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Страна: Великобритания

Год: 1915

Twin-engine, two-seat, two-bay biplane anti-airship bomber with twin fuselages and central wing-bay

A.Jackson Blackburn Aircraft since 1909 (Putnam)

Blackburn T.B.

   In May 1914 the Blackburn company received an Admiralty order for a batch of the Farnborough-designed B.E.2c biplane trainers which, together with larger and later batches, were built in new and bigger premises, the Olympia Works. They also built the Sopwith Cuckoo torpedo-bomber in quantity but still found time to work on a number of their own original prototypes. The first of these, first Blackburn design to bear the now legendary 'BA' monogram of the new company, and its first true military aircraft, was built in 1915 to an Admiralty specification which called for a long-range Zeppelin interceptor capable of operating over the sea at night. Its warload of Ranken incendiary steel darts, carried in canisters of 24, was intended to penetrate the airship's envelope and ignite the gas inside.
   Known as the T.B. or Twin Blackburn, the machine was a large biplane of unusual design having two wire-braced, fabric-covered, box girder fuselages, each with its own rotary engine, joined by a 10 ft centre section forward and a common tailplane at the rear. The fuselages were supported on the water by separate and unconnected bungee-sprung, stepped pontoons, and small tail floats were attached at the rear by short steel struts.
   Fabric-covered wooden mainplanes, built up from I-section spruce spars and ribs of three-ply spruce braced internally with drift struts and tie rods, were rigged in three bays. The considerable overhang at each end of the upper mainplane was wire-braced to triangular steel pylons above the outboard interplane struts. Fins and rudders were B.E.2c components taken from the Blackburn company's own production and slightly modified in shape.
   Long-range capability was to have been achieved by fitting the T.B. seaplane with a new type of 150 hp engine said to have an exceptionally low fuel consumption and a dry weight of only 380 lb. This was the ten-cylinder Smith radial, designed by John W. Smith, an American who brought his designs to England in January 1915 and somehow gained immediate Admiralty interest. A prototype engine was bench-tested successfully and a production contract was awarded to Heenan and Froude Ltd of Worcester, but only a few were delivered. When flown experimentally later in 1915 in the A.D. Navyplane and Vickers F.B.5 pusher biplane, the Smith engine proved unsatisfactory, and so eight of the nine T.B. seaplanes ordered by the Admiralty were completed with 100 hp Gnome Monosoupape rotary engines and the ninth and last with 110 hp Clergets.
   The first Gnome-powered machine, 1509, was rolled out at the Olympia works in August 1915 and, together with 1510 and the final Blackburn T.B., 1517 with Clergets, underwent type trials at RNAS Isle of Grain in 1916. In his memoirs, the flight test observer E. W. Stedman recalls how the pilot J. W. Seddon sat in one fuselage with all the flying and engine controls, while he sat several feet away in the other with no controls except the starting handle for the engine on his side. Starting on the water needed discipline, courage and agility, for a pool of excess petrol, which formed on the float when the Gnome was primed, promptly ignited when the engine fired. The observer's job was to lie on the lower centre section and put out the fire on the pilot's side with an extinguisher, scramble into his own cockpit to start the second engine and then leap out again to extinguish the fire on his own float.
   Once in the air, mainplane deflection was such that the aileron control cables became slack and all lateral control was lost. This defect was soon put right by the manufacturers but there remained a disconcerting amount of relative movement between the fuselages caused by flexibility in the wire-braced centre section. Furthermore, on only two-thirds of the designed power, performance was mediocre, and to achieve a worthwhile four-hour endurance the military load had to be limited to 70 lb of steel darts. Hand signalling, the only means of communication between the crew members, was hardly an ideal arrangement when in action against an enemy airship, thus, despite the fact that the three trials aircraft and four others were sent to RNAS Killingholme, they were little used and were eventually broken up. This fate also overtook the two remaining aircraft, 1511 and 1512, which were held in store at the RNAS Depot, Crystal Palace, London, until struck off charge.

SPECIFICATION AND DATA
   Manufacturers: The Blackburn Aeroplane and Motor Co Ltd, Olympia Works, Roundhay Road, Leeds, Yorks.
   Power Plants:
   Two 150 hp Smith
   Two 100 hp Gnome Monosoupape
   Two 110 hp Clerget 9b
   Dimensions:
   Span (upper) 60 ft 6 in (lower) 45 ft 0 in
   Length 36 ft 6 in Height 13 ft 6 in
   Wing area 585 sq ft
   Weights: (Gnomes) Tare weight 2,310 lb All-up weight 3,500 ib
   Performance: (Gnomes)
   Maximum speed at sea level 86 mph
   Climb to 5,000 ft 12 min Endurance 4 hr
Production: Nine aircraft 1509-1517, all Gnome-powered except 1517 with Clergets. 1509, 1510 and 1517 Isle of Grain trials aircraft 1916, broken up at RNAS Killingholme August 1917; 1511 and 1512 stored at RNAS Crystal Palace, s.o.c. June 1917, broken up July 1917; 1513-1516 to RNAS Killingholme, broken up August 1917.

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Описание:

  • A.Jackson Blackburn Aircraft since 1909 (Putnam)
  • F.Manson British Bomber Since 1914 (Putnam)
  • P.Lewis British Bomber since 1914 (Putnam)
  • J.Bruce British Aeroplanes 1914-1918 (Putnam)
  • H.King Armament of British Aircraft (Putnam)
  • Журнал Flight
  • A.Jackson - Blackburn Aircraft since 1909 /Putnam/

    One of the Gnome-powered T.B. prototypes at the RNAS experimental establishment on the Isle of Grain in 1916.

  • A.Jackson - Blackburn Aircraft since 1909 /Putnam/

    The last production T.B. seaplane, 1517, with Clerget engines.

  • P.Lewis - British Bomber since 1914 /Putnam/

    The ninth and last T.B. built. No 1517 with Clerget engines, at the Isle of Grain (just visible in the right background is a Port Victoria seaplane. Note the T.B. s unmistakable B.E.2C fins and rudders.
    From all reports, the cumbersome Blackburn TB was a real pilot frightener from the moment it first appeared in August 1915. Designed around the unsuccessful 150hp Smith radial, the two man TB was meant to serve as a long range, over-water Zeppelin destroyer. As if the failure of the Smith engine was not enough, leaving the TB underpowered as it did, the airframe itself, left much to be desired in terms of structural bracing. During the 1916 flight trials, this weakness manifested itself not just in excessive drag, but, even more alarmingly, in a tendency for the outer wings to warp in opposition to aileron input from the pilot, making for ineffective roll control. Of the nine TBs built, eight ended up using twin 100hp Gnomes, while the final example, serial no 1517 seen here, had twin 110hp Clergets. Top level speed was a desultory 86mph at sea level and of the seven machines delivered and flown by the RNAS, none were put into operational service prior to the TB's early withdrawal from inventory.

  • J.Bruce - British Aeroplanes 1914-1918 /Putnam/

    Rear view of the Clerget-engined T.B. seaplane.

  • Журнал - Flight за 1919 г.

    The Blackburn Type "T.B." seaplane, two 110 h.p. Clerget engines