FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1916
1916 - 0036.PDF
A "POPULAR" TYPE By C. M (Continued "AVING decided on the general outline of the body, the next thing to be done in the design of our machine is to see how we can carry out the construction of it in such a manner that the nearest approach to the perfect streamline of the model B.F. 36 is obtained. The monoeooue type of construction has already been discarded as being too costly for our purpose of designing a low-priced aeroplane. The first alternative that comes to mind is the girder type of fuselage. When it is desired to incor porate rounded sides with this form of construction, it is general practice to retain the rectangular section fuselage built up of four longerons connected by struts and cross- members, To each bay of the girder are then attached AEROPLANE DESIGN. . POULSEN. frontpage 17.) point clear. While by having a sufficiently large number of stringers a very close approximation to the circular section may be obtained with this type of body, the disadvantages pointed out render some other form advisable, and we must therefore try to hit upon an arrangement in which all members are doing useful work. This object is attained by letting the longerons per form at the same time the duty of stringers. The result, it will be easily seen, is a compromise, since the greatest possible number of stringers is an advantage from the point of view of resistance, while for constructional reasons the number of longerons should be kept as smalj Sketch showing how longerons are partly let Into the formers. segment-shaped formers, frequently made of three-ply wood, which support thin strips of wood running longi tudinally. Let us examine the merits and disadvantages of this form of construction. The rectangular main structure is easy and cheap to make, and commends itself to our purpose on that account. The objection to it, however, is that the whole outer portion—i.e., the formers and stringers—is doing very little work beyond providing the fair shape, not helping to any appreciable extent to The wiring plates which also secure formers. the longerons to the as possible. Suppose we make the fuselage of hexagonal section. With an overall diameter of 3 feet we obtain with this form flat sides of considerable area, while, if we make the formers—which are, of course, really struts and cross members in another form—of 3-ply wood and of the shape shown in the second sketch, there is as much waste of internal space as in the rectangular section body. Let us now try to add another two longerons, and see whether and how this improves matters. Sketch No. 3 y,tri?.U^i5eLh°d» f obtaiDin8 PoJYBOMl sections with the girder type of fuselage.-Oa the left an ordinary square section surrounded by stringers mounted on three-ply formers. In the centre a hexagonal section with the longerons mounted on three-ply formers. On the right a similar construitlon, but with 8 longerons. strengthen the body, while adding considerably to the weight. Apart from this disadvantage, the rectangular body surrounded by stringers wastes room, since for a polygonal section of 3 ft. diameter the space left inside the struts is approximately 2 ft. only. A reference to one of the accompanying sketches should make this 36 shows that a considerable improvement in section is obtained by choosing the octagonal type. Also the space taken up by the formers is considerably reduced. If still more longerons be added, the resultant section approaches very closely to the circle, but then the angle of the bracing wires begins to become too flat, unless we place
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
