Armstrong Siddeley Mongoose

The Armstrong Siddeley Mongoose is a British five-cylinder radial aero engine produced by Armstrong Siddeley. Developed in the mid-1920s it was used in the Hawker Tomtit trainer and Parnall Peto seaplane amongst others. With a displacement of 540 cubic inches (9 litres) the Mongoose had a maximum power output of 155 horsepower (115 kilowatts).

Mongoose
Armstrong Siddeley Mongoose fitted to the Shuttleworth Collection's airworthy Hawker Tomtit
Type	Radial engine
National origin	United Kingdom
Manufacturer	Armstrong Siddeley
First run	1926
Major applications	Hawker Tomtit Avro 504N
Developed into	Armstrong Siddeley Serval

A Mongoose engine powers the sole remaining airworthy Hawker Tomtit, based at Old Warden.

Design and development

The Mongoose is a five-cylinder, single-row, air-cooled radial piston engine. The engine features twin forward-mounted ignition magnetos and enclosed valve rockers, the cylinders being the same as those used for the earlier Jaguar engine.^[1] An unusual feature of the Mongoose is the vertical position of the lower cylinder, a design thought likely to promote oil fouling of the spark plugs.^[2]

Built in several variants, power output ranged between 135 and 155 hp (100-115 kW).

Variants

Mongoose I

1926, 135 hp.

Mongoose II

1930, 155 hp.

Mongoose III

1929.

Mongoose IIIA

1929, civil use.

Mongoose IIIC

1929, Military use based on IIIA.

Applications

Mongoose-powered Hawker Tomtit

Note:^[3]

• ANBO III (Second batch, 1931)^[4]
• Avro 504N
• Avro 504R
• Avro Tutor
• Avro Type 621 Trainer
• Handley Page Hamlet
• Handley Page Gugnunc
• Hawker Tomtit
• Parnall Peto
• Fokker S.IV

Surviving engines

An Armstrong Siddeley Mongoose IIIC powers the sole remaining airworthy Hawker Tomtit, K1786/G-AFTA, owned and operated by the Shuttleworth Collection this aircraft flies regularly throughout the summer months.^[5]

Specifications (Mongoose I)

Data from Lumsden.^[2][6]

General characteristics

• Type: 5-cylinder single-row radial
• Bore: 5 in (127 mm)
• Stroke: 5.5 in (139.7 mm)
• Displacement: 540 cu in (8.8 L)
• Length: 36.6 in (93 cm)
• Diameter: 45.6 in (116 cm)
• Dry weight: 340 lb (154 kg)

Components

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

Performance

• Power output: 138 hp (103 kW) at 1,750 rpm at sea level
• Compression ratio: 5:1
• Power-to-weight ratio: 0.4 hp/lb (0.67 kW/kg)

See also

Related development

• Armstrong Siddeley Serval

Comparable engines

• Kinner R-5
• Shvetsov M-11
• Wright R-540

Related lists

• List of aircraft engines