GB384587A - Improvements in or relating to aerofoils - Google Patents

Abstract

384,587. Aerofoil structures. BUDD MANUFACTURING CO., E. G., 2500,Hunting Park Avenue, Philadelphia, U.S.A.-(Assignees of Ragsdale, E. J. W. ; Curren Terrace, Norristown, Pennsylvania, U.S.A.) June 23, 1932, No. 17737. Convention date, June 23, 1931. [Class 4.] An aerofoil comprises spaced ribs interconnected by angle-section longitudinal members, each having an arm extending into marginal slots of the ribs and another arm secured to marginal flanges of the ribs, while a metallic skin is secured to the ribs and longitudinal members to constitute therewith a rigid structure. As applied to one wing or blade of a rotary wing system ribs 10 formed in one piece stampings from light gauge sheet metal have upper and lower flanges 11 and oppositely flanged lightening holes 16. The ribs are spaced closely at the root 14 where the blade is to be attached to a hub member and at 15 where a bracing member is to be secured, and are interconnected by a series of angle-section longitudinals 18 of light gauge strip metal. The flanged edges of the ribs are formed with a series of kerfs 19 corresponding to the number and position of the longitudinals 18. One arm 20 of the members 18 is inserted into the corresponding kerfs of the ribs which are held in a jig and the other arm 21 spot welded to the flanges 11. Vertical angle members 22, Fig. 1, have one arm welded to the web of the rib and the other arm which vertically overlaps vertically opposed longitudinals welded to their arms 20. The sheet-metal wing covering is made in upper and lower portions flanged inwardly at their forward edges which are located in kerf 28, Fig. 2. Either the lower or upper portion of the wing covering is first assembled by first engaging the flanged forward edge in kerf 28 then spot welding to longitudinals 18 and rib flanges 11. The remaining portion of the covering is then applied, its edge flange being inserted in kerf 28 and welded to the flange of the other sheet, then the sheet progressively welded to longitudinals and ribs from leading to trailing edge, the flange 10 being cut away at 13 to permit easy access of welding tongs to the covering as the trailing edge is approached. Finally the overlapping trailing edges of the covering are welded together. In an alternative method, the forward edge flanges of the covering sheets are welded together then located in kerf 28, the lower section then welded to the framework with the upper section bent forwardly out of the way, and finally the upper section attached progressively to the framework as before. The wing tip 28<1> is formed from two shaped sheets lap welded together at the leading edge and spot welded at their abutting trailing edges. The wing tip is reinforced by ribs 31 welded to the skin, the inner rib being spaced from the mouth of the tip to permit the ends 32 of longitudinals 18 to telescope some distance into the tip to the skins of which they are welded. The tip is assembled before the main covering sheets.