FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1917
1917 - 0223.PDF
MARCH 8, 1917.' METAL IN AEROPLANE CONSTRUCTION. (Concluded from page 177.) IN Fig. 1, a and b, are shown side elevation and plan of a body of the proportions assumed for the wire braced body. For the struts we have chosen a uniform length of 2 ft. 6 ins., the uniform length being advantageous from the manufacturing point of view. By suitably crossing and recrossing the struts, the " free length " of longeron between struts can be fairly well proportioned in accordance with the load at any point. We have not taken into account the opening in the top of the body where occurs the pilot's seat, as the slightly different arrangement of the transverse struts in this place will have no appreciable influence on the weight calculation. For purposes of calcula- tion a channel section form of strut has been chosen, the proportions of which are shown in d, Fig. 1. One reason for choosing a strut of this shape is that, but which does have the advantage of being easily produced as a stamping, the area is about 28 sq. ins. An 18-gauge strut would probably be sufficiently strong, bearing in mind the fact that the longeron is 16 gauge. We have then : • Area of one strut = about 28 sq. ins. Thickness (assumed) =18 gauge = .048 in. Cubic contents of one strut = 28 x 0.048 = 1.34 cu. ins. Cubic contents of 76 struts = 76 x 1.34 = 101.84, say, 102 cu. ins. Weight of 1 cu. in. of aluminium alloy = 0.1 lb. Weight of 102 cu. ins. = 102 x 0.1 = 10.2 lbs. Assuming a weight of 2 lbs. for the necessary rivets, we have a total weight of 9 + 10.2 + 2 = 21.2 lbs. Compared with a weight of 41 lbs. for the wire braced Fig. 1.—a and b are diagrammatic side elevation and plan respectively of the suggested form of metalconstruction for a single-seater body. In c is shown the application of the same size struts to the body of a two-seater. The proportions suggested for the struts are indicated in the diagram d, whilethe inset is a sketch of the finished construction. except where the longerons are parallel, the point where the struts cross each other will not lie in the centre of the strut, and that therefore the majority •f the struts will have to be riveted at some point not in their centre. With the proportions of the various parts calculated or assumed, the weight of the aluminium alloy body can be estimated. Length of longerons 15.5 ft. Area of section 0.12 sq. in. Cubic contents of one longeron = 15.5 x 12 x 0.12 = 22.32 cu. ins. Cubic contents of four longerons =22.32 x 4 = 89.28 cu. ins. Weight of aluminium alloy -= 0.1 lb./cu. in. Weight of four longerons = 8.928 lbs., say 9 lbs. With the type of strut shown, which we do not, of course, necessarily claim to be the best possible form, body, this figure looks very promising, being only slightly over half the weight. Even if it be found in practice that a certain amount of reinforcement si advisable in places, as for instance at the points where wings and chassis struts are attached, and possibly at the rear to take shearing stresses, there is a large margin before the weight of the wood girder body is reached. It, therefore, appears reasonable to suppose that it is possible to construct an aeroplane body of metal, which for the same strength works out at certainly not a greater weight and in all probability will be found to come out a good deal lighter, while at the same time possessing undoubted advantages from the point of view of rapid production. In order to illustrate the possibility of employing the same stamping in machines of different sizes we hare sketched a two-seater body of considerably larger dimensions in c Fig. 1. We do not, of course, mean 223
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
