GB381959A - Sheet metal structures - Google Patents

Abstract

381,959. Aircraft structures ; floats. ARMSTRONG WHITWORTH AIRCRAFT, Ltd., SIR W. G. and WYLIE, H. N., Whitley, near Coventry. July 15, 1931, No. 20315. [Classes 4 and 113 (ii).] A covering for a hollow, metal structure such as a fuselage or float comprises thin metal planks, of tapering width, with edges that are flanged and with longitudinal surface grooves mainly of uniform width but converging towards one another and decreasing in number as the surface becomes narrower. Fig. 1 shows a float of which the surface is built up from metal planks 2 of approximately fifteenthousandths of an inch in thickness. The planks have straight or regularly curved edges. One edge of each plank is flanged at 3, Fig. 3, and grooves 4, 4 are formed on the surface parallel to the flange 3, the grooves dying out if they tend to run into the other edge of the plank. The partly-formed plank is then marked out in position for the flange 3a on the other side edge and is completed bv forming further grooves 4a, 4a parallel to the edge 3a. The grooves are formed by stretching the metal, the forming rolls gripping the metal on either side of the groove being formed, and are caused to die out by relieving the pressure on the rolls. The flanges of adjoining planks are united by a clamping strip 8, Fig. 4, the edges of the flanges being outwardly turned as at 9 and string or other absorbent packing 10 saturated with marine glue compressed in the recess so formed. The invention may be applied to internal structures such as tapered wing spars.