RU2798591C1 - Device for prediction of takeoff and flight path of aircraft over high altitude obstacles - Google Patents

Abstract

FIELD: aircraft.

SUBSTANCE: group of inventions relates to a method and device for an energy method for predicting the trajectory of take-off and flight of an aircraft over a high-altitude obstacle. To predict the trajectory, the distance to the characteristic points on the forward trajectory of the aircraft during take-off is predicted, an algorithm for calculating the distance to the point of making a decision on the possibility of take-off in the presence of high-altitude obstacles along the course is developed, the correction of the results of the initial forecast is introduced, and an information message is formed in the pilot's field of view. The device comprises computing units for implementing the method.

EFFECT: reduced probability of flight accidents.

2 cl, 2 dwg

Description

The invention relates to the field of aviation instrumentation and is intended for the formation in the working space of a pilot piloting an aircraft, notifications in the form of text, figurative or sound signals about the distance to the take-off capability point in the presence of high-altitude obstacles on the ahead trajectory

Due to the intensification of air traffic and the expansion of operational ranges, aviation safety issues are becoming more acute.

Statistics of aviation accidents (AA) based on the latest foreign [1-4] and domestic [5, 6] studies show that the proportion of accidents caused by human participation in the process of performing a flight task varies from 50 to 70% depending on the assessment methods.

A chronological analysis of the state of the domestic aircraft fleet also did not reveal a trend towards a decrease in the overall accident rate [7]. The analysis shows that as technology improves, the proportion of accidents associated with shortcomings in aircraft systems and their characteristics has decreased from 40% to 15%, and the proportion of accidents caused by deviations in the work of personnel, mainly the crew, has increased from 50% to 80% ). Such a high proportion of negative incidents is due to increased psychological stress, the transience of processes and the lack of time for decision-making.

The analysis of the state of flight safety (SF) at the “TAKEOFF” stage revealed that the main causes of the accident are:

- erroneous actions/inaction of the crew due to the late decision to terminate the takeoff;

- unsatisfactory condition of the runway;

- dangerous effects of external factors;

- failures of power plants and systems of an aircraft (AC).

An analysis of the accident statistics recorded over the past 30 years and associated with the termination of takeoff allows us to draw the following conclusions:

- more than half of the accidents indicate the adoption of a decision and the start of actions by the crew at a speed exceeding V ₁ , when it is practically impossible to prevent the aircraft from overrunning the runway;

- more than 30% of the accidents occurred on a wet, snowy or icy runway;

- 25% of accidents are related to power plant (PU) failures;

- about 25% of aborted takeoffs were due to the destruction of the landing gear tires and other aircraft system failures.

From the analysis of the accident, it was also revealed that the aircraft crews make systematic errors, in particular:

- in the installation of a configuration that does not correspond to the actual meteorological conditions, the technical condition of the runway, the actual takeoff weight, including the deliberate installation of mechanization in a configuration that differs from the requirements of the Flight Manual;

- performance of takeoffs from short runways that do not meet the conditions of safe takeoff; - collisions with terrain and artificial obstacles on the air section of the takeoff distance.

In this regard, it becomes obvious that it is necessary to improve the information support of the pilot, create a friendly environment for the interaction of the pilot with the cockpit instrumentation, as well as develop methods for advanced and predictive notification of crews about characteristic events on the forward trajectory.

The claimed invention describes a method and algorithm for predicting the movement of aircraft (LA) on the ground sections of the trajectory [8-13]. The methodological base of developments is the energy approach to the control of the spatial motion of an aircraft [14-16].

The method takes into account the accumulation of energy on the trajectory ahead, including the air segment, and therefore the forecast of the possibility of a safe takeoff is far ahead of the moment when the takeoff speed required by the flight manual (AFM) is reached.

A large amount of statistical testing of prediction algorithms has been performed in a wide range of runway conditions. The results of the analysis demonstrate the high accuracy and reliability of the algorithms for predicting events on the takeoff trajectory.

To improve the situational awareness of the pilot and visual assessment of the development of the situation, a prototype of the take-off indicator in the cockpit is proposed.

Known device "Onboard integrated information support system for the crew and the cognitive format for the presentation of flight information at the stage of "takeoff" multi-engine aircraft" (RU 2550887 C2, 20.05.2015). The on-board system is designed for information support at the stages of pre-flight, pre-launch preparation and on the air section of the full take-off distance due to a significant increase in the level of situational (information) awareness and serves to provide the crew with complete, reliable, up-to-date, consistent and interactive information. In the mentioned device, in order to increase the level of intellectual support for the crew, the activation of visual (imaginative) thinking is used, which allows unloading the mental activity of the crew.

