RU58719U1 - HELICOPTER SPEED METER - Google Patents

Abstract

The invention relates to the improvement of a speed meter for a helicopter.

The technical result consists in the possibility of measuring the three components of the helicopter airspeed vector in a coupled coordinate system in the entire range of operating speeds and increasing the measurement accuracy.

A helicopter air velocity meter is proposed, comprising a sensor of the velocity vector of the total air flow (inductive from the main rotor and translational from helicopter motion), a flow temperature sensor, a helicopter weight sensor, a vertical overload sensor, three sensors of the components of the angular velocity vector of the helicopter relative to its center of mass, first, second, third and fourth converters.

In the first converter, based on the signals from the sensor of the total air flow vector according to the parameters of the angular position of the two-stage weather vane and the pneumatic signals from the air pressure receiver located on the two-stage weather vane, as well as the signals from the temperature sensor, the signals of the components of the vector of the total flow in the connected helicopter coordinate system.

In the fourth converter, based on the signals from the first, second, and third converters, the signals of the components of the helicopter air velocity vector in the associated coordinate system are generated at its output.

4 ill.

Description

The claimed utility model relates to airborne signal systems for helicopters.

The problem of measuring the airspeed of a helicopter, especially in the low-speed range, is still at the stage of its resolution. There are a fairly large number of attempts to create airspeed meters for helicopters by both domestic and foreign companies. The most attractive technical solutions can be considered the decision to place the means of perception of the primary parameters of the air flow on the rotor blades or on the rotary rods by using the reference flow created by the rotational movement of these funds and the perception of the total air flow from the movement of the helicopter and the rotation of the blades or rotary rods .

One such solution is described in US patent No. 3373605, 1968 C. 73-182, in which at the ends of the rotary rods are placed means of perception of air pressure. In the calculator, the longitudinal and transverse components of the helicopter air velocity vector are determined by the pressure difference in the fixed azimuthal positions of the rods relative to the connected axes of the helicopter.

In domestic practice, one can also name a number of technical solutions related to the placement of means of sensing air flow parameters on helicopter blades or rotary rods, described, for example, in copyright certificates No. 1039344 of 05/03/83, No. 1138744 of 08/10/84, No. 1454088 dated 09/22/88.

The first Loras low-speed system in accordance with US Pat. No. 3,337,605 was created by Pacer Systems, Inc. for aircraft with vertical take-off X-22 [1], and later

On this basis, an advanced omnidirectional air data system OADS-2000 was built [2].

According to the results of testing the system in a UH-1C helicopter, the preferred location is its extension over the rotor hub.

The main technical drawback of the described solutions is that they basically cannot measure the vertical component of the helicopter airspeed vector.

At the same time, there are other organizational, technical, and operational obstacles, for example, placing on the main rotor blades the means of sensing primary parameters, delivering signals from the rotating part to the fuselage, increasing the range of blades with and without sensing means, which reduce the consumer’s interest in such technical decisions.

The placement of pressure sensing devices on the rods, and the omnidirectional sensor above the rotor hub, leads to an increase in the dimensions of the helicopter, which together with the indicated technical drawback also limits the need for systems such as Loras and OADS.

Another noteworthy technical solution for measuring the components of a helicopter airspeed vector is to place an air pressure receiver on a two-stage gimbal weather vane under the rotor of the helicopter. Here, the inductive flow from the rotor is used as the reference flow in the region of low speeds of the helicopter. The air pressure receiver rotates freely around two axes, while the longitudinal axis of the receiver and the weather vane are set in the direction of the local air flow, which is the result of the vector addition of the helicopter speed and inductive flow from the rotor.

Marconi Avionics has proposed an industrial design of the Lassie Low Speed Airborne Speed Measurement and Display System, which was installed on a DFVLR VO-105 helicopter for evaluation tests.

The test results were presented by an aircraft engineer J.KALETKA in a report published in the journal JOURNAL OF THE AMERICAN HELICOPTER SOCIETY, V 28, No. 4, 1983. This report describes the system and its principle of operation.

The system includes a vane flow direction sensor mounted on the fuselage under the rotor with a receiver of full and static pressure. The angular position of the receiver mounted on a two-stage weather vane is measured by two sine-cosine transformers (SKT). Pneumatic pressure signals are supplied to the corresponding sensors of full and static pressure in the air data converter, the input of which receives signals from the SKT corresponding to the position of the LDPE receiver and the weather vane relative to the coordinate axes of the helicopter. Based on this data and the signal from the air temperature sensor, the converter calculates the components of the helicopter airspeed vector, which are indicated on the corresponding indicators.

