RU99181U1 - SYSTEM FOR DETERMINING THE CHARACTERISTICS OF ON-BOARD MEASUREMENTS FOR MEASURING AIR PARAMETERS AND FLIGHT TECHNICAL CHARACTERISTICS OF THE AIRCRAFT AT THE PERFORMANCE OF FLIGHT TESTS - Google Patents

Abstract

 1. A system for determining the characteristics of airborne measuring instruments for air parameters and flight performance of an aircraft during flight tests, consisting of series-connected units:! a unit for recording data of the angular parameters of the position of the aircraft (LA) in space, the mass of the aircraft, acceleration components, trajectory flight parameters, air parameters from the on-board systems in probing systems, in the form of a horizontal platform (GP) without sliding, and flight test modes; ! block correction of total and static pressure in sounding modes, the second input of which is connected to the block characteristics! ! where Pc ISM, Pn ISM - measured values of static and total pressures, M; ! α - measured values of the Mach number and angle of attack; ! δ - aircraft configuration,! a unit for determining the true values of air velocity and atmospheric parameters — pressure, temperature, wind velocity vector at the height of the sounding mode by temperature values, total and static pressure, and trajectory parameters in the sounding mode; ! comparison unit ΔH≤ΔHset, where ΔH is the change in flight altitude in test mode, ΔHset is the set value of the change in altitude, the output of which is connected to a normally open relay connecting the output of the unit for determining the true values of the air velocity of atmospheric parameters with the input of the calculation unit. true values of air parameters - air speed V, number M, static pressure, angle of attack α and slip β in test mode according to atmospheric conditions obtained in sounding mode, current trajectory measurements, angular �

Description

The utility model relates to technical physics, measuring and aeronautical engineering, namely, to measuring parameters of the flight parameters of an aircraft (LA) and can be used in flight tests of an aircraft to determine the flight technical characteristics and characteristics of on-board measuring instruments for air parameters.

The utility model is focused on testing aircraft equipped with modern flight and navigation systems.

In practice, flight tests of aircraft use various methods and approaches to solving the problem of determining the characteristics of aircraft and airborne means for determining air parameters. Common to all methods is the need to determine the true values of air parameters: barometric altitude, indicated ground speed, number M, angles of attack and slip. To solve the problem of determining air parameters, methods using standard receivers and indirect methods can be distinguished using trajectory measurements and information about the parameters of the state of the atmosphere.

In systems using reference receivers, the air parameters are determined from the values of the parameters measured by the standard means (see AC-21-40 (0), Measurement of airspeed in light aircraft - certification requirements, 2005). The main task in this case is the standardization of the reference tools themselves.

Technical difficulties arise due to the need to remove receivers from the aerodynamic influence zone of the aircraft. The implementation of the methods involves the study of the installation of reference facilities on an airplane, and the equipping of aircraft with special technological devices. Due to the difficulty of completely eliminating the aerodynamic effect of the aircraft on measuring air parameters, the application of the methods requires special studies for each type of aircraft to evaluate the flow perturbation in the area of the placement of the reference means.

Systems using reference receivers are widely used in flight tests of aircraft abroad. By AC-25-7A EASA, in order to ensure aircraft testing under braking conditions with access to large angles of attack, to determine stall speeds, the necessary condition for determining which is to calculate the aerodynamic characteristics of aircraft, it is prescribed to use a nose bar with an air pressure receiver (LDPE) - an analog .

The methods for determining aerodynamic characteristics and evaluating air parameters indicated in the analogue require installation of additional remote LDPEs on the aircraft, for example, on the nose rod.

Among the indirect methods, the “Method for determining the aerodynamic errors of air pressure receivers in flight tests of an aircraft” is known, RF patent No. 2375690, including the implementation of horizontal platforms (GP) at given heights, speeds (Mach numbers) and angles of attack α, measurement of current static values pressure and total pressure, geometric height h, air temperature T, determination of changes in atmospheric pressure with a change in geometric flight altitude, determination of the dependence of the perception error ment total and static pressures full operational range of the speed (Mach number) and angle of attack. A system for its implementation, including a unit for recording data of the angular parameters of the position of the aircraft (LA) in space, masses of aircraft, acceleration components, orbital flight parameters in probes, in the form of a horizontal platform (GP) without sliding, and test flight modes, characteristics block and where P _{c ism} , P _{n ism} is the measured values of static and total pressures, M, α are the measured values of the Mach number and angle of attack, δ is the configuration of the aircraft is an analogue of the proposed utility model.

