C.E. A-12 Transcontinental Triplane
Flight, July 20, 1916.
THE C.E. TRANSCONTINENTAL TRIPLANE.
WITH the coming of the large-sized aeroplane the question of multiplanes at once suggests itself as being a means of overcoming many of the problems involved. Apart from the obvious advantages as regards construction and weight-saving this arrangement of lifting surfaces offers, there is, we believe, much to be gained aerodynamically. Since the early, and by no means unsuccessful, efforts of A. V. Roe, little has been done in the way of triplanes, or machines having a greater number of lifting surfaces, and it is only recently that designers appear to be turning their attention in this direction. An interesting example of one of these efforts is to be found in the large C.E. Transcontinental triplane built at Anderson, Ind., U.S.A., some particulars of which have appeared in our American contemporary, Aerial Age. Although this machine is essentially a large one, having over 1,000 sq. ft. of lifting surface, it will be seen from the accompanying scale drawings that by virtue of the arrangement of the planes the overall dimensions are by no means abnormal, the length being 32 ft. 6 ins., and the span 59 ft. It has been designed for use over both land and water, a four-wheeled running gear being fitted to the boat-like body. The latter consists of a rectangular fuselage constructed of ash and spruce longitudinals and struts, which tapers to a horizontal knife-edge at the rear and to a point at the front. The whole body is strongly wire braced, and is given a streamline shape by means of formers and stringers, and a covering of three-ply spruce and a single layer of specially treated cloth. Provision is made for eight passengers, who are totally enclosed by the body, vision being obtained by means of windows.
The most interesting feature in the design of this machine, however, is to be found in the main planes. It will be noticed that the gap is exceptionally small in comparison with the chord - far too small, we should say, to get the best results from the planes. The wing-section employed is that of Kauffman (Eiffel No. 37), which compares favourably with the best wing-sections of to-day. It is doubtful, however, if the designers of the C.E. triplane have taken full advantage of its characteristics, for apart from the question of the small gap previously referred to, the normal angle of incidence given (8') does not appear to be the best under the circumstances. A section of the wing used on the C.E. triplane with dimensions is shown in one of the accompanying illustrations, whilst the general characteristics of a similar model section tested at the Eiffel Laboratory are also given. The planes are built up on two main tubular steel spars with 3/4 spruce battens nailed and glued to hollow laminated birch and mahogany webs. Some 2 ft. 4 ins. from the trailing edge is a third spar. The interplane struts are arranged in sets of three - a strut from each spar - in all, eight sets or 24 struts between each plane. In the centre the top and middle planes are supported by two sets of struts each, the lower ones being mounted on the body, to which the lower plane is attached direct. Level with the middle plane, one on either side of the body, are the two engines, 8-cylinder 140 h.p. turtevants. These are housed in streamlined laminated wood nacelles, each of which carries a passenger - presumably to look after the engine. Located in each of these nacelles is a 30 gallon fuel tank, fed from the six 40-gallon tanks located in the body of the machine by a special vacuum-feed system. The engines are coupled direct to tractor screws about 10 ft. in diameter. Ailerons are hinged to the extremities of the top and middle planes only, and a stabilising plane of some 43 sq. ft. area is mounted above the stern of the body slightly below the line of thrust. Hinged to the trailing edge of the tail plane is the elevator, which is divided into three by the two partly balanced rudders. Both elevator and rudder controls, as well as that of the ailerons, are incorporated in one operating column.
It is intended to build a second machine after the first one has gone through its air tests, and in this second machine steel will be used practically throughout. The principal characteristics of the first C.E. triplane are as follows:-
Span, 59 ft.; chord, 6 ft. 6 ins.; gap, 4 ft.; area of main planes, 1,650 sq. ft.; overall length, 32 ft. 6 ins.; weight complete, 5,500 lbs.; speed range (calculated), 48-98 m.p.h.; climbing speed, 900 ft. per min.; petrol capacity, 300 gallons.