Continental O-170
The Continental O-170 engine is the collective military designation for a family of small aircraft engines, known under the company designation of A50, A65, A75 and A80. The line was designed and built by Continental Motors commencing in the 1940s. It was employed as the powerplant for civil and military light aircraft.[1]
The horizontally opposed, four-cylinder engines in this family are all identical in appearance, bore, stroke, dry weight and piston displacement. All feature a bottom-mounted updraft carburetor fuel delivery system. The higher power variants differ only in compression ratio and maximum allowable rpm, plus minor modifications. The lower power versions are fully convertible to the higher rated versions.[1]
Design and development
In all models of this family of engines the cylinder heads are of aluminum alloy, screwed and shrunk onto steel barrels. Spark plug inserts and intake valve seats are made from aluminum-bronze alloy, while the exhaust valve seats are steel. The engines all employ hydraulic tappets which operate in aluminum guides that are machined into the crankcase. The tappets are built from four parts, a cam follower body, cup, cylinder and piston and operate with clearances of 0.03 in (1 mm) to 0.11 in (3 mm). The pushrods are steel and feature pressed-in ball ends.[1]
Lubricating oil is delivered under pressure from the 4 US qt (4 L) oil sump to the drive bearings and the crankpins though the crankshaft. The cylinder walls and pistons are spray lubricated. Normal operating oil pressure is 35 psi, with minimum idle oil pressure 10 psi.[1]
Variants
- A50
- 50 hp (37 kW), Compression ratio 5.4:1, max rpm 1900, fuel consumption at cruise 3.8 US gph[1]
- A65
- 65 hp (48 kW), Compression ratio 6.3:1, max rpm 2300, fuel consumption at cruise 4.4 US gph. The exhaust valves have stellite faces. The pistons have three rings, although some early production A65s had four piston rings.[1][2]
- A75
- 75 hp (56 kW), Compression ratio 6.3:1, max rpm 2600, fuel consumption at cruise 4.8 US gph. The exhaust valves have stellite faces and the connecting rods have a 0.125 in (3 mm) hole drilled in the rod cap to improve lubrication. The pistons have three rings and smaller piston pins.[1][2]
- A80
- 80 hp (60 kW), Compression ratio 7.55:1, max rpm 2700, fuel consumption at cruise 5.2 US gph. The connecting rods have a 0.125 in (3 mm) hole drilled in the rod cap to improve lubrication. The pistons have five rings and smaller piston pins.[1]
Applications
- A50
- A65
- A75
Specifications (O-170-3 or A-65-8)
Data from Continental Aircraft Engine Operator's Manual[2]
General characteristics
- Type: 4-cylinder air-cooled horizontally opposed aircraft piston engine
- Bore: 3.875 in (98 mm)
- Stroke: 3.625 in (92 mm)
- Displacement: 171 in³ (2.8 L)
- Length: 31 in (787 mm)
- Width: 31.5 in (800 mm)
- Height: 29 5/16 in (745 mm)
- Dry weight: 170 lb (77 kg)
Components
Performance
See also
- Related lists
Notes
References
- Christy, Joe: Engines for Homebuilt Aircraft & Ultralights, pages 43-52. TAB Books, 1983. ISBN 0830623477
- Donald, David (1995). American Warplanes of World War II. New York: Barnes & Noble Books. ISBN 0760722749.
- Jackson, A.J. (1974). British Civil Aircraft since 1919 Volume 3. London: Putnam. ISBN 037010014X.
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