A-3/Model A
Lawrance Model A engine on display at the Aviation Hall of Fame and Museum of New Jersey
Type	Piston aero engine
National origin	United States
Manufacturer	Lawrance Aero Engine Company
Designer	Charles Lawrance
First run	c.1916
Produced	c.450

The Lawrance A-3 or Lawrance Model A was an American twin-cylinder aircraft piston engine. Designed by Charles Lawrance in the mid-1910s the engine was produced by the Lawrance Aero Engine Company and under license by Excelsior. Weighing 200 lb (90 kg) the engine produced 28 horsepower (21 kW).^[1] A feature of this engine was the shared use of a single crankpin for both cylinders, this caused vibration as the pistons moved in the same direction.^[1]

Applications

• Breese Penguin (flightless ground training aircraft)
• Driggs Dart
• Mummert Cootie
• Shinnecock lightplane
• Swanson SS-3
• Waco Cootie I (monoplane)
• Waco Cootie II (biplane)

Engines on display

• A Lawrance A-3 is on public display at the Aerospace Museum of California

Specifications

Data from Gunston.^[1]

General characteristics

• Type: Two-cylinder, air-cooled horizontally opposed piston aircraft engine
• Dry weight: 200 lb (91 kg)

Components

• Cooling system: Air-cooled

Performance

• Power output: 28 hp (21 kW) at 1400 rpm