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Armstrong Siddeley

Merged with Hawker Aircraft (1935)

Merged with Bristol Aero Engines (1960)
Successor Bristol Siddeley
Founded 1919
Defunct 1960
Headquarters United Kingdom Coventry, England, UK
Key people John Davenport Siddeley

Motor cars
Aircraft engines

Light engineering
Parent Armstrong Whitworth (1919 - 1927)
Subsidiaries Armstrong Whitworth Aircraft (1927-1935)

Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury motor cars and aircraft engines.


Armstrong Siddley car bonnet oranament IMG 1958

A Armstrong Siddley Bonnet mascot

Armstrong Siddeley 6hp engine

Armstrong Siddeley 6hp engine DE7939

Siddeley Autocars[]

Siddeley Autocars, of Coventry, was founded by John Davenport Siddeley (1866-1953) in 1902. Its products were heavily based on Peugeots, using many of their parts but fitted with English-built bodies. This company merged with Wolseley in 1905 and made stately Wolseley-Siddeley motorcars. They were used by Queen Alexandra and the Duke of York, the later King Edward VII.


Main article: Siddeley-Deasy

In 1909, J. D. Siddeley resigned from Wolseley and took over the Deasy Motor Co and the company became known as Siddeley-Deasy. In 1912 the cars used the slogan "As silent as the Sphinx" and started to sport a Sphinx [1] as a bonnet ornament, a symbol become synonymous with descendent companies. During World War I the company produced trucks, ambulances, and staff cars. In 1915 airframes and aero-engines started to be produced as well.


In 1919 Siddeley-Deasy was bought out by Armstrong Whitworth Development Company of Newcastle upon Tyne and became the Armstrong Siddeley Motors subsidiary. In 1927, Armstrong Whitworth merged its heavy engineering interests with Vickers to form Vickers-Armstrongs. At this point, J. D. Siddeley bought Armstrong Siddeley and Armstrong Whitworth Aircraft into his control. In 1928, Siddeley partnered with Walter Gordon Wilson, inventor of the pre-selector gearbox, to create Improved Gears Ltd, which later became Self-Changing Gears.

Armstrong Siddeley manufactured luxury cars, and later, aircraft engines. In 1935, J. D. Siddeley's interests were purchased by Hawker Aircraft to form Hawker Siddeley, a famous name in British aircraft production. Armstrong Whitworth Aircraft became a subsidiary of Hawker. The aviation pioneer Thomas Octave Murdoch - Tommy, later Sir Thomas, Sopwith - became chairman of Armstrong Siddeley Motors, a Hawker Siddeley subsidiary.

Armstrong Siddeley produced their last cars in 1960 and the aircraft engine business was merged with that of Bristol Aero Engines to form Bristol Siddeley as part of an ongoing rationalisation of the British aerospace sector. Bristol Siddeley and Rolls-Royce merged in 1966, the latter name subsuming the former.

Diesel engines[]

Between 1930 and 1955, Armstrong Siddeley produced the 'AS' range of medium-speed diesel engines, with a top speed of 1500 RPM. These air-cooled engines were intended for industrial and marine use, producing 10 horsepower (7.4 kW) per cylinder, and each cylinder had a capacity of 988cc (60.2 cubic inches). 1-, 2- and 3-cylinder engines were produced, designated the AS1, AS2 and AS3 respectively. The engines were often used in barges and narrowboats on British canals, as well in domestic and light industrial electric generator sets.


Motor cars[]

Armstrong Siddeley 12

1936 Armstrong Siddeley 12 HP


1939 Armstrong Siddeley 16 HP

Armstrong-Siddeley Hurricane Drophead Coupe 1946

Armstrong-Siddeley Hurricane Drophead Coupé 1946

The first car produced from the union was a fairly massive machine, a 5-litre 30 hp; a smaller 18 appeared in 1922 and a 2-litre 14 hp was introduced in 1923. 1928 saw the company's first 15 hp six; 1929 saw the introduction of a 12 hp vehicle. This was a pioneering year for the marque, during which it first offered the Wilson preselector gearbox as an optional extra; it became standard issue on all cars from 1933. In 1930 the company marketed four models, of 12, 15, 20, and 30 hp, the latter costing £1450.

The company's rather staid image was endorsed during the 1930s by the introduction of a range of six-cylinder cars with ohv engines, though a four-cylinder 12 hp was kept in production until 1936. In 1933 the 5-litre six-cylinder Siddeley Special was announced, featuring a Hiduminium (aluminum alloy) engine; this model cost £950. Car production continued at a reduced rate throughout 1940, and a few were assembled in 1941.

The week that World War II ended in Europe, Armstrong Siddeley introduced its first post-war models; these were the Lancaster four-door saloon and the Hurricane drophead coupe. The names of these models echoed the names of aircraft produced by the Hawker Siddeley Group (the name adopted by the company in 1935) during the war. These cars all used a 2-litre six-cylinder engines, increased to 2.3-litre engines in 1949. From 1953 the company produced the Sapphire, with a 3.4 litre six-cylinder engine.

In 1956 the model range was expanded with the addition of the 234 (a 2.3-litre four cylinder) and the 236 (with the older 2.3 litre six-cylinder engine). The Sapphire 346 sported a bonnet mascot in the shape of a Sphinx with namesake Armstrong Siddeley Sapphire jet engines attached. The 234 and 236 Sapphires were a radical departure from the traditional Armstrong Siddeley appearance. This, coming in a time of conservative auto design, was not well received by the marque's loyal customers. Hence, the "baby Sapphire" brought about the beginning of the end for Armstrong Siddeley.

