RU2041136C1 - Device for determination of angle of attack of aircraft - Google Patents

Abstract

FIELD: aviation instrumentation engineering. SUBSTANCE: device is additionally provided with mass sensor 3, ram air pressure sensor 4, normal g-load sensor 5, selector 6 for setting initial lift coefficient, flap present position sensor 7, landing gear condition sensor 8, selector 9 for setting initial value of lift curve slope in function of angle of attack, Mach number sensor 10, Mach number threshold value selector 11, second true angle-of-attack forming unit 13, scaler 14, first, second and third adders 15, 16 and 17, comparator 18, first and second division units 19 and 24, first and second switches 20 and 21, multiplier unit 22 and fourth adder 23. EFFECT: high safety of flight through redundancy and check of angle-of-attack sensors. 1 dwg

Description

 The invention relates to aircraft instrumentation, and in particular to devices for determining the angle of attack of an aircraft.

 The known automatic machine for determining and displaying angles of attack and overloads AUASP-R, which includes an angle of attack sensor, the output of which is connected to the first input of the tracking system, the second input of which is connected to the testing element (feedback potentiometer) of the angle of attack indicator, and the output with the engine, gear located also in the indicator.

 This device provides the crew with information about the current value of the angle of attack since the machine was turned on.

 However, there are significant drawbacks, which are as follows.

 1. Any failure in the chain of calculation of the angle of attack leads either to loss of information about the current values of the angle of attack, or to the issuance of insufficient information without any signaling to the crew.

 2. The information provided to the crew is unreliable due to the neglect of the influence on the local flows, in which the sensitive element of the angle of attack sensor is installed, and other flight parameters, among which the gliding angle of the aircraft has the main effect.

 There is also a device for determining the indication and signaling of angles of attack and overloads UDUA-6, adopted as a prototype, containing two sensors of the angle of attack, which, for subsequent compensation of the influence of the slip angle on the local angle of attack, are installed on opposite sides (left and right) of the aircraft, an averaging device , a true angle of attack calculator and a control unit, wherein the output of the left angle of attack sensor is simultaneously connected to the first inputs of the control unit and the averaging device, the output of the right angle of attack sensor at the same time it is connected to the second inputs of the control unit and the averaging device, the output of the averaging device is connected to the input of the true attack angle calculator, and from the outputs of the true angle of attack calculator and the control unit, information (true angle of attack and signaling of serviceability of the channel for forming the angle of attack, respectively) is given to the corresponding consumer ( for indication, alarm, self-propelled guns, etc.).

среднее значение местного угла атаки.This device generates a signal of true angle of attack according to the following relationship:
alpha _ist K _α ˙α _Wed + α _about where α _cp =

average local angle of attack.

K _{α is the} coefficient of transition from local angles of attack to true;
α _о true angle of attack at zero value of the local angle of attack;
α _{local left} , α local _right local angle of attack signals taken from the left and right sensors, respectively.

 The signal of serviceability of the channel of the angle of attack is generated in the control unit and is issued if the absolute difference between the values of the left and right angles of attack exceeds a certain value that is predetermined and adjusted according to the results of flight tests.

 This device is free from the second drawback noted for the analogue, but the first continues to be present in it, which significantly reduces the safety of piloting.

 The aim of the invention is to increase flight safety by backing up and monitoring angle of attack sensors.

 The drawing shows a device for forming an angle of attack of an airplane.

 The device comprises a first sensor 1 of the angle of attack, a second sensor 2 of the angle of attack; weight sensor 3, pressure head sensor 4, normal overload sensor 5, setpoint 6 of the initial lift coefficient coefficient, flaps current position sensor 7, landing gear sensor 8, setpoint switch 9 of the initial slope of the lift characteristic as a function of angle of attack, number 10 sensor Mach, master 11 of the threshold value of the Mach number, the first block 12 of the formation of the true value of the angle of attack, the second block 13 of the formation of the true value of the angle of attack, the scale amplifier 14, the first adder 15, the second adder 16, third th adder 17, comparator 18, first division unit 19, first switch 20, second switch 21, multiplication unit 22, fourth adder 23, second division unit 24, control unit 25, switching unit 26, averaging device 27.

 The device operates as follows.

