A.Jackson British Civil Aircraft since 1919 vol.1 (Putnam)
Single-seat floatplane powered by one 240-h.p. Siddeley Puma, built for 1919 Schneider Trophy by A. V. Roe and Co. Ltd., Hamble. One aircraft only: G-EALG, c/n 539/1, first flown 29.8.19. Modified with balanced rudder and elongated fin prior to contest 10.9.19, from which it was eliminated. Pilot H. A. Hamersley. Span, 25 ft. 6 in. Length, 21 ft. 4 in. Tare wt., 1,670 lb. A.U.W., 2,119 lb.
Conversion of Avro 539 to landplane with revised fin for 1920 Aerial Derby, pilot D. G. Westgarth-Heslam. One aircraft only: G-EALG, c/n 539 A/1. Made a forced landing at Abridge, Essex.
Avro 539A rebuilt for the 1921 Aerial Derby with 450-h.p. Napier Lion, plywood rear fuselage and revised undercarriage. One aircraft only: G-EAXM, c/n 539 B/1. D. G. Westgarth-Heslam injured and aircraft destroyed in landing accident at Hamble on eve of race, July 1921. Span, 25 ft. 6 in. Length, 18 ft. 2 in.
Flight, September 4, 1919.
THE JACQUES SCHNEIDER CUP RACE
The Avro Seaplane
As the accompanying illustrations will show, the Avro machine entered for the Schneider race is quite a small machine, its overall span being only 35 ft. 6 ins., and its length overall 21 ft. 4 ins. In general outline the Avro shows little resemblance to the other members of the Avro family; so little in fact that it would be impossible to identify it as an Avro from mere outward appearances. The detail construction, however, follows more or less standard Avro lines.
If for no other reason, the Avro would be of interest on account of the fact that it is fitted with the lowest powered engine entered in the race. The Siddeley "Puma" is rated at 240 h.p., whereas the next larger engine - the Isotta Fraschini fitted on the Italian Savoia flying-boat - is rated at 250 h.p.
This low power, however, does not necessarily mean that the machine will not be fast. Avro machines have in the past proved very efficient, and there is no reason to suppose that the present type will prove an exception. Naturally the makers are not anxious to give particulars of performance at the present time, but the small size of the machine, combined with the careful streamlining of all exposed component parts, should give her quite a good turn of speed.
The fuselage is of rectangular section as regards its main structure, and is surmounted by a curved top which in front encloses all but the top of the cylinders of the "Puma" engine. The six exhaust pipes project horizontally through the top covering of the body. Behind the pilot's cockpit the deck fairing is fairly deep to form a fairing for the pilot's head.
The upper longerons, it will be noticed, are straight and horizontal, thus forming a good datum line from which to true up the fuselage.
The radiator is placed in the nose of the fuselage, motor car fashion, and is of generous proportions. The result is that the body does not taper off towards the nose, as is the case in the Avro Baby, for instance, but has its sides parallel from the neighbourhood of the pilot's cockpit. The warm air is allowed to escape from the engine-housing through louvres in the side of the aluminium cowl.
A chassis structure of streamline steel tubes carries the two floats, which are of considerable length (14 ft.), and have one small step, occurring immediately underneath the rear chassis strut attachment. No tail float is fitted, the main floats being so placed as to make this unnecessary. The floats are placed fairly far apart, their track being 7 ft., and with the short span bottom plane avoid the use of wing-tip floats.
One of the most interesting features of the Avro seaplane is the shape of the wing tips. From the plan view of the general arrangement drawings it will be seen that the tips are distinctly rounded, a fact which contrasts markedly with the usual square-tipped Avro wings. Otherwise the wings are characterised by a fairly high aspect ratio - nearly 6.
The top plane, which is in one piece, has no dihedral angle, but the shorter bottom plane is set at a very marked dihedral angle. There is only one pair of inter-plane struts on each side. Owing to the slight difference in span, the inter-plane struts are sloped so as to get the best load distribution. The centre section struts, or rather the struts supporting the centre of the top plane, are sloped outwards in the usual way to reduce the length of "free" spar in the top plane.
The tail surfaces also differ from the usual Avro tails. The fixed tail plane, which is of symmetrical section, is no longer rectangular, but is shaped as shown in the plan view. The addition of a fin, doubtlessly necessitated by the deep nose of the body and by the side area presented by the two long floats, changes the appearance of the tail, and the rudder has not the usual semi-circular balance which characterizes so many other Avro machines.
Altogether the Avro seaplane, which, by the way, answers to the series number 539A, impresses one as being a very serviceable little machine, not only for the race contemplated, but also for purposes other than racing.