C.Barnes Bristol Aircraft since 1910 (Putnam)

In January 1913 Coanda designed a central-float seaplane, which resembled in some ways the G.E.3 and may have owed something to it, for the fuselage was faired to a circular section and mounted midway between the wings; the fuel tanks and system were also arranged in the same way as in Gordon England's design. On completion, this seaplane, No. 120, was sent to Cowes and was fitted with a wide central float built of mahogany designed by Oscar Gnosspelius, who had pioneered the design of hydroplanes on Lake Windermere and had produced similar floats for seaplanes. Stability afloat was ensured by two small torpedo-shaped floats under the wing-tips; there was no tail-float, but two water rudders were fitted at the rear of the main float. The two tandem cockpits had dual handwheel controls and there was a gap between the upper wing-roots above the front cockpits. The 80 h.p. Gnome was installed in a close-fitting aluminium cowling and had a starting handle in the cockpit, with an interconnected hand-starting magneto. A standard Coanda rudder and tailplane were fitted, but an extra rectangular rudder was later added under the tail to offset the keel surface of the main float. In the early buoyancy tests, the Gnosspelius float was satisfactory, but after being moored out for some days it soaked up an excessive weight of water and at his first attempt Busteed was unable to take-off. He therefore arranged with S.E. Saunders and Co. of Cowes to build a specially light float, using their patent wire-sewn plywood; this float was attached to the seaplane during the first week in April, and on the 15th Busteed succeeded in taking-off. His troubles had only just begun, however, for the Gnome engine was too closely cowled and quickly overheated. Losing power rapidly, Busteed had to alight abruptly and the impact was too much for the lightweight float, which burst open, throwing the pilot into the Solent. He was a strong swimmer, but was near exhaustion before being seen and rescued half an hour later by a dredger.
   No. 120, although begun as a private venture, had been purchased, subject to acceptance trials, by the Admiralty and was to have carried the R.N.A.S. number 15. The Admiralty had also ordered a landplane derived from the Coanda monoplane; this was a fairly straightforward conversion of No. 121, which had returned to Filton in February 1913 for overhaul after service at the Larkhill school since the previous October. It thus became the prototype of the Gnome-engined biplane known as the T.B.8, and in July and August at Larkhill soon showed that it had a much better performance than the B.R.7. It was next converted into a twin-float seaplane, for which purpose No. 120's original Gnosspelius float was divided down the centre line and made into a pair of narrower floats. In this form, with a steerable tail float and extra fin area added, No. 121 was sent to Dale on Milford Haven on 20 September 1913. It was flown through all its tests satisfactorily by Busteed and his assistant G. B. Dacre, until rough weather made further flying impossible. It was then returned to Filton in December, stripped, overhauled and rebuilt with a new fuselage as No. 205 and delivered to Calshot as the agreed substitute for No. 120, receiving the latter's intended serial 15. It had a tendency to fly nose down and in April 1914 it was again rebuilt at Filton with new floats, staggered wings with ailerons and a revised fin; in this form it was flown at the Spithead naval review in July 1914. Before agreeing to accept No. 205, it seems that the Admiralty had asked for a larger seaplane, and drawings have survived of a project called B.C.2, showing a tandem two-seater with a fuel system similar to No. l20's, and a circular monocoque fuselage, with a 200 h.p. eight-cylinder watercooled Clerget engine, for which Coanda designed an ingenious two-speed reduction gear, with internal clutches for changing speed, in place of the chain gear formerly employed. The design is dated between April and June 1913, after which it seems to have been discontinued.

Model Hydro 120 T.B.8H
Power Plant 80 hp 80 hp
   Gnome Gnome
Span 38 ft 8 in 37 ft 8 in
Length 27 ft 10 in 30 ft 6 in
Wing Area 436 sq ft 450 sq ft
Duration 4 hours
Accommodation 2 2
Production 1 1
Sequence Nos. 120 205

M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)

P.Lewis British Aircraft 1809-1914 (Putnam)

Bristol Coanda Hydro-biplane

   The Coanda Hydro-biplane was designed by Mons. Henri Coanda and built during 1913. It seated two in tandem cockpits in a streamlined, circular-section fuselage which was suspended between the wings. One large central float, augmented by a small pair at the wing-tips, supported the machine on the water. The first main float of Gnosspelius design (illustrated) proved to be too heavy and was replaced by a lighter one of the same size made by S. E. Saunders of Cowes on their Consuta system. The engine was the 80 h.p. Gnome, and an extra rudder was mounted below the tail to balance the additional side area of the float. The machine was given works number 120. It was wrecked when the float collapsed during a landing being made on 15th April, 1913, off Cowes by Harry Busteed. Span, 40 ft. (approx.). Length, 30 ft. (approx.). Wing area, 500 sq. ft.


Bristol T.B.8 Hydro-biplane

   As a quick replacement for number 120, in the summer of 1913 one of the 1912 Improved Coanda Military Monoplanes, works number 121, was converted direct into a T.B.8 Hydro-biplane and was tested in July at Larkhill with a landplane undercarriage. Twin floats were then made for it by employing the simple expedient of taking the unsuccessful original Gnosspelius single float of the Coanda Hydro-biplane number 120 and cutting it down the centre-line to make two. Wing-tip and tail floats were not used, but fins above and below the fuselage were added, together with a small rudder on the underside of the tail.
   The machine first flew successfully from the water at Dale, Pembrokeshire, on 20th September, 1913. Some three months later, in December, it was returned to Filton and reconstructed under works number 205, during which time the wing-warping control was replaced by ailerons. Number 205 was then delivered on 2nd January, 1914, to the Admiralty at Calshot as naval aircraft 15. Throughout these changes, the machine retained the 80 h.p. Gnome engine.