The signals from the sensors 1 and 2 of the angle of attack are received respectively at the inputs of the first and second blocks for generating signals of the true value of the angle of attack 12 and 13, in which the signals of the true angle of attack are formed, respectively, according to the following relationships:
α ₁ = K _α ˙α _{lion places} + α _about and
α ₂ = K _α ˙ _{α right places} + α _about
The signals α ₁ and α ₂ formed according to these dependences are then fed through the switching unit 26 to the first and second inputs of the averaging device 27. The signal of the true angle of attack α ₃ calculated by the indirect method, which is calculated as follows, is also sent to the third input of the averaging device .

а учитывая то, что для режимов горизонтального полета G=Y= C_угп.˙q˙S получают n_у=

где С_у текущий коэффициент подъемной силы;
q скоростной напор;
S эффективная площадь крыла;
G текущий вес самолета;
Y подъемная сила самолета;
C_угп=

коэффициент подъемной силы при горизонтальном полете.The normal overload n _у , measured by the sensor in the coupled axes, is determined by the expression
n _y =

and taking into account the fact that for the horizontal flight modes G = Y = C, the _angles .qqS get n _y =

where C _{y the} current coefficient of lift;
q speed head;
S effective wing area;
G current aircraft weight;
Y aircraft lift;
C _UGP =

lift coefficient for horizontal flight.

The lift coefficient is related to the angle of attack by the following relationship:
C _y = C _yo + C _y ^α α where C _{yo is the} initial value of the coefficient of lift corresponding to α0;
C _y ^{α the} steepness of the slope of the lift coefficient with respect to the angle of attack.

Определяющее влияние на значения C_y ^α и С_уо оказывают число М, механизация крыла, конкретно текущее положение закрылков и взлетно-полетно-посадочная конфигурация самолета.Expressing the angle of attack through the coefficient of lift, get
α =

The decisive influence on the values of C _y ^α and С _{у is} exerted by the number M, the mechanization of the wing, specifically the current position of the flaps and the take-off and landing configuration of the aircraft.

In accordance with this, as well as modeling data, the values of C _yo C _y ^α can be determined as follows.

=

C $\genfrac{}{}{0ex}{}{\text{α}}{\text{у}}$

где, δ₃ текущее положение угла отклонения закрылков;
K₁, K₂, K₃ коэффициенты пропорциональности, определяемые эмпирически;
С_уо1, С_уо2 начальные значения коэффициента подъемной силы, определяемые эмпирически;
C_yн ^α значение крутизны наклона С_у по углу атаки до определенного значения числа М=М_о.C

=

C $\genfrac{}{}{0ex}{}{\text{α}}{\text{at}}$

where, δ _{3 is the} current position of the flap deflection angle;
K ₁ , K ₂ , K ₃ proportionality coefficients, determined empirically;
С _уо1 , С _уо2 initial values of the coefficient of lift, determined empirically;
C _yн ^{α the} value of the slope of the slope C _y on the angle of attack to a certain value of the number M = M _about .

The values of C _yн ^α and М _{о are} determined empirically.

It should be noted that this method of determining the angle of attack is valid only for the region of the linear portion of the dependence С _у = f (α) for this type of aircraft.

However, taking into account the fact that the range of operational angles of attack of the aircraft is limited by the linear part of the characteristic С _у = f (α) and amounts to 70-80% of С _udop , as well as the results of the simulation, we can conclude that this method with a sufficient degree accuracy is suitable for determining the angle of attack for warning systems used on non-maneuverable heavy aircraft, since the response of the crew or self-propelled guns to the appearance of warning alarms is governed by the basic safety requirements and years should be clearly displayed in the area allowed for the operation angles of attack.

