|Type||Piston inline aero engine|
|National origin||United Kingdom|
|Manufacturer||Royal Aircraft Factory|
|First run||September 1914|
|Major applications||Royal Aircraft Factory R.E.7|
|Developed from||RAF 1|
|Developed into||RAF 4|
The RAF 3 was a British liquid-cooled, V-12 engine developed for aircraft use during World War I. Based on the eight–cylinder RAF 1 it was designed by the Royal Aircraft Factory but produced by the two British companies of Armstrong Whitworth and Napier & Son. The RAF 7 was a high compression version of the same engine.
- RAF 3
- 1914 - Prototype engine, 200 horsepower (150 kW).
- RAF 3a
- 1914 - Main production variant, increased bore, 260 horsepower (194 kW). 29 built by Armstrong Whitworth, 260 built by Napier & Son.
- RAF 7
- 300 horsepower (224 kW) high compression version with high-lift camshafts.
Specifications (RAF 3a)
Data from Lumsden
- Type: 12-cylinder, upright, 60-degree Vee engine
- Bore: 4.5 in (114.3 mm)
- Stroke: 5.5 in (140 mm)
- Displacement: 1,049.4 cu in (17.24 L)
- Dry weight: 780 lb (354 kg)
- Valvetrain: Overhead valve, both valves operated by a single pushrod
- Cooling system: Liquid-cooled
- Reduction gear: 0.5:1, left-hand tractor
- Power output: 260 hp (194 kW) at 1,750 rpm (takeoff power)
- Specific power: 0.25 hp/cu in (11.25 kW/L)
- Compression ratio: 5.3:1
- Power-to-weight ratio: 0.33 hp/lb (0.54 kW/kg)
- Related development
- Comparable engines
- Related lists
- Gunston, 1989, p. 156.
- Lumsden 2003, p. 223.