RU2749167C1 - Method for plane control when returning to airfield under fuel-saving conditions - Google Patents

Abstract

FIELD: aviation.SUBSTANCE: invention relates to a method for controlling an aircraft when returning to an airfield at a high altitude, at a high initial flight speed and at large distances from the runway under conditions of fuel economy. To do this, one should use sequentially automated processes of stabilization of the aircraft positions on a given descent trajectory during the transition to the circle height with subsequent stabilization at this height and of stabilization of the aircraft position on the landing glide path. At the same time, when the aircraft descends, the processes of stabilization of a given flight speed with a vertical speed limitation are used, and the propulsion system is transferred to a fixed operating mode, characterized by a minimum fuel consumption.EFFECT: operation is ensured at large distances from the runway, at high initial altitudes and flight speeds, as well as decreased fuel consumption.1 cl, 2 dwg

Description

The invention relates to the field of aviation technology, namely to systems for automatic control of an aircraft in the longitudinal plane when returning to an airfield from a high altitude (including> 11 km) and with a high initial flight speed (including with the number M> 1) at a significant distance (including> 150 km) from the runway (runway) in fuel economy conditions.

Known methods of automatic aircraft control during descent, applicable to perform the "return to the airfield" mode, implemented in control systems presented in patents RU No. 2542686 "Automatic aircraft control system during descent", RU No. 2703378 "Automatic aircraft control system during descent at the stage circle height stabilization ". Their use does not provide for operation from large distances from the runway, from high initial altitudes and flight speeds. They also do not provide for a solution to the actual issue of fuel economy in practice.

The logic of aircraft control in the "return to the airfield" mode is aimed at achieving maximum fuel economy and consists in the sequential execution of three stages (Fig. 1).

In the first of them, an aircraft moving at a high altitude and with a high flight speed is brought from an initial position remote from the runway to a given cruising flight altitude. This requires maximum fuel economy at a fixed operating mode of the propulsion system, characterized by minimum fuel consumption. It is also necessary to maintain the specified indicated airspeed (V _pr ) and not exceed the maximum negative vertical speed (V _y ) of descent. Aircraft movement occurs with a loss of flight altitude up to a certain predetermined value (up to the so-called "cruising altitude" H _cruise ) and is performed in one or several passes. After reaching the "cruising altitude", the mode of stabilization of this flight altitude is performed until the moment of intersection with the specified descent trajectory.

The second stage of control consists in stabilizing the position of the aircraft on a given descent trajectory, which is a straight line with a certain angle of inclination to the horizon plane (in particular, equal to 6 °) and in transition to a given circle height with its subsequent stabilization.

At the third, final control stage, the aircraft position is stabilized on the landing glide path of descent.

The listed steps are performed sequentially one after another.

At the first stage of the “return to the airfield” mode, the aircraft descends with an admissible vertical speed 0> V _y > V _{y min} , where V _{y min =} - (100 ÷ 150) m / s, or by several programmable levels in altitude H _back , the last of which is the cruising altitude H _cruise , or immediately to the cruising altitude. In this case, maximum fuel economy is required for a fixed operating mode of the propulsion system (in particular, in the "low throttle"mode); it is also required to maintain a given indicated flight speed (V _pr ). The value of the stabilized speed is selected from the conditions for ensuring the maximum aerodynamic quality to ensure the minimum kilometer fuel consumption. If the required value of the indicated airspeed is less than the minimum permissible flight speed, the set speed is equated to the minimum permissible. If the minimum permissible flight speed depends on the flight altitude (as a rule, with an increase in altitude, the value of the minimum permissible flight speed increases), the descent is divided into several sections, while the altitudes at which the minimum change occurs as the echelons of the specified heights - permissible flight speed. Thus, the aircraft passes along the profile at the optimum indicated speed (in terms of kilometer fuel consumption) or at the minimum permissible speed. As a result, the minimum fuel consumption is provided for reaching the cruising flight altitude. After reaching the "cruising altitude" of the flight, the stabilization mode of this altitude is performed until the moment of intersection with the specified descent trajectory.

At the first stage of the "return to the airfield" mode, the aircraft control process is carried out using an automatic control system in accordance with the patent RU No. 2619793 "Aircraft automatic control system when climbing and stabilizing a given altitude" by transferring its operating mode from climb to altitude lowering ... With the preserved general structure of the control system presented in patent No. 2619793, the distinctive features of its use in the descent mode are:

- block 1 for generating a given flight speed V _back and block 14 for forming a given cruising flight altitude H _back have the ability to programmatically change and, thus, the set values of the flight speed V _back and the altitude of descent _{levels H back} can be changed according to specified programs in order to ensure economical operation propulsion system;

ограничивается в области отрицательных значений

, где V_{y min}=-(100÷450) м/с; за счет этого исключается набор высоты и ограничивается максимальная вертикальная скорость снижение на уровне допустимых значений;- in block 21 limiting signals in magnitude, the total signal of a given vertical speed of the aircraft

limited to negative values

, where V _{y min} = - (100 ÷ 450) m / s; due to this, the climb is excluded and the maximum vertical speed of descent is limited to the level of permissible values;

- the logic block 22 transfers the control of the aircraft from the mode of descent to the mode of stabilization of the cruising altitude H _cruise on the basis of H <(H _back + Δ _H ), Δ _H = (100 ÷ 200) m; due to this, a smooth (without overshoot) process of the aircraft reaching the cruising altitude H _{cruise is provided} with the subsequent stabilization of this flight altitude.