This system allows you to determine the air parameters only in horizontal steady flight modes.

Various systems are known for determining the aerodynamic characteristics of aircraft models in wind tunnels. Their disadvantages are the inability to accurately recreate atmospheric conditions in the wind tunnel, the discrepancy between the aircraft and its model.

The well-known "Method for calibrating the aerodynamic angle sensor of an aircraft", RF patent No. 2277698, including the implementation of sounding modes, determining wind speed, measuring aerodynamic angles and pitch angle.

This method is limited to use only for aerodynamic angle sensors. In this method, significant errors may occur in determining the air speed and wind speed due to the aerodynamic errors of the air pressure receivers, speed inconsistencies when flying in opposite courses, a large interval between atmospheric sounding and the test mode. This will lead to errors in the determination of calibration dependences for aerodynamic angle sensors.

The technical result, which the utility model aims to achieve, is to determine the actual values of air parameters, calibration dependences for receivers and sensors, aerodynamic force and moment coefficients, critical values of aircraft speed and aerodynamic angles in unsteady flight modes, for example, with large angles of attack, flight test results.

In the system for determining the characteristics of airborne measuring instruments for air parameters and flight performance of an aircraft during flight tests, consisting of series-connected blocks:

a unit for recording data of the angular parameters of the position of the aircraft (LA) in space, the mass of the aircraft, acceleration components, trajectory flight parameters, air parameters from the on-board systems in probing systems, in the form of a horizontal platform (GP) without sliding, and flight test modes;

block correction of total and static pressure in sounding modes, the second input of which is connected to the block characteristics and where P _{c ism} , P _{n ism} are the measured values of static and total pressures, M, α are the measured values of the Mach number and angle of attack, δ is the configuration of the aircraft;

true airspeed determination unit and atmospheric parameters - pressure, temperature, wind speed vector at the height of the sounding mode according to temperature values, total and static pressure and trajectory parameters in the sounding mode; comparison unit ΔH≤ΔH _ass , where ΔH is the change in flight altitude in test mode, ΔH _ass is the set value of the altitude change, the output of which is connected to a normally open relay connecting the output of the true airspeed determination unit and atmospheric parameters with the input of the unit for calculating the true values of air parameters - air speed V, number M, static pressure, angle of attack α and slip β in a test mode according to atmospheric conditions obtained in a sounding mode, current trajectory measurements, angular position parameters of the aircraft in space, a unit for calculating calibration dependencies for airborne characteristics air pressure receivers was introduced and , aerodynamic angle sensors, aircraft performance characteristics related to the aerodynamics and dynamics of the aircraft - c _{x, y, z} , m _{x, y, z} , critical values of speed V _s , angle of attack (Xs based on the true values of the air parameters, trajectory measurements for a number of similar modes depending on the parameters of the incoming flow, aircraft configuration, and dynamic parameters.The input of the unit is connected to the output of the unit for calculating the true values of the air parameters.

In addition, in the system for determining the characteristics of airborne measuring instruments for air parameters and flight performance of an aircraft during flight tests, a unit connected with the unit for determining the true values of air speed and atmospheric parameters, the second comparison unit ΔH> ΔH _ass , the output of which is connected to the second normally open relay. Relay connects output of true airspeed detection unit and atmospheric parameters with the input of the unit for calculating the values of the components of the vector of wind speed U _x (H) and U _z (H) at the heights of the test mode. The output of the unit is connected to the input of the unit for calculating the true values of the air parameters in test mode. This will allow to take into account the change in the wind characteristics of the atmosphere at various heights.

