RU2782807C1 - System for warning the pilot about the occurrence of an unintentional turn to the left of a single-rotor helicopter - Google Patents

Abstract

FIELD: warning systems.

SUBSTANCE: system for warning the pilot about the occurrence of an unintended turn to the left of a single-rotor helicopter contains two airspeed receivers with a frequency output and two electronic modules for comparing the output frequencies of the receivers, while one airspeed receiver is located on the steering beam, the second is located on the end beam in the tail rotor area, while modules are connected to receivers in a certain way.

EFFECT: flight safety is ensured by warning the pilot of a dangerous situation.

1 cl, 2 dwg

Description

The invention relates to the field of aviation safety, in particular to the safety of civil aviation, and is proposed for use in single-rotor helicopters.

According to various data, 235 accidents occurred on single-rotor helicopters in state aviation, as well as in airlines and civil aviation enterprises, 42 (18%) of them were due to helicopters falling into spontaneous left rotation.

Known recommendations for pilots falling into the mode of involuntary unintentional left rotation of the helicopter (Belichenko I.A. Spontaneous turn // Helicopter. - 2000. - No. 1. - P. 24-25). The disadvantage of the recommendations is the need for preliminary training of the crew of single-rotor helicopters, either on simulators or in real flights, which requires financial support and further flight practice. In addition, there are currently no helicopter simulators that could qualitatively and quantitatively reproduce this phenomenon.

A known system for reducing the likelihood of an unintentional turn to the left of a single-rotor helicopter is a device for changing the direction of rotation of the tail rotor (Method for selecting the parameters of the tail rotor of a single-rotor helicopter corresponding to the maximum weight return coefficient. Helicopters: Proceedings of the OKB MVZ named after M. L. Mil. Issue 3. M. , Mashinostroenie-Polyot, 2018, pp. 219-247). Previously, with the same direction of rotation (the upper blade of the tail rotor moves forward), the rotation of the tail rotor coincided with the direction of circulation of vortices from the main rotor in front-to-right wind, which led to a decrease in the efficiency of the tail rotor. The device for changing the direction of rotation (the upper blade of the tail rotor moves back) significantly increased the efficiency of the tail rotor, which made it possible to improve the directional controllability of a single-rotor helicopter at low speeds when flying to the left and hovering with wind from front to right (5-7 m / s). The disadvantage of the known solution is the lack of information about the direction and speed of the crosswind, so an inexperienced pilot does not have time to prevent uncontrolled left rotation (especially if it occurs at low altitudes during takeoffs and landings) and the helicopter can get into an accident.

A known system for automatic withdrawal from left rotation (Dequin A-M, The Myth of Losing Tail Rotor effectiveness. 45th European ^Rotorcraft Forum, Warsaw, Poland, 17-20 September. 2019. Paper # 17. p. 1-15), adopted for the prototype. The complex electrical remote control system automatically determines the turn speed command. However, the system is complex, overloaded with additional devices, and to ensure its full operation, information about the air flow that occurs at the tail rotor is necessary.

The technical result of the proposed technical solution is to obtain data on the speed and direction of turn of the beam with a tail rotor, as well as in a crosswind, obtaining information about the air flow in the tail rotor area of a single-rotor helicopter to alert the pilot about a dangerous situation in various flight modes.

The technical result is achieved by the fact that the system for warning the pilot about the occurrence of an unintentional turn to the left of a single-rotor helicopter, characterized in that it contains two airspeed receivers with a frequency output and two modules for comparing the output frequencies of the receivers, the first module is connected to the one located on the steering beam by the first crosswind airspeed receiver, the second module is connected to the second airspeed receiver located on the end beam in the tail rotor area by the safe frequency of the tail rotor inductive speed, the modules are connected by the signals of the simultaneous comparison algorithm, the resulting signal of the first module is processed by comparing the signals of the first and the second receiver according to the formula - (ƒ ₁ V _z /ƒ ₁ V _and )≥0.75, the resulting signal of the second module is worked out by comparing the signals of the first and second receivers according to the formula (ƒ ₂ V _z /ƒ ₂ V _and )≥0.75, modules are independently connected to the saw that signal of the approach of a dangerous regime is uncontrolled self-rotation.