с выхода блока 19 поступает на вход блока умножения 22, на второй вход которого поступает сигнал нормальной перегрузки n_у с датчика 5. В умножителе происходит операция перемножения сигналов С_угп и nу и сформированный сигнал С_угп.n_упоступает на первый вход первого сумматора 15. С первого и второго выходов задатчика 6 начального значения коэффициента подъемной силы С_у01и С_у02 подаются соответственно на первые входы второго и третьего сумматоров 16 и 17, на вторые входы которых одновременно подается сигнал текущего положения закрылков с выхода датчика 7. В сумматорах 16 и 17 происходит операция суммирования сигналов С_у01 +К_i δ₃ и С_у02+ К₂ δ₃соответственно. Сформированные сигналы поступают на первый и второй управляемые входы второго коммутатора 20, на управляющий вход которого подается сигнал шасси убрано или шасси выпущено с выхода датчика 8. При наличии на своем управляющем входе сигнала шасси убрано, коммутатор 20 пропускает на выход сигнал первого управляемого входа С_у01 + К₁ δ₃, при смене сигнала на управляющем входе (т.е. появления сигнала шасси выпущено), коммутатор 20 пропускает на выход сигнал второго управляемого входа С_у02+ К₂ δ₃.So the signal from the weight sensor 3 is fed to a large-scale amplifier 14, the transmission coefficient of which contains the effective wing area for this type of aircraft (K _p = 1 / S). Formed signal G / S from the output of scaling amplifier 14 is supplied to the first input of the first dividing unit 19, to the second input of which the velocity pressure signal from the sensor 4. In block 19 there is a division operation signal and a signal generated _OCR = C

from the output of block 19, it enters the input of the multiplication block 22, the second input of which receives the signal of normal overload n _y from the sensor 5. In the multiplier, the operation of multiplying the signals C _dmp and ny and the generated signal C _dp. n _{y is} supplied to the first input of the first adder 15. From the first and second outputs of the setter 6, the initial values of the lifting coefficient С _у01 and С _у02 are applied respectively to the first inputs of the second and third adders 16 and 17, the second inputs of which simultaneously signal the current position of the flaps from the output of the sensor 7. In the adders 16 and 17, the operation of summing the signals С _у01 + К _i δ ₃ and С _у02 + К ₂ δ _3, respectively. The generated signals are fed to the first and second controlled inputs of the second switch 20, to the control input of which the chassis signal is removed or the chassis is released from the output of the sensor 8. If the chassis signal is removed on its control input, the switch 20 passes the output of the first controlled input C _{u01 to the output} + K ₁ δ ₃ , when changing the signal at the control input (i.e., the appearance of a chassis signal is issued), the switch 20 passes the output of the second controlled input С _у02 + К ₂ δ ₃ to the output.

Thus, the generated signal C _y6 from the output of the switch 20 is fed to the second input of the first at the adder 15 (at its first input there is a signal C _UGP ˙n _y ). In the adder 23, the operation of subtracting signals is performed, i.e., a signal C _{UHP is generated.} n _y -C _y0 , which from the output of the adder is fed to the first input of the second divider 24.

который с выхода делителя 24 подается через блок коммутации 26 на третий вход усредняющего устройства 27. В усредняющем устройстве формируется среднее значение сигналов

и с его выхода выдается потребителю, а также на четвертый вход блока контроля 25, на первый, второй и третий входы которого подаются сигналы α₁, α ₂, α₃соответственно с выходов блоков 12, 13 и 14. В блоке контроля 25 производится сравнение среднего значения

с абсолютными значениями сигналов α₁, α₂, α ₃ (с каждым в отдельности) и формирование их сигналов исправности (отказов). Сигналы исправности формируются на основе сравнения величины разности между средним значением угла атаки и абсолютным значением соответствующего подканала вычисления угла атаки с определенной, заранее выбранной величиной, которая в совокупности включает в себя и методические и инструментальные погрешности. На основе сформированных таким образом сигналов исправности (отказов) трех каналов вычисления в блоке контроля формируется также сигнал полного отказа всех каналов вычисления, заключающийся в отказе двух любых каналов. Сигналы отказов (исправности отдельных каналов вычисления и сигнал полного отказа поступают с выхода блока контроля 25 на первый, второй, третий и четвертый входы четвертого коммутатора 26 и одновременно потребителю. В коммутаторе 26 происходит процесс управления сигналами, вычисленными всеми тремя каналами, заключающийся в том, что при наличии всех сигналов исправности коммутатор пропускает на усредняющее устройство 27 все три сигнала α₁, α₂, α₃, а при отказе любого из них на усредняющее устройство поступает только два исправных сигнала.The signal C _yн ^α from the output of the setter 9 is supplied simultaneously to the first input of the fourth adder 23 and the first input of the second switch 21. The signals of the current value of the number M (M) from the output of the sensor 10 are simultaneously transmitted to the second input of the fourth adder 23 and the first input of the comparator 18, and the signal of the threshold value of the number M (M _o ) from the output of the setter 11 is supplied simultaneously to the third input of the adder 23 and the second input of the comparator 18. A signal C _yн ^α + К ₃ (М-М _o ) is generated in the adder 23, which then goes to the second input second switch 21. Comparator 18 crav ivaet signals _of M and M, and generates two control signals M ≅ M _o and M> M _o, which on one line are supplied to the control input of the third switch 21. In the presence of M commands ≅ M _of the switch 21 passes the output signal _yn C ^α and in the presence of the command M> M _о signal C _yн ^α + К ₃ (М-М _о ). Signal C _y ^α output from the switch 21 is supplied to the second input of the second divider 24. The divider 24 is an operation division signal C _UGP .n _y -C _y0 (first input signal) to the signal C _y ^α which the formation process is completed signal α ₃ =

