| 摘要 |
1,262,704. Winding rotor blade reinforcements. MESSERSCHMITT BOLKOW - BLOHM G.m.b.H. 30 July, 1969 [10 Aug., 1968], No. 38323/69. Heading B8G. [Also in Divisions B5 and B7] A helicopter rotor blade (Fig. 9) comprises an inner reinforcing spar and an outer shell, possibly with a filler 22 of cellular plastics material (Fig. 8). 'The spar is formed by winding a layer of foil 21 on to a cylindrical mandrel 7 (Fig. 4), and then winding a plurality of partially overlapping layers 13, 14, 15 of synthetic resin impregnated filamentary material over the foil, abutting flanges 11, 12 being placed around the foil. The foil and windings, whilst still flexible, are removed from the mandrel, with the assistance of pressurized air P emerging from holes 10, and are placed in a mould, against which they are held by internal applied pressure, and cured. The layers of winding may be of different pitches, as shown in Fig. 4, to provide the desired strength characteristics along the finished spar. The outer shell of the blade is formed by winding synthetic resin impregnated filamentary material 3 on to a foil 2 wound on a mandrel (Fig. 1, not shown), slitting the foil and winding to form one or more mats, and moulding two of the mats to form symmetrical halves of the shell. Vacuum may be applied to draw the mat into the mould (Fig. 3), and a seal 6 may be provided to prevent the entry of air. Either the foil or the wound material may be outermost in the finished shell. |
