BUILDING A VERTICAL WITH THE HELP OF A PHYSICAL PENDULUM ON A PLANE

When piloting an aircraft, it is necessary to know its position relative to the plane of the earth's horizon. The position of the aircraft relative to the plane of the horizon is determined by two angles: the pitch angle and the roll angle. Pitch angle - the angle between the longitudinal axis of the aircraft and the horizon plane, measured in the vertical plane. Bank angle - the angle of rotation of the aircraft around its longitudinal axis, measured from a vertical plane passing through the longitudinal axis of the aircraft

Fig. 4.1 physical pendulum - the determinant of the vertical on the plane.

Thus, the position of the aircraft relative to the plane of the horizon can be determined if the direction of the true vertical is known on the aircraft, i.e., the direction of the line passing through the center of the Earth and the aircraft, and the deviation of the aircraft from this direction is measured.

The deviation from the vertical on the ground is determined by an ordinary plumb line, that is, a physical pendulum.

Assume that a physical pendulum is mounted on an airplane that is flying horizontally with acceleration a(Fig. 4.1). To the mass of the pendulum t forces will act from the acceleration of gravity g and inertial force from acceleration a. The sum of the moments from these forces relative to the suspension point of the pendulum is zero and is expressed by the equation

where l- pendulum length;

α - pendulum deflection angle

From equation (4.1) we have

(4.2)

Consequently, a pendulum mounted on an object moving with acceleration deviates in the direction opposite to the action of acceleration, and shows the so-called "apparent vertical". Modern transport aircraft can have accelerations commensurate in magnitude with the acceleration of gravity, so the angle α of deviation of the pendulum from the vertical can reach significant values. Thus, a physical pendulum is not suitable for determining the direction of the vertical position, i.e., for measuring the angles of roll and pitch, if the aircraft is flying with acceleration.

AIRHORIZONS

Earlier it was noted that the pendulum can be used to determine the vertical only when flying without accelerations, and a free three-degree gyroscope can maintain a given spatial position, regardless of the current accelerations, only for a short time.

Therefore, these two devices are connected together, using the positive properties of each. In the absence of accelerations using the pendulum, the main axis of the gyroscope is set vertically. In those moments when accelerations act on the pendulum, it is turned off and the gyroscope operates in the "memory" mode.

The device by which the pendulum acts on the gyroscope is called the pendulum correction system. A gyroscope with such a correction is called a vertical gyroscope. The vertical gyro, which visually shows the position of the aircraft relative to the earth's horizon, is called the artificial horizon.

The artificial horizons use an electrolytic pendulum (Fig. 4.2), which is a flat copper bowl 3, filled with conductive liquid 1 with high electrical resistivity. There is so much liquid in the bowl that there is room for an air bubble 2 . The bowl is closed with a lid made of insulating material, in which four contacts are mounted. 4, the fifth contact is the bowl itself. If the pendulum is located horizontally, then all four contacts are evenly overlapped by the liquid and the electrical resistance of the sections between them and the bowl is the same. If the bowl tilts, then the air bubble, occupying the upper position in the bowl, will expose one of the contacts and thereby change the electrical resistance of the section, which at small angles (up to 30 ") is proportional to the angle of the bowl.

The pendulum contacts are connected to the electrical circuit, as shown in fig. 4.3. When the pendulum is tilted, the resistance between pins 0 and 1 will be greater than the resistance between pins 0 and 3. Then the current i 1 which passes through the control winding OY 1, there will be less current i 2 windings OY 2 correction motor. The windings OY 1 and OY 2 are wound oppositely, so the difference current Δ i=i 2 -i 1 creates a magnetic flux, which, interacting with the magnetic flux of the field winding, causes a torque. The motor rotor is fixed on the gimbal axis, therefore, a moment is applied to the gimbal axis, under the action of which the gyroscope precesses. The precession of the gyroscope continues as long as there is a moment along the gimbal axis, and this moment acts until the pendulum is set to a horizontal position, at which the current i 1 =i 2. By connecting the pendulum with the inner , frame of the cardan suspension and placing correction motors along the axes of the suspension, we obtain a vertical gyro with electromechanical pendulum correction (Fig. 4.4). So the electrolytic pendulum 1 , acting on the gyroscope through correction motors 2 and 3 , will always bring the main axis of the gyroscope to the vertical position. When the correction is turned off, the gyroscope will retain its previous position in space with an accuracy determined by its own errors, for example, due to precession caused by friction moments along the axes of the gimbal.

Correction systems differ in types of characteristics. The correction characteristic is the law of change in the moment developed by the correction engine, depending on the deviation of the main axis of the gyroscope from the vertical position.

In aviation instruments, the mixed correction characteristic has become most widespread (Fig. 4.5). Area ±Δ α defines the dead zone of the system. Up to some extreme angles α etc,

β pr moment of correction M k varies in proportion to the angles α and β and then becomes constant.

ERRORS OF GYROVERTICALS

The error from the moments of friction in the axes of the card and o v a p o dvesa. Friction moments inevitably exist in the axes of the gimbals, so the precession of the gyroscope under the action of correction moments continues until the correction moment is greater than the friction moment. The movement of the gyroscope stops when these moments are equal:

It follows from this that the main axis of the gyroscope will not reach the vertical position at angles α * and β *:

Thus, due to friction in the axes of the gimbal suspension, the vertical gyro has a stagnation zone, which depends on the value of the friction moment in the axes of the gimbal suspension and, naturally, on the dead zone of the pendulum correction (see Fig. 4.5). The greater the specific moment developed by the correction engines, the smaller the stagnation zone. Too much specific moment leads to significant errors in the turn. For artificial horizons, the stagnation zone is usually 0.5-1°.

Visual error. When the plane makes a turn with an angular velocity ω, then on the pendulum, in addition to gravity mg, there is still centrifugal force mω 2 R, and the pendulum is not set along the true vertical, but along the resultant of these forces (Fig. 4.7). Signals are sent to the correction motors, and the main axis of the gyroscope is set to the position of the apparent vertical. This process is the faster, the greater the specific moments k x , k y correction systems. As can be seen from Fig. 3.10, the lateral correction system generally works incorrectly on a turn. Therefore, in modern gyro-verticals and artificial horizons, the transverse correction on turns is turned off by a special device.

Naturally, the linear acceleration of the aircraft, for example, with an increase in speed, also leads to similar errors. Therefore, in such artificial horizons as AGD-1, longitudinal correction is also disabled. When the correction is disabled, the vertical gyro operates in the “memory” mode. After the end of the evolution of the aircraft associated with accelerations, the correction system turns on and brings the main axis of the gyroscope to a vertical position if it deviated during operation in the "memory" mode.

An error appears at the gyro-verticals both due to the daily rotation of the Earth and due to the aircraft's own flight speed, but for transport aircraft this error does not exceed a few arc minutes.

a red flag will appear 12. This switch connects the control windings of the transverse correction motor 4 with phase C, bypassing the resistance R2, and thereby increases

current in the motor, and consequently, the correction torque developed by it.

After the device reaches the nominal operating mode, the switch 10 should be returned to its original position (the flag will disappear from view). In the nominal mode of operation, the control windings of the correction motor 4 connected to phase C through the contacts of the correction switch VK-53RB.

AVIAGORIZON AGI-1s

The attitude indicator is designed to determine the position of the aircraft in space relative to the true horizon line, it has a built-in glide indicator device. The artificial horizon is installed on transport aircraft of civil aviation.

The kinematic scheme of the device is shown in fig. 4.8, simplified electrical - in fig. 4.9, and a view of the scale - in fig. 4.10.