which from the output of the divider 24 is fed through the switching unit 26 to the third input of the averaging device 27. In the averaging device, the average value of the signals

and from its output it is issued to the consumer, as well as to the fourth input of the control unit 25, to the first, second and third inputs of which the signals α ₁ , α ₂ , α ₃ are supplied from the outputs of blocks 12, 13 and 14. In the control unit 25, a comparison is made average value

with the absolute values of the signals α ₁ , α ₂ , α ₃ (each separately) and the formation of their health signals (failures). Service signals are generated by comparing the difference between the average value of the angle of attack and the absolute value of the corresponding subchannel of calculating the angle of attack with a specific, pre-selected value, which together includes both methodological and instrumental errors. On the basis of the health signals (failures) of the three calculation channels generated in this way, a signal of complete failure of all the calculation channels, consisting in the failure of any two channels, is also generated in the control unit. Failure signals (the health of individual calculation channels and a complete failure signal are received from the output of the control unit 25 to the first, second, third and fourth inputs of the fourth switch 26 and simultaneously to the consumer. In the switch 26 there is a process of controlling the signals calculated by all three channels, which consists in that in the presence of all health signals, the switch passes to the averaging device 27 all three signals α ₁ , α ₂ , α ₃ , and in case of failure of any of them, only two working signals arrive at the averaging device.

 In case of failure (sequential in time) of any of the remaining serviceable signals, the control unit 25 issues a signal of complete failure and the switch 26 disconnects both remaining signals from the averaging device.

Claims (1)

 A DEVICE FOR DETERMINING AN ATTACK ANGLE, which contains the first angle of attack sensor and the first unit of formation of the true value of the angle of attack, the second angle of attack sensor, an averaging device, and a control unit, characterized in that, in order to increase flight safety by backing up and monitoring angle sensors attack, it is additionally introduced the second block of formation of the true value of the angle of attack, the input of which is connected to the output of the second sensor of the angle of attack, the switching unit, the first, second and third output which are connected to the first, second and third inputs of the averaging device, the output of which is the output of the device for determining the angle of attack, a weight sensor, a scale amplifier, a first division unit, a multiplication unit, a first adder and a second division unit, outputs of the first and second blocks generating signals of the true value of the angle of attack and the second division unit are connected respectively to the first, second and third inputs of the control unit and the switching unit, the fourth input of the control unit is connected to the output ohms of the averaging device, the first, second, third and fourth outputs of the control unit are connected to the fourth, fifth, sixth and seventh inputs of the switching unit, a pressure head sensor, the output of which is connected to the second input of the first division unit, and a normal overload sensor, the output of which is connected to the second input of the multiplication unit, connected in series to the initial value of the coefficient of lift, the second adder and the first switch, the output of which is connected to the second inverse input of the first adder, the third sum a torus, the output of which is connected to the second input of the first switch, and the first input with the second output of the initial value adjuster of the lift coefficient, a flap current position sensor, the output of which is connected to the second inputs of the second and third adders, respectively, and a chassis status sensor, the output of which is connected to the control input of the first switch, the second switch, the output of which is connected to the second input of the second division unit, the fourth adder and comparator, the initial value of the slope the lift variables as a function of the angle of attack, the output of which is connected respectively to the first inputs of the second switch and the fourth adder, the Mach number detector, the output of which is connected respectively to the second input of the fourth adder, whose output is connected to the second input of the second switch, and the first input of the comparator, output which is connected to the control input of the second switch, the threshold value of the Mach number, the output of which is connected to the third inverse input of the fourth adder and the second input of the comparator and accordingly.