Lycoming O-145

Lycoming’s early history is founded in the manufacture of sewing machines and automobile engines. In 1929 they produced their first aircraft engine—the widely used nine-cylinder R-680 radial. They also designed high-powered aircraft engines in the 1930s and 40s, but none went into production. Their most successful post-war products were a series of air-cooled flat-4 and flat-6 engines for light aircraft, such as the O-235, O-360 and O-540.

The engine on display is Lycoming’s first production 4-cylinder engine that was built from 1938. It was aimed at the light aircraft market and was used in Aeronca, Mooney, Piper and Taylorcraft aircraft in the late 1930s and early 1940s. It has no provision for a starter or generator—designed for the simplicity of aircraft that were started by swinging the propeller. One of these engines powered the first flight of the first practical helicopter—Igor Sikorsky’s VS-300—in 1939.
All models of the O-145 series had the same bore, stroke and displacement, additional horsepower being generated by increasing compression ratio and maximum rpm. The O-145’s construction features the crankcase and cylinder combination of cast iron with bolt-on aluminium cylinder heads. Contemporary engines were the Franklin 4AC and the Continental C-65.
To compete with the Continental A-65, Lycoming boosted the initial 55 hp output of the O-145 model to 65 hp at 2550 rpm and finally 75 hp at 3100 rpm. The GO-145 is a geared model, introduced in 1939, that used a 1.59:1 reduction gearbox to produce 75 hp at 3200 crankshaft rpm, giving about 2000 propeller rpm.

Technical Details:  (Lycoming O-145-A2)

Engine Type: 4-cylinder, air-cooled, horizontally opposed
Power: 55 hp (41 kW) at 2,300 rpm
Weight: 157 lb (71 kg)
Cylinder: bore 3 5/8 in (92 mm), stroke 3½ in (88.9 mm)
Displacement: 144.5 cubic inches (2.36 litres)
Compression ratio: 5.65:1