In FIG. Figure 1 on the helicopter shows the layout of the true airspeed receiver 1 with a frequency output for measuring the circumferential fuselage turning speed and lateral wind speed, as well as the true airspeed receiver 2 with a frequency output for measuring the inductive speed of the tail rotor of the helicopter, both receivers are designed for simultaneous operation in first and second modules.

In FIG. Figure 2 shows a diagram for comparing the signals of airspeed receivers 1 and 2 in modules 1 and 2 in various modes - "flight" and "hover".

The operation of the pilot warning system about the occurrence of an unintentional turn to the left of a single-rotor helicopter in two modes (flight and hover) occurs as follows (Fig. 2).

Flight mode. At the end of the completed task in flight, the helicopter is transferred to the level flight mode V _x ≤V _x =10-20 m/s with a decrease in altitude and a turn maneuver at a speed of V _z together with a side wind. The airspeed receiver 1 V _z (~≥ 5 m/s) sends a frequency signal ƒ ₁ V _z (e.g. ≅90 Hz) about the speed when turning into the electronic module 1 for comparison with the simultaneous incoming signal of the inductive speed V _and from the area tail rotor, located on the steering beam, with frequency output ƒ ₁ V _and . If the accepted ratio of frequency signals according to the formula (ƒ ₁ V _z /ƒ ₁ V _and )≥0.75, calculated in the electronic module 1, does not correspond to the limitation mode, a danger signal is given to the pilot to change the flight mode to satisfy the ratio of the frequency signals of the turn rate and the inductive speed equal to (ƒ ₁ V _z /ƒ ₁ V _and )<0.75.

Frequency signal measurements by airspeed receivers are based on a flow jet self-oscillator. The work of the jet oscillator is as follows.

The oncoming flow V _z passes through the inlet channel into a three-stage jet self-oscillator, at the output of which pneumatic self-oscillations of air pressure are formed, converted by a pneumo-piezo-electric converter into an electrical frequency signal. Further, the frequency signals after comparison in the electronic comparison module are transmitted to the cockpit as a danger signal (sound and light).

In the "hovering" mode at a speed V _z (~≥ 12 m/s) of a crosswind, an airspeed receiver with a frequency output ƒ ₂ V _z (for example, ≅120 Hz) located on the steering beam sends a signal to the electronic module 2 for comparison with simultaneous inductive speed signal V _and from the tail rotor area located on the steering beam, with frequency output ƒ ₂ V _and . If the accepted ratio of frequency signals according to the formula (ƒ ₂ V _z /ƒ ₂ V _and )≥0.75, calculated in the electronic module 2, does not correspond to the limitation mode, a danger signal is given to the pilot to change the flight mode to satisfy the ratio of the frequency signals of the turn rate and the inductive speed equal to (ƒ ₂ V _z /ƒ ₂ V _and )<0.75.

The inclusion of the "flight" or "hovering" modes is automatically determined by the standard speed device on the helicopter.

The proposed method achieves obtaining data on the speed of turn of the beam with a tail rotor, as well as obtaining information about the air flow in the tail rotor area of a single-rotor helicopter in a crosswind to alert the pilot about a dangerous situation in various flight modes.

Claims (9)

The system for warning the pilot about the occurrence of an unintentional turn to the left of a single-rotor helicopter, characterized in that it contains two airspeed receivers with a frequency output and two modules for comparing the output frequencies of the receivers, the first module is connected to the first sidewind airspeed receiver located on the steering beam. wind, the second module is connected to the second airspeed receiver located on the end beam in the tail rotor area by the safe frequency of the tail rotor inductive speed, the modules are connected by the signals of the simultaneous comparison algorithm, the resulting signal of the first module is processed by comparing the signals of the first and second receivers according to the formula (ƒ ₁ V _z /ƒ ₁ V _and )≥0.75, where ƒ ₁ - frequency of the first airspeed receiver; V _z - side wind speed; V _and - inductive speed of the screw; the resulting signal of the second module is processed by comparing the signals of the first and second receivers according to the formula (ƒ ₂ V _z /ƒ ₂ V _and )≥0.75, where ƒ ₂ - frequency of the second airspeed receiver, while the modules are independently connected with the pilot by a signal about the approach of the dangerous mode "uncontrolled self-rotation".

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