Consider the operation of the device. Own axis of rotation of the gyroscope (see Fig. 4.8) according to signals from the electrolytic pendulum 8 with corrective motors 3 and 10 installed and held in a vertical position.

A feature of the AGI-lc artificial horizon is the ability to work in an unlimited range of roll and pitch angles. This is possible due to the use of an additional tracking frame in the device. 4, the axis of which coincides with the longitudinal axis of the aircraft, and the frame itself can be rotated relative to the aircraft by the engine 11 . The purpose of the additional tracking frame is to ensure the perpendicularity of the axis of the gyroscope's own rotation and the axis of the outer frame of the gimbals. When the aircraft rolls, the outer frame 5 gimbal pivots around the axis of the inner frame. This rotation is fixed by a switch 9 (see fig. 4.8 and 4.9), with which the engine is turned on 11 , turning the follower frame 4 , and with it the frame 5 in the opposite direction. Therefore, the perpendicularity of the gyroscope's own axis 6 and the axes of the outer frame are not violated. When the aircraft makes pitch evolutions at angles greater than 90˚, using the switch 12 the direction of rotation of the motor changes 11. For example, if the aircraft makes the figure "Nesterov's loop", then at the moment when it is in an inverted state, i.e., it changes its position relative to the main axis of the gyroscope by 180 °, the direction of rotation of the engine 11 to rotate the follower frame must be reversed.

When the aircraft performs evolution in pitch, the aircraft rolls around the axis of the outer frame of the gimbals and therefore has a range of 360°.

Indication of the position of the aircraft relative to the plane of the horizon in AGI-1s is carried out according to the silhouette of the aircraft (see Fig. 4.8 and 4.10), mounted on the body of the device, and the spherical scale 2, connected with the axis of the inner frame 7 of the gimbal suspension of the gyroscope. spherical scale 2 colored brown above the horizon and blue below the horizon. On the brown field there is the inscription "Descent", on the blue one - "Ascent". Thus, when climbing, the silhouette of the aircraft, together with the aircraft itself, will move to the blue field, as shown in Fig. 3.18, in, since the scale 2, associated with the gyroscope, will remain motionless in space. It should be noted that the indications of the attitude indicator AGI-lc in pitch are opposite to those of AGB-2. This is extremely important, since both instruments are sometimes installed on the same aircraft.

Figure 4.9 Electrical diagram of the artificial horizon AGI-1.

Reducing the time of the initial alignment of the axis of the gyroscope's own rotation to the vertical position is achieved by successively switching on the excitation windings of the correction motors 3 and 10 with gyro motor stator windings. In addition, there is a mechanical pendulum on the inner frame 7, which, when the device is not turned on, keeps the frame system approximately at zero

position. For the same purpose, a mechanical arrester is used, when the button is pressed 15 which (see Fig. 4.10) the additional follow-up frame is set to the zero position. On the button there is an inscription "Press before starting". In order to reduce the turn error of the artificial horizon, the transverse correction engine 3 on a bend it is turned off by the correction switch VK-53RB. On the front side of the device, at the bottom, there is a slip indicator 13 and on the left - the handle 14 to change the position of the aircraft silhouette.

AV-HORIZON AGD-1

The remote attitude indicator AGD-1 provides the crew with an easily perceived large-scale indication of the position of the aircraft relative to the plane of the true horizon and

gives consumers (autopilot, heading system, radar stations) electrical signals proportional to aircraft roll and pitch deviations.

AGD-1 consists of two devices: 1) a three-degree gyroscope with pendulum correction, called a gyro sensor, which is installed as close as possible to the center of gravity of the aircraft; 2) signs placed on the dashboards of the crew. Up to three pointers can be connected to one gyro sensor.

The principal electromechanical diagram of AGD-1 is shown in fig. 4.12, a view of the indicator scale is shown in fig. 4.13

Figure 4.13 front side of the AGD-1 artificial horizon.

36-catch button, 37- lamp, other designations are the same kA on 4.12.

The gyro sensor is a three-stage gyroscope, the axis of the outer gimbal frame of which is mounted in the follower frame 7. The purpose of the follower frame is to ensure the operation of the device in a roll in an unlimited range of angles. Follower frame 7 ensures the perpendicularity of the axis of own rotation of the gyroscope to the axis of the external frame of the suspension with the help of an induction sensor

chika 3 and engine generator 2, amplifier controlled 1 . Anchor 5 sensor is fixed on the axis of the inner frame, and the stator 3 rigidly connected to the outer frame 8 cardan suspension.

Switch 4 changes the direction of rotation of the motor 2, when the aircraft makes pitch changes with angles greater than 90°. Thus, the tracking frame 7 performs the same functions as in the artificial horizon AGI-1s.

A feature of the tracking system for testing the frame 7 in roll in the attitude indicator AGD-1 is the use of an amplifier based on semiconductor elements and a motor-generator. The pendulum correction of AGD-1 is similar to the correction of AGI-lc and AGB-2, but differs in that the transverse correction motor 6 switched off not only by the switch 17, which is controlled by the VK-53RB correction switch, but also by a special lamellar device (not shown in the diagram) at rolls of 8-10 °. In addition, the longitudinal correction motor 10 controlled by an electrolytic pendulum 13 via fluid accelerometer 16. It is a device similar to a liquid pendulum. During longitudinal accelerations of the aircraft, the conductive fluid shifts to one of the contacts under the action of inertial forces, and due to an increase in the electrical resistance of the circuit, the correction is weakened by 50%.

Aircraft roll and pitch deviations are measured by a gyro sensor and transmitted to the pointer by two identical tracking systems:

1) a roll tracking system, which consists of a selsyn sensor 9, selsyn-receiver 20, amplifier 18 and engine generator 19;

2) tracking system in pitch, which includes: synchro-sensor 14, synchro-receiver 23, amplifier 24, engine-generator 25.

Switch 15 is included in the tracking system in pitch for its correct operation at an angle of more than 90 °. A feature of tracking systems in AGD-1 is the use of engine-generators as actuators. The engine-generator is an electric machine consisting of a motor and a generator mounted on a single shaft. The voltage generated in the generator is proportional to the engine speed. In the servo system, it serves as a high-speed feedback signal for damping system oscillations. engine-generator 19 turns the gear 21 with the silhouette of an airplane 22 relative to the body of the device, and the engine-generator 25 rotates the pitch scale 26,

having a two-tone color: above the horizon - blue, below - brown. Thus, the indication of indications is carried out according to the movable silhouette of the aircraft and the movable pitch scale.

The indication of the position of the aircraft relative to the plane of the horizon in AGD-1 is natural, that is, corresponding to the image that the crew imagines about the position of the aircraft relative to the ground. A rough reading of the roll is possible on a digitized fixed scale on the instrument body and on the silhouette of the aircraft; on a scale 26 and the silhouette of the aircraft approximately determine the pitch angles. The indication of the AGD-1 pointer for roll and pitch is shown in fig. 4.11. In our opinion, determining the position of the aircraft in AGD-1 is more convenient than in AGB-2 and AGI-1s.

The artificial horizon AGD-1 uses a special device called a arrester, which allows you to quickly bring the frame of the device and the gyromotor into a strictly defined position relative to the body of the device and, consequently, the aircraft. The kinematic diagram of the electromechanical remote caging device AGD-1 is shown in fig. 4.14.

The device works as follows. By pressing the red button 36 (see Fig. 4.13), located on the front side of the indicator, voltage is applied to the motor 34 (see Fig. 4.14. which, rotating, causes the rod to move forward 33 using a finger moving along the screw slot, i.e. the rotating nut is stationary, and the screw moves. Stock 33 through roller 32 abuts against an additional follow-up frame 7, which has a wedge-shaped ring 35.