The last model produced by Armstrong Siddeley was 1958's Star Sapphire, with a 4-litre engine, and automatic transmission. The Armstrong Siddeley was a casualty of the 1960 merger with Bristol; the last car left the Coventry factory in 1960.

Model list[]

Cars produced by Armstrong Siddeley had designations that implied their engine displacement.

Model Name Type Engine From To No. Produced Photo
Thirty Various 4960 cc 1919 1931 2770
Eighteen Various 2400 cc 1921 1925 2500 inc 18/50
18/50 or 18 Mk.II Various 2872 cc 1925 1926 2500 inc Eighteen
Four-Fourteen Various 1852 cc 1923 1929 13,365
Twenty Short and Long chassis 2872 cc 1926 1936 8847
Fifteen Tourer, saloon 1900 cc 1921 1925 7203 inc 15/6
Twelve Tourer, saloon, sports 1236 (1434 cc from 1931) 1929 1937 12500
15/6 Tourer, saloon, sports 1900 cc (2169 cc from 1933) 1928 1934 7206 inc Fifteen
Siddeley Special Tourer, saloon, limousine 4960 cc 1933 1937 253
Short 17 Coupe, saloon, sports saloon 2394 cc 1935 1938 4260 inc Long 17
Long 17 Saloon, tourer, Atlanta sports saloon, Limousine, landaulette 2394 cc 1935 1939 4260 inc Short 17
12 Plus & 14 Saloon, tourer 1666 cc 1936 1939 3750
20/25 Saloon, tourer, Atlanta sports saloon

Limousine, landaulette

3670 cc 1936 1940 884
16 Saloon, Sports saloon 1991 cc 1938 1941 950
Lancaster 16 4 door saloon 1991 cc 1945 1952 12470 inc Hurricane, Whitley, Typhoon and Tempest.
Lancaster 18 4 door saloon 2309 cc 1945 1952 12470 inc Hurricane, Whitley, Typhoon and Tempest.
Hurricane 16 Drophead coupe 1991 cc 1945 1953 12470 inc Lancaster, Whitley, Typhoon and Tempest.
Hurricane 18 Drophead coupe 2309 cc 1945 1953 12470 inc Lancaster, Whitley, Typhoon and Tempest.
Typhoon Fixed head coupe 1991 cc 1946 1949 12470 inc Lancaster, Whitley and Tempest.
Tempest coupe 1991 cc 1946 1949 12470 inc Lancaster, Whitley and Typhoon.
Whitley 18 Various 2309 cc 1946 1949 12470 inc Lancaster, Hurricane, Typhoon and Tempest.
Sapphire 346 4 door saloon & Limousine 3435 cc 1952 1958 7697
Sapphire 234 4 door saloon 2290 cc 1955 1958 803
Sapphire 236 4 door saloon 2309 cc 1955 1957 603 Armstrong Siddeley Sapphire 236 - WUG 250 at Kettering 08 - IMG 1947
Star Sapphire Saloon & Limousine 3990 cc 1958 1960 980
Star Sapphire Mk II Saloon & Limousine 3990 cc 1960 1960 1

A feature of many of their later cars was the option of an electrically controlled pre-selector gearbox. Like many British cars of the age there is an active owners club supporting their continued use.

Aircraft engines[]

AS Cooma A S Lynx radial

Armstrong Siddeley Lynx 7 cylinder radial from the Avro 618 Ten aircraft, Southern Cloud.

Throughout the 1920s and 1930s, Armstrong Siddeley produced a range of low- and mid-power aircraft radial engines, all named after big cats. They also produced a tiny 2-cylinder engine called the Ounce, for ultralight aircraft.

The company started work on their first gas turbine engine in 1939, following the design pioneered at the Royal Aircraft Establishment by Alan Arnold Griffith. Known as the "ASX" for "Armstrong Siddeley eXperimental", the original pure-turbojet design was later adapted to drive a propeller, resulting in the "ASP". From then on, AS turbine engines were named after snakes. The Mamba and Double Mamba were turboprop engines, the latter being a complex piece of engineering with two side-by-side Mambas driving through a common gearbox, and could be found on the Fairey Gannet. The Python turboprop powered the Westland Wyvern strike aircraft. Further development of the Mamba removed the reduction gearbox to give the Adder turbojet.

Another pioneer in the production of the RAE engine design was Metrovick, who started with a design known as the Metrovick F.2. This engine never entered production, and Metrovick turned to a larger design, the Beryl, and then to an even larger design, the Sapphire. Armstrong Siddeley later took over the Sapphire design, and it went on to be one of the most successful 2nd generation jet engines, competing with the better-known Rolls-Royce Avon.

The company went on to develop an engine - originally for unmanned Jindivik target drones - called the Viper. This product was further developed by Bristol Siddeley and, later, Rolls-Royce and was sold in great numbers over many years. A range of rocket motors were also produced, including the Snarler and Stentor. The rocket development complemented that of Bristol, and Bristol Siddeley would become the leading British manufacturer of rocket engines for missiles.

Industrial engine range[]

Armstrong-Siddeley 2 cylinder engine - Anglesey 2010 - IMG 2455

A 2-cylinder Armstrong-Siddeley engine mounted to fit on a three-point linkage and fitted with safety guards to allow it to be demonstrated working at shows

(details of engine models needed, can you help) ?


  • MF 701 baler - Baler mounted engine in place of PTO drive for early tractors with no PTO, or lack of suitable power.

See also[]

References / sources[]

External links[]

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