Ounce
Type	Piston engine
National origin	United Kingdom
Manufacturer	Armstrong Siddeley
First run	1920

The Armstrong Siddeley Ounce was a small two-cylinder aero engine developed by Armstrong Siddeley in 1920.^[1] The engine was originally conceived as a test piece but ran very well and was put into production for early ultralight aircraft and use in target drones. The Ounce used two cylinders from the preceding Jaguar I radial engine.

Applications

• Bristol Babe
• 1920 redesigns of the '1917 Type Aerial Target'

Specifications (Ounce)

Data from Lumsden.^[2]

General characteristics

• Type: Two cylinder, horizontally-opposed air cooled piston engine
• Bore: 5.0 in (127 mm)
• Stroke: 5.0 in (127 mm)
• Displacement: 196 cu in (3.2 L)
• Length: 20.5 in (521 mm)
• Width: 39.5 in (1003 mm)
• Height: 24.5 in (622 mm)
• Dry weight: 170 lb (77 kg)

Components

• Valvetrain: Overhead valve
• Fuel system: Carburettor
• Cooling system: Air cooled

Performance

• Power output: 45 hp (33.5 kW) at 1,500 rpm
• Compression ratio: 5:1
• Power-to-weight ratio: 0.26 hp/lb (0.43 kW/kg)

See also

Comparable engines

• ABC Scorpion
• Aeronca E-113
• Bristol Cherub
• Walter Atom

Related lists

• List of aircraft engines

References

Notes

Bibliography

External links

Wikimedia Commons has media related to Armstrong Siddeley Ounce.

• AS Ounce information and images at the Power House Museum, Sydney, Australia