Serval/Double Mongoose
Type	Radial engine
National origin	United Kingdom
Manufacturer	Armstrong Siddeley
First run	1928
Major applications	Armstrong Whitworth Atalanta Saro Cloud

The Armstrong Siddeley Serval was a British ten-cylinder aero engine developed by Armstrong Siddeley in the late 1920s. Following company tradition, the engine was named for the serval.

The Serval was a ten-cylinder, double-row, air-cooled radial piston engine. It was developed from the Armstrong Siddeley Mongoose and was, more or less, two Mongooses built around a single crankcase. In fact, it first appeared as the Double Mongoose in May 1928.^[1]

Built in several variants, power output was about 340 hp (254 kW).

Serval I initially Double Mongoose

(1931) 340 hp.

Serval III

(1932)

Serval IIIB

(1932) 310 hp.

Serval IV

310 hp.

Serval V

(1933) 340 hp.

• Airco DH.9
• Armstrong Whitworth Atalanta
• BFW M.36
• Canadian Vickers Vancouver
• Fairey Fox
• ICAR Comercial
• Saro Cloud
• Stampe et Vertongen SV.5 Tornado

Data from Lumsden.^[2]

• Type: 10-cylinder double-row radial
• Bore: 5 in (127 mm)
• Stroke: 5.5 in (139.7 mm)
• Displacement: 1,080 cu in (17.7 L)
• Length: 54.25 in (1,378 mm)
• Diameter: 45.6 in (1,158 mm)
• Dry weight: 714 lb (324 kg)

• Valvetrain: Overhead poppet valves
• Fuel type: 77 Octane petrol
• Cooling system: Air-cooled
• Reduction gear: Direct drive, Left hand tractor

• Power output: 340 hp at 2,000 rpm at sea level
• Compression ratio: 5:1
• Power-to-weight ratio: 0.47 hp/lb

Related development

• Armstrong Siddeley Mongoose

Related lists

• List of aircraft engines