| 摘要 |
589,161. Aircraft structures. HAWKER AIRCRAFT, Ltd., BETTERIDGE, P. D., and ROWE, E. T. March 15, 1945, No. 6600. [Class 4] In order to impart a smooth surface, free from irregularities, to the skin of aircraft components, a predetermined tension is imparted to the skin prior to its application to the supporting structure and maintained during the application of the skin. The skin may be stressed by springs, or by heating same, securing its edges to a rigid frame while expanded and then allowing it to cool. Heating may be effected by electric pads, steam, or heated liquid. In the case of components such as ailerons, elevators, or flaps, which are of narrow chord in proportion to their length stress may be applied in the direction of their length only. Fig. 1 shows a jig for the assembly of such a long, narrow, component comprising rib-locating members 18 at the base and spring tensioners 22 passing through side members 12 and connected to rigid clamps 24, secured to the narrow ends of the plate 20. The tensioning members are capable of adjustment to enable the stress applied to the skin to be varied. For stressing larger sheets, holes may be drilled along its edges for the insertion of the ends of springs carried by a jig frame extending around the edges of the sheet (Fig. 7, not shown). Figs. 3 and 6 show an arrangement suitable for the assembly of a fin or rudder, the base 42 of the jig having an opening 44, conforming to the spar contour, and a vertical plate 46 having an opening 48, conforming to the profile of the component. The sides of the jig are formed by inclinedmembers 52. The component is assembled by inserting the ribs 59 and associated structure, laying the skin sheets 66 on opposite sides of the jig, heating the sheets, for example, by electric pads 62, drilling holes at the edges of.the sheets corresponding to holes 56 along the edges of the jig for the reception of securing bolts, allowing the .sheets to cool to induce the desired stress, and then securing them in position by rivets passing through the sheets and internal structural members. An alternative method of inducing stress .in the skin consists in securing its edges to a rigid frame, the latter of which is heated and thereby expanded, (Fig. 8, not shown). |
