Packard V-1650 Merlin

Last updated

V-1650 Merlin
Packard Merlin V1650 7 2.jpg
Packard V-1650-7 Merlin
TypeLiquid-cooled V-12 piston engine
National originUnited Kingdom/United States
Manufacturer Packard
First runAugust 1941
Major applications North American P-51 Mustang
Supermarine Spitfire
Avro Lancaster
Number built55,523
Developed from Rolls-Royce 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. [1] The engine was licensed to expand production of the Rolls-Royce Merlin for British use. The engine also filled a gap in the U.S. at a time when similarly powered American-made engines were not available.

Contents

The first V-1650s, with a one-stage supercharger, equivalent to the Merlin XX, were used in the P-40F Kittyhawk fighter and in Canadian-built Hawker Hurricanes [ broken anchor ]. Later versions based on the Merlin 60 series included a more advanced two-stage supercharger for improved performance at high altitudes. It found its most notable application in the North American P-51 Mustang fighter, improving the aircraft's performance so it could escort Allied heavy bombers from Britain to Germany and back.

Design and development

Packard V-1650 in Deutsches Museum Munchen Packard V1650.jpg
Packard V-1650 in Deutsches Museum München

At the outbreak of World War Two, the British aviation industry expanded greatly. There was great need for the Rolls-Royce Merlin engine with shadow factories being established in Crewe, Manchester, and Glasgow. This was not enough to meet increasing demand with the British government looking to expand production using U.S. manufacturers. An agreement was reached between Rolls-Royce and the Packard Motor Car Company in September 1940 to manufacture the Merlin under license, with a $130,000,000 order being placed. The first Packard-built engine, designated V-1650-1, ran in August 1941. [2] [3]

The first American model was a version of the Mark XX, designated the V-1650-1 by the American military and the Packard Merlin 28 by the British. This engine used a single-stage, two-speed supercharger, the gear changing mechanism of which originally came from a French Farman patent license. The Merlin 28 was used for the Avro Lancaster bomber. The USAAF V-1650-1 version of this engine was used in the Curtiss P-40Fs. The initial Packard modifications to this engine changed the main crankshaft bearings from a copper-lead alloy to a silver-lead combination and featured indium plating. This had been developed by General Motors' Pontiac Division to prevent corrosion, which was possible with lubricating oils that were used at that time. The bearing coating also improved the break-in (running-in) and load-carrying abilities of the surface.[ citation needed ]

In answer to a request from the British Air Ministry for a high-altitude Merlin for the pressurised Wellington VI high-altitude bomber, a Rolls-Royce team under the direction of Stanley Hooker developed a Merlin with two-stage supercharging, which became the Merlin 60-series. The first 60-series engine ran in March 1941, and was first flown in July the same year. [4] When only 63 examples of the otherwise-cancelled Wellington VI were produced, these engines were instead introduced on the Spitfire IX as the Merlin 61.

This model was later produced by Packard as the V-1650-3 and became known as the "high altitude" Merlin destined for the P-51, the first two-stage Merlin-Mustang conversion flying with a Merlin 61 [5] as the Mustang X in October 1942, the production V-1650-3 engined P-51B (Mustang III) entering service in 1943. The two-speed, two-stage supercharger section of the two-stage Merlins and V-1650-3 featured two separate impellers on the same shaft that were normally driven through a gear train at a ratio of 6.391:1. A hydraulic gear change arrangement of oil-operated clutches could be engaged by an electric solenoid to increase this ratio to 8.095:1 in high speed blower position.[ citation needed ]

The high speed gear ratio of the impellers was not as high as the ratio used in the Allison, but impeller speed is not the only factor that determines engine performance, which is also a function of the size and pitch of the impeller blades. The gear-driven supercharger is a parasitic accessory; therefore, impeller gearing and blade profiles are carefully designed for maximum power at altitude without compromise of available power at the critical take off stage of flight. The double staging of the compressed fuel/air mixture provided the boost pressure through a diffuser to the intake manifolds that increased the critical altitude of the power plant.[ citation needed ]