Due to this profile of the ring, when pressure is applied to the frame from the rod side, the ring 35 together with the gyro unit rotates around the axis of the frame 7 until the roller 32 will not be in the lower position of the ring. The plane of the frame 7 is parallel to the plane of the wings of the aircraft. Next stock 33 moves the profile bar 31, which rests on the fist 30 and creates a moment around the axis of the outer frame 8. Under the action of this moment, the gyroscope precesses around the axis of the inner frame and reaches the stop, after which the precession stops, and the gyroscope begins to rotate around the axis of the outer frame until the protrusion of the bar 31 will not fit into the cam cutout 30, thus fixing the frame 8 in a position where the axis of the inner frame is parallel to the longitudinal axis of the aircraft.

At the same time, the finger 28, resting against cam 27, installs the inner frame 12 to a position in which the axis of the gyroscope's own rotation is perpendicular to the axes of the outer and inner frames of the gimbals. Then stem 33 under the action of the return spring present in it, it reclines to its original position and allows the bar 31 release the cams 27 and 30.

Thus, the arrester, having set the frames of the gyro node to a certain position, immediately releases them. If caging is performed on the ground, when the aircraft is level, or in level flight, then the own axis of rotation of the gyroscope is set in the direction of the vertical position. Caging should be carried out only in level flight, as the inscription on the button reminds the crew 36 "Charging in level flight."

If caging is performed, for example, during a roll, then when switching to level flight, the attitude indicator will show a false roll. True, under the action of the pendulum correction, the own axis of the gyroscope will be set to a vertical position, and, naturally, false readings will disappear, but this will take time, sufficient for the crew to make mistakes in piloting. It should be noted that the electrical caging circuit is designed in such a way that when the AGD-1 is turned on, the caging occurs automatically, without pressing a button. When re-caging, for example, in case of a temporary power failure of the AGD-1, pressing the button 36 mandatory, but only in level flight.

There is a signal lamp on the front side of the indicator 37 (see Fig. 4.13), which lights up, firstly, if the caging process occurs and, secondly, in case of malfunctions in the power supply circuits of the gyromotor and DC ±27 V.

AV-HORIZON AGB-3 (AGB-Zk)

The main purpose of the AGB-3 attitude indicator is to provide the crew with an easily perceived large-scale indication of the position of an aircraft or helicopter in terms of roll and pitch angles relative to the plane of the true horizon. In addition, the artificial horizon allows you to issue electrical signals proportional to the angles of roll and pitch, external consumers available on the plane and helicopter (autopilot, heading system, etc.).

The attitude indicator AGB-Zk is a modification of the attitude indicator AGB-3. differs only in the presence of built-in fittings of red illumination to illuminate the front of the device and the color of the elements: indication.

The electromechanical scheme of the AGB-3 artificial horizon is shown in fig. 4.15, electrical circuit - in fig. 4.16, and a view of its scale - in fig. 4.17. The own axis of the gyroscope is brought to a vertical position by a pendulum correction system, which includes two electrolytic pendulums 20 and 21, controlling correction engines 7 and 9. AGB-3 uses single-coordinate: electrolytic pendulums operating on the same principle as two-coordinate, which are used in AGB-2, AGI-lc and AGD-1. A one-axis pendulum has three contacts and only responds to tilts in one direction. There is a contact in the transverse correction circuit 16 correction switch VK-53RB, which breaks the circuit when the aircraft makes turns, reducing the turning error.

The time the device is ready to work in the artificial horizon is reduced by a mechanical lock (it is not shown in Fig. 4.15). If the aircraft is in a horizontal position, then the arrester sets the frame of the gyro unit to its initial state, in which the main axis of the gyroscope coincides with the vertical position. The arrester is used before starting the device, when for one reason or another it is necessary to quickly bring the frame of the device to its original position. The arrester in the AGB-3 is of a push type, i.e. for its operation it is necessary to press the button 26 (see Fig. 4.17) to failure. The frames are automatically released from the cage when the button is released.

The operation of the arresting device is similar to the operation of the arrester in the artificial horizon AGD-1. The artificial horizon AGB-3 has a mechanical arrester.

To provide consumers with signals of aircraft deviation in roll and pitch, a selsyn sensor is installed on the axis of the outer frame of the gimbals 14 (see Fig. 4.15, 4.16), and on the axis of the inner frame - the selsyn sensor 15.

On an aircraft, the attitude indicator is set in such a way that the axis
outer frame 8 (see Fig. 4.15) is directed parallel to the longitudinal axis of the aircraft. This ensures the operation of the device in a roll in the range of angles of 360°.

The axis of the inner frame of the gimbals is parallel at the initial moment to the transverse axis of the aircraft. Since additional

There is no tracking frame in AGB-3, as in AGI-lc and AGD-1, then the operating range in pitch in this attitude is limited to angles of ±80°. Indeed, if the aircraft has a pitch angle of 90°, then the axis of the outer frame will be aligned with the axis of the gyroscope's own rotation. The gyroscope, having lost one degree of freedom, becomes unstable. However, to provide the crew with a correct indication of the position of the aircraft relative to the plane of the horizon in an inverted state (for example, when performing the figure “Nesterov’s loop”), stops are used in the device 10 and 11 (see figure 4.15). When performing complex evolutions with an aircraft with a pitch angle of more than 80 °, the stop 10, located on the outer frame, will begin to put pressure on the stop 11, fixed on the axis of the inner frame. This creates a moment around the axis of the inner frame. According to the law of precession, the gyroscope precesses under the action of this moment, i.e., rotates around the axis of the outer frame, trying to align the axis of its own rotation with the axis of application of the moment along the shortest distance. Thus, the outer frame is cardan under. weight rotates 180°. When the pitch angle is over 90°, the stop 11 get off the hook 10, precession will stop, and the silhouette of the aircraft 4 will be inverted by 180° relative to the pitch scale 3, which will indicate the inverted position of the aircraft by 180 relative to the horizon plane.

Indication of the position of the aircraft relative to the plane of the horizon in AGB-3 is carried out as follows. During rolls, the body of the device, together with the aircraft, rotates around the axis of the outer frame by a roll angle, since the own axis of rotation of the gyroscope maintains a vertical direction. Airplane silhouette 4 at the same time, it participates in two movements: 1) portable - together with the body of the device at a roll angle at(Fig. 4.18) and 2) rotational (tribe 6 rolls around the tribka fixed in roll 5) at the same angle Y- As a result of these two movements, the silhouette of the aircraft in space rotates by a double angle of the aircraft roll. The crew, on the other hand, observes the roll angle by the movement of the aircraft silhouette 4 relative to the scale 3. In this case, the silhouette turns to a natural bank angle in the same direction as the aircraft.

Rough reading of roll angles can be made on a scale 27 on the body of the device, and the pitch angles - on the scale 3 and the silhouette of the plane 4. The pitch scale follows the pitch angles of the aircraft thanks to a tracking system that includes a synchro 15, located on the internal axis of the gimbals, selsyn-receiver 19, amplifier 17 and engine generator 18. In the slot of scale 3 there passes an axis on which the silhouette of the aircraft is fixed.

Thus, the roll and pitch readings in the AGB-3 are natural and identical to those of the AGD-1 (see Fig. 4.11).

AGB-3 has a circuit for signaling a failure in the power supply circuits of the device, containing the following elements: power failure motor 1 with a flag 2 (see fig. 4.15 and 4.16) and two relays 22 and 23. Motor windings 1 connected in series with the gyro motor stator windings 13. With serviceable AC circuits of 36 V, currents of the gyromotor and selsyn sensors flow through the motor windings 14 and 15.

