FR2601326A1 - APPARATUS FOR AUTOMATICALLY AUTOMATIC AUTOMATION OF A HELICOPTER ROTOR - Google Patents

Abstract

THE PRESENT INVENTION CONCERNS AN APPARATUS FOR AUTOMATICALLY STARTING IN AUTOROTATION OF THE ROTOR OF A HELICOPTER INCLUDING AN AUTOMATIC FLIGHT CONTROL SYSTEM. THIS APPARATUS IS CHARACTERIZED IN THAT IT INCLUDES 10 MEANS FOR PROVIDING A SIGNAL OF ENGINE FAILURE INDICTING SUCH A FAILURE, 21 MEANS FOR PROVIDING A COLLECTIVE CONTROL ORDER SIGNAL TH, 28 MEANS FOR PROVIDING A NOT SIGNAL BS, MEANS 34 FOR PROVIDING A ROLLS ORDER SIGNAL AS AND MEANS 40 FOR PROVIDING A LACET ORDER SIGNAL TH, THESE SIGNALS BEING APPLIED TO AN AUTOMATIC FLIGHT CONTROL SYSTEM 26.

Description

The present invention relates to a setting apparatus

  automatic autorotation of a rotnr of a helicopter.

  The tendency to use lower rotor rotors in modern helicopters results in a reduction in the level of kinetic energy stored in the rotor and makes it more susceptible to irrespective rotational speed variations during maneuvers. fast. Therefore it is generally known to provide integration of control and propulsion. This is discussed, for example, in an article in the journal Technoloyy Today vol. 30, No. 6, entitled "Rotorcraft Flight-Propulsion Control Integration". Despite

  From this general knowledge, there are many particular problems which must be taken into account and the invention concerns one of them.

  During a high-speed flight, the engine transmits maximum torque levels to the rotor. The failure of an engine in a multiple engine arrangement or even more significantly, the failure of all the engines causes a rapid drop in speed or rotor, and so fast in fact that the pilot is unable to initiate autorotation to maintain rotor speed. The loss of power also eliminates the need for tail rotor anti-torque balancing. As a result, the aircraft performs rapid lurching and, as a result of roll / ylissade coupling, rapid rolling is ensured. It is therefore an object of the present invention to provide automatic control inputs which counterbalance the adverse aerodynamic effects which immediately follow an engine failure, thus ensuring automatic autorotation and attitude control much faster. than could a pilot. Following the autorotational passage, the pilot can resume control and land in

  autorotation in a normal way.

o

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  According to the invention during the first few seconds after a failure of an engine, autorotation is automatically established by providing collective command, pitch, roll and yaw commands to an automatic flight control system. in order to adjust the collective control in order to maintain a desired rotor speed, to step the pitch so as to lie within stress limits, to control the roll so as to avoid roll attitude changes, and to control the yaw so as to avoid unwanted transient lurching which would otherwise result from a motor failure (no anti-torque control is no longer required). Signals indicative of the existing speed and attitude are processed to provide the above orders to the automatic flight control system. The following will be described by way of non-limiting examples, various embodiments of the present invention, with reference to the accompanying drawing in which: The single figure is a block diagram of the

  control device according to the invention.

  The figure of the drawing shows a failure detector of a motor 10 as described in US-4,454,754. A signal indicating a fault or motor is provided on a line 12. The output of the detector is applied to four switches. 14,16,1b, 2U which arm a logic control to complete the logic of passage

  automatic autorotation.

  The following parameters are monitored, in a closed loop, in accordance with well-known detection techniques: NR: rotor speed; NR: rotor acceleration; NZ: load factor; Q: step rate; v: speed forward (own speed); P: angular acceleration of roll;

R: lace acceleration.

