 * Curtiss H-16 *

Curtiss HS The Curtiss HS was a single-engined patrol flying boat built for the United States Navy during World War I. Large numbers were built from 1917 to 1919, with the type being used to carry out anti-submarine patrols from bases in France from June 1 ...

* Curtiss NC * Curtiss Carrier Pigeon *

Douglas C-1 The Douglas C-1 was a cargo/transport aircraft produced by the Douglas Aircraft Corporation for the United States Army Air Service starting in 1925. Design and development Douglas received an order for nine single-engined transport aircraft in 1 ...

* Douglas DT * Douglas O-2 * Felixstowe F5L * Fokker T.II * Handley Page H.P.20 *

Keystone LB-5 The Keystone LB-5 (originally ordered under the Huff-Daland name) was a bomber aircraft produced in the United States in the late 1920s. Its manufacturer nicknamed it the Pirate, but this name was not officially adopted by the United States Army ...

* 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'', a single engined vehicle *

White Triplex The White Triplex (also known as the "Triplex Special" and the "Spirit of Elkdom") was an American land speed record car built for J. H. White and driven by Ray Keech. It was powered by three 27-litre Liberty L-12, Liberty Aircraft engine, aero en ...

, 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 of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...

cylinders rather than drawn

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

ones. One hundred tanks were manufactured at the

Rock Island Arsenal The Rock Island Arsenal comprises 946 acres (383 ha) and is located on Arsenal Island, originally known as Rock Island, on the Mississippi River between the cities of Davenport, Iowa, and Rock Island, Illinois. It is home to the United Stat ...

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 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

, 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 Crusader, in full "Tank, Cruiser Mk VI, Crusader", also known by its List of tanks of the United Kingdom#General Staff numbers, General Staff number A.15, was one of the primary British cruiser tanks during the early part of the World War II, ...

– Nuffield Liberty Mk III, IIIA, IIIB, or IV *

Cavalier tank The Tank, Cruiser, Mk VII Cavalier (A24) was an interim design of British cruiser tank during the Second World War. It was derived as a follow on from the Nuffield's A15 Crusader tank as it was expected to enter production in 1942. A paralle ...

– Nuffield Liberty Mk IVA *

Centaur 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 ...

– a parallel version of the

Meteor A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a ...

-engined Cromwell 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 sp ...

watercraft developed by the scientist

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

. 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 the Darwin, Northern Ter ...

in Darwin, Northern Territory ;United Kingdom * A Nuffield Liberty is on display at

The Tank Museum The Tank Museum (previously the Bovington Tank Museum) is a collection of armoured fighting vehicles at Bovington Camp in Dorset, South West England. It is about north of the village of Wool and west of the major port of Poole. The collectio ...

, Bovington ;United States * A 12A is on display at the

New England Air Museum The New England Air Museum (NEAM) is an American aerospace museum located adjacent to Bradley International Airport in Windsor Locks, Connecticut. The museum consists of three display hangars with additional storage and restoration hangars. Its ...

Bradley International Airport Bradley International Airport – historically known as Bradley Field – is a public international airport in Windsor Locks, Connecticut, Windsor Locks, Connecticut, United States. Owned and operated by the Connecticut Airport Authority, Con ...

Windsor Locks Windsor Locks is a town in Hartford County, Connecticut, United States. The town is part of the Capitol Planning Region. As of the 2020 census, its population was 12,613. It is the site of Bradley International Airport, which serves the Greate ...

, 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 Red Hook, New York, Red Hook, New York, adjacent to the town of Rhinebeck (town), New York, Rhinebeck. Founded in 1958, it owns many examples of airworthy aircraft from the Aviation in the pioneer ...

'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 state of being free within society from oppressive restrictions imposed by authority on one's way of life, behavior, or political views. The concept of liberty can vary depending on perspective and context. In the Constitutional ...

V12 aircraft engines