Moreover, in the system for determining the characteristics of on-board means of measuring air parameters and flight performance of an aircraft during flight tests in the case of a test mode without sliding, an additional circuit of series-connected blocks connected to the output of the correction block is additionally introduced:

determination of atmospheric parameters at the height of the sounding mode, with the exception of wind speed;

calculating the true values of the air parameters - air speed V, number M, static pressure, angle of attack in the test mode according to the conditions of the atmosphere obtained in the sounding mode, current trajectory measurements, angular parameters of the position of the aircraft in space;

calculation of calibration dependences for airborne pressure receivers, angle of attack sensors, aircraft performance characteristics in the longitudinal channel, related to aerodynamics and aircraft dynamics - with _y , m _z , V _s , α _s for a number of similar modes.

This allows you to determine the aerodynamic characteristics of the aircraft based on trajectory measurements without using a significant number of on-board measurements, to increase the accuracy of determining air parameters in flight tests of aircraft in various flight modes.

A utility model is illustrated in the following figures.

Figure 1 shows a block diagram of the system with a brief description of each of them.

Figure 2 shows the values of the coefficient of lift for various values of the true angle of attack.

The system consists of the following blocks, as shown in figure 1:

1 - a unit for recording data of the angular parameters of the position of the aircraft (LA) in space, the mass of the aircraft, acceleration components, trajectory flight parameters, air parameters from the on-board systems in probing systems, in the form of a horizontal platform (GP) without sliding, and flight test modes;

2 - characteristics block and where P _{c ism} , P _{n ism} are the measured values of static and total pressures, M, α are the measured values of the Mach number and angle of attack, δ is the configuration of the aircraft;

3 - block correction of the total and static pressures in sounding modes, the inputs of which are connected to the outputs of blocks 1 and 2;

4 - unit for determining true airspeed values and atmospheric parameters - pressure, temperature, wind speed vector at the height of the sounding mode in terms of temperature, total and static pressure and trajectory parameters in the sounding mode, the input of which is connected to the output of block 3, and the outputs are connected to comparison blocks 5 and 9, and blocks 6 and 10 through normally open relays controlled by the outputs from blocks 5 and 9;

5 - the first comparison unit ΔH≤ΔH _ass , where ΔH is the change in altitude in the test mode, ΔH _ass is the set value of the altitude change, the second input of which is connected to the output of block 8;

6 - unit for calculating the true values of air parameters — air speed V, number M, static pressure, angle of attack α and slip β in a test mode according to atmospheric conditions obtained in a sounding mode, current trajectory measurements, angular parameters of the position of the aircraft in space;

7 - unit for calculating calibration dependencies for airborne receivers of air pressure characteristics and , aerodynamic angle sensors, aircraft flight characteristics related to the aerodynamics and dynamics of the aircraft - with _{x, y, z} , m _{x, y, z} , critical values of speed V _s , angle of attack α _s based on true values of air parameters, trajectory measurements for a number of similar modes depending on the parameters of the incoming flow, aircraft configuration, dynamic parameters, the input of which is connected to the output of block 6,

8 is a block of the set values of the change in height ΔH _ass in the test mode;

9 - the second unit of comparison ΔH> ΔH _ass , the second input of which is connected to the output of block 8;

10 - unit for calculating the values of the components of the vector of wind speed U _x (H) and U _z (H) at the heights of the test mode, the output of which is connected to the input of block 6;

11 is a block for determining atmospheric parameters at the height of the sounding mode, with the exception of wind speed, the input of which is connected to the second output of block 3;

12 - unit for calculating the true values of air parameters - air speed V, number M, static pressure, angle of attack α test mode according to atmospheric conditions obtained in the sounding mode, current trajectory measurements, angular parameters of the position of the aircraft in space, the input of which is connected to the output block 11;

13 is a block for calculating calibration dependences for airborne pressure receivers, angle of attack sensors, and aircraft performance characteristics in the longitudinal channel associated with the aerodynamics and dynamics of the aircraft — c _y , m _z , V _s , α _s for a number of similar modes, the input of which connected to the output of block 12.

The principle of the system is as follows.

According to the data coming from block 1 and 2 in block 3 in probing mode, the true static and complete pressure according to the measured values of static P _{c ISM} , full P _{n ISM} pressure taking into account previously obtained characteristics and :

Where , - calibration dependences of LDPE obtained in horizontal flight, ΔP _c = P _{c ISM} -P _c , ΔP _n = P _{n ISM} -P _n ;

M _ISM - measured Mach number;

α _ISM - measured angle of attack;

δ is the configuration of the aircraft.