The ability of the supercharger to maintain a sea level pressure in the induction system to the cylinders allowed the Packard Merlin to develop more than 1,270 horsepower (950 kW) above 30,000 feet (9,100 m).[ citation needed ] The two-stage impeller created extreme heating of the fuel/air mixture during the compression process, and, to prevent detonation of the compressed charge, it was necessary to cool the mixture prior to entry into the cylinders. The cooling was accomplished in an intercooler passage cast into the wheel case housing between the first and second-stage impellers. [ citation needed ] Ethylene glycol coolant was circulated by a pump through this passage to carry off the excess heat generated by the impellers. Without the intercooler the temperature of the charge could be as high as 400 °F (204 °C).[ citation needed ] The intercooler in itself was not adequate to deal with the high temperature and an additional cooling fin and tube core was placed between the outlet of the blower and the induction manifold to the cylinders. This radiator was known as an aftercooler and served as a reservoir for the supercharger cooling system. The glycol mixture used for cooling was independent of the main engine cooling system and used a centrifugal pump driven by the engine to circulate the coolant through an aircraft radiator system at a maximum rate of 36 U.S. gallons (136 litres, 30 Imperial gallons) per minute, depending on engine rpm.[ citation needed ] This combined system reduced the charge temperature to suitable levels.

Throttle valves in the updraft carburettor throat were controlled by an automatic boost control through the throttle linkage to maintain the selected manifold pressure with changes in altitude. The valves were only partially open during ground and low-level operation to prevent overboosting of the engine. As air density decreases with increased altitude, the throttle valves were progressively opened in response to the reducing atmospheric pressure. This system provided full power within engine boost limitations up to the critical altitude of 26,000 feet (7,900 m).[ citation needed ]

Measurement of boost pressure

The British measured boost pressure as lbf/in2 (psi). The normal atmospheric pressure at sea level is 14.7 psi, so a reading of +6 means that the air/fuel mix is being compressed by a supercharger blower to 20.7 psi before entering the engine; +25 means that the air/fuel mix is now being compressed to 39.7 psi.

The Americans measured their boost ratings using inches of mercury (inHg). One pound-force per square inch equals 2.036 inHg or 6.895 kPa, and a standard atmosphere is 101.325 kPa =29.92 inHg =14.70 lbf/in2. In early Merlin engines the maximum manifold (boost) pressure was +18. This was increased in later models.

Inches of mercury (inHg)
absolute pressure
Pounds per square inch of boost [6]
gauge pressure
81 inHg=+25 lbf/in2 boost
66.5 inHg=+18 lbf/in2 boost
60 inHg=+15 lbf/in2 boost
46 inHg=+8 lbf/in2 boost
42 inHg=+6 lbf/in2 boost

Postwar use

In the United States many war surplus engines and airframes were sold relatively cheaply – two of the most popular items were North American P-51 Mustangs and Packard V-1650 Merlin engines, several of which were "souped up" and modified for air racing in the Bendix Trophy, the Cleveland Air Races, [7] and the Thompson Trophy. Many of these engines remain heavily used to this day in Drag Racing, Hydroplane racing, and Land Speed Racing at places like the Bonneville Salt Flats. The Mynarski Lancaster flown by the Canadian Warplane Heritage Museum in Hamilton, Ontario, Canada, one of only two Lancasters flying in the world, uses four Packard Merlin engines. [8]

Work continues on increasing the power output of the Merlin for the Unlimited Class racers at the Reno Air Races. Innovations, such as the use of Allison V-1710 connecting rods and the replacement of the intercooler with ADI (Anti-Detonation Injection) (50% Distilled Water and 50% Methanol), nearly identical in chemical composition to the Luftwaffe's wartime MW 50 system, and similar to the water injection system used on Pratt & Whitney engines during World War II, have allowed great increases in power output. [9] [10] Many of the fastest Unlimited racers increase Merlin manifold pressures as high as 145 inHg (56.6 psi, 4.8 atm) to obtain up to 2,835 kW (3,800 horsepower), achieving Mustang speeds up to 490 mph. [11] [12]

Variants

Applications

Specifications (V-1650)

General characteristics

Components

Performance

See also

Related development

Comparable engines

Related lists

Related Research Articles

<span class="mw-page-title-main">Rolls-Royce Merlin</span> Aircraft engine family by Rolls-Royce

The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litre 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 called Merlin following the company convention of naming its four-stroke piston aero engines after birds of prey. The engine benefitted from the racing experiences of precursor engines in the 1930s.

<span class="mw-page-title-main">Allison V-1710</span> Aircraft engine produced and manufactured by Allison Engine Company

The Allison V-1710 aircraft engine designed and produced by the Allison Engine Company was the only US-developed V-12 liquid-cooled engine to see service during World War II. Versions with a turbocharger gave excellent performance at high altitude in the twin-engined Lockheed P-38 Lightning, and turbo-superchargers were fitted to experimental single-engined fighters with similar results.

