RU155282U1 - AIR SIGNAL SYSTEM - Google Patents

Abstract

An air signal system comprising a receiver and a full pressure sensor, a receiver and a brake temperature sensor and a calculator connected to sensors, characterized in that a weather vane is placed on a leg in its supports on an axis perpendicular to its chord and axis, legs, spaced apart relative to the axis of the leg symmetrically and rigidly connected with it, restricting the angular movement of the vane relative to the axis of the leg, a shaft placed in supports associated with the aircraft, rigidly connected with the leg at right angles to the axis of the leg having a balance bar rigidly associated with the shaft, the balancer wind vane, disposed on the weather vane, a sensor of the angular frequency of oscillation of the shaft and a sensor of the angular position of the shaft, the outputs of which are connected to the calculator, wherein the total pressure receiver is installed along the axis of the legs.

Description

The utility model relates to measuring equipment and can be used in aviation to determine the speed and altitude parameters necessary for controlling an aircraft in the subsonic range of flight speeds.

Known are traditional SHS air signal systems, described, for example, in [1] and [2] as velocity and altitude centrals for indirect measurement of true air speed V, number M, air density ρ, outdoor temperature T _n , instrument speed V _pr , pressure head q, and also, if necessary, to measure their deviations from the set values.

As primary parameters in known traditional systems (centrals), the total pressure of the inhibited flow p _p , the static pressure of the unperturbed flow p _n and the temperature of the inhibited flow T _{P are used} [2].

The pressures p _p , p _n and T _{P are} perceived by the respective receivers and are measured by the corresponding sensors, which are connected by their outputs to the computer.

Based on the primary parameters and the known relations in the calculator, the required set of output signals and their deviations from the set values are determined.

The main disadvantage of traditional systems that determine the accuracy of calculating the output signals is the low accuracy of measuring static pressure. Each aircraft requires significant technical and time resources to determine the location of the receiver and determine the laws of amendments at its location. Taking these corrections into account does not make it possible to completely eliminate them, especially in the presence of bevel angles (angle of attack and slip).

On the contrary, the perception by the receivers of the pressure p _p and the braking temperature T _P does not cause any particular difficulties due to their rather wide angular characteristics, which make it possible to accurately perceive these primary parameters within the operational angles of the bevel relative to the aircraft.

The task to which the claimed utility model is aimed is to increase the accuracy of measuring the output parameters of the SHS without using a static pressure receiver in it, which eliminates the need for establishing the location of the static pressure receiver on the aircraft and establishing corrections for this primary parameter.

The technical result consists in increasing the accuracy of measuring the output parameters of the SHS and reducing maintenance costs.

The solution to this problem is achieved by the fact that the air signal system contains a receiver and a full pressure sensor, a receiver and a brake temperature sensor and a calculator connected to the sensors, a weather vane located on the leg in its supports on an axis perpendicular to its chord and legs axis, the stops are symmetrical and rigid associated with the leg, limiting the angular movement of the weather vane relative to the axis of the leg, a shaft located in the supports of the aircraft, rigidly connected to the leg at a right angle to the axis of the leg and having a balancer, rigidly connected minutes with a shaft speed sensor and the angular sensor shaft oscillation of its angular position outputs of which are connected to the calculator, wherein the total pressure receiver is installed along the axis of the legs.

The essence of the utility model is illustrated by drawings.

In FIG. 1 presents a structural-kinematic diagram of the proposed system of air signals. The air signal system contains

1 - weather vane;

2 - axis of rotation of the weather vane 1, perpendicular to its chord;

3 - leg;

4 - support axis 2 of the weather vane 1, placed on the leg 3;

5 - stops restricting the rotation of the weather vane 1 relative to the axis of the legs 3;

6 - receiver full pressure mounted on the leg 3 along its axis;

7 - shaft;

8 - shaft supports 7 located on the aircraft and associated with it;

9 - balancer on shaft 7;

10 - balancer of a weather vane 1;

11 - the receiver of the braking temperature T _P ;

12 - brake temperature sensor T _P ;

13 - full pressure sensor p _p

14 - frequency sensor of angular vibrations of the shaft 7,

15 - the sensor of the angular position of the shaft 7;

16 - calculator;

XYZ - coordinate system associated with the aircraft.

In FIG. 2 presents the test results in the wind tunnel of the moving part of the experimental sample of the system located on the shaft 7, which includes the vane 1, the axis 2 of rotation of the vane 1 in the supports 4, the balance 9, the balance of the vane 10, the stops 5, leg 3, the receiver full pressure 6, the frequency sensor of the angular vibrations 14 of the shaft 7, where f is the frequency of oscillations, V _CR - flow rate.

