The first design by Frederick (Frits) Koolhoven after joining the British Aerial Transport Company (B.A.T.), the private-venture F.K.22 single-seat fighter flown in September 1917 was of wooden construction with a monocoque fuselage. Powered by a 120hp A.B.C. Mosquito six-cylinder radial engine, it displayed sufficient promise to win an official contract for a batch of six development aircraft. The first and third of these were powered by the 170hp A.B.C. Wasp seven-cylinder radial (F.K.22/1) and the second by a 100hp Gnome Monosoupape nine-cylinder rotary (F.K.22/2), the remaining three eventually being completed as prototypes for the F.K.23. The F.K.22/2, retroactively named Bantam II, was the first to fly, commencing its trials in December 1917 and being delivered to Martlesham for official trials on 19 January 1918. Armament comprised two synchronised 7.7mm Vickers guns, and this prototype, later re-engined with a 110hp Le Rhone 9J nine-cylinder rotary, was eventually assigned to the Central Flying School at Upavon.
F.K.22/1 Engine: 170hp A.B.C. Wasp seven-cylinder radial
F.K.22/2 Engine: 100hp Gnome Monosoupape nine-cylinder rotary Take-off weight: 571 kg / 1259 lb Empty weight: 393 kg / 866 lb Wingspan: 7.52 m / 24 ft 8 in Length: 6.30 m / 20 ft 8 in Height: 2.26 m / 7 ft 5 in Wing area: 21.37 sq.m / 230.02 sq ft Max. speed: 161 km/h / 100 mph
The first Gordon England design, the G.E.1, was a two-bay equal-span tractor configuration biplane powered by a 50 hp (37 kW) Clerget four-cylinder water-cooled engine, driving the two-bladed propeller via a chain drive giving a 2:1 speed reduction. The crew of two were accommodated side-by-side in a single cockpit, fitted with dual controls. The empennage consisted of a small triangular tailplane and elevators mounted on top of the rectangular-section fuselage and elongated triangular fins above and below the fuselage with the unbalanced rudder mounted on the trailing edge.
After testing during May and June 1912 the fins were removed, and an enlarged aerodynamically balanced rudder fitted. The aircraft was sold to the Deutsche Bristol Werke. However it was found to be unsuitable for use as a trainer, and was returned to the Bristol works at Filton in September 1912 and scrapped.
The G.E.2 was an enlargement and refinement of the previous design. The fuselage was carried on the innermost pairs of interplane struts, so that there was a gap between the fuselage and the lower wing, and a shallow curved fairing was added to the top and bottom of the fuselage. The tailplane was enlarged and mounted in a mid-fuselage position. Two examples were built, one powered by a 100 hp (75 kW) Gnome double Omega twin-row rotary engine and the other with a 70 hp (53 kW) four-cylinder inline water-cooled Daimler. Both were entered in the British military aeroplane trials held in August 1912, the first to be flown by Gordon England and the other by Howard Pixton but were unsuccessful, completing only the quick-assembly tests. The Daimler-engined version proved underpowered, and the other aircraft was damaged in an accident early in the competition, which was won by the Cody V biplane. Bristol did have some success, however: their monoplane design being placed equal third.
The design was further refined in the G.E.3, of which two were built for the Turkish government. This had a fuselage faired to a circular cross-section with the crew in two tandem cockpits, with fuel and oil tanks sufficient for three hours flight between them, and was powered by an 80 hp (60 kW) Gnome Lambda single-row rotary engine threequarters enclosed in a circular cowling. The continuous inmost interplane struts were replaced by short struts between the lower longerons and the lower wing and a cabane consisting of two sets of inverted V struts supplemented by a single strut between the centre of the upper wing and the nose of the aircraft. Trials of the aircraft revealed that the wing spars were too flexible, and although an attempt was made to address this problem by adding short kingpost-bracing to the rear spar, by this time the Italian blockade of Turkey made delivery difficult, and no further development was carried out.
G.E.1 Engine: 1 x 50hp Clerget Wingspan: 10.26 m / 33 ft 8 in Length: 8.84 m / 29 ft 0 in Wing area: 29.73 sq.m / 320.01 sq ft Max. speed: 105 km/h / 65 mph
G.E.2 Powerplant: 1 × Gnome double Omega, 100 hp (75 kW) Wingspan: 40 ft 0 in (12.20 m) Wing area: 400 sq ft (37.2 sq.m) Length: 31 ft 0 in (9.45 m) Empty weight: 1,080 lb (480 kg) Gross weight: 2,000 lb (907 kg) General characteristics Maximum speed: 68 mph (109 km/h, 59 kn) Crew: two, pilot and observer
The Bristol TB.8 two-seat trainer of 1914-15 was powered by 80 hp rotary engines. Various makes were used including Gnome, Le Rhone and Clerget. Later models were powered by a 100 hp Gnome Monosoupape engine.
