| 摘要 |
1,125,513. Helicopter blades. UNITED AIRCRAFT CORP. 23 Sept., 1966 [22 Oct., 1965], No. 42444/66. Heading B7W. [Also in Division B5] A fibreglass cloth reinforced plastics helicopter blade 10 has at the root end 14 a series of reinforcing plates 70, 72, e.g. of aluminium, interleaved with layers 74, 76 of fibreglass cloth impregnated with plastics to adhere the assembly together, there being holes 90, 92 through the root end for the bolts (36, 38), Fig. 1 (not shown), attaching the blade to the helicopter. The blade construction may comprise a central spar 50 of plastics reinforced with glass rovings, cavities 40, 42, 44 and a skin 88 of plastics impregnated glass cloth, the reinforcing plates 70, 72 being of graded sizes and distributed to give a tapering pattern. The recommended thickness of each of the plates 70, 72 and of the fibreglass cloth is 0À010 inch. Methods of construction comprising winding either preimpregnated fibreglass cloth, or dry fibreglass cloth when the assembly is subsequently impregnated are described.
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