<span class="mw-page-title-main">Napier Sabre</span> 1930s British aircraft piston engine

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 piston aircraft engines in the world, developing from 2,200 hp (1,600 kW) in its earlier versions to 3,500 hp (2,600 kW) in late-model prototypes.

<span class="mw-page-title-main">Rolls-Royce Clyde</span> 1940s British turboprop aircraft engine

The Rolls-Royce RB.39 Clyde was Rolls-Royce's first purpose-designed turboprop engine and the first turboprop engine to pass its civil and military type-tests.

<span class="mw-page-title-main">Junkers Jumo 213</span> WW2 Aircraft Engine

The Junkers Jumo 213 was a World War II-era V-12 liquid-cooled aircraft engine, a development of Junkers Motoren's earlier design, the Jumo 211. The design added two features, a pressurized cooling system that required considerably less cooling fluid which allowed the engine to be built smaller and lighter, and a number of improvements that allowed it to run at higher RPM. These changes boosted power by over 500 hp and made the 213 one of the most sought-after Axis engine designs in the late-war era.

<span class="mw-page-title-main">Rolls-Royce Griffon</span> 1930s British piston aircraft engine

The Rolls-Royce Griffon is a British 37-litre capacity, 60-degree V-12, liquid-cooled aero engine designed and built by Rolls-Royce Limited. In keeping with company convention, the Griffon was named after a bird of prey, in this case the griffon vulture.

<span class="mw-page-title-main">Rolls-Royce Peregrine</span> 1930s British aircraft piston engine

The Rolls-Royce Peregrine was a 21-litre (1,300 cu in), 885-horsepower (660 kW) liquid-cooled V-12 aero engine designed and built by the British manufacturer Rolls-Royce in the late 1930s. It was essentially the ultimate development of the company's Kestrel engine, which had seen widespread use in military aircraft of the pre-war period.

<span class="mw-page-title-main">Rolls-Royce Kestrel</span>

The Rolls-Royce Kestrel is a 21.25 litre V-12 aircraft engine from Rolls-Royce. It was their first cast-block engine, and used as the pattern for most of their future piston-engine designs. Used during the interwar period, it was fitted to a number of British fighters and bombers of the era, including the Hawker Fury and Hawker Hart family, and the Handley Page Heyford. The Kestrel engine was also sold to international air force customers; in this role it was used to power prototypes of the German Messerschmitt Bf 109 and the Junkers Ju 87 "Stuka" dive-bomber, as the Junkers Jumo 210 engines were not ready to be fitted. Several examples of the Kestrel engine remain airworthy today.

<span class="mw-page-title-main">Rolls-Royce Eagle (1944)</span>

The Rolls-Royce Eagle Mk XXII is a British 24-cylinder, sleeve valve, H-block aero engine of 46 litre displacement. It was designed and built in the early-1940s by Rolls-Royce Limited and first ran in 1944. It was liquid-cooled, of flat H configuration with two crankshafts and was capable of 3,200 horsepower at 18 psi boost.

<span class="mw-page-title-main">Rolls-Royce Crecy</span> 1940s British piston aircraft engine

The Rolls-Royce Crecy was a British experimental two-stroke, 90-degree, V12, liquid-cooled aero-engine of 1,593.4 cu.in capacity, featuring sleeve valves and direct petrol injection. Initially intended for a high-speed "sprint" interceptor fighter, the Crecy was later seen as an economical high-altitude long-range powerplant. Developed between 1941 and 1946, it was among the most advanced two-stroke aero-engines ever built. The engine never reached flight trials and the project was cancelled in December 1945, overtaken by the progress of jet engine development.

<span class="mw-page-title-main">Klimov VK-107</span> 1940s Soviet piston aircraft engine

The Klimov VK-107 was a V-12 liquid-cooled piston aircraft engine used by Soviet aircraft during World War II.

<span class="mw-page-title-main">Rolls-Royce Goshawk</span> 1930s British piston aircraft engine

The Rolls-Royce Goshawk was a development of the Rolls-Royce Kestrel that used evaporative or steam cooling. In line with Rolls-Royce convention of naming piston engines after birds of prey, it was named after the goshawk.

<span class="mw-page-title-main">Allison V-3420</span> Large experimental piston aircraft engine

The Allison V-3420 was a large experimental piston aircraft engine, designed in 1937 by the American Allison Engine Company.

<span class="mw-page-title-main">Supercharger</span> Air compressor for an internal combustion engine explaning

In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.

