Packard V-1650 Merlin

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"V-1650" redirects here. For the Packard-produced engine also named V-1650, see Liberty L-12.
V-1650 Merlin
Packard V-1650-7 Merlin
Type Liquid-cooled V-12 piston engine
National origin United Kingdom/United States
Manufacturer Packard
First run August 1941
Major applications North American P-51 Mustang
Supermarine Spitfire
Avro Lancaster
Number built 55,523
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.

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. 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 München

At the outbreak of World War Two, the British aviation industry expanded greatly. There was great need for 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

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

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]

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
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

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

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

  • Type: 12-cylinder supercharged liquid-cooled 60° "Vee" piston aircraft engine
  • Bore: 5.4 in (137.16 mm)
  • Stroke: 6 in (152.4 mm)
  • Displacement: 1,649 in3 (27.04 L)
  • Length: 88.7 in (2,253 mm)
  • Width: 30.8 in (781 mm)
  • Height: 40 in (1016 mm)
  • Dry weight: 1,645 lb (746 kg)[13]

Components

Performance

See also

Related development

Comparable engines

Related lists

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

External links

Wikimedia Commons has media related to Packard V-1650.
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