Lawrance J-1

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Type Piston aero engine
National origin United States
Manufacturer Lawrance Aero Engine Company

The Lawrance J-1 was an engine developed by Charles Lanier Lawrance and used in American aircraft in the early 1920s. It was a nine-cylinder, air-cooled radial design.


During World War I the Lawrance Aero Engine Company of New York City produced the crude opposed twins that powered the Penguin trainers, and the Lawrance L-1 60 hp Y-type radial.[1]

After the end of World War I, the Lawrance engineers worked with both the Army and the Navy in developing their L-1 onto a nine-cylinder radial engine, which became the 200 hp Model J-1. It was the best American air-cooled engine at the time and passed its 50-hour test in 1922.[1]

The U.S. Navy badly needed light, reliable engines for its carrierborne aircraft. As a means of pressuring Wright and other companies into developing radial engines, it gave a contract to Lawrance for 200[2] of the J-1 radial and ceased buying the liquid-cooled Wright-Hispano engines.[1] At the urging of the Army and Navy the Wright Aeronautical Corporation bought the Lawrance Company, and subsequent engines were known as Wright radials. The Wright Whirlwind had essentially the same lower end (crankcase, cam, and crankshaft) as the J-1.[2]


Engines on display[edit]

The New England Air Museum in Windsor Locks, Connecticut, has a Lawrance J-1 on display.[3][4]

Specifications (J-1)[edit]

Data from A History of Aircraft Piston Engines [2]

General characteristics

  • Type: 9-cylinder air-cooled radial engine
  • Bore: 4.5 in (114 mm)
  • Stroke: 5.5 in (144 mm)
  • Displacement: 787 in3 (12.9 L)
  • Dry weight: 476 lb (216 kg)


  • Cooling system: Air-cooled



  1. ^ a b c Janes Fighting Aircraft of World War I by Michael John Haddrick Taylor (Random House Group Ltd. 20 Vauxhall Bridge Road, London SW1V 2SA, 2001, ISBN 1-85170-347-0), page 290
  2. ^ a b c "A History of Aircraft Piston Engines" by Herschel Smith, (Sunflower University Press Manhattan, Kansas, 1981, ISBN 0-89745-079-5), 255pp.
  3. ^ "Lawrance (Wright) J-1"
  4. ^ New England Air Museum in Windsor Locks, Connecticut, retrieved 2009-12-13 . The section "Images from Kimble D. McCutcheon" has photos of the museum's J-1.

External links[edit]

  • Wright J-5 "Whirlwind" (PDF), by Kimble D. McCutcheon, from the Aircraft Engine Historical Society (AEHS).
  • Part 2 of "Air-Cooled Aircraft Engine Cylinders", by George Genevro, also from AEHS.