RNAS TB.8 – 100 hp Gnome
About 36 were built, of which some were supplied to the RNAS and six went to Roumania.
Wingspan: 37 ft 8 in Length: 29 ft 3 in Max speed: 73 mph
In 1919 Frank Barnwell took the flying surfaces from a Badger – a proposed development of the F2B fighter – and made up a cheap slab-sided fuselage for experimental work. The whole thing cost £250 to build and was known as the Badger X, (and unofficially as Barnwell’s weekender).
It became the first aircraft to appear on the UK civil register as G-EABU on 30 May, by which time Barnwell had turned it over on the golf course adjacent to the Filton airfield. He was left unharmed but angry, hanging from the straps, and he got even angrier when someone released his straps before getting hold of him, and he landed on his head!
Captain Frank Barnwell designed the MF as an all-metal parasol-wing monoplane that could be flown as the MFA single-seat fighter or MFB two-seat reconnaissance plane. The latter had an extra fuselage section behind the cockpit for the gunner’s position and, below this on a short cabane arrangement, a cantilever second wing. In April 1921 the Air Ministry ordered three prototypes with wooden wings. Bristol proposed the name Pegasus, but this did not conform with current British practise and the two MFAs became Bullfinch Mk Is while the sole MFB became the two-seat Bullfinch Mk II. By March 1922, when the name Bullfinch was officially adopted, the decision had been taken to complete two of the prototypes as single-seaters, these being delivered in April 1923. Armed with two 7.7mm Vickers machine guns, the Bullfinch single-seaters were flown experimentally by the RAF and were found to offer a relatively good performance on the 425hp of a Bristol Jupiter III radial, but no production order was forthcoming. The Mk II was first flown on 15 February 1924 and delivered in March 1924. The Bullfinch II differed from the single-seat model primarily in having a 91.4cm section housing a self-contained gunner’s cockpit inserted in the fuselage immediately aft of the pilot’s cockpit and beneath which was attached a cantilever lower wing, the resultant shift of the centre of pressure compensating for the change in the CG. The only other change consisted of the repositioning of the main undercarriage members farther aft. The rear cockpit was fitted with a Scarff-mounted 7.7mm Lewis gun, and structural weight was increased by 145kg. The 425hp Jupiter III engine was insufficiently powerful to cater for the additional 400kg of the two-seater in fully loaded condition and the performance of the Bullfinch II suffered. Both variants were fully evaluated, but no orders followed.
Bullfinch II
Principal versions – Bullfinch Mk I (single-seat fighter prototype) and Bullfinch Mk II (two-seat reconnaissance prototype).
Bullfinch Mk.I Engine: one 450-hp (336-kW) Bristol Jupiter III radial Maximum speed 135 mph (217 km/h) at 15,000 ft (4,570 m) Srvice ceiling 22,000 ft (6,705 m) Endurance 4 hours 0 minutes. Empty weight 2,175 lb (987 kg) Maximum take-off weight 3.205 lb (1,454 kg). Wing span 38 ft 5 in (11.71 m) Length 24 ft 5 in (7.44 m) Height 10 ft 9 in (3.27 m) Wing area 267.0 sq ft (24.80 sq.m). Armament: two 0.303-in (7.7-mm) fixed machine guns.
Bullfinch Mk.II Engine: 425hp Jupiter III Take-off weight: 1854 kg / 4087 lb Empty weight: 1132 kg / 2496 lb Wingspan: 11.71 m / 38 ft 5 in Length: 8.38 m / 27 ft 6 in Height: 3.28 m / 10 ft 9 in Wing area: 36.32 sq.m / 390.94 sq ft Max. speed: 193 km/h / 120 mph
The Type 123 was built as a private venture to meet the requirements of Specification F.7/30, a 695hp Rolls- Royce Goshawk III steam-cooled engine being provided by the Air Ministry. Of high-tensile steel construction with fabric-covered wings, rear fuselage and tail assembly, the Type 123 carried an armament of four fuselage-mounted 7.7mm Vickers machine guns, and was first flown on 12 June 1934, having been delayed by difficulties with the engine cooling system. Subsequently the Type 123 was found to suffer from lateral instability at high speed and further development was abandoned.
Engine: 695hp Rolls- Royce Goshawk III steam-cooled Take-off weight: 2149 kg / 4738 lb Empty weight: 1497 kg / 3300 lb Wingspan: 9.02 m / 29 ft 7 in Length: 7.67 m / 25 ft 2 in Height: 2.89 m / 9 ft 6 in Wing area: 23.04 sq.m / 248.00 sq ft Max. speed: 378 km/h / 235 mph
One prototype, first flown on 29 January 1932. No production.
