GB871625A - Rotor blade structure and method of molding same - Google Patents

Abstract

871,625. Helicopter rotor blades. PARSONS CORPORATION. Nov. 13, 1957 [Nov. 13, 1956], No. 35417 /57. Class 4. A helicopter rotor blade incorporates a moulded shell having a plurality of spanwise extending flatsided tubular sheet elements arranged chordwise adjacent each other and impregnated with a moulding composition, the adjacent sides of the elements being joined together to form webs, and a wrap around skin impregnated with moulding composition and joined to upper and lower surfaces of the elements to form upper and lower blade surfaces, the elements and skin extending the entire blade span, and the elements having rounded edge portions at the margins of their adjacent sides, joined to the skin so that spanwise extending fillets of moulding composition are formed between the rounded edge portions and the skin. Fig. 3 shows one end of a rotor blade composed of a leading edge metal spar 10 with trailing edges 13, 14, bonded by rubber, based adhesive layers 18, 19 to a trailing edge structure 20 comprising tubular members 36, 37, 38, 39 bonded together and to a wrap-around skin 43 also enclosing a trailing edge insert 33. Member 36 is of less depth than member 37, forming joggles 45, 46 in the skin so that the spar 10 and the skin form a continuous aerofoil section. The members 36 39 and the skin are of sheet material e.g. fibreglass, and are impregnated with a moulding composition, e.g. a resin, and during the moulding process, fillets 47 of moulding composition are formed at the rounded edges of members 36. 39. The members 37-39 may be replaced by members which are triangular in section, forming a Warren-type truss, Fig. 5 (not shown), and the spar 10 may have a channel-shaped reinforeing member extending from its upper to its lower surface. In making the trailing edge structure 20, four spanwise extending mandrels are wrapped with one or two layers of impregnated material, placed in chordwise juxtaposition, and wrapped overall with one or two layers of impregnated material to form the skin. The mandrels taper alternately in opposite directions, so that after the moulding process, they may be withdrawn simultaneously, alternate mandrels in opposite directions.