RAF 4
The RAF 4 is a British air-cooled, V12 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 Daimler and Siddeley-Deasy. The RAF 5 was a pusher version of the same engine.
01Turbocharger
A turbocharged experimental version of the RAF 4, the RAF 4d, was developed using a Rateau exhaust-driven turbocharger. The engine was test-flown in a R.E.8, but the turbocharging experiments were abandoned after the turbine failed on 4 May 1918.
02Variants
- RAF 4
- 1914 - Prototype engine, 140 horsepower (104 kW).
- RAF 4a
- 1917 - Main production variant, 150 horsepower (112 kW). 3,608 built.
- RAF 4d
- 1916 - 180 horsepower (134 kW), experimental supercharger installation. 16 built.
- RAF 4e
- 1917 - 240 horsepower (180 kW), strengthened cylinders and enlarged valves.
- RAF 5
- 1915 - 150 horsepower (112 kW), pusher version with fan-cooling.
- RAF 5b
- 170 horsepower (127 kW), increased bore version of RAF 5.
03Applications
04Engines on display
A preserved RAF 4a engine is on public display at the Science Museum (London).
05Specifications (RAF 4a)
Data from Lumsden
General characteristics
- Type: 12-cylinder, upright, 60-degree Vee engine
- Bore: 3.94 in (100 mm)
- Stroke: 5.51 in (140 mm)
- Displacement: 806.15 cu in (13.2 L)
- Dry weight: 680 lb (308 kg)
Components
- Valvetrain: EOI (side-valve inlet, exhaust overhead)
- Fuel system: Twin Claudel-Hobson Mk.1A carburettors
- Cooling system: Air-cooled
- Reduction gear: 0.5:1, Left-hand tractor
Performance
- Power output: 163 hp (122 kW) at 1,800 rpm (takeoff power)
- Specific power: 0.2 hp/cu in (9.2 kW/L)
- Compression ratio: 4.3:1
- Power-to-weight ratio: 0.24 hp/lb (0.4 kW/kg)
Sources and credits
This article is adapted from the Wikipedia article “RAF 4”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- RAF4engine.JPG by Nimbus227, Public domain
- Royal Aircraft Factory RE8 1.jpg by Great War Observer, Public domain
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