As a result, a torque is generated on the motor shaft 1, under the influence of which the flag 2 signaling device mounted on the motor shaft is removed from the visible area of ​​the front of the device.

If there is no AC voltage in the power supply circuit of the gyro motor or a phase failure occurs, then the engine torque drops sharply and, under the influence of a spring, the flag is thrown into the visible zone of the front of the device.

Relay 22 and 23 are connected in parallel to the power supply circuit of the pitch tracking system amplifier. In the absence of 27 V DC voltage, the contacts 24 and 25 these relays close, shunting two phases of the windings of motor 1, therefore, its torque decreases, and the spring throws out the flag 2, which indicates a power failure.

Thus, an open in a circuit with a voltage of 36 V, a frequency of 400 Hz or in a circuit with a voltage of 27 V, as well as the absence of one of these types of power supply, can be determined by the presence of a signaling flag in the field of view of the scale of the instrument.

AVIAGORIZON AGK-47B

The attitude indicator is combined, since three devices are mounted in one housing: an attitude indicator, a direction indicator and a slip indicator.

The purpose of the artificial horizon is to provide the crew with information about the position of the aircraft relative to the horizon plane. The turn indicator is used to determine the direction of the aircraft's turn, and the slip indicator measures the slip. The direction indicator is discussed in sec. 4.2, and the slip indicator - in sec. 3.11. Simplified kinematic, electrical diagrams and the front side of the attitude indicator are shown in fig. 4.19, 4.20, 4.21; All designations in the figures are the same.

The own axis of rotation of the gyroscope 7 (see Fig. 4.19, 4.20) is brought to a vertical position using a pendulum correction system, which includes an electrolytic pendulum, / 6 and two solenoids 13 and 14, Solenoid 13 located perpendicular to the outer axis at gimbals, and the solenoid 14 - perpendicular to the inner axis X gimbals on inner frame 6, made in the form of a casing. Each of the solenoids has two windings, which, when currents pass through them, create magnetic fields in the opposite direction. Solenoids have metal cores that have the ability to move inside the solenoids. If the own axis of rotation of the gyroscope coincides with the direction of the local vertical, then the electrolytic pendulum receives the same signals from the electrolytic pendulum to the windings of the solenoids and the cores, being in the middle position, do not create moments around the axes of the gimbals. If the main axis of the gyroscope deviates from the vertical direction, the currents flowing through the windings of the solenoids will not be equal due to the unequal resistances between the contacts of the electrolytic pendulum. This will lead to the movement of the cores in the solenoids, and due to their weight around the axes of the gimbal, moments will arise that will return the axis of the gyroscope's own rotation to a vertical position. So solenoid 14 participates in creating a moment around the internal axis of the gimbal, and the solenoid 13 - around the outer axis of the suspension.

The outer axis of the artificial horizon gimbal is parallel to the transverse axis of the aircraft, so the pitch indication is carried out on a circular scale 4, associated with the outer frame of the gimbals 5, and the horizon line associated with the body of the device. When diving or pitching, the horizon line moves relative to a fixed scale - the picture appears to the pilot in reverse: the silhouette of the aircraft 1 along with the scale 4 descends or rises relative to the horizon line. The roll indication is carried out according to the relative position of the aircraft silhouette /, connected with the internal frame of the gimbals, and the scale 3, mounted on the outer frame of the gimbals. In order for the indication of the roll to be natural, i.e., the silhouette of the aircraft imitated a roll relative to the horizon plane, just like in AGB-3, a pair of gears with a gear ratio of 1:1 was used in AGK.-47B. The pitch scale is digitized at 20°, and the roll scale is marked at 15°. The roll and pitch indication of the AGK-47B during aircraft evolutions is shown in fig. 4.11.

The artificial horizon has a fixed-type mechanical arrester, i.e. if in AGB-3 and AGD-1 the arrester works only when the button is pressed, then in AGK-47B it is possible by extending the arrester rod 20 (Fig. 4.21) towards you, fix it in this position. When the device is locked, a red flag appears on the front side of the device with the inscription "Clamped". When the device is locked, the axis of the gyroscope's own rotation coincides with the vertical axis of the aircraft, and the axes at and x coincide respectively with the longitudinal and transverse axes of the aircraft. On the control handle of the arrester, it is written "Pull arrester".

With the help of a cremal 22 it is possible to change the position of the artificial horizon line relative to the body of the device to some extent, which is sometimes advisable to do for the convenience of maintaining the flight path in pitch, during a long non-horizontal flight.

Like any artificial horizon, the AGK-47B is subject to a turn error, but due to the fact that it is intended for installation on light aircraft, where there may not be a correction switch, the correction is not turned off in it. At the same time, to reduce the error during a left turn, the device is designed in such a way that the normal position of the axis of its own rotation is its inclined position forward, along the flight, by 2°. The decrease in the error specifically for the left turn can probably be explained by the fact that aircraft make left turns more often, since the aircraft commander sits in the cockpit on the left seat. Indeed, with a left bend, the electrolytic pendulum will show an apparent vertical, which deviates inside the bend by an angle

where ω is the angular velocity of the turn; V- aircraft flight speed; g- acceleration of gravity.

Under the action of the transverse correction system using a solenoid 13 the gyroscope will begin to precess towards the apparent vertical at a speed

At the same time, when turning, the end of the gyroscope's own axis of rotation will turn around the position of the true vertical with a speed

(4.5)

where α 0 is the initial angle of inclination of the gyroscope's own rotation axis forward (Fig. 4.22), directed in the opposite direction, since the gyroscope seeks to keep the position of the gyroscope's own rotation axis in space unchanged. The direction of the velocity ω γ is opposite to the direction of the gyroscope precession velocity β.

Obviously, in order for there to be no error during the left bend, the condition must be satisfied

or for small angles β 0 (4.6) one can write

(4.7)

(4.8)

Knowing K u the artificial horizon and the most common speeds at which the turn occurs, it is possible to determine the required angle α 0 of inclination of the gyroscope axis.

AV-HORIZON AGR-144

The AGR-144 attitude indicator is a combined instrument; three instruments are mounted in it: an attitude indicator, a direction indicator and a slip indicator.

The purpose of the artificial horizon is to provide the crew with information about the aircraft's position relative to the horizon plane. The direction indicator is used to determine the presence and direction of the aircraft's turn around its vertical axis. The glide indicator measures the aircraft's glide. In addition, when coordinated

Basic dynamic forces

A jump is a complex concept: the result of the interaction of two or more variables, the operation of the laws of physics and man. To understand how such an interaction occurs, it is necessary to consider each quantity separately.

"Magnet under the table"

If I scattered metal filings on the table, you would probably look at me in surprise. But if I placed a magnet under the surface of the table and started moving it, you would think that I am a magician. Of course, there are no miracles here. This is a simple operation of the laws of physics. The obvious reality is the movement of metal filings on the surface of the table for no apparent reason. In fact, the magnet acts on sawdust as it should act without any interference from otherworldly forces. Approximately the same thing happens with the flight. Until we deal with the basic dynamic forces, we will assume that some kind of miracle is happening. To learn how to fly, you must understand how these forces operate.

It is necessary to learn to understand the situation as a whole. Take, for example, birds. They are not considered the smartest in the world. They have not even attended kindergarten, however, they have a comprehensive understanding of the basic principles of flight, which allows them to fly safely and more gracefully than a person does. Maybe we think too much? However, a person can fly. We can learn to deal with situations and relationships. It is our rational understanding of the principles of flight that makes it possible. We will never get to where our thoughts have not yet been. When you have thought and analyzed everything, you understand that there are a huge number of details that control a flying body. We must study each component of the jump, look at it under a microscope in order to understand how a whole is formed from separate parts. I propose to start by learning the language of flight.

