Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Patent
1998-01-05
2000-02-08
Poon, Peter M.
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
244 52, 244 125, 23926523, 23926529, B64C 2782
Patent
active
060219769
DESCRIPTION:
BRIEF SUMMARY
OPERATION OF A HELICOPTER
THIS INVENTION relates to operation of a helicopter. It relates more specifically to a method of controlling yaw of a helicopter. It further relates to a thruster for a helicopter, and to a helicopter.
It is known, for example from U.S. Pat. No. 4,948,068, to counteract drive torque transmitted to a main helicopter rotor and to control yaw by controlling circulation of airflow around the tail boom and by controlling air expelled laterally through a thruster from a side or sides of the rear end of the tail boom of the helicopter.
The Applicant believes that systems generally corresponding to the system of U.S. Pat. No. 4,948,068 are power hungry and require more power to operate than a comparable conventional tail rotor.
In accordance with a first aspect of this invention, in a helicopter including a main rotor, a tail boom having opposed sides and a rear end portion, a longitudinal circulation control slot along a predetermined one side of the tail boom and a thruster which is accommodated in the rear portion of the tail boom, there is provided a method of operating the thruster, to control yaw of the helicopter, which method includes vanes of the thruster which deflecting vanes are arranged to deflect longitudinal air flow laterally toward opposed sides of the helicopter and toward openings in the sides of the rear portion of the tail boom; and which height dimension is generally normal to both the longitudinal and lateral directions, generally symmetrically from opposed extremities of the opening such that a geometrical centre of the opening remains substantially static regardless of the status of adjustment of the respective opening.
Thus, in use, a centre line of air flow out of the opening will remain static relative to the helicopter regardless of the status of adjustment of the respective opening.
Adjusting the opening may be by moving a pair of shutters from the extremities of the openings selectively toward each other and away from each other.
Preferably, when the tail boom is round, the shutters may be complementally part round, and moving the shutters may be by pivoting the shutters about an axis of the tail boom. Most preferably, the tail boom may be round cylindrical, and the shutters may be complementally part round cylindrical.
Advantageously, the shutters may be linked (e.g. mechanically linked) to be pivotal simultaneously in opposite directions and at equal angular rates. Most advantageously, the pair of shutters may be of a size, shape and arrangement to serve both openings simultaneously, and adjusting the shutters to enlarge one opening may be such as to simultaneously reduce the size of the other opening.
In accordance with a second aspect, the invention extends to a thruster a helicopter which includes a main rotor, a tail boom having opposed sides and a rear end portion adapted to house the thruster, and a longitudinal circulation control slot along a predetermined one side of the tail boom, the thruster comprising flowing longitudinally along the tail boom laterally toward opposed sides of the helicopter; laterally deflected portions of the air flow stream in use; dimension, which will generally be normal to both the longitudinal and lateral directions, generally symmetrically from opposed extremities of each opening such that a geometrical centre of each opening remains substantially static regardless of a status of adjustment of the respective opening.
In a preferred embodiment, the shutter assembly may comprise a pair of shutters which are linked (e.g. mechanically linked) to be movable toward each other and away from each symmetrically, in opposite directions, at equal angular speeds.
Advantageously, the tail boom may be round, the shutters may be complementally part round and may be pivotal about an axis of the tail boom. Most advantageously, the tail boom may be round cylindrical and the shutters may be correspondingly round cylindrical.
In a most preferred embodiment, the shutters of the pair of shutters may be provided in a size and shape and may
REFERENCES:
patent: 3026068 (1962-03-01), Spearman
patent: 3807662 (1974-04-01), Velazquez
patent: 3957226 (1976-05-01), Daggett et al.
patent: 4200252 (1980-04-01), Logan et al.
patent: 4398682 (1983-08-01), Bithrey
patent: 4660785 (1987-04-01), Munski
patent: 5676335 (1997-10-01), Murgia et al.
Denel (Proprietary) Limited
Dinh Tien
Poon Peter M.
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