|A preserved Packard 3A-2500 on display at the National Museum of the United States Air Force|
|Type||Liquid-cooled V12 engine|
|National origin||United States|
|Unit cost||$19,375 (Geared 3A-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 versions, used most prominently in American World War II PT-boats, the 3M-2500, 4M-2500, and 5M-2500, were also derived from it.
As a result of Packard's World War II collaboration with British Rolls-Royce to produce the Packard-Merlin version of the V-12 Rolls-Royce Merlin, engines in the 1A-1500 - 5M-2500 series are often confused with both.
- Boeing TB
- Heinkel HE 8
- Martin T3M
- Naval Aircraft Factory PN
- Huff-Daland LB-1
- PT boats - marine versions of the 3M/4M/5M-2500
- 1924, 800 hp. Six built.
- 1925, 800 hp. 75 built.
- 1926, Geared propeller drive option, 800 hp. 175 built.
- 1927, fitted with a supercharger, 900 hp. One built.
- 1930, experimental use only, 1500 hp. One built.
- Marine version
- Marine version, 1200 hp (895 kW), subsequently upgraded in stages to 1500 hp (1,150 kW)
- Marine version, larger supercharger, aftercooler, and power output of 1850 hp
Engines on display
- A Packard 3A-2500 is on display at the National Museum of the United States Air Force.
- Type: 12-cylinder V engine
- Bore: 6 3⁄8 in (160 mm)
- Stroke: 6 1⁄2 in (170 mm)
- Displacement: 2,490 cu in (40.8 L)
- Dry weight: 1,120 lb (510 kg)
- Valvetrain: Four valves per cylinder, overhead camshaft
- Fuel type: Petrol
- Cooling system: Liquid-cooled
- Power output: 850 hp (630 kW) at 2,500 rpm
- Specific power: 0.33 hp/in³ (15.2 kW/L)
- Power-to-weight ratio: 0.76 hp/lb (1.25 kW/kg)
- Comparable engines
- Related lists
- Gunston 1989, p.109.
- Aircraft Engine Historical Society - Packard Retrieved: 30 January 2009
- Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
- Aircraft Engine Historical Society - Packard Engines
- Matthews, Birch. Race With the Wind. Osceola, WI. MBI Publishing, 2001. ISBN 0-7603-0729-6
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