C.Barnes Bristol Aircraft since 1910 (Putnam)

The Bristol Zodiac

   The Societe Zodiac of Paris was formed in the late nineteenth century to make balloons, and in due course extended its activities to include small dirigible airships. By 1907 the brothers Gabriel and Charles Voisin had developed their 'boxkite' type of biplane to the point where, on 13 January 1908, Henri Farman was able to fly one round a closed course of 1 kilometre, thereby winning the prize of 50,000 francs offered for this feat by Ernest Archdeacon and Henri Deutsch de la Meurthe. This achievement brought the Voisins into the ranks of the leading aeroplane designers of the day, and the Societe Zodiac extended its interests to include manufacture of biplanes and monoplanes designed by Gabriel Voisin. These had been placed on the market by the end of 1909, and were offered with a guarantee of flight. Sir George White, having consulted Emile Stern on the choice of a suitable aeroplane to begin manufacturing at Filton, was advised to consider the Zodiac models and in due course arranged to acquire the British manufacturing rights for them. Meanwhile, Henri Farman, having introduced improvements in a new Voisin biplane which he had ordered but never received, set up his own workshop and brought out replicas of the Farman III, which set the pattern for simplicity and performance for some years to come. Farman and his brothers were not much concerned with high-grade finish, although their materials were sound and their methods of construction safe enough for competition flying. Gabriel Voisin, having lost a good customer in Henri Farman, was anxious to advertise the superior workmanship of his products, and so the Zodiac biplane, though of outmoded design, was strongly recommended to Sir George White and chosen because of the excellence of its finish. Having decided that the newly formed British and Colonial Aeroplane Company should take a stand at the Aero Show at Olympia in March 1910, the Directors speedly authorised the importation of a Zodiac biplane, to be exhibited as a sample of the type to be built by the firm, and this was delivered in crates to Filton just in time to be prepared for the Exhibition. This preparation was no mere formality, for it was found that the 50 h.p. four-cylinder upright Darracq engine, purchased with the biplane, had no mounting lugs or other means of attachment to the airframe, so Charles Briginshaw, the fitter deputed to install the engine, had to make clamps to fit round the crankcase.
   Like most of the Voisin biplanes, the Zodiac had a single elevator in front and a biplane tail carried on four booms, the engine being mounted on the lower wing and driving a propeller behind the trailing edge. A single vertical rudder was provided between the tailplanes, and vertical surfaces were also fixed to the outer pairs of interplane struts; these were intended to resist any tendency to sideslip in a turn, but had been discarded by the Farmans and others after Wilbur Wright had demonstrated the safe and natural technique of banking on turns. The camber of the mainplanes and tailplanes was unusually flat, but both upper and lower surfaces were fabric-covered. Ailerons were fitted to the lower wing only and were linked to the rudder, which was controlled by rotating a handwheel which also moved fore-and-aft to control the elevator. Ailerons had not been a feature of earlier Voisin designs but were among the improvements introduced by Henri Farman. The undercarriage comprised a pair of skids each pivoted at the rear end to an inverted pyramid of steel tubes attached under the wing; a pair of wheels was mounted behind the pivot-point so that, when landing, the front of the skid was pulled down against a rubber shock absorber into contact with the ground. Two small castoring wheels supported the tail. Unfortunately the excellent workmanship was not matched by aerodynamic knowledge, and many of the refinements served only to increase weight without any corresponding gain in lift.
   After the Aero Show, the Zodiac was returned to Filton to be tuned for flight tests for which a Belgian pilot, Arthur Duray, had been engaged. Tests should have begun on 30 April, but the biplane was then still at Filton; meanwhile, Duray met with an accident in France and another pilot had to be sought. The Zodiac arrived at Brooklands on 10 May and was forthwith erected in the 'Bristol' shed by Sydney Smith and his assistants Leslie Macdonald, Charles Briginshaw and Henri Labouchere. From the first it proved to be very underpowered and all efforts to coax it off the ground failed. New wings with increased camber were assembled and eventually, on 28 May, it made a single brief hop in the hands of Edmond, who had taken Duray's place. Edmond thought little of its prospects and, after a final attempt to fly it on 15 June, when the landing gear was damaged, he persuaded Sydney Smith to abandon it in favour of the successful Henri Farman. The five Bristol-Zodiacs already started at Filton were scrapped and the Zodiac licence was cancelled soon afterwards.

   SPECIFICATION AND DATA
Type: Zodiac 52B
Manufacturers: The British and Colonial Aeroplane Co., Ltd., Filton, Bristol, under licence from Societe Zodiac, Paris
Power Plant: One 50 hp Darracq
Span: 33 ft 3 in
Length: 39 ft 3 in
Height: 10ft 2in
Wing Area: 525 sq ft
Empty Weight: 1,000 lb
Speed: 35 mph
Accommodation: Pilot and Passenger
Production: 1 assembled, 5 abandoned
Sequence Nos: 1 to 6 inclusive