Engine: 1 x 600hp Bristol Mercury V Take-off weight: 2361 kg / 5205 lb Empty weight: 1649 kg / 3635 lb Wingspan: 12.40 m / 40 ft 8 in Length: 10.36 m / 33 ft 12 in Height: 3.66 m / 12 ft 0 in Wing area: 34.93 sq.m / 375.98 sq ft Max. Speed: 279 km/h / 173 mph Ceiling: 7772 m / 25500 ft Crew: 2 Armament: 2 x 7.7mm machine-guns, 4 x 100kg bombs
Bristol 110A Engine: 1 x 220hp Bristol Titan Take-off weight: 1979 kg / 4363 lb Empty weight: 1058 kg / 2333 lb Wingspan: 12.34 m / 40 ft 6 in Length: 10.21 m / 33 ft 6 in Height: 3.10 m / 10 ft 2 in Wing area: 36.14 sq.m / 389.01 sq ft Max. Speed: 201 km/h / 125 mph Crew: 1 Passengers: 4
Engine: 1 x 480hp Bristol Jupiter VIII Take-off weight: 4449 kg / 9808 lb Empty weight: 2088 kg / 4603 lb Wingspan: 15.60 m / 51 ft 2 in Length: 11.51 m / 37 ft 9 in Height: 4.27 m / 14 ft 0 in Wing area: 65.03 sq.m / 699.98 sq ft Max. speed: 145 km/h / 90 mph Range: 5313 km / 3301 miles
In 1926, the British Air Ministry issued F.9/26 specification for a radial-piston engine fighter design that could operate during the day or night, armed with twin Vickers-type machine guns, and capable of engaging the top enemy bombers of the day. Bristol responded with the Bulldog I as a private venture, designed by Frank Barnwell, which was used as a developmental model to ultimately become the Bulldog II.
The Bristol Jupiter engine, which in the initial production Bulldog II was a 328kW Jupiter VII, was mounted in a streamlined nose with its cylinders projecting uncowled but with streamlined fairings and cooling baffles. The propeller had two wooden blades. Features included Frise ailerons on the large upper wing and an adjustable trimming tailplane.
The Bulldog II had an all-metal fuselage with a fabric skin covering. The biplane wings were equal span with single bays and a single pair of parallel support struts. Armament consisted of 2 x 7.7mm Vickers machine guns with their breeches accessible to the pilot, synchronized to fire through the spinning propeller via an interrupter gear. Four 9 kg bombs could be carried under the small lower wing.
The undercarriage was fixed with a tail skid and both were designed to operate from grass runways. The pilot sat behind and underneath the upper wing in an open cockpit, with an oxygen supply for high altitudes and a short-wave two-way radio. Optional armament included 4 x 20lb bombs under the wings.
From the first flight on 17 May 1927, it was entered in the F9/26 competition at Martlesham Heath against the officially sponsored Armstrong Whitworth Starling, Boulton-Paul Partridge, Gloster Goldfinch and Hawker Hawfinch. The Bulldog was well liked by the RAF test pilots and could be dived to terminal velocity without damage to its robust steel structure. The only criticism involved the spin recovery which was overcome with a longer fuselage, larger fin and rudder.
Because of the closeness of the competition between the Bulldog and the Hawfinch the British Government ordered a single Bulldog II for further trials. The Bulldog II had a longer rear fuselage to overcome the spin deficiency of the prototype. First flown on January 21, 1928, the Bulldog II was tested against the Hawfinch at Martlesham, but the competition proved so close that a final decision was reserved until service pilots could assess both types. Eventually the decision was based on the ease of maintenance and here the Bulldog, with its single bay wings as against the twin bay wings of the Hawfinch, won. This Mk II prototype modification made cross wind landings and taxiing more difficult.
Nine Bulldogs were ordered, deliveries to 3 Squadron RAF, starting on May 8, 1929.
The first batch comprised 25 aircraft, of which 23 went to RAF fighter squadrons beginning with No 3 in 1929. Altogether 92 Bulldog II were built, one of which was retained for trials with Mercury engines in more advanced forms of cowling. Seventeen went to Latvia, eight to the RAAF, two to the US Navy, two to Siam, 12 to Estonia, three to Sweden and one to Chile.
US Navy A8607 at Anacostia 3 June 1930
In 1930 the two Bulldogs were purchased for evaluation by the US Navy, at the same time as one was supplied to the Imperial Japanese Navy. Both USN Bulldog IIAs, powered by Bristol Jupiter VIIF engines, were shipped in crates from Filton via Avonmouth Docks. The US Navy makings were applied on reassembly, the Bulldogs being supplied directly from the production line. The first, c/n 7358, left England on 10 October 1929, but developed aileron flutter and wing rib failure during the prescribed terminal velocity diving sequence. The Second. c/n 7398 left England on 24 February 1930, had revised aileron mass balance and strengthened wing ribs.
