A.Jackson Blackburn Aircraft since 1909 (Putnam)
Lack of success with the twin-fuselage T.B. design prompted the Blackburn company to set about the construction of a more conventional twin-engined type. This was a three-seat, long-range, anti-submarine patrol bomber known as the G.P. or General Purpose seaplane. It had mainplanes of modified RAF 3 section, a long, slim fuselage of unusually small cross-section, inline water-cooled engines housed in nacelles on the lower mainplane and a large twin-ruddered biplane tail unit. Nevertheless, the G.P.'s long, wire-braced upper mainplane extensions and wide-track, divided float undercarriage proclaimed its T.B. ancestry, but this time the pontoons were bungee sprung and divided internally into twelve watertight compartments. For ease of storage the two-spar mainplanes folded backwards outboard of the engine nacelles, reducing the overall width to 27 ft 10 in.
Blackburns built only two of the type and these differed considerably in detail. The first, which appeared in July 1916 with the naval serial 1415, was powered by two opposite-handed 150 hp Sunbeam Nubian engines driving four-bladed airscrews and cooled by vertical radiator blocks clamped to struts at the rear of each nacelle.
Three crew members sat in open cockpits, with the bomb-aimer gunner in the nose, the pilot just ahead of the centre section and the rear gunner aft of the wings. A bomb sight was mounted externally on the starboard side of the front cockpit and, in addition to the two Scarff-mounted Lewis guns, armament consisted of four 230-lb bombs carried on racks under the wings. As there were no connecting struts between the main floats, alternative armament was a torpedo carried centrally under the fuselage. Although there is no evidence that the G.P. seaplane was ever airborne with a torpedo in position, it was one of the first British aircraft with this capability, and one of the first designed to carry W/T apparatus as standard equipment.
On completion, the G.P. seaplane went to the Isle of Grain for trials which included mooring in a rough sea for several days, an ordeal realistically described at the time as a 'destructive test'.
Meanwhile, the site for Blackburn's new aerodrome and seaplane base had been chosen on the River Humber at Brough, where the first experimental hangar and slipway were completed by the time the second G.P. seaplane was ready for erection later in 1916. Numbered 1416, this was a developed version of the original, and was sometimes known as the S.P. or Special Purpose seaplane. It was powered by two opposite-handed 190 hp Rolls-Royce engines (later named Falcons) cooled in the same manner as the Sunbeams and likewise driving four-bladed airscrews. However, unlike the Sunbeam engines of the first aircraft, the Rolls-Royces had exhaust manifolds on the outside walls of the cylinder blocks, making it convenient to run exhaust pipes along the sides instead of over the tops of the nacelles. Oil tanks were suspended between the inboard nacelle struts ahead of the radiator blocks.
The new machine was structurally stronger than 1415 through the greater use of heavier-gauge metal fittings, and whereas the first had ailerons only on the upper mainplane, the second boasted four ailerons - two of increased length on the upper mainplane connected by link struts of faired tubular steel to short-span units on the lower wing. A wire trailing edge, first employed on the Triplane, was also used for all flying and control surfaces, so that unlike 1415 which had straight edges, those of 1416 were of the familiar scalloped pattern. It was, in fact, a retrograde step as wire trailing edges on seaplanes were a constant source of trouble because they rusted through and split the fabric.
In a lecture given before the Brough branch of the Royal Aeronautical Society in November 1958, G. E. Petty recalled the nightmare of conducting manufacturer's trials on the G.P. seaplane in midwinter with drift ice on the Humber. Launching was simple and the first flight successful, but the strong tide made recovery difficult, and the wading team led by Robert Blackburn's brother-in-law, R. R. Rhodes, were literally frozen stiff and had to be carried in on planks and thawed out in front of fires lighted in the hangar. Afterwards the machine was flown to the Great Yarmouth Air Station for Service trials but did not secure a production contract. Nevertheless a landplane version was built in small numbers as the Blackburn Kangaroo.
SPECIFICATION AND DATA
Manufacturers: The Blackburn Aeroplane and Motor Co Ltd, Olympia Works, Leeds, and Brough, East Yorks.
Two 150 hp Sunbeam Nubian
Two 190 hp Rolls-Royce
Span (upper) 71 ft 10] in (lower) 52 ft 10.1 in
Length 46 ft 0 in Height 16 ft 10 in
Wing area 880 sq ft
(Sunbeam) All-up weight 8,100 lb
(Rolls-Royce) Tare weight 5,840 lb All-up weight 8,600 lb
Maximum speed at sea level 97 mph
Climb to 5,000 ft 10 min
Ceiling 11,000 ft Endurance 8 hr
Production: Two aircraft only.
1415 with Sunbeam engines, first flown at RNAS Isle of Grain July 1916.
1416 with Rolls-Royce engines, first flown at Brough late 1916 and delivered to the Great Yarmouth Air Station.
F.Manson British Bomber Since 1914 (Putnam)
Designed by Bob Copley, who had been largely responsible for the earlier TB floatplane, the Blackburn GP was a more orthodox attempt to interest the Admiralty in a large torpedo- and bomb-carrying seaplane to complement the Handley Page O/100 land-based heavy bomber, also destined for the RNAS. Design had started in the late autumn of 1915, and the first prototype, No 1415, was completed and first flown at RNAS Isle o f Grain in July 1916 powered, like the Avro Type 523, by a pair of handed 150hp Sunbeam Nubian engines, but driving four-blade tractor propellers.
