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Страна: Великобритания

Год: 1918

Single-seater Biplane

C.Barnes Bristol Aircraft since 1910 (Putnam)

The Bristol Scouts E and F

   In the autumn of 1916, before the Bristol Fighter had been issued to the Royal Flying Corps squadrons in France, desperate efforts were being made to produce single-seater fighting Scouts capable of outflying their German opponents, in the struggle to gain local air superiority over the artillery lines. A limit had almost been reached in the power available from rotary engines and attention turned to various alternative designs, both in-line and radial. Typical of the former was the Hispano-Suiza, but its reliability was poor and supplies of serviceable engines so limited that they were reserved for the officially-designed S.E.5a Scout, the first prototype of which flew in December 1916.
   Designers looked hopefully around for other engines, and Capt. Barnwell was informed of a proposal by Harry R. Ricardo and Frank B. Halford for a ten-cylinder two-row watercooled radial of 200 h.p., the 'Cruciform'. This engine gained no official support and was not built even as a prototype, but nevertheless Barnwell designed round it two alternative single-seater schemes, one a tractor biplane and the other a pusher. The latter, drawn by W. T. Reid on 25 January 1917, remained a preliminary layout only, and showed a conventional equal-span two-bay biplane with the pilot's cockpit in a nacelle mounted high up, as in the contemporary Vickers F.B.26; armament comprised two Lewis guns. The tractor design, drawn by Barnwell himself, was dated two days earlier and showed a neat single-bay biplane combining the aerodynamic refinement of the M.1C with the compact layout of the Scout D. The wings had rounded raked tips as in the monoplane and four small strut-linked ailerons of equal area. The fuselage was a wire-braced structure aft, but a Warren girder forward of the cockpit. The undercarriage was a simple Vee type with rubber-sprung cross-axle, and the engine was installed with a annular radiator forward, to which air was admitted through a large diameter annular spinner surrounding a cone at the centre; this arrangement foreshadowed the low-drag cowling developed 30 years later by Napiers for the Hawker Tempest. Armament consisted of a single synchronized Vickers gun recessed into the top of the fuselage ahead of the pilot and a Lewis gun on the top centre section which could be elevated through 45 degrees from its lowest position, which was arranged just to clear the airscrew.
   A fair amount of design work was done on the tractor project, Scout E, during February and March 1917, and sequence number 2844 was reserved for a prototype; but then it became apparent that the Cruciform engine would not be built, and early in May the Company was promised a few 200 h.p. Hispano-Suiza engines and a contract for six prototypes of a modified design. Barnwell at once revised Scout E to suit the Hispano-Suiza and changed the wing arrangement to one of unequal span with ailerons only on the top wing; at the same time the Lewis gun was deleted and two synchronized Vickers guns were arranged side-by-side in place of the single one. The revised project was named Scout F and retained the rear fuselage and tail unit of Scout E almost unchanged, but the deeper front end necessitated a new, shorter undercarriage. When the contract was issued on 4 June it specified the Sunbeam Arab engine, because of the shortage of Hispano-Suizas, and this was accommodated without much difficulty, but the cooling system gave some trouble and the header tank had to be raised to a position where it made a slight bulge in the top of the cowling. The radiator layout of Scout F matched that of Scout E in neatness and imagination, for it comprised a rectangular block mounted in an under-belly tunnel fairing, with two independent shutters, which could be set to various angles to maintain optimum water temperature. This permitted a low-drag nose design with a conical spinner over the airscrew boss. A good many revisions were made in cockpit details, flying controls and gun installation while construction of the prototype proceeded, and the design was not completed until November 1917, by which time the first few Sunbeam Arabs had begun to demonstrate the incurability of their vibration trouble. It was therefore decided to complete only the first two Scouts F, Nos. 2845 and 2846 (B3989 and B3990), with Arabs and to seek a better alternative engine for the others.
   The first Scout F was flown in March 1918 and had a remarkably fine performance, reaching 138 m.p.h. at sea level and 128 m.p.h. at 10,000 ft. The second Scout F was flown at the Central Flying School by all the most experienced fighter pilots of the day, amongst them Major Oliver Stewart, who rated it as a better aerobatic machine than the S.E.5a; but it was condemned by its engine and no attempt seems to have been made to revert to the Hispano-Suiza version. By this time, however, a new and promising small-diameter radial engine had arrived; this was the Cosmos Mercury of 315 h.p. designed originally for an Admiralty application by A. H. R. Fedden and L. F. G. Butler of Brazil Straker and Co. Ltd. of Fishponds, Bristol, who had been awarded a contract for 200 production engines of the type. Seeking a suitable aeroplane in which to install the Mercury engine for flight testing, Fedden approached Barnwell, who was looking for a substitute for the Sunbeam Arab and was predisposed in favour of a radial since his study for Scout E. The upshot of this meeting was the modification of the third Scout F, No. 2847 (B3991), to take the Mercury, which was installed in a low-drag cowling with only the cylinder heads and exhaust stubs exposed.
   Known as Scout F.l, B3991 was flown for the first time at Filton on 6 September 1918 and on 26 October it became the first Bristol prototype to be flown by the Company's new test pilot, Cyril F. Uwins, who had joined the staff the day before. Although the Armistice put an end to any hope of production of the Scout F.1, it was very successful in its trials and in December 1918 was delivered to Farnborough. There, in April 1919, it put up unofficial records by climbing to 10,000 ft. in 5·4 min. and to 20,000 ft. in 16·25 min.; its maximum speed at sea level was 145 m.p.h. After these trials no further development took place because the Cosmos Mercury contract had been cancelled; the fourth Scout F, No. 2848 (B3992), was completed as a spare airframe, but the last two aircraft of the order were still unfinished in April 1919; the question did arise of completing one of them with a Hispano-Suiza for offer to Senor Juan Pombo instead of the Scout D he had asked for, but he accepted the alternative offer of an M.1C, as recorded earlier. The mainplanes of B3992 were the subject of static strength tests at the RA.E. in 1919, and as late as March 1921 Capt. Barnwell suggested adapting this airframe as a flying test-bed for a new Curtiss engine, but this proposal was not approved.

SPECIFICATION AND DATA
Type: Scout F
Manufacturers: The British & Colonial Aeroplane Co. Ltd., Filton, Bristol
Power Plants: One 200 hp Sunbeam Arab
   One 315 hp Cosmos Mercury
Span: 29 ft 7 in
Length: (Arab) 20 ft 10 in
   (Mercury) 20 ft
Height: 8 ft 4 in
Wing Area: 260 sq ft
Empty Weight: 1,440 lb
All-up Weight: (Arab) 2,200 lb
   (Mercury) 2,260 lb
Max. Speed: (Arab) 138 mph
   (Mercury) 145 mph
Climb to 10,000 ft: (Arab) 9t min
   (Mercury) 5 1/2 min
Accommodation: Pilot only
Production: 4
Sequence Nos.: 2845-2848

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Описание:

  • C.Barnes Bristol Aircraft since 1910 (Putnam)
  • P.Lewis The British Fighter since 1912 (Putnam)
  • F.Mason The British Fighter since 1912 (Putnam)
  • W.Green, G.Swanborough The Complete Book of Fighters
  • J.Bruce British Aeroplanes 1914-1918 (Putnam)
  • H.King Armament of British Aircraft (Putnam)
  • Jane's All The World Aircraft 1919
  • C.Owers British Aircraft of WWI. Vol.7: Experimental Fighters Part 3 (A Centennial Perspective on Great War Airplanes 81)
  • Журнал Flight