The Bulldog II entered RAF service in June of 1929 and effectively replaced the aging Gloster Gamecock and Armstrong Whitworth Siskin fighters then in frontline use. It was successively upgraded, the Bulldog IVA with the Bristol Mercury VIS 2 engine being the last version to be built in quantity.
A civil demonstrator flown in June 1930 was stressed for greater gross weight and led to the main production version, the Bulldog IIA, the usual engine of which was the 365kW Jupiter VIIF with forged cylinder heads. By November 1933 Bristol had built 262 of this model, of which eight went to Sweden and 253 to the RAF. Four more, called Bristol 105D, were supplied to Denmark with Madsen guns and other changes. Two improved and much faster aircraft with the Mercury engine and Townend ring cowl were designated Bulldog IIIA, leading to the strengthened four-aileron Bulldog IVA, with a 477kW Mercury VIS2 and full-length cowl. This was beaten by the Gladiator for RAF orders, but 17 were built for Finland in the first two months of 1935. The Australian Air Board approved the purchase of the six Bulldogs on Januany 17, 1929, at an estimated cost of £34,700. In May it was noted that Order No.244 was “held up in London owing to argument between Air Ministry, our Liaison Officer and the Bristol Company in regard to price.” The RAAF had previously used a two scat SE.5a to introduce pilots to single seat fighters and was interested in increasing the order by adding a two seat Bulldog. The Liaison Officer had to advise that the type was not being constructed for preliminary instruction for single seat fighters, two seat Armstrong Whitworth Siskins were standardised for this purpose. It was now evident that funds for the eight were available and as it was thought that a better price per unit could be obtained for a larger number, Order No.277 was raised to cover two additional Bulldogs. These aircraft were identical to the RAF Bulldog II except for the choice of engine and supplied under Air Ministry Contracts No.901228/29 for aircraft, and 934691/29 for engines respectively. “As supplied to the Royal Air Force (the Bulldog) is fitted with a Jupiter Mk VII (supercharged) engine for speed at heights above 10,000ft, but as operations at these heights are not called for in our case, as the ‘Bulldog’ with Mk VI is faster than with the Mk VII below 8,000ft,” the RAAF ordered the Bulldog with the Jupiter VI engine. The eight Australian Bulldogs (Bristol construction sequence numbers 7389 7396) were allocated the serials A12 1 to A12 8. The price quoted for each was £3,750. They arrived in Melbourne, Victoria, aboard the SS Fordsdale on March 14, 1930. Assembly took place at 1 Air Depot, Laverton, and the first was flight tested by F/Lt F R W Scherger on May 1.
RAAF Bulldog
RAAF Bulldogs entered service in 1930. Equipping No 1 Sqn at Point Cook, five of the eight were lost in crashes. One of these resulted in the first recorded RAAF pilot successfully bailing out, after an attempted outside loop caused a structural problem.
The Bulldog was constructed of ribbon steel worked up into suitable corrugated sections. The process was not in operation in Australia and major spares were necessarily obtained from overseas, but items “such as tanks, metal fittings and small parts… [were] obtained locally.” The upper wings were of greater span and chord than the lower wings. All fuel was carried in two gravity tanks recessed into the upper wings. The undercarriage featured oleo dampened rubber in compression legs which were attached to the top longerons. Two Vickers guns were mounted on each side of the cockpit. Provision was made for a wireless transmitter receiver to be carried in a compartment just behind the cockpit. The last Bulldog was an all-stainless-steel Mk IIA for the Air Ministry.
Bulldog II’s would never saw combat in British service but foreign users of the type did. Finnish pilots used Bulldogs against Soviet invaders in World War 2. Other foreign operators included Spain. In 1931 a Mk IIA had been rebuilt into a dual-control advanced trainer. In December 1932 a modified trainer, called Bulldog TM (Training Machine), went into production as a standard type for the RAF. By December 1934 no fewer than 60 had been delivered. They were designed so that by fitting different rear fuselages, and adding guns (for which provision was made), they became fighters. Bulldogs remained in full RAF service until 1937, and until 1940 with Baltic air forces.
Bulldog TM 23 June 1934 – TM3181, 450 hp Bristol Jupiter VI
Some 443 examples were produced from 1928 until 1935 including a total of 293 Bulldogs built for the RAF. The Bristol Bulldog was replaced in RAF service by the Gloster Gauntlet.
Nakajima of Japan produced two examples of the Bulldog as the J.S.S.F.
All Aero 