M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
Flight, August 14, 1914.
THE "ROUND BRITAIN" MACHINES.
WE continue this week the illustrated description of the machines entered for the Circuit of Britain, with the British-built
Beardmore "D.F.W." Tractor Biplane,
which has been officially numbered 2 in the race. This machine is very similar to the one which established a new world's altitude record lately, by going up to a height of 26,568 ft.
Aerodynamically, the new D.F.W. biplane, constructed by the great British armament firm of Wm. Beardmore and Co., is chiefly remarkable for its good streamline fuselage and back-swept wings, and constructionally it is interesting on account of the fact that it is built of steel practically throughout. The fuselage, which is of rectangular section, is built up of four longerons converging towards the rear, where they meet the rudder post and forming, in the nose of the machine, an exceptionally good entry for the air. Struts and cross members made of steel tubing connect the four longerons,to which they are secured by means of acetylene welding. Diagonal cross-bracing completes the internal construction of the fuselage, which is of enormous strength, both as regards torsional and bending stresses. In the nose of the fuselage are the supports for the engine - a 120 h.p. British-built Beardmore Austro-Daimler - which are also made of steel. A hemispherical nose-piece of aluminium covers the front part of the body, the sides of which are covered with the same material up to the rear inter-plane struts. From this point to the stern the fuselage is covered with fabric laced on. An aluminium turtle back, made out of a single sheet, and having openings cut out for the engine and pilot's and passenger's cockpits, gives the top of the fuselage a particularly good streamline.
The main planes are, as we have already pointed out, of the back-swept or arrow type, and are in addition heavily staggered. The upper plane, which is of slightly greater span than the lower one, is made in two sections joining in the centre to a cabane of the monoplane type consisting of four struts of streamline steel tubes resting with their lower ends on the upper longerons of the fuselage and carrying at the top a horizontal member to which the two sections of the upper plane are secured. The inner ends of the spars of the lower plane are attached to the lower fuselage longerons by means of quick release devices.
Two pairs of steel tube struts on each side connect the main planes and by means of a special lever on the lower end of the struts these can be dismantled in a few minutes without interfering in the slightest with the bracing cables, so that no tuning up is necessary every time the machine is erected. The saving in time thus effected should be of the greatest value in a military machine.
Although the D.F.W. biplane is practically inherently stable laterally ailerons are fitted to the outer extremities of the planes. These ailerons are of triangular shape and have a negative or reversed camber. In normal flight they therefore are slightly negatively loaded, thus tending to increase the lateral stability of the machine. They are operated by means of cables passing round a drum on the control wheel. The latter is mounted on a vertical column, which is free to move in a forward and backward direction and to which are attached the elevator control cables. Steering is effected in the ordinary way by a pivoted foot bar.
The pilot's and observer's quarters are most comfortable in addition to affording an exceptionally good view in practically all directions. The seats themselves are made of aluminium and are of the bucket type, well upholstered with leather. The front seat is occupied by the observer, who is placed sufficiently far forward to be able to look out over the leading edge of the lower plane. The rear seat, on the other hand, is situated so far back that the pilot obtains an unrestricted view in a downward direction, which is of course of great advantage for alighting on the sea.
The tail planes are of the usual type and consist of a flat stabilising plane, the angle of incidence of which can be varied, although not during flight as in previous D.F.W. machines. To the trailing edge of the stabilizing plane is hinged the divided elevator, whilst to a continuation of the stern post is hinged the rudder. A small fixed vertical tail fin is fitted. A small egg-shaped metal float supports the tail planes when the machine is at rest.
For the race round Britain a float chassis was, of course, fitted, but a land chassis can be very quickly substituted should it be desired to use the machine for overland flying. The float chassis consists of two sets of struts made of streamlined steel tube. Both sets are in the form of the letter "M," as seen from the front, and the lower extremities of the struts are connected by a transverse tube to which the floats are attached. The upper ends of the front set of struts join the lower longerons of the fuselage immediately under the engine, whilst the rear struts join on to the lower longerons at the point where are attached the front spars of the lower main plane. The radiator occupies a rather unusual position in being mounted underneath the fuselage between the chassis struts. Bosch ignition and self-starter is fitted, so that it is possible to start the engine from the pilot's seat without any necessity for swinging the propeller. The weight of the machine empty is 1,500 lbs., and a speed range of 45 to 85 miles per hour is expected. It is anticipated that the climbing capabilities of the machine will be at the rate of 3,500 ft. in 6 mins. with a load of 125 lbs. in addition to pilot and observer and sufficient petrol, oil and water for six hours' flight.