The GP featured a long, slim fuselage accommodating pilot and two gunners, one of the latter being charged with bomb aiming and provided with a bomb sight attached externally to the starboard side of the nose. Construction was largely of wood with metal joint fittings, the box girder structure carrying formers to provide rounded top decking. The wings, with considerable overhang, employed kingpost bracing and were of parallel chord, being rigged without stagger so as to simplify folding a feature demanded in all large naval aeroplanes.
To facilitate the carriage of torpedo and bombs, the twin floats were independently mounted beneath the engine bearer struts without cross-members, and the weapon racks were attached to the fuselage and lower wing roots with provision to carry either a 1,100 lb 18in torpedo or four 230 lb bombs, the latter in tandem on parallel beams.
Fuel sufficient for eight hours' patrol was carried in tanks located aft of the engines in the long nacelles which were positioned on the upper surface of the lower wings.
A second prototype*, No 1416, was also completed in 1916, and this differed from the first machine in numerous respects. Not least of these was the considerable airframe strengthening throughout in order to conform to Admiralty requirements which stipulated strength factors of 5 and 4 on front and rear trusses respectively, necessitating the use of heavier-gauge metal joint fittings. Power for 1416 was provided by a pair of 190hp Rolls-Royce Falcon engines whose nacelles were now located in mid-gap.
Both GPs underwent testing at the Isle of Grain, and the second aircraft participated in Service trials at RNAS Great Yarmouth early in 1917. However the GP failed to secure a production contract, presumably because the Short 184 had demonstrated continued reliability in the bomb-carrying patrol role at much less cost.
* For many years the second aircraft was referred to as the Blackburn SP. It seems likely however, as pointed out by J M Bruce, that no such designation existed, and possibly resulted from an error in, or misreading of, company documents.
Type: Twin-engine, three-crew, three-bay biplane long-range patrol bomber seaplane.
Manufacturer: The Blackburn Aeroplane and Motor Co Ltd, Leeds and Brough, Yorkshire.
Powerplant: Two 150hp Sunbeam Nubian or 190hp Rolls-Royce (Falcon) water-cooled in-line engines driving four-blade handed propellers.
Dimensions: Span, 74ft 10 1/2in; length, 46ft 0in; height, 16ft 10in; wing area, 880 sq ft.
Weights (Rolls-Royce engines): Tare, 5,840 lb; all-up, 8,600 lb.
Performance (Rolls-Royce engines): Max speed, 97 mph at sea level; climb to 5,000ft, 10 min; ceiling, 11,000ft; endurance, 8 hr.
Armament: Two Lewis machine guns with Scarff rings on bow and midships gunners' positions. War load comprised either four 230 lb bombs or one 18in Whitehead torpedo.
Prototypes: Two, Nos 1415 and 1416. No 1415 (GP) first flown at RNAS Isle of Grain in July 1916; No 1416 first flown at Brough late in 1916. No production.
P.Lewis British Bomber since 1914 (Putnam)
Blackburn entered the field of torpedo-carrying, patrol-bomber design during 1916 with the advent of their two large three-seat biplanes, the G.P. and the S.P. One only of each was built - 1415 the G.P. with two 225 h.p. Sunbeam engines and 1416 the S.P. using two 250 h.p. Rolls-Royce Falcons. The 74 ft. 10-25 in. upper wings overhung the lower planes by 21 ft. 9-75 in. and were made to fold. Apart from the power plants used, there was comparatively little to distinguish the machines from each other. Both were mounted on independent main pontoon float units with a single float at the tail, but the S.P. incorporated ailerons in its lower wings also. 1415 was put through its Admiralty trials at the Isle of Grain, but those of 1416 were undertaken at Brough; in the event, neither was ordered for service.
H.King Armament of British Aircraft (Putnam)
G.P. and S.P. These floatplane forerunners of the Kangaroo (1916/17) had nose and dorsal Scarff ring-mountings, with a Lewis gun each (one Blackburn document mentioned twin guns) installed on the top longerons, with the coaming built up fore and aft. They were designed to carry four 230-lb bombs under the wings or a 14-in torpedo under the fuselage. The bomb-sight was fixed to the starboard side of the front cockpit.
Flight, December 11, 1919.
THE BLACKBURN MACHINES.
The "G.P." Seaplane, or "Kangaroo" Seaplane. (July, 1916)
Probably the best known of all the Blackburn machines is the "Kangaroo" land machine, and it is not generally known that the prototype of this machine was a seaplane. This is, however, the case, the machine which led to the production later of the famous "Kangaroo" being a seaplane with two engines placed on the wings, and otherwise being, generally speaking, similar to the land machine that was to follow. This machine was known as the "G.P." (general purpose) seaplane, and the first made its appearance in July, 1916. The experimental machine was fitted with two Sunbeam engines of 160 h.p. each. The second experimental machine had two Rolls-Royce engines of 190 h.p. each, and finally the production machines were fitted with two Rolls-Royce Falcon engines of 250 h.p. each. There was a plain, non-stepped float underneath each engine, and a single tail float under the stern of the fuselage. The crew consisted of three men, the pilot being placed about halfway between the leading edge of the planes and the nose of the fuselage. In front of him was a gunner armed with a machine gun on a gun ring, and farther aft in the body was another gunner whose duty it was to defend the machine against attacks from behind. In addition to the guns and their ammunition, the G.P. seaplane was designed to carry bombs, or even a torpedo, so that it was well armed for either offensive or defensive purposes.