  A shaping circuit 21 responds to the speed of the

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  rotor (iNI), at the rotor uceling (NR) and at a desired rotor speed 22, selected by the pilot, to provide a collective control command signal on a line 24, through the switch 14 when it is armed, in the direction of the collective control channel of an automatic flight control system 26, to automatically adjust the collective pitch of the rotor so as to maintain a desirable rotor speed in autorotation, such as 100D NR. A shaping circuit 28 is responsive to the load factor (Nz), the step rate (Q), the eigen speed (v), and a reference 30 indicating a load factor limit, so as to provide a signal. longitudinal cyclic order (not) Lls, at the flight channel of the automatic flight control system of flight 26, on a line 32, through

  the switch 16, to order the attitude of the pitch during the passage autorotation, thus avoiding excessive stresses on the aircraft during this maneuver.

  A shaper circuit 34 responds to the angular acceleration in roll (P) and to a roll reference 36

  equal to zero in order to provide a lateral cyclic (roll) signal Als, on a line 3b, in the direction of the roll channel of the automatic flight control system, through the switch 11, in order to maintain a flight " at the wing level "during autorotation.

  A shaper circuit 40 responds to the lae acceleration (R) and to a yaw reference 42, which is nominally zero, to provide a yaw order signal (eTR), on a line 44, to the channel of the yarn 26 of the automatic control system of the flight 26, through the switch 18, raie to control the collective pitch of the tail rotor and to prevent an incorrect correction of the lanet during the passage in autorotation, how it has been

indicated previously.

  The above-described auto-torque coil stabilizes the aircraft and initiates an autorotation under circumstances (engine failure) in which the pilot could not react quickly enough, and provides

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  control input signals similar to those that the pilot would have issued in less critical circumstances. The control inputs are faster than a pilot but they are well within the limits of known flight or automatic stability systems.

  A short time after the autorotation is set up, for example after two to three seconds, the command signals (60, bis, Als, OTR) from that system can be eliminated or deleted in order to provide 10 an affirmative order to the pilot.

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Claims (2)

  1. Apparatus for automatic autorotation of the rotor of a helicorpter comprising an automatic flight control system, comprising col5 leetive control channels, pitch, roll and yaw, characterized in that it comprises means (11) to provide a motor failure signal indicative of such a failure, means (22) for providing a rotor speed reference signal indicating a desired rotor speed in autorotation, means for providing a speed signal of the rotor, rotor (Ni {) representing the actual speed of the rotor, means for providing a rotor acceleration siynal (Nij) representing the variation of the rotor speed, means (21) for providing a control command signal. the collective control channel of the automatic flight control system, depending on the rotor speed reference signal, the rotor speed signal and the rotor acceleration signal so as to initiating the rotor speed equal to the desired autorotation rotor speed, in the presence of the engine failure signal, means (30) for providing a load factor limit signal, representing a constraint limit for the helicopter means for providing a load factor signal (NZ) representing the helicopter stress, means for providing a pitch rate signal ((i) representing pitch rate of the helix flyer, means for providing a clean speed signal (v) representing the own speed of the helicopter, means (2b) for providing a pitch command signal (bls), the step channel of the automatic control system of 3G. the flight, according to the load factor limit signal, the load factor signal, the pitch rate signal and the own speed signal, to control the attitude of the pitch to avoid overstressing the helicopter by presence of the failure signal d a motor, means for providing a roll angular acceleration signal (P) representing the roll angular acceleration of the helicopter, means (34) for providing a roll order signal (Als) -au roll cani 6 2 6 02601326   automatic flight robbery system according to the roll acceleration signal (P), to maintain a desired roll attitude of the helicopter, in the presence of the engine failure signal, means (42) for providing a yaw reference signal representing a desired yaw attitude during autorotation, means for providing a yaw acceleration signal (R) representing yaw acceleration of the aircraft, and means (40) for providing a yaw rate Yaw command signal (ÈTR) to the yaw channel of the automatic flight control system in. function   the yaw acceleration signal, thereby eliminating erroneous yawing during autorotation in the presence of the engine failure signal.   2. Apparatus according to claim 1, characterized in that the collective pitch command signal, the pitch order signal, the roll order signal and the yaw order signal are retracted. short moment after   the delivery of the engine failure signal.