Bristol Bulldog

In 1926, with a need to re-equip the RAFs fighter squadrons, which at the time lacked a warplane with the performance that would allow them to intercept and tackle the new generation of bombers, such as the Fairey Fox, the Air Ministry drew up Specification F. 9/26. This called for a single-seat day/night fighter powered by an air-cooled radial engine and armed with two Vickers machine guns.

Bulldog I

Designed by Frank S Barnwell and built as a private venture, the Bulldog was flown for the first time on 17 May 1927.with test pilot Cyril Unwin at the controls. The aircraft owed its existence to a serious delay in providing sufficient Mercury geared radial engines for the company’s Type 107 Bullpup fighter (design of which had been commenced to meet an earlier Air Ministry Specification of 1924). Thus it was decided to fit the 440 hp Bristol Jupiter VII radial engine in order to get an aircraft available for the F.9/26 contest to choose a replacement to the RAF’s existing Hawker Woodcocks. .

Of high tensile steel strip construction with fabric skinning, the Bulldog was designed to carry an armament of two Synchronized 0.303-in (7.7 mm) Vickers II guns, and although not an official contender for the F.9/26 Specification, it was evaluated at Martlesham Heath within a month of its initial flight, displaying a superiority over all of the official contenders, except for the Hawker Hawkfinch. The successful trials at Martlesham would result in an Air Ministry order for one example of the modified Type 105A Bulldog II for extended competition with the Hawkfinch (The first machine being subsequently modified with an enlarged rudder and larger-span wing cellule for an attempt on the altitude and climb-to-height records). Meanwhile, Bristol offered an export version of the Bulldog I and built a prototype which was exhibited in Paris in June 1928, but was never flown.

Bulldog II & IIA

First flown on January 21, 1928, the second Bulldog prototype (designated Bulldog II and given the serial number J9480) was selected as the winner in the F.9/26 contest, the RAF’s most hotly contested programme of the inter-war years ( the runner–up being the Hawker Hawkfinch) and was subsequently purchased by the Air Ministry for the sum of £4,800. An initial contract for 25 Bulldog IIs (J9567-J9594) was placed by the Ministry in August 1928, these carrying an armament of two 0.303-in (7.7 mm) Browning machine guns. RAF deliveries commencing on 8 May 1929 with No.3 squadron based at Upavon, Wiltshire receiving the first issue. No.17 Squadron, also at Upavon, followed in October 1928.

A second contract called for a further 23 aircraft to complete the equipment of No.17 Squadron, and also allowed for a third squadron (No. 54) to also exchange their Woodcocks. The Bulldog II soon proved popular amongst .the RAF pilots who appreciated that the fighter’s manoeuvrability was a great improvement on its predecessors. The low cost of the Jupiter engine also ensured its preference over other designs during the depressed years of 1930-33.

The nimble little fighter soon attracted the attention of foreign nations. One of the first production batch was diverted to Japan but1 this was replaced by an additional aircraft (K9591) which became the Testbed for the geared Mercury IV engine. Five Bulldog IIs with Gnome-Rhone Jupiter VI engines and Oerlikon machine guns were supplied to Latvia in2 1929 and 12 similar aircraft were sold to Estonia, 11 of the Estonian aircraft being later resold to Spain. Two Bulldog IIs were sold to the US Navy for testing (although no order was obtained for production aircraft), In January 1930 the Royal Siamese Air Force purchased two machines with Australia purchasing eight others (Nos. 7389-7396 /Australian designation A-12-1 to A-12-8) .3In the same month, Sweden acquired three machines and Latvia would increase its order by a further seven aircraft.

The most notably difference over the Bulldog I was that the production aircraft had a longer rear fuselage and wider wing span.

The first improved Bulldog to meet Air Ministry Specification F.11/29 was the Bulldog IIA, which embodied a Jupiter VIIF engine and minor structural revisions to the wing spars and strengthening to allow an increased all-up weight. (Some were later trialed with the Townend ring around the cylinder heads), The RAF ordered 92 Bulldog IIAs, in May 1930, these being delivered between October 1930 and May 1931. A further order for another 100 machines was placed in 1931 and by the end of that year 10 of the 13 Home Based fighter squadrons had re-equipped with the Bulldog (The others receiving the Hawker Fury Mk.1 with one flight in no.23 squadron flying the Hawker Demon). Ultimately the RAF would take charge of some 268 Bulldog IIA fighters in addition to the original 92 Mk.IIs (including the prototype) already supplied. The Bulldog’s service with the RAF was sadly rather short lived. As early as 1933 Bulldogs were being phased out, with No.23 Sqn. being the first to complete a change over to the Demon in April. No.3 squadron having taken its aircraft to the Khartoum in October to meet a crisis in Abyssinia would be the last to discard the machine in June 1937.