Next, in block 4 in the probing mode, the values of the Mach number M _s and air speed according to the formulas:

where R is the universal gas constant;

g is the acceleration of gravity;

k is the adiabatic exponent;

- the outdoor temperature at the time of the sounding mode, determined from the ratio:

where T _T is the braking temperature measured by the airborne receiver.

N is the airborne receiver quality factor.

Knowing the value of the air speed, the components of the wind speed U _x and U _z in the probing mode can be determined from the relations:

where ψ is the course angle of the sounding mode;

W _x , W _z are projections of the ground speed vector.

It is assumed that the wind velocity vector lies in the horizon plane and does not change over time.

Performing a probing mode without sliding immediately before the test mode:

- provides the determination of the basic parameters of the atmosphere (static pressure, temperature, wind velocity vector) necessary to solve the problem, with small errors due to correction of pressure perception errors in the sounding mode;

- significantly reduces the influence of random factors (spatio-temporal variability of atmospheric parameters) on determining the actual values of air parameters.

When the signal passes through block 5 in block 6 with known wind characteristics U _x , U _z , the air speed V _in the test mode is determined from the ratio:

where W _y is the component of the speed of the aircraft, the normal plane of the horizon.

The outdoor temperature in test mode is determined by the formula:

where Δh is the difference between the current geometric height and the height of the sounding mode;

τ = 0.0065 deg / m.

Then, from the ratio (3) using the obtained values of the outdoor temperature and air speed in the test mode, the number M is determined.

The true value of the static pressure in the test mode is determined by recalculation from the sounding mode using the equations of state of the gas and the statics of the atmosphere:

To determine the true angles of attack and slip, it is necessary to calculate the projection of air speed on the connected axis of the aircraft V _x1 , V _y1 , V _z1 according to the formulas:

where ϑ is the pitch angle;

γ is the angle of heel.

Taking into account relations (11) - (13), we obtain the expressions for the true angles of attack α and slip β:

In block 7, the values of the pressure head q are determined from the relation:

Then the calculation of aerodynamic coefficients is performed according to well-known formulas, for example:

where n _{x, y, z} are the overloads along the corresponding axes of the coordinate system associated with the aircraft;

m is the mass of the aircraft,

g is the acceleration of gravity;

S is the wing area of the aircraft;

After that, calibration dependences are determined for air pressure receivers, aerodynamic angle sensors, dependences c _{x, y, z} = f [α, β, M, δ, ...) and m _{x, y, z} = f [α, β, M, δ, ...), stall speeds V _s , critical angles of attack α _s and other aircraft performance characteristics. Obtained using the presented model, the values of c _y are shown in figure 2.

When the signal passes through block 9 in block 10 in the test mode, the components of the wind velocity vector U _x , U _z at the heights H of the test mode are additionally determined. For this, in sounding modes performed at the heights of the beginning H ₁ and end H _{2 of the} test mode, wind speeds are determined, after which the following relationships are used:

In block 11, the determination of air speed without taking into account wind speed is performed as follows. Let the aircraft in front of an unsteady mode of motion perform a sounding mode withstanding airspeed V ₁ , altitude H ₁ , heading angle ψ ₁ , with values of projections of ground speed W _x1 , W _z1 , and at some point in time t _{2 of} unsteady motion has values of the horizontal component air velocity V ₂ , course angle ψ ₂ , projections of ground speed W _x2 , W _y2 , W _z2 .

It is assumed that during the time from the beginning of the probing mode to the end of the unsteady mode of motion, the wind velocity vector is unchanged and lies in the plane of the horizon, the movement is performed without sliding. Then, based on the equation of cosines, the current projection of the airspeed V ₂ in the plane of the horizon at time t ₂ unsteady mode of motion is determined by the expression:

From:

Where:

the sign (+) is taken in acceleration mode, the sign (-) in braking mode;

(ΔW) ² = (W _x1 -W _x2 ) ² + (W _z1 -W _z2 ) ² ,

Δψ = ψ ₁ -ψ ₂ ,

ΔW is the module of the vector of the change in ground speed in the horizon plane.

