Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Patent
1996-07-01
1998-04-14
Grant, William
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
244175, 73178H, B64C 2757, G05D 108, G05D 1308
Patent
active
057383006
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and to associated apparatus for automatically controlling the control surfaces of an aircraft by using an autopilot. In particular it provides apparatus for assisting automatic piloting of rotary wing aircraft for the purpose of keeping the lateral and longitudinal airspeed components equal to desired reference values therefor.
It is known that autopilots can be used to control the flight control means of rotary wing aircraft, such as helicopters. Such autopilots are constituted by two servo-control systems, commonly referred to as the "basic autopilot" for fixing and conserving a reference value, said reference value being relative to the lateral trim of the fuselage for one of the systems and relative to the longitudinal trim for the other.
The terms "roll" and "pitch" are also used for those two kinds of trim respectively.
The reference values are fixed, either by the trim values at the instant at which the corresponding system is put into operation, or else subsequently by certain actions of the pilot on the flight controls, referred to as a "transparent piloting" function, or else finally by putting into operation an optional member referred to as a "flight coupler".
A flight coupler is an electronic computer which, depending on the functions given thereto by the manufacturer, applies new reference fuselage trim values to the "basic autopilot".
To stabilize an airspeed, it is presently necessary to provide the "basic autopilot" with a "speed retention coupler". Even if the fuselage maintains trim perfectly, the speed of a helicopter can vary over very wide ranges, which is considered as being a major defect, particularly when flying on instruments. The speed retention coupler requires at least one speed sensor, function switching means, and means for inputting reference speed values.
In outline, an air speed retention coupler operates as follows:
the difference between the actual airspeed and the reference airspeed is used to generate a new reference trim value for the fuselage, which is then forwarded to the "basic automatic pilot" to be implemented.
Thus, to implement an important piloting function, it is necessary to make use of a system that is somewhat complex, and for which it is also difficult to ensure transparency once the "coupler" has been engaged.
The object of the invention is, in particular, to remedy the above complexity by combining in an entirely novel manner signals that are already available on board helicopters, with such combination eliminating any need for initially maintaining any particular fuselage trim for the helicopter, and thus avoiding any need for an airspeed coupler to exist.
The invention provides apparatus for assisting automatic piloting of rotating wing aircraft for the purpose of keeping the lateral and longitudinal components of the airspeed equal to desired reference values therefor, which apparatus comprises two systems, one for roll and the other for pitch, each of said systems having means for generating a signal that is a function of the trim of the fuselage, signal summing means, signal integrator means, and means for actuating the corresponding flight controls, the apparatus being characterized in that it includes means for generating a signal (24S) that is a function of the position of the cyclic control for the blades of the main rotor or, where appropriate, of the main rotors.
According to a characteristic, at least the signal which is a function of the trim of the fuselage and the signal (24S) which is a function of the position of the cyclic control for the blades of the main rotor, or where appropriate of the main rotors, is used in the summing means of each of the systems.
According to an additional characteristic, for one of the systems, the fuselage trim signal (1S) is a pitch trim signal (THETAF) and the cyclic control position signal (24S) is a longitudinal cyclic control position signal (DM1), and for the other system, the fuselage trim signal (1S) is a roll trim signal (PHIF) and the cyclic control posi
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patent: 4702106 (1987-10-01), Hassenpflug et al.
patent: 4829441 (1989-05-01), Mandle et al.
patent: 4834318 (1989-05-01), Taylor et al.
patent: 5169090 (1992-12-01), Wright et al.
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