Spatial Language

The various variables related to flight require clarification (definition) of what can be done with language. Such language is very specific to aviation, where ordinary and familiar words take on a different meaning depending on the specific situation.

Roll, pitch and yaw

Orientation or location should be understood only in relation to something. This “something” is the celestial body closest to us, that is, the Earth. When we start parachuting onto other celestial bodies with less gravity than the earth, we will determine our position in relation to the nearest planets. The system that we use to determine our position requires the construction of three axes of orientation. Let's simplify our task by taking the human body for a flying body. If you spread your arms out to the sides, your arms will represent the "Pitch Axis". Off-axis can be demonstrated by tilting the body forward and backward. The "Axis of Roll" is the pole that goes through your chest. Deviation from this axis will be slopes to the sides. The third axis is the "Yaw Axis" (the axis of rotation in the horizontal plane around the vertical axis). It can be thought of as a pole running through your body from head to toe. Deviation from this axis will be a turn-pirouette to the right or left.

Let's check the correctness of your understanding of these terms with specific examples. Imagine that you are an airplane flying at a certain altitude. If you are asked to deviate from the pitch axis down, you will force the plane to drop its nose. Increasing the axis will force you to lift your nose up in relation to your tail. If you need to roll to the right, you lower the right wing and raise the left. "Yaw" to the right would be a simple turn to the right in the horizontal plane.

Attention! This site is not updated. New version: shatalov.su

Transformations: The Last Stand

Creation date: 2009-10-20 03:43:37
Last edited: 2012-02-08 09:36:52

Preliminary Lessons:
1. Trigonometry. Go.
2. Vectors. Go.
3. Matrices. Go.
4. coordinate spaces. Go.
5. Transformations of coordinate spaces. Go.
6. perspective projection. Go.

Something we haven't remembered about the transformations for a long time! Probably, my dear reader, have you already missed them? As practice shows, transformations are the most favorite topic for those who study three-dimensional programming.

At this point, you should already be well versed in transformations.

45. The principle of operation of the roll, pitch and yaw channels of the autopilot.

If not, then look at the preliminary lessons.

When we were just starting to study transformations, I wrote that with the help of matrices, you can manipulate objects in space: move, rotate, increase. If you have studied all the previous lessons and tried to apply the acquired knowledge in practice, then most likely you had to face certain difficulties: how to move objects in an arbitrary direction, how to make a matrix for converting to camera space, how to rotate objects in an arbitrary direction?

We will consider these issues today.

Moving in space

A small note: we will denote the world space of coordinates by the axes x, y, z. The basis vectors forming the local (object, camera) space will be denoted as i=(1,0,0), j=(0,1,0), k=(0,0,1) (vector names are read as: and, zhi, ka). Vector i is parallel to the x-axis, vector j— y-axes, vector k- z-axis.

I remind you that any vector of space can be expressed using a linear combination (sum) of basis vectors. Also, do not forget that the length of the basis vectors is equal to one.

Now let's look at the picture:

For simplicity, we have discarded one dimension - vertical. Accordingly, the pictures show a top view.

Let's say we are at some point in world space. In this case, the pronoun "we" can mean anything: an object in the game world, a character, a camera. In this case ( fig.a) we look towards the point A. How do we know that the "look" is directed towards the point A? Well, when we discussed cameras, we agreed that the vector k indicates the direction of view.

We are separated from the center of the world (world coordinate space) by the vector v. And suddenly! We terribly wanted to approach the point A. First thought: remove the value (dz) from the “forward” arrow and add it to the third component of the vector v. The result of this misunderstanding can be seen in fig.b. It would seem that everything is gone - goodbye dreams of your own quake. Stop panic! You just need to carefully consider the current situation.

Imagine that we are already at the point A- look at fig.c. As can be seen from the figure, after moving the vectors k and i not changed. Accordingly, we will not touch them.

Looking at the rest of the picture: vector v after moving is the sum of two vectors: the vector v before moving and the vector unknown to us, coinciding in direction with the vector k… But now we can easily find an unknown vector!

If you carefully studied the lesson about vectors, then you remember that multiplying a scalar by a vector increases (if the scalar is greater than one) the vector. Therefore, the unknown vector is k*dz. Accordingly, the vector v after moving can be found by the formula:

Well, isn't it simple?

Rotation around axes

We already know the formulas for rotation around the axes. In this section, I will simply explain them more clearly. Consider the rotation of two vectors around the center of coordinates in two-dimensional space.

Since we know the angle of rotation (angle alpha), then the coordinates of the basis vectors of the space can be easily calculated using trigonometric functions:

i.x = cos(a); i.z = sin(a); k.x = -sin(a); k.y = cos(a);

Now let's look at the rotation matrices around the axes in three-dimensional space and at the corresponding illustrations.

Rotation around the x-axis:

Rotation around the y-axis:

Rotation around the z-axis:

The figures show exactly which vectors change their coordinates.

A small note: it is wrong to talk about rotation around the axes. Rotation happens around vectors. We do not know how to represent straight lines (axes) in computer memory. But vectors are easy.

And one more thing: how is the positive and negative rotation angle determined? It's easy: you need to "stand" in the center of coordinates and look towards the positive direction of the axis (straight line). Counterclockwise rotation is positive, clockwise rotation is negative. Accordingly, in the figures above, the angles of rotation around x and y are negative, and the angle of rotation around the z-axis is positive.

Rotation around an arbitrary line

Imagine this situation: you rotate the camera with a matrix around the x-axis (tilt the camera) twenty degrees. Now you need to rotate the camera twenty degrees around the y-axis. Yes, no problem, you say ... Stop! And around what now you need to rotate the object? Around the y-axis that was before the previous rotation or after? After all, these are two completely different axes. If you simply create two rotation matrices (around the x-axis and around the y-axis) and multiply them, the second rotation will be around the original y-axis. But what if we need the second option? In this case, we will need to learn how to rotate objects around an arbitrary straight line. But first, a little test:

How many vectors are in the following picture?

The correct answer is three vectors. Remember: vectors are length and direction. If two vectors in space have the same length and direction, but are located in different places, then we can assume that this is the same vector. In addition, in the figure, I depicted the sum of vectors. Vector v = v 1 + v 2 .

In the lesson on vectors, we briefly looked at the scalar and cross product of vectors. Unfortunately, we have not studied this topic in more detail. The formula below will use both the dot and cross product. Therefore, just a couple of words: the value of the scalar product is the projection of the first vector onto the second. With a vector product of two vectors: a x b = c, vector c perpendicular to the vectors a and b.

We look at the following figure: a vector is defined in space v. And this vector needs to be rotated around the straight line l (el):

We do not know how to represent lines in programs. Therefore, we represent the line as a unit vector n, which coincides in direction with the straight line l (el). Let's look at a more detailed picture:

What we have:
1. Line l represented by a vector of unit length n. As mentioned above, the rotation of the vector v will be carried out around a vector, not a straight line.
2. Vector v, to be rotated around the vector n. As a result of rotation, we should get a vector u(read as at).
3. The angle by which the vector needs to be rotated v.

Knowing these three quantities, we must express the vector u.

Vector v can be represented as the sum of two vectors: v = v ⊥ + v|| . In this case, the vector v || - parallel to the vector n(you can even say: v || is a projection v on the n), and the vector v⊥ perpendicular n. As you might guess, you need to rotate only perpendicular to the vector n part of vector v. That is - v ⊥ .

