F.Manson British Bomber Since 1914 (Putnam)

Blackburn GP

   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.

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Blackburn G.P. and S.P.

  THE Blackburn G.P. appeared in 1916. It was a large twin-engined biplane with a twin-float undercarriage, and was designed as a three-seat patrol bomber. It was one of the earliest aircraft designed to carry a torpedo. The upper wings had long wire-braced extensions, and bore the ailerons; there were no control surfaces on the lower wings. The G.P. was powered by two 225 h.p. Sunbeam engines which drove opposite-handed four-bladed airscrews. The radiators were mounted vertically on each rear interplane strut flanking the engine nacelles.
  The wings could be folded to facilitate stowage. This structural feature was not unique in 1916, but was still regarded as unusual, particularly in such a large machine.
  The second aircraft to be built to the same basic design as the G.P. embodied a greater proportion of metal components, and was powered by two 250 h.p. Rolls-Royce Falcon engines. This version was designated Blackburn S.P., and externally had little to distinguish it from the G.P. The engines again drove four-bladed airscrews, but the exhaust pipes ran along the sides of the nacelles instead of above, as in the case of the Sunbeam engines which had their exhaust valves on the inboard sides of the cylinders.
  The principal difference between the S.P. and the G.P. lay in the greatly increased aileron area of the S.P. Ailerons were fitted to the lower mainplanes: they extended from the second pair of interplane struts out to the wing-tips, and the ailerons on the upper wing were lengthened correspondingly. Upper and lower ailerons were connected by a faired steel tube, and it seems probable that they may have been arranged to droop together and thus act as air-brakes, in the manner of the later Kangaroo. The trailing edges of the S.P.’s rudders were made of wire; consequently they were “feathered”, whereas the more substantial trailing edges of the rudders of the G.P. were quite straight.
  The type did not go into production, but a landplane conversion named the Kangaroo was built in some numbers. The tests of the G.P. were carried out at the Isle of Grain, and the S.P. was tested at Brough.


SPECIFICATION
  Manufacturers: The Blackburn Aeroplane & Motor Co., Ltd., Olympia, Leeds.
  Power: G.P.: two 225 h.p. Sunbeam. S.P.: two 250 h.p. Rolls-Royce Falcon.
  Dimensions: Span: upper 74 ft 10 1/4 in., lower 52 ft 10 1/2 in. Length: 46 ft. Height: 16 ft 10 in. Chord: 7 ft 3 in. Gap: 7 ft 3 in. Stagger: nil. Dihedral: 5. Incidence: 5. Span of tail: 17 ft 6 in.
  Areas: Wings: upper 536 sq ft, lower 344 sq ft, total 880 sq ft. Ailerons: total 166-5 sq ft (on S.P.). Tailplanes: 80 sq ft. Elevators: 63-5 sq ft. Fins: 25 sq ft. Rudders: 22-5 sq ft.
  Weights: (S.P.) Empty: 5,840 lb. Military load: 1,170 lb. Crew: 540 lb. Fuel and oil: 1,050 lb. Weight loaded: 8,600 lb.
  Performance: (S.P.) Maximum speed at sea level: 97 m.p.h.; at 10,000 ft: 77 m.p.h. Climb to 5,000 ft: 10 min; to 10,000 ft: 30 min. Ceiling: 11,000 ft. Endurance: 8 hours.
  Tankage: Petrol: 230 gallons. Oil: 18 gallons.
  Armament: Two free Lewis machine-guns on Scarff ring-mountings, one on the nose cockpit, the other on the rear cockpit aft of the wings. Four 230-lb bombs or one torpedo.
  Serial Numbers: 1415 (G.P.) and 1416 (S.P.).

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.

Журнал Flight

Flight, December 11, 1919.

"MILESTONES"
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.