The structural diagram of the Lassie meter is presented in figure 1. The meter includes a sensor 1 of the vector of the total air flow from the movement of the helicopter and inductive flow from the main rotor, consisting of a receiver 2 of the total pressure P _P and the pressure of the undisturbed stream P _N located on a two-stage weather vane 3, orienting the receiver 2 along the total flow, two sensors 4 and 5 of the angular position φ ₁ and φ _{2 of the} weather vane 3. The meter also contains a sensor 6 for the flow temperature, a transducer 7, which forms, based on the input information from the sensors

1 and 6 signals about the longitudinal u, transverse ν and vertical w components of the total flow vector in accordance with the proposed algorithms:

Where:

u, ν, w - respectively the longitudinal, transverse and vertical components of the vector of the total air flow caused by the translational movement of the helicopter and the inductive flow from the rotor;

V _Σ is the module of the total air velocity vector, the result of adding the inductive flux vector from the rotor and the helicopter velocity vector;

φ ₁ and φ ₂ - the angular position of the weather vane 3 of the sensor 1 of the vector of the total air flow relative to the associated axes of the helicopter.

The Lassie meter works as follows. Air pressure receiver 2, mounted along the total air flow perceives the pressure of the complete deceleration of the flow P _P and the pressure of the unperturbed flow P _N , which in the converter 7 together with the temperature of the unperturbed flow T _N from the sensor 6 provide the calculation of the total speed V _Σ in accordance with the known standard dependence. Based on the information from the sensors 4 and 5 of the angular position of the weather vane 3 φ ₁ and φ ₂ , the signals u, ν and w of the longitudinal, transverse and vertical components of the velocity vector are formed at the output of the transducer 7 .

The helicopter Lassie test results presented in the J.KALETKA report showed a significant scatter of data, compared with the standard measuring instruments, both longitudinal and

transverse component of the velocity vector. Even after adjusting the Lassie data and using linear regression, the spread was about 8 m / s (28.8 km / h). The vertical component of the velocity was estimated by changing the static pressure measured by the receiver air pressure (component in the earth's coordinate system). In accordance with the proposed algorithm, the vertical component of the helicopter's velocity vector V _y cannot be determined only by component w due to the significant magnitude of the vertical component of the inductive flux vector from the rotor of the helicopter V _iy .

The problem to which the claimed utility model is directed is to create a speed meter for a helicopter, free of these shortcomings and having higher technical characteristics.

The technical result is expressed in increasing the accuracy of the meter.

The solution to this problem is achieved by the fact that in the known speed meter for helicopters, which includes a vector sensor of the total air flow from the rotor and the movement of the helicopter, a combined receiver of full and static pressure, located on a two-stage weather vane, two sensors of the angular position of the weather vane relative to the connected axes of the helicopter , a flow temperature sensor and a transducer containing sensors for full and static pressures; helicopter weight and vertical overload sensors were also introduced tchiki vector components of the angular rotation velocity of the helicopter in the related coordinate system, the second, third and fourth transducers.

The second converter with its inputs is connected to the helicopter weight sensor, vertical overload sensor, flow temperature sensor, weather vane angle sensors and the first converter according to the parameters of static pressure and total flow.

The third converter is connected by its inputs to the outputs of the sensors making up the angular velocity vector, and the fourth converter is connected by its inputs to the outputs of the first, second, and third converters.

A feature of the claimed technical solution is that at the output of the second converter the components of the vector of the inductive flow from the rotor of the helicopter are formed.

At the output of the third converter, the components of the vector of portable speed from the rotation of the sensor of the vector of the total flow relative to the center of mass of the helicopter are formed, and at the output of the fourth converter, the desired projections of the vector of the air velocity of the helicopter on the associated coordinate axes are formed.

In more detail, the essence of the proposed technical solution is illustrated by drawings.

Figure 2 shows the sensor of the air velocity vector, placed under the rotor, and a vector diagram of flow rates.

Figure 3 shows the location of the air velocity vector sensor relative to the center of mass of the helicopter.

Figure 4 shows a structural diagram of the inventive speed meter for a helicopter.

In the figures indicated:

1 - sensor vector total air flow;

2 - combined receiver of the total pressure R _P and the pressure of the unperturbed flow R _N ;

3 - two-stage weather vane;

4 - sensor angular position angle φ ₁ ;

5 - sensor angular position angle φ ₂ ;

6 - flow temperature sensor;

7 - the first converter.