In FIG. 3 is a diagram explaining the sequence of the temporary position of the moving part of the proposed system, where the symbols marked 1, 2, 4, 5, 8 correspond to the symbols in FIG. 1 as well

Y is the lifting force of the weather vane;

M _z is the moment of lifting force relative to the Z axis;

φ ₀ - the angle between the leg 3 and the weather vane 1, located on the stops 5;

α is the angle of attack.

As can be seen from FIG. 1, the proposed system does not contain a receiver and a static pressure sensor. As in the traditional SHS system, the proposed system uses a full pressure receiver 6 and a full pressure sensor p _p 13, a braking temperature receiver T _p 11 and a braking temperature sensor 12 and an output signal calculator 16. In contrast to the traditional SHS, a weather vane 1 is introduced into it on the axis 2, which is perpendicular to the leg 3 and its chord, a shaft 7 installed in the supports 8, rigidly connected to the leg 3 at right angles, a balancer 9, rigidly connected to the shaft 7, axis 2 the vane 1 in the supports 4, rigidly connected with the vane 1 perpendicular to its chord, the stops 5, rigidly connected with the leg 3 and spaced symmetrically about its axis by a distance restricting the angular movement of the vane 1 relative to the axis of the leg 3, the balancer of the vane 10 placed on the vane 1, angular frequency sensor 14 the shaft 7 and the sensor of angular displacements 15 of the shaft 7, the outputs of which together with the sensors of the total pressure 13 and the braking temperature 12 are connected to the calculator 16.

The basis for constructing the proposed utility model was the fact that when conducting tests in a wind tunnel and flight tests of vane-free, non-damped angle of attack (slip) sensors, it was noticed that the moving part of the sensor oscillates at its own frequency with a small amplitude of up to ~ 1 °.

The circular natural frequency of such sensors is

where: J _z - moment of inertia of the wind vane relative to the axis of rotation;

- аэродинамический коэффициент момента инерции флюгера относительно оси вращения;

- aerodynamic coefficient of moment of inertia of the wind vane relative to the axis of rotation;

q = 0.7 · M ² · p _n - pressure head;

S is the characteristic area of the vane blade;

p _n - static pressure at a height of H;

M is the Mach number;

ρ is the air density;

V is true airspeed.

Such a sensor functions satisfactorily if there is a multiple of the natural frequency of the sensor and a sufficient moment of lifting force in the spectrum of the noise component of the incident frequency stream incident on it and can overcome friction in the sensor supports. If these conditions are not met, the sensor ceases to oscillate, but at the same time regularly measures the angle of attack (or slip).

Stable vibrations of sufficient amplitude can be obtained by providing additional limited freedom of the angular movement of the vane relative to the axis of the leg. In this case, the guaranteed angle of inclination of the flow between the plane of the wind vane lying on the abutment and the flow provides a sufficient moment of lifting force. Moreover, the square of the frequency of the angular oscillations of the moving system relative to the axis of the shaft 7 for the selected position of the stops 5 relative to the legs 3 is proportional to the pressure head, i.e.

, K - постоянный коэффициент, учитывающий положение упоров относительно ножки.Where

, K is a constant coefficient taking into account the position of the stops relative to the legs.

At low speeds V≤400 km / h speed head [2]

from here

that is, the oscillation frequency of the moving part of the system is proportional to the instrumental speed V _CR at a standard air density at sea level ρ = ρ ₀ .

Tests of the experimental model of the sensor with limited freedom of movement of the wind vane relative to the legs carried out in the wind tunnel showed the linearity of the characteristics of changes in the vibrations of the moving system from the instrument speed. In FIG. 2 shows the specified characteristic. As a result of studies, it was found that the oscillations are carried out with equal amplitude relative to the incoming flow, which allows one to obtain the angle of attack (slip) of such a sensor. It was also established that the oscillation frequency decreases with increasing distance of the stops relative to the leg, and the amplitude of the oscillations of the mobile system increases, while the linearity of characteristics (2) and (4) is preserved.

As

and

, тоand

then

where from:

из (8) нетрудно вычислить число M полета. Статическое давление p_н можно вычислить из (5) или (6), то естьWith a measured ratio

from (8) it is easy to calculate the number M of the flight. The static pressure p _n can be calculated from (5) or (6), i.e.

or

The outside temperature T _N can be obtained from the measured braking temperature T _P and the calculated number M from (8), i.e.

Dynamic pressure can be calculated

or

и вычисленному из (8) числу M.according to the measured p _P ;

and the number M. calculated from (8)

Instrument speed can be calculated by dynamic pressure

where: p _Н0 , T _Н0 - pressure and temperature at sea level in a standard atmosphere;

V _ol - instrument speed;

K is the adiabatic exponent;

R is the specific gas constant.

True airspeed can be calculated from the ratio

where: the number M from (8), and T _Н from (9), i.e.