At the second stage of returning the aircraft to the airfield, the process of stabilizing its position on a given descent trajectory is carried out using an automatic control system in accordance with patent RU No. 2703378 "Aircraft automatic control system during descent at the stage of circle height stabilization." The control system is activated at the moment of intersection of the flight path at cruising flight altitude with a given descent path. With the help of the same control system, a smooth process of the aircraft reaching the given height of the circle H _circle (without "dips" in height below the height of the circle) and the subsequent stabilization of its position at this height is carried out.

At the third, final stage of returning the aircraft to the airfield, the process of stabilizing the position of the aircraft on the landing glide path of descent is carried out using an automatic control system in accordance with patent RU No. 2537201 - "Automatic aircraft control system during landing approach."

The essence of the invention is illustrated by graphic images:

in fig. 1 shows a graphical diagram of the sequentially executed stages of aircraft control in the "return to the airfield" mode - the so-called. Flight "profile";

in fig. 2 shows the graphs of changes in the main flight parameters (altitude, flight speed, vertical speed) at the first stage of the "return to the airfield" mode.

FIG. 1, 2, the following designations are used:

Runway - runway;

Н - current flight altitude;

t, s - current time;

H _circle - the height of the circle;

H _cruise - cruising altitude;

Н_0 - initial altitude occupied by the aircraft before performing the “return to the airfield” mode;

Н_1 - the first (intermediate) value of the specified height;

H _kr - the second (final) value of the specified altitude (cruising altitude);

V _y - vertical speed of descent of the aircraft;

V _min is the maximum permissible negative value of the vertical speed;

V _pr is the indicated flight speed of the aircraft;

V_0 - initial speed before the "return to the airfield" mode;

V_1 is the estimated flight speed corresponding to the economic fuel consumption of the propulsion system during the transition to the first (intermediate) value of the given altitude;

V_kr is the estimated flight speed corresponding to the economical fuel consumption of the propulsion system during the transition to the cruising flight altitude.

In the example considered, the aircraft control process at the first stage of the “return to the airfield” mode consists of two fragments: lowering the aircraft from the initial altitude H_0 to the intermediate preset altitude H_1 followed by transition to the preset cruising flight altitude H _kr .

From the materials presented in figure 2, it follows that:

- the process of lowering the aircraft to an intermediate preset altitude H_1 and further to the cruising altitude H _{kr is} carried out, respectively, at the flight speeds V_1 and V_kr, determined from the conditions of economic fuel consumption of the propulsion system at these altitudes; the flight speeds V_1 and V_kr after the end of the transient processes are kept constant at the calculated values;

- vertical flight speed V _y does not exceed the maximum permissible negative values.

Claims (2)

1. A method of aircraft control when returning to an airfield from a high altitude, incl. > 11 km, with a high initial speed, incl. with M> 1, from large distances from the runway, incl. > 150 km, in conditions of fuel economy, consisting in the use of automated processes for stabilizing the position of the aircraft on a given descent trajectory, the transition of the aircraft to a circle height with subsequent stabilization of its position at this altitude and stabilization of the aircraft position on the landing glide path of descent, involving the use of an information and navigation system , which forms altitude and speed parameters, a given descent trajectory, a landing glide path, signals of a given, cruising and current flight altitude, a signal of a circle height, a signal of deviation from a given descent trajectory, a signal of deviation from the landing glide path, signals of longitudinal and vertical g-forces, speed signals flight and vertical speed, an automatic system for stabilizing the position of the aircraft on a given descent trajectory, an automatic system for stabilizing the position of the aircraft at a circle height and an automatic system for stabilizing the position of an aircraft on a landing glide during descent, in this case, the automated process of lowering the aircraft from the current flight altitude to the cruising altitude is additionally used with simultaneous stabilization of the specified flight speed, with the limitation of the vertical speed and with the subsequent stabilization of the aircraft position at the cruising flight altitude, and the propulsion system is transferred to a fixed operating mode, characterized by minimum fuel consumption. 2. A method for controlling an aircraft when returning to an airfield according to claim 1, characterized in that the automated control processes for lowering the aircraft to the cruising flight altitude, stabilizing the aircraft position at the cruising flight altitude, stabilizing the aircraft position on a given descent trajectory, transitioning the aircraft to a circle height from subsequent stabilization of its position at this altitude and stabilization of the aircraft position on the landing glide path, the descents are carried out sequentially one after the other.

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