8 - weight sensor G of the helicopter;

9 - vertical overload sensor n _y ;

10 - sensor component of the vector of the angular velocity of rotation of the helicopter ω _x ;

11 - sensor component of the vector of the angular velocity of rotation of the helicopter ω _y ;

12 - sensor component of the vector of the angular velocity of rotation of the helicopter ω _z ;

13 - the second Converter;

14 - the third Converter;

15 - the fourth Converter.

Figure 2 shows the position of the total vector air speed along which the sensor 1 is oriented with respect to the associated axes of the XYZ helicopter. Vector value consists of two vectors:

- vector of inductive flux and

- helicopter airspeed vector whose components are speeds: longitudinal V _x , transverse V _z and vertical Y _y .

The position of the inductive flux vector relative to the XYZ axes is determined by the angle of rotation of the rotor shaft i, the angle of obstruction of the axis of the cone of the rotor "a" in the XY plane and the angle of the obstruction of the axis of the cone of the rotor "b" in the ZY plane. The angle φ ₁ determines the position of the sensor relative to the XZ plane, and the angle φ ₂ relative to the XY plane.

According to the drawing in figure 2, the components of the helicopter speed vector can be determined from the following relationships:

- longitudinal component:

- transverse component:

- vertical component:

From the same drawing it also follows that:

those. those algorithms that were the basis of the Lassie system.

From relations (4) and (1), the longitudinal component of the helicopter's velocity vector is equal to:

From relations (5) and (2), the transverse component is

From relations (6) and (3), the vertical component of the helicopter's velocity vector is equal to:

From the expressions (7) - (9) it follows that for the accurate measurement of the components V _x , V _y , V _z it is necessary to take into account the change in the second terms of the right-hand side of expressions (7) - (9), which are projections of the inductive flow velocity on the connected coordinate axes V _ix , V _iy , V _iz , in which unknown

are the inductive speed V _i and the blockages of the axis of the rotor cone, i.e. angles "a" and "b".

From the aerodynamics of helicopters [3] (pp. 16-18) for the hovering mode, based on the impulse theory of an ideal propeller, a relation is given that relates its thrust T and inductive speed V _i :

Where:

ρ is the density;

F - swept area of the rotor.

Setting ρ = ρ ₀ -Δ and T = G, ρ ₀ = 0.125 KGS ² / m ⁴ is the standard density at sea level, the inductive speed in the mode of helicopter hovering is:

Where:

G is the mass of the helicopter;

Δ is the relative density of air.

In the same source [3] (p. 30-31) in the modes of vertical typing and lowering the helicopter, the thrust of the rotor is:

Where:

V ₁ = V _i ± V _y (plus sign for typing, minus sign for vertical decrease),

n _y - vertical overload.

Then, taking into account V ₁ from equation (12) we have:

Where:

V _ins - inductive speed during vertical typing / lowering of the helicopter;

V _y - the vertical speed of the helicopter.

In the same source [3] on page 41 the relation for the rotor thrust in oblique flow mode is given (general case):

Where:

χ is the coefficient of end losses of the rotor, χ = 0.9 ÷ 0.92;

V _iк - inductive speed with oblique flow around the rotor.

From figure 2 it also follows that as a result of addition of vectors helicopter speeds and inductive flux, vector equal to the total flow vector .

With this in mind, from (14) it follows:

Comparing relations (11); (13) and (16) for the considered cases of helicopter flight can be considered the reference value for calculating the inductive flow velocity V _{i the} value:

or

The product of this reference quantity (17) by Cosb-Sin (i + a) determines the projection of the inductive velocity vector on the x axis, i.e.

Projection of the vector of inductive speed on the Z axis:

Projection of the vector of inductive speed on the y axis:

The value of the obstruction axis of the cone, i.e. angles "a" and "b" are also unknown, and also depend on the flight modes of the helicopter. The values of the angles “a” and “b” in the operational range vary slightly and are estimated “a” = about 5–6 °, and the value “b” = 2–3 °.

Members facing the reference value in expressions (18) ÷ (20) for projections of the inductive velocity vector V _ix ; V _iz ; V _iy can be considered an integral part of the correction factors K _x ; K _z ; K _y , which can be determined by the results of flight tests of the system and are a function of the parameters of the total flux vector measured by sensor 1 by linear or nonlinear regression.

Thus, the expressions for the projections of the air velocity vector of the helicopter (7) ÷ (9) on the connected axes X, Y, Z with the steady translational movement of the helicopter can be written:

Expressions (21) ÷ (23) are valid when the vector of the angular velocity of rotation of the helicopter relative to its associated axes is zero, i.e. = 0.