There is another vector in the figure - p. This vector is perpendicular to the plane formed by the vectors v|| and v ⊥ , |v ⊥ | = |p| (the lengths of these vectors are equal) and p = n x v.

u ⊥ = v⊥ cosa + p sina

If it is not clear why u⊥ is calculated in this way, remember what sine and cosine are and what multiplication of a scalar value by a vector represents.

Now we need to remove from the last equation v⊥ and p. This is done using simple substitutions:

v || = n(v · n) v ⊥ = v — v || = v — n(v · n) p = n x vu || = v || u ⊥ = v⊥ cosa + p sina = ( v — n(v · n)) cosa + ( n x v)sina u = u ⊥ + v || = (v — n(v · n)) cosa + ( n x v)sina + n(v · n)

Here is such a squiggle!

This is the vector rotation formula v by an angle a (alpha) around the vector n. Now with this formula we can calculate the basis vectors:

Exercises

1. Mandatory: substitute the basis vectors into the formula for the rotation of a vector around an arbitrary line. Count (using a pencil and a piece of paper). After all the simplifications, you should get basis vectors like in the last picture. The exercise will take you ten minutes.

That's all.

Roman Shatalov 2009-2012

Introduction.
Quaternion
Basic operations on quaternions.
Quaternions of unit length
Interpolation
Convert from two directions
Composition of spins
Physics

Introduction.

Let's briefly define the terminology. Everyone imagines what the orientation of an object is. The term "orientation" implies that we are in some given frame of reference. For example, the phrase "he turned his head to the left" makes sense only when we imagine where "left" is and where the head was before. This is an important point to understand, because if it was a monster with its head on its stomach with the top of its head down, then the phrase "he turned his head to the left" would no longer seem so unambiguous.

A transformation that rotates in a certain way from one orientation to another is called a rotation. Rotation can also describe the orientation of an object by entering a default orientation as a reference point. For example, any object described with a set of triangles already has a default orientation. The coordinates of its vertices are described in the local coordinate system of this object. An arbitrary orientation of this object can be described by a rotation matrix about its local coordinate system. You can also highlight such a thing as "rotation". By rotation we will understand the change in the orientation of an object in a given way in time. To uniquely set the rotation, it is necessary that at any time we can determine the exact orientation of the rotated object. In other words, rotation defines the "path" traveled by an object when changing orientation. In this terminology, rotation does not specify a unique rotation of an object. It is important to understand that, for example, the matrix does not specify a unique rotation of the body, the same rotation matrix can be obtained by rotating the object 180 degrees around a fixed axis and 180 + 360 or 180 - 360. I use these terms to demonstrate the differences in concepts , and in no way do I insist on using it. In the future, I reserve the right to say "rotation matrices".

The word orientation is often associated with direction. You can often hear phrases like "he turned his head towards the approaching locomotive." For example, the orientation of a car could be described by the direction in which its headlights are pointing. However, the direction is given by two parameters (for example, as in a spherical coordinate system), and objects in three-dimensional space have three degrees of freedom (rotation). In the case of a car, it can look in the same direction both while standing on its wheels, and lying on its side or on the roof. Orientation can indeed be set by direction, but two of them are required. Let's look at orientation using a simple example of a human head.

Let's agree on the initial position in which the head is oriented by default (without rotation). For the initial position, we take the position in which the head looks with its face in the direction of the "z" axis, and upwards (crown) looks in the direction of the "y" axis. Let's call the direction in which the face is turned "dir" (without rotation it is the same as "z"), and the direction where the crown is looking "up" (without rotation it is the same as "y"). Now we have a reference point, there is a local coordinate system of the head "dir", "up" and a global one with x, y, z axes. Arbitrarily turn the head and note where the face is looking. Looking in the same direction it is possible to rotate the head around the axis coinciding with the direction of view "dir".

For example, tilting the head to the side (pressing the cheek against the shoulder) will look in the same direction, but the orientation of the head will change. To fix the rotation around the direction of view, we also use the direction "up" (directed towards the top of the head). In this case, we have unambiguously described the orientation of the head and will not be able to rotate it without changing the direction of the "dir" and "up" axes.

We have considered a fairly natural and simple way to set the orientation using two directions. How to describe our directions in the program so that they are convenient to use? A simple and familiar way to store these directions as vectors. Let's describe directions using vectors of length one (unit vectors) in our global coordinate system xyz. The first important question is, how would we communicate our directions in an understandable way to the graphics API? Graphics APIs work primarily with matrices. We would like to get a rotation matrix from the available vectors. Two vectors describing the direction "dir" and "up" are the same rotation matrix, or rather two components of the 3×3 rotation matrix. The third component of the matrix can be obtained from the cross product of the vectors "dir" and "up" (let's call it "side"). In the head example, the "side" vector will point towards one of the ears. The rotation matrix is ​​the coordinates of the three vectors "dir", "up" and "side" after the rotation. Before rotation, these vectors coincided with the axes of the global coordinate system xyz. It is in the form of a rotation matrix that the orientation of objects is very often stored (sometimes the matrix is ​​stored in the form of three vectors). The matrix can specify the orientation (if the default orientation is known) and the rotation.

A similar way of representing orientation is called Euler Angles, with the only difference being that the "dir" direction is given in spherical coordinates, while "up" is described by a single rotation around "dir". As a result, we obtain three angles of rotation around mutually perpendicular axes. In aerodynamics, they are called Roll, Pitch, Yaw (Roll, Pitch, Yaw or Bank, Heading, Attitude). Roll (Roll) is a tilt of the head to the right or left (towards the shoulders), rotation around an axis passing through the nose and back of the head. Pitch is the tilt of the head up and down around an axis passing through the ears. And Yaw is turning the head around the neck. It must be remembered that rotations in three-dimensional space are not commutative, which means that the order of rotations affects the result. If we turn to R1 and then to R2, the orientation of the object is not necessarily the same as the orientation when turning to R2 and then to R1. That is why when using Euler angles, the order of rotations around the axes is important. Please note that the mathematics of Euler angles depends on the selected axes (we used only one of the possible options), on the order of rotation around them, and also on which coordinate system the rotations are made in, in the world or local object. Euler angles can store both rotation and rotation.

A huge disadvantage of this representation is the lack of a rotation combination operation. Don't try to add component-by-component Euler angles. The final turn will not be a combination of the original turns. This is one of the most common mistakes novice developers make. To rotate an object by storing the rotation in Euler angles, we have to translate the rotation into another form, such as a matrix. Then multiply the matrices of two rotations and extract the Euler angles from the final matrix. The problem is further complicated by the fact that in special cases the direct addition of Euler angles works. In the case of a combination of rotations around the same axis, this method is mathematically correct. Rotating 30 degrees around the X axis, and then rotating around X again by 40 degrees, we get a rotation around X by 70 degrees. In the case of rotations along two axes, a simple addition of angles can give some "expected" result.

Roll, pitch and yaw

But as soon as there is rotation along the third axis, the orientation begins to behave unpredictably. Many developers spend months of labor trying to get the camera to work "correctly". I recommend paying close attention to this shortcoming, especially if you have already decided to use Euler angles to represent rotations. It seems to novice programmers that using Euler angles is the easiest. Let me express my personal opinion that the mathematics of Euler angles is much more complicated and insidious than the mathematics of quaternions.

Euler angles are a combination (composition) of rotations about base axes. There is another, simpler way to set rotation. This method can be called a "mixture" of rotations around the base coordinate axes, or simply rotation around an arbitrary fixed axis. Three components describing the rotation form a vector lying on the axis around which the object rotates. Usually store the axis of rotation as a unit vector and the angle of rotation around this axis in radians or degrees (Axis Angle). By selecting the appropriate axis and angle, you can set any orientation of the object. In some cases it is convenient to store the angle of rotation and the axis in the same vector. The direction of the vector in this case coincides with the direction of the axis of rotation, and its length is equal to the angle of rotation. In physics, thus, store the angular velocity. A vector with the same direction as the axis of rotation and a length representing the speed in radians per second.