<span class="mw-page-title-main">Rolls-Royce Mustang Mk.X</span> Experimental variant of the P-51 Mustang


The North American Mustang Mk.X, also known as the "Rolls-Royce Mustang" or Mustang X, was an experimental variant of the North American Mustang I, where the Allison engine was replaced by a Rolls Royce Merlin. The improvements in performance led to the adoption of the Merlin, in the form of the licence-built Packard V-1650 version of the Merlin, in following production of the P-51 Mustang.

<span class="mw-page-title-main">Rolls-Royce Exe</span> 1930s British piston aircraft engine

The Rolls-Royce Exe, or Boreas, was a 24-cylinder air-cooled X block sleeve valve aircraft engine intended primarily for the new Fairey Fleet Air Arm aircraft, particularly the Fairey Barracuda. The Exe was relatively powerful for its era, producing about 1,100 hp (820 kW). This is notable given the relatively small 1,300 cubic inches (22 L) displacement, the Merlin requiring 1,600 cubic inches (27 L) for approximately the same power level. The X-24 layout made this quite a compact engine.

<span class="mw-page-title-main">Continental XI-1430</span> American aircraft engine

The Continental XI-1430 Hyper engine was a liquid-cooled aircraft engine developed in the United States by a partnership between the US Army Air Corps and Continental Motors. It was the "official" result of the USAAC's hyper engine efforts that started in 1932, but never entered widespread production as it was not better than other available engines when it finally matured. In 1939, the I-1430-3 was designated as the engine to power the Curtiss XP-55, an extremely radical pusher-engine fighter design that would not reach production.

<span class="mw-page-title-main">Supermarine Spitfire variants: specifications, performance and armament</span> Type of aircraft

The British Supermarine Spitfire was one of the most popular fighter aircraft of the Second World War. The basic airframe proved to be extremely adaptable, capable of taking far more powerful engines and far greater loads than its original role as a short-range interceptor had allowed for. This would lead to 24 marks of Spitfire, and many sub-variants within the marks, being produced throughout the Second World War and beyond, in continuing efforts to fulfill Royal Air Force requirements and successfully combat ever-improving enemy aircraft.

<span class="mw-page-title-main">North American P-51 Mustang variants</span>

Over twenty variants of the North American P-51 Mustang fighter were produced from 1940, when it first flew, to after World War II, some of which were employed also in the Korean War and in several other conflicts.

The Avro 684 was a proposed British high altitude heavy bomber of the Second World War, based on Avro's successful Lancaster.

References

Notes

  1. Gunston 1995, p. 144.
  2. Lumsden 2003, pp. 215–216.
  3. "Business: Ford's Rolls-Royces." Time Magazine, 8 July 1940. Retrieved: 26 August 2009.
  4. 1943 | 2161 | Flight Archive
  5. hucknall | flying bedstead | flight international | 1971 | 0667 | Flight Archive
  6. Gruenhagen 1980 p. 191.
  7. "Cleveland Air Races." airracinghistory.freeola.com. Retrieved: 4 September 2009.
  8. Aircraft Details | Canadian Warplane Heritage Museum
  9. "Frank WalkerWeb1.pdf" (PDF). Archived from the original (PDF) on 2 February 2013. Retrieved 7 January 2014.
  10. "Going Fast – Modifications". Archived from the original on 2 April 2012. Retrieved 28 January 2013.
  11. "Going Fast – Modifications." Archived 27 July 2011 at the Wayback Machine warbirdaeropress.com. Retrieved: 24 September 2011.
  12. "Masters of the V-12." airspacemag.com. Retrieved: 25 September 2011.
  13. No coolant or fuel.

Bibliography

  • Bridgman, L. (ed.) Jane's fighting aircraft of World War II. London: Crescent, 1998. ISBN   0-517-67964-7.
  • Fozard, John W (editor).Sydney Camm and the Hurricane: Perspectives on the Master Fighter Designer and his Finest Achievement. Shrewsbury, Shropshire, UK: Airlife, 1991. ISBN   1-85310-270-9.
  • Gunston, Bill. World Encyclopaedia of Aero Engines (3rd edition). Sparkford, Somerset, UK: Patrick Stephens Limited, 1995. ISBN   1-85260-509-X.
  • Hooker, Stanley Not Much of an Engineer. London: Airlife, 1984. ISBN   1-85310-285-7
  • Harvey-Bailey, A. The Merlin in Perspective: The Combat Years. Derby, England: Rolls-Royce Heritage Trust, 1983. ISBN   1-872922-06-6.
  • Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN   1-85310-294-6.
  • Rubbra, AA. Rolls-Royce Piston Aero Engines: A Designer Remembers. Derby, England: Rolls-Royce Heritage Trust, 1990. ISBN   1-872922-00-7.