For normal operation of the weather vane of the air velocity vector sensor, it should be located in the zone of maximum inductive speed of the main rotor at an optimum distance from the main rotor shaft of 0.6 ÷ 0.7 of the main rotor radius, and have the coordinates of the installation on the fuselage X ₀ , Z ₀ , Y ₀ from the center of mass of the helicopter.

Figure 3 shows the location of the sensor 1 relative to the center "0" of the masses of the helicopter associated axes X, Y, Z and components ω _x ; ω _y ; ω _z angular velocity vector rotation of the helicopter relative to the indicated axes.

From the drawing in figure 3 it follows that when ≠ 0, the appearance of additional components of the vector of portable speed from the rotation of the sensor 1 relative to the center of mass of the helicopter.

Taking into account (24) ÷ (26), the expressions for the projections of the air velocity vector of the helicopter motion on the associated coordinate axes will have the form:

Thus, in contrast to the described Lassie system, when measuring the components of the helicopter air velocity vector in accordance with the presented relations (27) ÷ (29), it is also necessary to take into account such parameters as G; n _y ; Δ = f (T _H ; P _N ); ω _x ; ω _y ; ω _z .

The speed meter shown in figure 4, includes a sensor 1 of the vector of the total flow from the rotor and the speed of the helicopter, containing a two-stage weather vane 3 and placed on it a combined receiver 2 of full P _P and static R _N pressure. The meter also contains two sensors 4 and 5 of the angular position of the weather vane 3 and the receiver 2 relative to the associated axes of the helicopter; temperature sensor 6; a transducer 7 with pressure sensors (not shown in the drawing); G weight sensor 8 of the helicopter; sensor 9 vertical overload n _y ; sensors 10, 11, 12 of the components of the vector of the angular velocity of rotation of the helicopter ω _x , ω _y , ω _z , second 13, third 14 and fourth 15 converters.

The inputs of the first transducer 7 are connected to the outputs of the sensor 4 and 5 of a two-stage weather vane 3, a pressure receiver 2 and a flow temperature sensor 6. The inputs of the second transducer 13 are connected to the outputs of the helicopter weight sensor 8, the vertical overload sensor 9, the sensors 4 and 5 of the two-stage weather vane 3, the temperature sensor T _N and the outputs of the first converter according to the parameters of the static pressure P _N and the total flow V _Σ .

The inputs of the third Converter 14 are connected to the outputs of the sensors 10, 11, 12 of the components of the rotation vector of the helicopter relative to the associated axes, i.e. ω _x , ω _y , ω _z . The inputs of the fourth Converter 15

connected to the outputs of the first transducer 7, generating signals of the components of the air velocity vector of the total flux u, ν and w in the associated coordinate system of the helicopter, as well as the outputs of the second transducer 13, generating signals of the components of the velocity vector of the inductive flux V _ix , V _iz , V _iy in the connected coordinate system and to the outputs of the third Converter 15, which generates the signals of the components of the vector of portable speed from the rotation of the sensor 1 relative to the center of mass of the helicopter in the associated coordinate system ΔV _x , ΔV _y , ΔV _z .

At the output of the fourth converter 15, the desired signals are formed of the components of the helicopter airspeed vector in the associated coordinate system of the helicopter XYZ, i.e. V _x , V _y , V _z .

In the drawing of FIG. 4, the double lines show the blocks and connections of a known meter, the newly introduced blocks and connections are shown in single lines.

The work of the proposed speed meter for a helicopter is as follows. Sensor 1 of the velocity vector is mounted on the fuselage of the helicopter relative to its center of mass with coordinates X ₀ ; Y ₀ ; Z ₀ (as shown in FIG. 3) under the rotor 2 (as shown in FIG. 2). Using a two-stage weather vane 3, it is oriented along the total flow vector whose angular position relative to the X, Y, Z coordinates associated with the helicopter is determined by the angles φ ₁ and φ ₂ . The combined pressure receiver 2 along with the weather vane 3 are also installed along the total flow vector .

