GB756673A - An improved structure of aerofoil shape for use in aircraft - Google Patents

Abstract

756,673. Aircraft framework. CLEMENS, R. Aug. 4, 1954 [Aug. 5, 1953], No. 21624/53. Class 4. [Also in Group V] A structure of aerofoil shape for aircraft, such as a wing aileron, rudder, elevator or helicopter rotor blade, comprises a leading portion 2 and a trailing portion 3, the leading portion having a steel skin 4, a spar 5 of fibre - reinforced plastic of high density, a massbalance rod 6, a duct 7 of resinous material and a root member 8 made of the same material as the spar 5 but embodying steel laminµ 9 and a metal cruciform member 10 comprising trunnions 11 and a duct 12 joined with the duct 7 to convey air or gaseous or liquid fuel to propulsion means mounted on the blade. The laminµ 9 are U-shaped to wrap around the trunnions 11 though they may be separate strips united by bolts passing transversely through the root fitting. The trailing portion comprises a steel shin 13, thin walled tubes 14 of pliable material forming lightening cavities and a resinous, solidified foam filler 15. Ribs 26, bonded at their forward ends to the spar 5 and at their trailing ends to a trailing edge member 25, may be provided. The leading portion 2 is constructed separately under pressure in a die (not shown) and when removed from this die the portion 2 is placed in a further heated die 23 with the roughly pre-formed skin 13 and tubes 14 which are filled with compressed air to prevent them from collapsing when the foaming filler 15 is injected under pressure. The interior faces of the die 23 conform to the required aerofoil contour and the filler 15 forces the skin 13 against the die face thereby causing it to take the correct contour. When the filler 15 has solidified the air is released from the tubes 14 and the completed blade removed from the die. Although the materials used join by natural fusing characteristics, additional adhesives may be applied where necessary to facilitate bonding. In an alternative construction the portions 2 and 3 may be made entirely separately in which case the trailing portion 3 would have a spar (not shown) connecting the forward edges of the ribs 26 and secured by adhesive to the spar 5.