Four special Bulldog IIAs (Type 105D) were purchased by the Royal Danish Flying Corps with unsupercharged Jupiter VIF-H engines and 0.3-in (7.62mm) Madsen guns. These aircraft were shipped out from the Filton factory in March 1931 and were still being used as trainers, in Denmark when the Germans invaded in 1940. Sweden ordered eight Bulldog IIAs with ski undercarriages-these being flown out by Swedish pilots to Malmslätt in May 1931. These Swedish machines would ultimately be passed on to Finland.

Bulldog IIIA

The result of progressive experiments with Mercury engine installations and a series of wind tunnel tests, led (as a private venture) to the building of Bulldog IIIA during 1931. This was originally powered by a Mercury IVA engine, but later changed to the 560hp Mercury IVS-2.

A prototype was flown for the first time on 17 September of that year and competed with the Gloster S.S.19B in Air Ministry trials to decide a Bulldog IIA replacement. The Bulldog IIIA had a deeper, biconvex wing sections which permitted the fuel tanks to be accommodated completely within the wing profile. It also had reducing lower wing chord to improve the pilot’s view; single in place of double lift wires; a deeper rear fuselage of increased stiffness; a short-chord Townend ring for the Bristol Mercury engine, and undercarriage wheel spats.

The first Bulldog IIIA crashed on 30 March 1933, after demonstrating a 33 mph (53 km/h) increase in speed over the Mk IIA at 15,000 ft (4,572 m). A second prototype was then built, also as a private venture, and flown on 13 April 1933, but ultimately both the Bulldog IIIA and the Gloster aircraft would lose out to the superior Gauntlet and Gladiator aircraft for acceptance into RAF service. In 1932 the second Bulldog IIIA would be converted as the prototype for the four-gun Bulldog IV.

Bulldog IVA

Intended to meet the requirements of Specification F.7/30 calling for a four-gun day and night fighter, the Bulldog IV prototype was, as mentioned above, the second Bulldog IIIA converted. Flown in its new guise in the spring of 1934, it competed with the Gloster S.S.37 (prototype of the Gladiator) which was eventually selected to fulfil the requirement. Meanwhile, in April 1934, the Finnish government signed a contract for 17 Bulldog IVAs powered by the Mercury VIS 2 engine rated at 620 hp for take off and 654 hp at 16,500 ft (4,724 m), enclosed by a long chord cowling. These were the last Bulldogs to be built at the Filton factory and were delivered early in 1935. The Finnish Bulldogs carried an armament of two 0.303-in (7.7mm) Vickers Mk.II machine guns and remained in front-line service until the spring of 1940.seeing combat against the Soviets during the Winter War (in which they notched up several kills). Finnish Bulldogs came equipped with a controllable landing light in the lower port wing edge for winter work in the Arctic. They also had electrically heated clothing for the pilot and a gun heating facility to ensure that the guns would operate in sub-temperature arctic conditions.

Bulldog TM

The Bulldog TM was a training version which incorporated a second cockpit with dual controls, but with no armament. The rear fuselage could be replaced by a standard fighter rear fuselage and there was provision for the installation of machine guns so that the TM could be rapidly converted into a fighter if required. This first trainer model (K2218) came from the original batch of 100 Mk.11As fighters and had been retained by Bristol for conversion to a two-seat and dual control trainers at the end of 1931. This machine was evaluated by the Central Flying School during 1931 resulting in an order for seventeen aircraft. These trainers were distributed between the CFS and Coastal area at Leuchars as well as amongst six of the RAF’s fighter Squadrons A total of 59 Bulldog TMs would eventually be built (some of the latter serving at the Royal Air Force College, Cranwell) and remained in RAF service with training schools until 1939. The TM was the only version of the Bulldog to serve on a permanent basis overseas- the RAF equipping No.4 FTS at Abu Sueir in Egypt.


The Bristol Bulldog would be fondly remembers by all those who flew it, many considering it as the finest aerobatic aircraft ever built. It would regularly thrill the spectators at many a pre-war Air Show with a fine display of Squadron formation flying with coloured smoke. Of the 441 bulldogs built at Filton the last flying example (K2227, formerly G-ABBB) was owned by the Shuttleworth Collection in the UK until destroyed in a flying accident at Farnborough in September 1964. The only complete example surviving today now resides in the Finnish air force museum

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