Quaternion

After a brief overview of orientation representations, let's move on to an introduction to the quaternion.

Quaternion- this is a quadruple of numbers that was put into circulation (according to historians) by William Hamilton in the form of a hypercomplex number. In this article, I propose to consider a quaternion as four real numbers, such as a 4d vector or a 3d vector and a scalar.

q = [ x, y, z, w ] = [ v, w ]

There are other representations of the quaternion that I won't go into.
How is rotation stored in a quaternion? Much like in the "Axis Angle" representation, the first three components represent a vector lying on the axis of rotation, with the length of the vector depending on the angle of rotation. The fourth component depends only on the angle of rotation. The dependence is quite simple - if we take a unit vector V per axis of rotation and angle alpha per rotation about that axis, then the quaternion representing that rotation
can be written as:

q = [ V*sin(alpha/2), cos(alpha/2) ]

To understand how a quaternion stores a rotation, let's remember about two-dimensional rotations. Rotation in the plane can be specified by a 2×2 matrix, in which the cosines and sines of the rotation angle will be written. You can think of a quaternion as storing a combination of a rotation axis and a half-rotation matrix around that axis.

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#quaternions, #mathematics

The question was asked for a reason. The plane, which now only the dumb does not talk about, crashed after a go-around. That is, he came in for a landing, descended to a certain height (not very low, they write about 400m), after which he went into a set (that is, in our opinion, "went to the second circle"), gained a height of about 900m, then...

How is the go-around going?

About the same as taking off. The pilot sets the increased thrust to the engines, puts the plane into a set. During this maneuver, the aircraft accelerates, the pilots remove the mechanization of the wing and landing gear.

If the go-around is associated with wind shear (it must be a very sensitive shear, and not just the wind has changed), then the procedure is somewhat more complicated, and the position of the mechanization and the landing gear do not change until a safe height is reached for this.

In the go-around there is nothing super complicated . There are, I think, no less than a hundred such departures in one single day around the world, if not more - I simply do not have statistics. If you have, please share.

But sometimes things go wrong. And catastrophes similar to what happened in Rostov do happen.

Why?

Let's get back to the question. The author of the question assumes that for some reason a very high pitch was allowed during the go-around ( ref. - "excessively turned up nose"). Well, than not an option.

"Very high pitch" is a complex spatial situation. In our case, such a pitch means a pitch value of more than 25 degrees, or less than this, but at a speed inadequate to the flight conditions (for example, you are flying in a landing configuration, at a speed less than expected - in such a situation, a pitch of 10 will be "very large").

This situation is fraught with a rapid drop in speed and stall. True, in a calm atmosphere, if you do not interfere this aircraft, in most of these situations it will simply drop its nose, accelerate and, if there is enough altitude, will be quite controllable again.

However, a very high pitch can lead to a VERY fast drop in speed, and other factors (gusty wind, icing of the aircraft) - to stall not on the nose, but in a deep roll (at already very low speed), in general, let's move on to corkscrew, so the pilot gotta do my best to prevent a situation in which the aircraft will crash.

I note that if the critical surfaces of the aircraft are significantly iced over, then stalling can occur at a speed at which the pilot simply does not expect it. Especially in a turbulent environment.

Returning to history. Unfortunately, there were quite a lot of accidents due to falling into a difficult spatial position.

Wikipedia:
A Boeing-compiled list determined that 2,051 lives were lost in 22 accidents in the years 1998-2007 due to LOC accidents. NTSB data for 1994-2003 count 32 accidents and more than 2,100 lives lost worldwide

On the other hand, if you are not ready for go-around, then you can run into a problem even in good weather, when go-around. One very famous airline in the recent past made a "nearly catastrophe" in one large Russian city, but the pilot recognized the position of UPSET and the drop in speed in time, and managed to perform the necessary actions, pulling the plane out near the ground.

I will talk about this procedure very soon.

Why can such a situation arise when going to the second round?

With all engines running, the maximum available engine thrust for a normal missed approach is excessive. Especially for a light aircraft.

That is, if you push the throttle all the way forward, the plane will start accelerating very intensively, and a large pitch will be required to maintain the desired speed. In most cases of escape, such thrust is simply not needed, and Mr. Boeing himself provided for this constructively - with the autothrottle running, one press of the TOGA (Takeoff / Go Around) button commands the installation of such an operating mode for the engines, which will provide a climb with a vertical speed from 1000 to 2000 feet per minute (5-10 m/s). The second press will set the full thrust, and there, how it will turn out.

In manual thrust control, what the pilot sets is what will happen. In most cases, I repeat, push the levers all the way not required . This can only aggravate the situation, especially if, after leaving, you need to gain quite a bit of height to the one that is available.

FCTM (Flight Crew Training Manual), which will be discussed below, gives quite detailed recommendations on this matter.

It should probably be said that history knows cases when pilots, tormented by a long night flight and performing a landing approach on drives, proceeded to go around, pressed TOGA, which gave the necessary indications on the flight instrument ... but, turned off (! ) by this point, the autothrottle, of course, did not move. The pilot increased the pitch, and the speed fell. Up to the operation of the stall warning system, which brought the crew back to reality.

There were very unique cases which fortunately ended without tragedy. Today they cause a smile, although one should blush, I guess.

Nevertheless, I will write separately once again - there are thousands of go-arounds in the world a week, tens, and maybe hundreds of thousands a year. So, there is no need to demonize this procedure once again. Properly performed go-arounds don't make it into the editorials.

There are also nuances

So, let's get back to high pitches and how to deal with them.

Ideally, in order not to fight, one should not allow such a situation. Nevertheless, people are not robots, and flight conditions are far from always "ice", therefore, in the event that the situation nevertheless occurred, recommendations were developed by the joint efforts of Western aircraft manufacturers on how to get out of it.

Specifically for a NOSE HIGH situation, the UPSET RECOVERY procedure prompts the pilot to:

0. Determine if the aircraft is in this situation

1. Disable autopilot and autothrottle

2. Reject the steering wheel "away from you"(if required, up to full deflection)

You should be careful with the intensity. output. If the g-force reaches negative values ​​at the same time, this can be disorienting for pilots who are not masters of sports in aerobatics. It is believed that a similar effect was an important factor in the disaster in Kazan.

3. If required, shift the stabilizer to a dive(you need to be more careful with this, because excessive shifting to a dive can aggravate the situation to an even more difficult one during the withdrawal)

4. Reduce traction(low-mounted engines give pitching moment, reducing thrust reduces it)

If these actions did not help, then continue the output maneuver:

5. Bank the plane

Here it is necessary to make a remark - Quick Reference Handbook (QRH, the screen from which is given above) does not write specific roll values. But writes FCTM. As an instructor, I require my pilots to study these documents in parallel - if QRH (or SOPs) contain "what to do" procedures, then FCTM has a lot of "how to do it and why" text. For example, recommendations and explanations on aircraft stalling and difficult spatial position take up several pages.

So, FCTM offers a roll from 45 to 60 degrees. Not a lot? Yes. Such a roll will contribute to an intensive decrease in the pitch angle, that is, what we need.

In addition, FCTM suggests (if all of the above did not help) one more step - a careful giving of the leg towards the "ground", but only a little. Harsh, deep pedaling can break that camel's back. The QRH maneuver does not contain this item.

