FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1926
1926 - 0386.PDF
small engine plate for the central " Jupiter " engine. The engine plate itself is made of Duralumin, and appears to be extremely light. It is attached to the steel tube longerons by four large bolts, and the engine is thus readily removable. The front panel of the main fuselage is triangulated by steel tubes, and in the case of two of these tubes, tie-rods run parallel with the tubes, although the latter are working in tension. We gather that the object of these tie-rods is not so much to provide duplication for the tubes as to prevent any play developing due to vibration, as the tie-rods can be so tightened up that there is no possibility of " chattering " occurring. The engine mounting is shown in a photograph, and some of its details are illustrated by sketches which should make the arrangement quite clear. The mounting is very clean, and leaves ample space for getting at the components mounted on the back of the engine. One of the disadvantages of the steel tubular fuselage in a machine of the type of the D.H. 66 is that the cabin has to be built up in the form of a three-ply " box " slipped into the fuselage from the top when the latter has been erected. This must necessarily mean a certain amount of extra weight and not inconsiderable extra expense, but it is difficult to see any way of getting around it. The floor of the cabin has fairly stout cross-members underneath, but these stop JUNE 10, 1926 In the general arrangement drawings published on page 331 will be seen a peculiar funnel projecting from the roof of the fuselage. This is a ventilator which, owing to the speed of the machine, will force air into a diffuser box from which in turn, fresh air will filter into the cabin without causing a draught. Details of the ventilating arrangement cannot be given at the moment, but when the machine is finished and flying we hope to publish another article and illustrations of certain features which cannot well be illustrated at the moment. The Wings. As already mentioned, the wings of the D.H. 66 are of perfectly normal construction, with box spars having plywood walls and spruce flanges. At the points where occur the attachments for the interplane struts, internal packing pieces are introduced and the form of these is illustrated by a sketch, from which it will be seen that these distance pieces are built up from multi-ply spruce. The ribs are of spruce and are of the same type as has been used by the De Havilland Aircraft Company in a great number of their types during recent years. The wing section used is R.A.F. 15. The wing covering is fabric, doped and varnished in the usual manner. Leading and trailing edges are in the form of Dura- lumin tubes, but with the exception of these and the internal drag bracing, the wings are of all-wood construction. Owing THE D.H. 66 : Some spar details. On the left, the distance-pieces separating the spar flanges in the inner bay, and on the right, the same, but in a slightly different form, in the end sections of the wing. The spars are of spruce, spindled out as indicated, and the distance-pieces are of laminated spruce, while the spar walls are of three-ply. short inside the bottom longerons, and the cabin " box " is supported at the corners only, so as to avoid placing bending stresses on the lower longerons due to the weight of the cabin and its contents. The actual supports under the corners of the cabin are in the form of wood blocks, shaped to fit over the top of the cross tubes in the bottom panel of the fuselage, so that all the stresses are concentrated very close to the joints and the bending moments imposed are a minimum. As the De Havilland type 66 is intended for use on the Cairo- Baghdad line which it is hoped to open next spring, the whole of the cabin space will probably not be devoted to passenger accommodation. and at the moment we understand it is intended to provide seats for seven passengers only, the rest of the space available (465 cub. ft.) being intended for goods and mails. Should it later be desired to use the machine entirely for passenger-carrying, a number of extra seats would, of course, be fitted. Aft of the cabin is another " box " of plywood which forms the luggage compartment. Vertical strips of wood of semi- circular section are tacked to the cabin in order to protect and stiffen the plywood against accidental damage by heavy luggage. The compartment is a large one (155 cub. ft.) and should be ample for the amount of personal luggage likely to be required for seven passengers. It is provided with a separate door. to the fact that two wing engines are mounted on the lower plane, the wing construction has been somewhat altered at the points where these two engines are mounted. From one of our sketches, which illustrates the framework carrying one of the wing engines, it will be seen that the lower plane incorporates at this point a system of triangulation formed by the front spar and two stout box ribs, the apex of the triangle falling on the rear spar. A result of this triangulated engine support is that the end rib of this section of the wing has a fairly pronounced rake. (The outer portion of the wing is, of course, raked at its inner end to the same angle.) The engine plate itself is bolted to this triangular structure and the front spar, but as the engine plates were not in place when our sketches were obtained it has not been possible to show the details of the wing engine mounting. Later on, when the construction of the machine is further advanced, we hope to illustrate this detail, as well as certain other features. The Tail. One of the unusual features in the design of the D.H. 66 is the tail unit. This comprises a biplane tail with a single elevator hinged to the lower tail plane only, and of three vertical fins and three rudders. The tail unit is built in two symmetrical halves in order to reduce the number of spares necessary. Thus a spare fin can be used either in the central 332
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
