GB663206A - Improvements relating to helicopters - Google Patents

Abstract

663,206. Helicopters. PENNINE AIRCRAFT, Ltd., and NEALE. J. S. Jan. 4, 1949, No. 154/49. Class 4, A helicopter has four rotors d, e of substantially equal diameters located at the four corners of a rectangle, the length of the shorter sides of the rectangle, which are substantially at right angles to the normal direction of flight, being about 6/10 of the rotor diameter and the length of the long sides being about 9/10 of the rotor diameter, so that the two forward rotors d overlap as do the two rear rotors e. The rotors on one side of the machine rotate in the opposite direction to the corresponding rotors on the other side, the blades on the inward side of each rotor being the retreating blades. Preferably means such as are described in Specification 663,205 are provided for automatically reducing the pitch of the retreating blades relative to that required to equalise lift reactions at all blade roots during translation. Such means may comprise a cyclic pitch change system as described in Specifications 605,561 and 647,744 or other known means. A fuselage a. for the accommodation of passengers and cargo extends along one of the long sides of the rectangle formed by the rotor heads, but is offset inwardly with respect thereto, and a compartment b for power units and fuel tanks, which is of less cross-sectional area than the fuselage a extends along the other long side, such structures being connected together by suitable beams c, the whole being arranged to provide broadly symmetrical lift and drag components about the four rotor systems.