Lycoming R-680

1920s American aircraft piston engine

The Lycoming R-680 is a nine-cylinder air-cooled radial engine, the first aero engine produced by Lycoming. The engine was produced in two types, the E and B series; both are essentially the same. The B4E was available in a trainer version with a front exhaust collector "ring" for use without cylinder air baffles. R-680 received Approved Type Certificate No. 42 on 4 Feb 1930.

Variants

R-680B4E

Rated at 225 hp (168 kW) at 2100 rpm.^[1]

R-680BA

Rated at 240 hp (180 kW)

R-680E3A

Rated at 285 hp (213 kW) at 2200 rpm.^[1]

R-680-6

Rated at 245 hp (183 kW)

R-680-13

Rated at 300 hp (220 kW) at 2200 rpm.^[1]

Applications

• Beech AT-10 Wichita
• Boeing-Stearman PT-13
• Cessna AT-8/AT-17
• Curtiss-Wright AT-9
• Fleetwings BQ-2
• Spartan NP-1
• Stinson Airliner
• Stinson Reliant
• Stinson L-1 Vigilant
• Waco S Series

Specifications (R-680-E3A)

Data from Jane's Fighting Aircraft of World War II.^[1]

General characteristics

• Type: Nine cylinder air-cooled radial
• Bore: 4 5⁄8 in (117 mm)
• Stroke: 4 1⁄2 in (114 mm)
• Displacement: 680 in³ (11.15 litres)
• Length: 37.5 in (953.1 mm)
• Diameter: 43.5 in (1104 mm)
• Dry weight: 515.46 lb (233.9 kg)

Components

• Valvetrain: One inlet and one exhaust valve per cylinder at 30 degrees.
• Fuel system: single-barrel carburetor
• Fuel type: 87 octane rating gasoline
• Oil system: Full pressure type
• Cooling system: Air-cooled

Performance

• Power output: 330 hp (246 kW) at 2,300 rpm at sea level
• Compression ratio: 7:1
• Power-to-weight ratio: 0.64 hp/lb (1.05 kW/kg)

See also

Comparable engines

• Bristol Jupiter
• Continental R-670
• Jacobs R-755
• Pratt & Whitney R-985
• Wright R-790 Whirlwind

Related lists

• List of aircraft engines

References

Notes

1. Bridgman 1988

Bibliography

• Bridgman, Leonard (1988). Jane's Fighting Aircraft of World War II. New York: Crescent Books. ISBN 0-517-67964-7.