Abstract: Provided is a vibration control system for a compound helicopter with a rotor and a fixed wing. The fixed wing includes a movable flap that is mounted on a rear edge of the fixed wing. The vibration control system periodically moves the movable flap so as to periodically change lift of the fixed wing such that vibration aerodynamically generated by the fixed wing is in anti-phase with vibration caused by rotation of the rotor.

Abstract: A main rotor blade 1, which is the main rotor blade 1 for a high-velocity helicopter, includes: a blade root part 10 having a length of 30% or more of a rotor radius R; and a blade main body 20 continuous with the blade root part 10. Preferably, a cross-sectional shape of the blade root part 10 satisfies (x/a)m+(y/b)m=1 and a>b, where m: arbitrary number, x: chord length direction, and y: blade thickness direction.

Abstract: Provided is a vibration control system for a compound helicopter with a rotor and a fixed wing. The fixed wing includes a movable flap that is mounted on a rear edge of the fixed wing. The vibration control system periodically moves the movable flap so as to periodically change lift of the fixed wing such that vibration aerodynamically generated by the fixed wing is in anti-phase with vibration caused by rotation of the rotor.

Abstract: Provided is a flight efficiency improving system for a compound helicopter with a rotor and fixed wings. In forward flight of the compound helicopter, the flight efficiency improving system does not perform a cyclic pitch control of the rotor so as to allow a difference in lift generated by the rotor between an advancing side and a retreating side of the rotor, or the flight efficiency improving system performs the cyclic pitch control to an extent that does not completely eliminate the difference. The fixed wings are provided respectively on left and right sides of a body and are asymmetric to each other so that influence of an aerodynamic interference between the rotor and the fixed wings is reduced.

Abstract: [Object] To provide a main rotor blade for a helicopter such as a main blade type helicopter, which may reduce a drag coefficient during high-velocity forward flight and which provides easy control. It is an object of the present invention to provide a helicopter including such a main rotor blade. [Solving Means] A main rotor blade 1, which is the main rotor blade 1 for a high-velocity helicopter, includes: a blade root part 10 having a length of 30% or more of a rotor radius R; and a blade main body 20 continuous with the blade root part 10. Preferably, a cross-sectional shape of the blade root part 10 satisfies (x/a)m+(y/b)m=1 and a>b, where m: arbitrary number, x: chord length direction, and y: blade thickness direction.

Abstract: A small unmanned airplane includes; a main wing having a camber airfoil whose under surface is approximately flat, narrowing in the shape of taper to a blade tip, leading edge of which holds sweepback angle, of flying wing type which has an aerodynamic surface of tailless wing type and is low aspect ratio; movable flaps extending approximately extreme breadth in trailing edge part of both left and right sides of the main wing, having a dihedral angle at least in level flight; vertical stabilizers placed at blade tips of left and right of the main wing; and two propellers installed on the top surface of the main wing. This can materialize miniaturization and weight saving of a small unmanned airplane for individual carrying capability and for suitability for such as lift-off by hand throw.

Abstract: In a blade vortex interaction (BVI) noise reduction system for a helicopter a rotor blade, a tab is movable via an actuator from a first position, wherein the tab is within the blade, to a second position, wherein the tab extends outwardly from a trailing edge of the rotor blade. The actuator is operated so that the tab advances and retreats in response to rotating timing of the rotor blade, to reduce the BVI noise of the rotor blade.

Abstract: The present method is characterized by providing the rotor blade with a tab 3, which can advance and retreat with respect to rear of rotating direction of the rotor blade between a position where the tab protrudes from a trailing edge of the rotor blade and a position where the tab does not, and providing an actuator 4, which advances and retreats the tab 3, and operating the actuator 4 so that the tab advances and retreats in response to rotating timing of the rotor blade 2, when reducing the BVI noise of the rotor blade of a helicopter. Thus, the BVI noise of a helicopter can be reduced effectively.

Abstract: The present method is characterized by providing the rotor blade with a tab 3, which can advance and retreat with respect to rear of rotating direction of the rotor blade between a position where the tab protrudes from a trailing edge of the rotor blade and a position where the tab does not, and providing an actuator 4, which advances and retreats the tab 3, and operating the actuator 4 so that the tab advances and retreats in response to rotating timing of the rotor blade 2, when reducing the BVI noise of the rotor blade of a helicopter. Thus, the BVI noise of a helicopter can be reduced effectively.

Abstract: A small unmanned airplane includes; a main wing having a camber airfoil whose under surface is approximately flat, narrowing in the shape of taper to a blade tip, leading edge of which holds sweepback angle, of flying wing type which has an aerodynamic surface of tailless wing type and is low aspect ratio; movable flaps extending approximately extreme breadth in trailing edge part of both left and right sides of the main wing, having a dihedral angle at least in level flight; vertical stabilizers placed at blade tips of left and right of the main wing; and two propellers installed on the top surface of the main wing. This can materialize miniaturization and weight saving of a small unmanned airplane for individual carrying capability and for suitability for such as lift-off by hand throw.

Abstract: Through differentiation of input signal Vw from a sensor the angular frequency &ohgr; becomes included in the amplitude component. Through a plurality of differential operations the amplitude including the angular frequency &ohgr; varies, but the time-dependent term becomes equal. Since the amplitude of the signal Vw outputted from the revolution speed sensor 10 is approximately constant, the angular frequency &ohgr; proportional to the revolution speed can be extracted by determining a ratio thereof.