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Aviation History
1909
1909 - 0637.PDF
OCTOBER 16, 1909. THE FARMAN BIPLANE. ONE of the most successful pioneers in- the practical side of aviation—winner of the historic Deutsch-Archdeacon prize by the accomplishment of the first circular kilom., and hero of the first cross-country flight—Henry Farman has only latterly taken up the design and construction of the machines which bear his name. In his early work he used a Voisin flyer, and throughout the many suc- ceeding experiments, in which one modification or another was made in respect to detail, the machine still retained most of what are, after all, the essential cha- racteristics of the Voisin type. The Farman flyer of to-day is a biplane; it has a biplane tail, carried on a rearwardly projecting outrigger, and it has a monoplane elevator in front. Where the Farman design differs materially from the Voisin system, however, is that the machine is totally devoid of vertical panels, either between the main decks or the supporting members of the tail. There is, of course, a rudder, or to be more precise two rudders which work in unison, thus 5*1. The framework of the decks consists of two parallel transverse main spars, which pass from one extremity of the span to the other and lie parallel about 4 ft. 9 ins. apart. Across these spars are fastened curved ribs which overlap the rear spar by a distance of 1 ft. 7 ins.; the ribs are flush with the front spar which forms the leading edge of. the deck. The decks are single-surfaced with ordinary fine canvas, but the spars and the ribs are nevertheless enclosed in pockets of the same material. This is done in order to avoid sharp angles. The strips of fabric forming pockets for the ribs are sewn on to the upper surface. The pocket for the front spar is formed by turning back the main sheet of fabric, the edge of which is then stuck down on to the under surface. The pocket for the rear spar is formed by similarly attaching another strip of fabric to the under surface of the deck. That part of the deck formed by the projection of the ribs beyond the rear spar constitutes a flexible trailing The Farman Biplane, with Mr. Henry Farman at the wheel. but there is no prow, not even so much as exists on the Voisin flyer, where the covering in of the elevator out- rigger serves this purpose to a certain extent. One very natural consequence of the absence of this vertical surfacing in the Farman machine, is that it has a much lighter appearance, for there is nothing so well calculated to make a flyer look heavy as to box it in with side curtains. Another important feature of the Farman flyer, and one which originated on this machine, is the combination wheel-and-ski chassis. Being designed for launching by running along the ground, wheels are essential in the construction, but Mr. Farman was one of the first to appreciate the advantages of the ski on the Wright machine when it came to landing after a flight. A suspension which is in every way satisfactory for running about over smooth ground, preparatory to the start, is by no means necessarily adequate to meet the very severe shocks which are apt to be associated with descents on ground which has not exactly been chosen for the purpose. Here the advantages of skis assert themselves, the extent of their tread and of their strength to resist impact being particularly valuable under such circumstances. The Main Decks. The main decks have a span of 32 ft. 6 ins., and measure 6 ft. 4 ins. on the chord; their aspect ratio is edge. It is not, however, continuous either in the top deck or the bottom deck, owing to the provision of hinged balancing flaps and the necessity for accommodating the propeller. The hinged balancing planes are constituted by those portions of the trailing edge lying between the last pair of main struts at each end of the span. The accommodation of the propeller involves the cutting away of the trailing edge of the lower deck only between the main spars of the outrigger frame. The main decks are separated by vertical ash struts, 6 ft. 4 ins. in height. The section of the struts forms a pointed oval. Diagonal wire ties crossing between the extremities of the struts brace the whole structure into a lattice girder. The Framework. In addition to the framework of the main decks, the complete machine includes two outriggers for the elevator and tail respectively, and a chassis for the support of the machine upon the ground. All of these members are constructed of timber and wire, ash being the principal wood used. The tail outrigger is built up of four longitudinal ash spars, having a rectangular section. These are braced by vertical ash struts set in flanged aluminium sockets, and lugs attached to these sockets afford an anchorage for the adjustable diagonal tie-wires. There are no 641 n
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