GB781074A - Improvements in or relating to controls for helicopters - Google Patents

Abstract

781,074. Helicopters. McCUTCHEN, C. W. June 10, 1955 [June 11, 1954], No. 17318/54. Class 4. A helicopter in which flapping movement of the blades is permitted is characterized by means which, upon the no-flapping axis and the nofeathering axis departing from a preselected relative orientation transmits a force to the pilot's control to indicate said departure, said force being proportional to the magnitude of said departure. The term " no-flapping axis " denotes an axis normal to the plane containing the tip path of the rotor blades and " nofeathering axis denotes that axis normal to a plane with respect to which the blades have constant pitch. The rotor blades 5 are secured to the rotor mast 6 through root members 7 which permit pitch, drag and flapping movements of the blades. Mounted on the mast 6 is a swash plate 8 which carries a control ring 10, the swash plate being connected to the rotor blades by links 12 for cyclic pitch change. Each blade 5 is further secured to the swashplate 8 by a spring in a housing 13 in such manner that the spring is unstressed when the aforementioned axes are at a preselected orientation. When this orientation is departed from the springs are stressed and apply a force through the swashplate to the pilot's control member to provide a warning in order that he may take the necessary correcting action. In a further embodiment the control rod 6 is extended above the plane of the rotor and each blade carries an upwardly extending arm, the springs being connected between these arms and the extension of the rod 6.