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Aviation History
1931
1931 - 1165.PDF
KLJGHT, OCTOBER 30, J931 The New Domier Lemdplane By EDWIN P. A. HEINZE ALREADY, in the issueof October 9, FLIGHTwas able to give someadvance details of the new Dornier machine, theDo-K, which is at present undergoing its approbationtests. Owing to the kindness of the makers, which we dulyacknowledge, the writer has received further interesting de-tails of the machine, which give a good idea of the construc-tional features of the plane. As our readers will recol-lect, the machine is an alto- gether new design, bearing noresemblance to the old Domier " Merkur " landplane, whichhad a single engine and could convey six, or at most eight,passengers besides the crew of two. The Do-K has a streamlin with a cantilever type wing of entirely new form securedon top, and has ample cabin space for ten passengers. The idea of the designers was to create a fast passengertransport machine incorporating a high degree of safety for flying over country offering few possibilities of alight-ing in cases of emergency, such as the Alps and big deserts. For this reason high aerodynamical efficiency hadto be secured, and the power plant had to be subdivided to as great an extent as was compatible with economicalworking. Four air-cooled Czecho-Slovakian Walter "Castor" engines of 240-h.p. output each were adoptedand suspended in couples, one behind the other, beneath the wing right and left of the fuselage. The front engineshave been provided with four-bladed wooden tractor screws and the rear with two-bladed pusher screws. With a fullflying weight of 13,200 lb. this machine, during its trials, was able to attain a maximum speed of 137 m.p.h., theaverage touring speed being 125 m.p.h. and the ceiling 20,600 ft. With the same weight and one engine " dead,''the machine was still able to rise to 12,800 ft., and with two engines stopped it climbed at the rate of 1.3 ft. persecond at an altitude of over 3,200 ft. with the same flying weight. y 5 The wing has a span of 82 ft., a maximum chord of13 ft. 9 in., and a lifting area of 977 sq. ft. To secure low profile height (or wing thickness), which onlv amounts THE DOK IN FLIGHT: The projections behindthe engines are the mudguards over the wheels. fuselage of oval section, to 27£ in., it was found advis-able to employ three spars in- stead of the two usuallyadopted. In this Dr. Dornit-r has followed the practice thathas already proved successful in the Do-X and the recentlyintroduced Do-S, a flying boat with cabin space for 22 passen-gers, which is a successor of the famous " Superwal " type.The three spars consist eacli ol a top and bottom rail of rolledduralumin of channel section. These rails are trussed by up-right and diagonal channels riveted in place, the compres-sion members of which are re- duced in weight by a numberof holes in the channel beds. The wing has a practicallystraight rear edge, to which the leading edge sweeps lound, and it tapers in thicknesstowards the tips. The spars are connected by fourteen main ribs, twelveauxiliary and a large number of forming ribs. The main ribs are constructed in a manner similar to the spars and,like the other ribs, of course, also are made of duralumin. They pass over the top and bottom surfaces of the spars,to which they are secured by short channel sections riveted on. The upright and diagonal bracings likewiseconsist of channels. The wing panels thus formed by the main ribs and spars are braced horizontally in two planesby cros^d wires. The upper channels of the main ribs between the spars being straight, forming ribs of smallerand lighter duralumin channels are superimposed. The lower channels are slightly arched upwards between thespars and for this forming ribs, which give a plane lower surface, had likewise to be employed. A number of auxiliary spars are formed by relativelysmall diameter tubes of oval section passing through the joints on the main and auxiliary ribs where the uprightand diagonal web channels meet. Over these tubes •' slipped a number of smajl pressed plates. Joints areformed by three rivets placed equidistantly around the cir- cumference, with a distance-piece between, and they serveto hold the top and bottom channels of the light forming ribs, which have no web structure of any kind. The leading edge of the wing is formed by shaped CAREFUL STREAMLINING: This side view of the Do K indicates that considerable care has been taken to reduce resistance. 1037
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