In the general case, when the transient mode is performed with a set, loss of altitude, it is necessary to take into account the vertical component of airspeed:

Otherwise, the system according to claim 3 uses the same relations as for the system according to claim 1, and there are blocks 12 and 13, similar to blocks 6 and 7.

The figure 2 shows the values of the coefficient of lift for different angles of attack. The figure shows: 14 - values of the angle of attack, 15 - values of the coefficient of lift, 16 - calculation results.

Thus, the proposed model allows us to determine: the values of atmospheric parameters — temperature, pressure, wind velocity vector, air parameters in test modes, calibration curves for air pressure receivers and aerodynamic angle sensors, aircraft flight performance; to reduce the influence of random factors of variability of atmospheric parameters on the error in determining the considered characteristics in the test flight mode; improve the reliability and accuracy of flight test results.

Claims (3)

1. A system for determining the characteristics of airborne measuring instruments for air parameters and flight performance of an aircraft during flight tests, consisting of series-connected units: a unit for recording data of the angular parameters of the position of the aircraft (LA) in space, the mass of the aircraft, acceleration components, trajectory flight parameters, air parameters from the on-board systems in probing systems, in the form of a horizontal platform (GP) without sliding, and flight test modes; block correction of total and static pressure in sounding modes, the second input of which is connected to the block characteristics

where P _{c ISM} , P _{n ISM} - measured values of static and total pressures, M; α - measured values of the Mach number and angle of attack; δ is the configuration of the aircraft, true airspeed determination unit

and atmospheric parameters - pressure, temperature, wind speed vector at the height of the sounding mode according to temperature values, total and static pressure and trajectory parameters in the sounding mode; comparison unit ΔH≤ΔH _ass , where ΔH is the change in flight altitude in test mode, ΔH _ass is the set value of the altitude change, the output of which is connected to a normally open relay connecting the output of the true airspeed determination unit

and atmospheric parameters with the input of the calculation unit. the true values of the air parameters - air speed V, number M, static pressure, angle of attack α and slip β in the test mode according to the conditions of the atmosphere obtained in the sounding mode, current trajectory measurements, the angular parameters of the position of the aircraft in space, characterized in that The system introduced a block for calculating calibration dependencies for airborne receivers of air pressure characteristics

sensors of aerodynamic angles, flight performance characteristics of the aircraft associated with the aerodynamics and dynamics of the aircraft - c _{x, y, z} , m _{x, y, z} critical values of speed V _s , angle of attack α _s based on true values of air parameters, trajectory measurements a number of similar modes, depending on the parameters of the incoming flow, aircraft configuration, dynamic parameters, the input of which is connected to the output of the unit for calculating the true values of air parameters. 2. The system for determining the characteristics of on-board means of measuring air parameters and flight performance of the aircraft during flight tests according to claim 1, characterized in that it is connected to the unit for determining the true values of air speed

and atmospheric parameters, the second comparison unit ΔH> ΔH is an _ass , the output of which is connected to the second normally open relay connecting the output of the unit for determining the true values of air speed

and atmospheric parameters with the input of the unit for calculating the values of the components of the wind velocity vector U _x (H) and U _z (H) at the heights of the test mode, the output of which is connected to the input of the unit for calculating the true values of the air parameters in the test mode. 3. The system for determining the characteristics of on-board measuring instruments for air parameters and flight technical characteristics of an aircraft during flight tests according to claim 1, characterized in that in the case of a test mode without sliding, an additional circuit of series-connected blocks connected to the output of the correction block is additionally introduced: determination of atmospheric parameters at the height of the sounding mode, with the exception of wind speed; calculation of the true values of the air parameters - air speed V, number M, static pressure, angle of attack α test mode according to atmospheric conditions obtained in the sounding mode, current trajectory measurements, angular parameters of the position of the aircraft in space; calculation of calibration dependences for airborne pressure receivers, angle of attack sensors, aircraft performance characteristics in the longitudinal channel, related to aerodynamics and aircraft dynamics - with _y , m _z , V _s , α _s for a number of similar modes.