Aircraft engine: RAF 3a Napier
|Configuration||12-cylinder V 60°|
|Displacement||17.2 l (1,049.4 cu in)|
|Weight||390 kg (860 lb)|
|Maximum power||260 hp at 1,750 RPM|
The engine was designed at the Royal Aircraft Factory based on the 8-cylinder RAF 1. A notable feature was that both intake and exhaust valves controlled by a single pushrod. Production of the new model was undertaken by Armstrong Whitworth and D. Napier & Son Ltd. The RAF 3a was the main production variant with increased bore compared to the original RAF 3 design.
260 examples overall were built by Napier & Son in addition to 29 manufactured by Armstrong Whitworth. The engine was fitted to the Airco DH.4 light bomber.