STRUCTURAL MEMBERS FOR USE IN AEROFOILS

1,220,504. Making aircraft; stamping. DOW CHEMICAL CO. 9 May, 1968, No. 22107/68. Headings B3A and B3Q. [Also in Division B7] A structural element of an aerofoil is formed from a sheet of rigid material which is indented over its entire surface to such a depth that the raised portions on opposite sides of the sheet conform to the aerofoil outer surface profiles or to one surface profile and to a plane corresponding to the mean chordal plane of the aerofoil. An initially flat sheet 44 is placed between opposed peg die plates 38, 42, the respective pegs 36, 40 being arranged in the regular pattern shown in Fig. 7 or in staggered formation (Fig. 9, not shown) and the heights of the pegs on each plate being such that when the two plates are brought together as shown in Fig. 5 the raised portions of the indentations on both sides of the sheet will conform to the external profiles of the aerofoil. In an alternative construction the pegs of one plate are of uniform length so that one side of the indented sheet will conform to the mean chordal plane of the aerofoil, two such indented plates being joined, as by spot welding or bonding on said planes to form an aerofoil structure. A skin (not shown) is attached to the profiled member by spot welding or bonding to provide a complete aerofoil.