GB1047568A - Improvements in or relating to aircraft rotors - Google Patents

Abstract

1,047,568. Convertible aircraft. WESTLAND AIRCRAFT Ltd. Sept. 3, 1964 [Oct. 9, 1963], No. 39743/63. Heading B7W. In a convertible aircraft, and to take account of the different characteristics of the rotor that are necessary with its axis vertical for take-off and landing and with its axis horizontal for forward flight, each rotor blade 31 (Fig. 5, not shown) is secured by its root rib 32 to a torque tube 33 which houses bearings for a torsion member 34 which is secured at its root end to the rotor head and at its outer end to a rib 39. The tube 33 carries an arm 35 connected by a link 36 to the collective pitch controlling mechanism and the blade is so constructed as to provide predetermined torsional flexibility along its length, so that the variation in pitch of the blade varies from a maximum at the root to a minimum at the tip in dependence on the aerodynamic loading of the blade and the propeller movement, such effect being considerably greater during landing and take-off than in forward flight. In a further embodiment the torsional flexibility of the blade is relied upon to achieve the desired result and in another embodiment the leading edge of the blade is formed by a hinged flap which has an outboardlydecreasing chord, the flap being connected by gearing to the non-rotating part of the blade root member so that when the blade is at minimum pitch and the leading edge member is depressed the mean chord at the root is substantially parallel to the chord line at the tip. Consequently when pitch is increased, as for take-off, the flap chord is automatically aligned at the root with the blade chord thus providing a decreasing pitch outwardly along the span of the blade.