When back in 2005 we were learning to fly the B737CL at United Airlines, the instructors were very fond of setting up such situations on the simulator, in which it was problematic to take the liner out without giving a leg.

6. When the pitch angle is reduced to an acceptable level - bring the plane out of the bank, increase thrust, trim the plane, in general, return everything to normal.

But.

All this sounds beautiful when the plane is not in a tailspin.

Or the pilot is at least in a constant control loop and was not distracted at the time of the development of the situation. Given the circus that was going on around the plane that night, and even the fatigue of the crew ... these are very negative factors that greatly complicate the situation.

Or all of this together.

Here is what they write on the bourgeois portal:

"I hope they will have a look into the fatigue reports. Pilots filled dozens of ASR regarding fatigue, nothing happened.... Flying 3 nights in a row then 2 days off and you start again 3 nights. Pilots have been complaining about being exhausted and fatigued last couple of months, and the morning of the accident Chief Pilots starts in the office that this accident has nothing to do with fatigue...

And one more thing I had 2 flights in flydubai last 4 years when the operations tried to force me to go back to the original destination after being decided to divert.... So you fly the aircraft in very bad wx conditions and from Dubai OPS calls you on SATCOM or Stockholm radio and all they want you go back hold and "try another approach as they say it"... It just happened so many guys but people don't dare to speak up, as they are afraid of losing their jobs...."

--==(o)==--

Is it possible to imagine such an option: when going to the second round, the nose turned up excessively

Yes, you can

(maybe jammed rudders or stabilizer)

The whole run didn’t jam, but here it jammed? - 99.99% no.

-> pilots, desperately trying to lower the nose, gave a big list -> could not get out of this situation?

I don't know how about "given a big roll." Unfortunately, yes, they couldn't.

--==(o)==--

Go-around after an approach attempt with two autopilots connected from a height less than 300 feet contains a very big trick. As you know, at this height, the automation shifts the stabilizer to pitch up, and the rebalancing is very significant. Under the control of the autopilot, outwardly this is not noticeable in any way, because. it compensates for this rebalancing by deflecting the RV into a dive.

If for some reason (usually just mechanically) during this departure you turn off the autopilot at the moment you press TOGA, then you will have NOSE HIGH almost 100% guaranteed. After all, it is embedded in my head - "go-around - take the helm!" That is, we have a stabilizer "towards ourselves", the steering wheel at the usual pace "towards ourselves" and ... flaps after cleaning from the landing position (especially from 40, which is recommended when entering in CATII / III conditions) to position 15 give sensitive contribution to the total pitching moment of the aircraft.

You will not have time to say "mom", as the pitch is already "there", and the speed drops.

It is very important to be always ready for go-around. Is always. "Landing is an aborted go-around" (c)

The attitude of the pilot to the upcoming landing should be built from the following thought:

“We will approach in a constant go-around readiness and go out as soon as possible. However, if we have established the necessary visual contact by the decision altitude and the aircraft is stabilized, then we can attempt to land while remaining ready for a go-around even after touching

The section is very easy to use. In the proposed field, just enter the desired word, and we will give you a list of its meanings. I would like to note that our site provides data from various sources - encyclopedic, explanatory, word-building dictionaries. Here you can also get acquainted with examples of the use of the word you entered.

The meaning of the word pitch

pitch in the crossword dictionary

Encyclopedic Dictionary, 1998

pitch

PITCH (French tangage - pitching) the angular movement of an aircraft or vessel relative to the transverse (horizontal) axis.

Pitch

(French tangage ≈ pitching), the angular movement of an aircraft or vessel relative to the main transverse axis of inertia. Angle T. ≈ the angle between the longitudinal axis of the aircraft or vessel and the horizontal plane. In aviation, T. is distinguished with an increase in angle (cabration) and with a decrease in angle (dive); caused by elevator deflection.

Wikipedia

Pitch

Pitch- the angular movement of the aircraft or vessel relative to the main transverse axis of inertia. pitch angle - the angle between the longitudinal axis of the aircraft or vessel and the horizontal plane. The pitch angle is denoted by the letter θ. In aviation, there are:

• positive pitch, with increasing angle - cabling , steering wheel towards yourself;
• negative, with decreasing angle - dive , steering wheel away from you.

Caused by elevator deflection.

This is one of the three angles (roll, pitch and yaw), which set the inclination of the aircraft relative to its center of inertia along three axes. In relation to sea vessels, the term "trim" is used with the same meaning. It is noteworthy that the trim has the opposite idea of ​​positivity/negativity.

Examples of the use of the word pitch in the literature.

Moreover, if keeping the course is carried out practically without much difficulty, then maintaining the glide path is associated with solving the complex problem of longitudinal balancing of the aircraft in terms of speed, engine operation mode and pitch, however, due to the less distraction in the selection and maintenance of the course, this task is easier to solve.

If this does not take into account the vertical speed, as well as the swings usually associated with its jumps pitch, then, with the formal maintenance of the course and glide path, with a constant indicated speed - nevertheless, in front of the butt end, an off-design high vertical speed is quite possible, the correction of which corrects the maintenance of the glide path, and the correction of the error of maintaining the glide path can add up with an already off-design vertical speed.

With the accumulation of experience, I realized that the basis of a soft landing is strict adherence to the course, which means the release of mental abilities to analyze the behavior of the car along the longitudinal channel: pitch, glide path, thrust, vertical speed.

Sensitive gyroscopic sensors pick up vibrations of the aircraft around three conditional axes and give signals for the deviation of certain rudders to correct the roll, pitch or course.

While all these manipulations are going on, I fix the angle on the artificial horizon pitch, I watch the speed and the vario and out of the corner of my eye I notice the red lights of the chassis alarms go out.

At the same time, it will be very problematic to accelerate the car to such a speed at which it is possible to remove the engine mode from the nominal one, and the aircraft will reduce pitch to acceptable drag.

Very low and very sharp alignment, with a clear fixation of the landing pitch, rubs against concrete inaudibly.

Sudden disengagement of the autopilot with an accumulated error of unbalanced roll forces and pitch can lead to an energetic throw of the aircraft in the direction of the direction of the released rudders.

If the increase in vertical speed is associated with suction under the glide path, then the director arrow will vigorously go up with the same pitch and at the same speed.

This confidence is that the heavy vehicle is approaching the concrete at a low vertical speed providing a soft landing, and that the decrease in this vertical speed on leveling is provided by sufficient controllability. pitch.

Upon reaching a speed of 550, a constant rate of climb is established, the aircraft is trimmed according to pitch, and then the indicated speed is maintained by lightly pressing the trimmer.

So vdolbi, in addition, to the student, that it’s better to hang yourself and swing in the noose than to swing pitch in front of the ground.

As soon as the slats were removed, the speed jumped over 500, and a further set, with a hundred passengers in the cabin, was carried out lying on his back: pitch 20 degrees, the variometer, scrolling the circle with the arrow, froze at 33.

I removed the spoilers, again began to balance with trimmers: pitch, roll.

It is the takeoff pitch and - out of the corner of my eye - the variometer determines the termination of the take-over of the helm.

• positive pitch, with increasing angle (nose up) - cabling , steering wheel towards yourself;
• negative, with a decrease in angle (lowering of the nose) - dive , steering wheel away from you.

This is one of the three angles (roll, pitch and yaw), which set the inclination of the aircraft relative to its center of inertia along three axes. In relation to ships, the term " trim" is used with the same meaning. It is noteworthy that the trim has the opposite idea of ​​positivity/negativity.

see also

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Notes

Links

• Aresti Aerobatic Catalog FAI = FAI Aresti Aerobatic Catalogue. - Federation Aeronautique Internationale, 2002.

An excerpt characterizing the pitch