| 1A-2500 | |
|---|---|
![]()  | |
| 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 | 
| Manufacturer | Packard | 
| First run | 1924 | 
| Number built | 258 | 
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.[1] 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.
Applications
- 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
 - Packard-Bentley one-off race car
 - USSR World War II torpedo boats and sub-chasers, which were fitted with 535 4M-2500 engines with W-8 modification under Lend-Lease
 
Variants
- 1A-2500
 - 1924, 800 hp. Six built.
 - 2A-2500
 - 1925, 800 hp. 75 built.
 - 2A-2540
 - ? Huff-Daland XHB-1
 - 3A-2500
 - 1926, Geared propeller drive option, 800 hp. 175 built.
 - 4A-2500
 - 1927, fitted with a supercharger, 900 hp. One built.
 - 5A-2500
 - 1930, experimental use only, 1500 hp. One built.
 - 3M-2500
 - Marine version
 - 4M-2500
 - Marine version, 1200 hp (895 kW), subsequently upgraded in stages to 1500 hp (1,150 kW).
 - 5M-2500
 - 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.[2]
 - A Packard 3A-2500 is in storage at the National Air and Space Museum.[3]
 - A Packard 3A-2500 is on display at the New England Air Museum.[4]
 - A Packard 4M-2500 is on display at the Packard Proving Grounds Historical Site in Shelby Twp., Michigan.
 - A Packard Series 142 Diesel Model 1D-1700 is on display at the Packard Proving Grounds Historical Site in Shelby Twp., Michigan.
 - Three working Packard 5M-2500s are installed the only operational PT boat, Higgins PT-658 in Portland, Oregon.
 
Specifications (1A-2500)
Data from Aircraft Engine Historical Society[5] and Race With the Wind By Birch Matthews
General characteristics
- Type: 12-cylinder V engine
 - Bore: 6+3⁄8 in (162 mm)
 - Stroke: 6+1⁄2 in (165 mm)
 - Displacement: 2,540 cu in (41.6 L)
 - Dry weight: 1,120 lb (510 kg)
 
Components
- Valvetrain: Four valves per cylinder, overhead camshaft
 - Fuel type: Petrol
 - Cooling system: Liquid-cooled
 
Performance
- 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)
 
See also
Comparable engines
Related lists
References
Notes
- ↑ Gunston 1989, p.109.
 - ↑ "Packard 3A-2500". National Museum of the United States Air Force. 8 June 2015. Retrieved 26 June 2020.
 - ↑ "Packard 3A-2500 Geared Drive, V-12 Engine". National Air and Space Museum. Smithsonian Institution. Retrieved 26 June 2020.
 - ↑ "Packard 3A-2500". New England Air Museum. Retrieved 26 June 2020.
 - ↑ Aircraft Engine Historical Society - Packard Archived 2015-03-25 at the Wayback Machine Retrieved: 30 January 2009
 
Bibliography
- 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
 
External links
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