The receiver 2 receives the total and static pressures, which in the form of pneumatic signals arrive at the corresponding pressure sensors located in the first transducer 7 (not shown in the drawing).

shown). The input of this Converter also receives signals from sensors 4 and 5 of the angular position of the vane 3 in the form of Sinφ ₁ ; Cosφ ₁ ; Sinφ ₂ ; Cosφ ₂ and the signal from the sensor 6 temperature T _N flow. In the converter 7, based on the signals from the pressure and temperature sensors, in accordance with the well-known standard dependence V _Σ = f (P _P ; P _N ; T _N ) [4], the value of the true air velocity modulus of the total flow is generated, and at its output vector components on the connected coordinate axes u, ν, w in accordance with the expression (1) ÷ (3). At the same time, in the proposed meter using the sensors 8, 9, 10, 11, 12, respectively, the weight of the helicopter G, the vertical overload n _y and the components of the angular velocity of rotation of the helicopter ω _x , ω _y , ω _z relative to its center of mass are measured. In the second transducer 13, based on the signals from the sensors 8, 9, 4, 5, 6 and the signals from the first transducer 7 according to the parameters, respectively, the weight of the helicopter, vertical overload, the angular position of the vane 3, temperature, pressure of the unperturbed flow and the module of the velocity vector of the total flow are formed the reference value of the inductive speed modulus in accordance with expression 17 and the correction coefficients K _x , K _y , K _z , and vector components form at its output , inductive flux to the associated coordinate axes in accordance with the expressions:

In the third converter 14, based on the signals from the sensors 10, 11, 12 of the components of the vector of the angular velocity of rotation of the helicopter ω _x ; ω _y ; ω _z , taking into account the coordinates of X ₀ ; Y ₀ ; Z ₀ placement of the sensor 1 of the velocity vector on the fuselage relative to the center of mass of the helicopter, the components are formed

vector of the transport speed from the rotation of the sensor 1 relative to the center of mass of the helicopter ΔV _x , ΔV _y , ΔV _z in accordance with expressions (24) ÷ (26).

In the fourth transducer 15, based on the signals from the first transducer 7, the second transducer 13 and the third transducer 14, signals are generated for the projections of the helicopter airspeed vector onto the associated coordinate axes, in accordance with expressions (27) ÷ (29), which can be used as for indication, as in other helicopter systems.

Correction factors K _x , K _y , K _z , depending on the flight modes of the helicopter, are determined in the second transducer 13 based on the signals from the sensor 1 of the vector of the total flow and signals from the first transducer 7, according to the parameters φ ₁ , φ _{2 of the} angular position of the vane 3, static pressure P _N and the module of the vector of total velocity V _Σ by linear or nonlinear regression for the accepted location of the sensor 1 on a helicopter with coordinates X ₀ , Y ₀ , Z ₀ . For the accepted placement of the sensor 1 of the velocity vector and for this type of helicopter, the functional dependences of the correction factors K _x , K _y , K _z are purely individual and can be established as a result of flight tests.

Attracting the weight of the helicopter, vertical overload, static pressure, flow temperature, components of the angular velocity vector of the helicopter in the proposed meter allows not only to increase the accuracy of measuring the longitudinal and transverse airspeed of the helicopter, but also made it possible to measure the vertical airspeed of the helicopter in a connected coordinate system.

Held on a Mi-28N helicopter tests of the speed meter, made in accordance with the claimed technical solution, showed that it has high accuracy characteristics. The error in measuring the components of the velocity vector along all axes at various heights and in the hover mode is less than 6 km / h.

Information sources

1. Flight Evaluation Pacer Systems, Inc. Loras II Airspeed System Final Report III, March, 1974.

2. Operation Guide for Pacer Systems OADS Omnidirectional Aerial Data System. Those. UVZ translation, 1983.

3. D.I. Bazov, Aerodynamics of a helicopter - M .: Transport, 1969.

4. D.A. Braslavsky, Aircraft Instruments - M.: Mechanical Engineering, 1964.

Claims (1)

A helicopter speed meter, including a sensor of the total air flow vector from the main rotor and helicopter movement, containing a full and static pressure receiver located on a two-stage weather vane for its orientation along the total flow, two sensors of the two-degree weather vane angular position relative to the connected axes of the helicopter, a temperature sensor a flow and a transmitter with pressure sensors, the inputs of which are connected to the outputs of these sensors and a receiver of full and static pressure, distinguishing I mean that the sensors of helicopter weight, vertical overload and three sensors of the components of the vector of the angular velocity of rotation of the helicopter in the associated coordinate system, the second, third and fourth converters are introduced into it, while the second converter is connected by its inputs to the helicopter weight sensor, vertical overload sensor, flow temperature sensor, angular position sensors of a two-stage weather vane and the first transducer according to the parameters of static pressure and total flow velocity, the third transducer is connected n its inputs with the outputs of three sensors making up the vector of the angular velocity of rotation of the helicopter, the fourth converter with its inputs is connected to the outputs of the first, second and third converters.