The density ρ of air can be calculated from the relation

by ρ _Н from (5) or (6) and T _Н from (9).

Barometric height can be calculated according to GOST 3295-73 from the ratio

where: p _H from (5) or (6).

Thus, it is possible to obtain in the proposed SHS the entire required set of output parameters of traditional SHS, including the necessary deviations from the set values, and it is also possible to calculate the angle of attack (slip).

The work of the proposed SHS is illustrated using Fig. 3.

The weather vane 1, having limited freedom of rotation between the stops 5 in the flow, deviates from its neutral position due to the noise components of the velocity along the Y axis and touches one of the stops 5 and takes position 1 in FIG. 3. In this position 1, at α = 0 °, the angle of inclination of the flow with respect to the wind vane will be equal to φ ₀ , and a lifting force Y and a moment M _Z > 0 relative to the supports 8 will appear, which rotates the moving part of the system clockwise. The angle of the bevel of the flow with respect to the vane 1 in this case decreases and in position 2 it becomes equal to zero, M _Z = 0 and Y = 0. Nevertheless, due to inertial forces, the mobile system continues its movement, the angle of the bevel of the flow with respect to the weather vane changes its sign, and the weather vane 1 instantly moves to the opposite stop 5. In FIG. 3, this corresponds to position 3. In this position, the angle of inclination of the flow becomes greater than φ ₀ and the resulting moment M _Z and lifting force Y rotate the moving part of the system counterclockwise. The angle of the bevel of the flow relative to the wind vane is reduced to zero. This corresponds to FIG. 3 to position 4. Under the action of inertial forces, the movable system continues to move, while the vane 1 becomes in flow with a bevel angle of the opposite sign and the resulting lifting force of the vane 1 returns the vane 1 to the opposite stop 5 to position 5 in FIG. 3.

In this position, M _z >0;Y> 0, which again rotate the movable system clockwise. In this case, the angle of inclination of the flow with respect to the wind vane decreases to zero, while the moving part of the system occupies position 6 in FIG. 3 (corresponding to position 2). Next, the movable system occupies position 3 and makes oscillations relative to the flow at a frequency that is determined by the mass inertial characteristics of the moving part of the system, the position of the stops relative to the leg 3, and the velocity head (speed). Oscillations of the mobile system are made with the same amplitude relative to the direction of flow, therefore, having an angle sensor 15 of the shaft 7, the angle of attack (slip) is easily determined.

As can be seen from FIG. 1 angular position sensor 15 of the shaft 7 and the angular vibration frequency sensor 14 of the shaft 7 together with the full pressure sensor 13 from the full pressure receiver 6 and the braking temperature sensor 12 from the braking temperature receiver 11 are connected to the calculator 16, where, in accordance with the above relations (1) (16) the required set of output parameters for the aircraft is solved.

The analysis of the measurement errors of the output parameters of the traditional and proposed SHS showed that, in terms of measuring the outdoor temperature T _N and density ρ, both systems are equivalent in accuracy, with respect to other parameters the proposed SHS has advantages in accuracy in the entire subsonic range of numbers M

The most significant advantages of the proposed SHS are observed at small numbers M. So, for example, at M = 0.5, the accuracy of the proposed SHS is higher than the accuracy of traditional SHS:

the parameter p _N ~ 2.8 times,

the parameter p _d in ~ 8.7 times,

by the parameter M ~ 8.2 times,

by the parameter q ~ 9.3 times,

by the parameter V by ~ 3 times,

by the parameter V _pr ~ 9.3 times.

A more accurate measurement of p _{H of the} proposed SHS provides a more accurate measurement of the barometric height H.

Information sources

1. D.A. Braslavsky et al. “Aviation devices”. Engineering, Moscow, 1964

2. V.A. Bodner "Aviation devices". Engineering, Moscow, 1969

3. G.I. Klyuev, N.N. Makarov, V.M. Soldatkin “Aviation devices and systems” Ulyanovsk, 2000

4. "Standard atmosphere." GOST 4401-73

5. "Hypsometric table." GOST 3295-73

Claims (1)

An air signal system comprising a receiver and a full pressure sensor, a receiver and a brake temperature sensor and a calculator connected to sensors, characterized in that a weather vane is placed on a leg in its supports on an axis perpendicular to its chord and axis, legs, spaced apart relative to the axis of the leg symmetrically and rigidly connected with it, restricting the angular movement of the vane relative to the axis of the leg, a shaft placed in supports associated with the aircraft, rigidly connected with the leg at right angles to the axis of the leg having a balance bar rigidly associated with the shaft, the balancer wind vane, disposed on the weather vane, a sensor of the angular frequency of oscillation of the shaft and a sensor of the angular position of the shaft, the outputs of which are connected to the calculator, wherein the total pressure receiver is installed along the axis of the legs.

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