The disadvantage of the known device is that only the current generalized coordinates of the object are received at its inputs, which does not allow the crew to be informed about upcoming events and take advanced actions.

The technical result of the device is the formation on the screen of the flight instrument alerts about the value of the corrected predictive range to the decision point on the trajectory of the rolling reserve to the runway edge, its coordinates and range until the nose wheel rise speed and the aircraft roll reserve to the runway edge are reached in the form of text or graphic messages , which expands the information capabilities of the on-board equipment of civil aviation aircraft, will increase the situational awareness of the pilot in conditions of atmospheric disturbances of a complex structure, thereby reducing stress loads in critical situations and, as a result, reducing the likelihood of flight accidents.

The technical result of the device is achieved by the fact that the device of the energy method for predicting the trajectory of the takeoff and flight of an aircraft over a high-altitude obstacle contains a block 1 for communication with on-board measuring equipment, a block 2 for calculating the predictive range to the decision point on the trajectory, a block 3 for calculating the correction coefficient at different rolling speeds aircraft, block 4 for calculating the corrected range to the decision point, block 5 for calculating the coordinates of the decision point, block 6 for calculating the aircraft rolling reserve to the runway edge, while the outputs of block 1 are connected to the inputs of blocks 2, 3, 5, 6 and block 7, the outputs of block 2 are fed to the inputs of block 4, and the outputs of block 3 are fed to block 4, and the outputs of blocks 4, 5, 6 and 7 are fed to the checkpoint screen.

Fig. 1 The structure of the forecasting method.

Fig. 2. Prototype of the take-off indicator in the cockpit.

Description of the energy method for predicting the trajectory of the take-off and flight of an aircraft over a high-altitude obstacle.

The mathematical formulation of the energy approach to flight control is the energy balance equation extended to ground motion modes. In symbolic form, the generalized equation is written as:

This equation establishes quantitative relationships between the energy source and all its consumers. The equation is written in the form of increments of the specific energy of motion:

where h is the geometric height, V is the inertial flight speed, m is the mass of the aircraft

- удельная работа двигателя,

- затраты энергии на преодоление силы лобового сопротивления,

- работа ветра. Для каждого члена уравнения баланса энергий в наших работах [14, 15] получены интегральные выраженияThe unit of measure for specific energy is the meter, which is why it is also called energy height. The equation contains terms: ΔH _E - energy height increment,

- specific work of the engine,

- energy costs to overcome the drag force,

- the work of the wind. For each term of the energy balance equation in our works [14, 15], integral expressions were obtained

в котором W_x и W_y - горизонтальная и вертикальная составляющие ветра.where θ is the angle of inclination of the trajectory; V _B - airspeed; P _n - engine thrust, normalized by the weight of the aircraft; D _H - normalized resultant of all external forces; α _in - angle of attack of the wing; ϕ _dv - angle of installation of the engine. The factor f _w is called the wind factor. It has an expression

in which W _x and W _y are the horizontal and vertical components of the wind.

отражающий процесс поглощения энергии на преодоление механических сил торможения, представлен в форме:New Member

reflecting the process of energy absorption to overcome the mechanical braking forces, is presented in the form:

where k _torm is a generalized normalized braking coefficient equal to the ratio of the total drag force from the landing gear to the weight of the aircraft.

In difficult conditions during the takeoff phase with reduced thrust-to-weight ratio due to engine failure or in high altitude conditions, or at elevated air temperatures, or at maximum payloads, it is necessary to evaluate and inform the pilot the ability of the aircraft to take off to takeoff speed within the runway in order to gain sufficient height for overflight over obstacles in the form of artificial structures or natural elevations of the terrain along the take-off course.

At the time of passing over an obstacle, the aircraft must have a speed not lower than the minimum speed of steady horizontal flight V ₂ known for each type of aircraft. Thus, the total energy of motion at the moment of overcoming the obstacle E _Hprep must contain the necessary minimum of the kinetic component and the stock of the potential component, which determine the achievable height _Hprep of flight over the obstacle:

The value of the total accumulated energy at the end of any maneuver is the sum of the current kinetic and potential components and the work of all external forces F _i , on the trajectory of the maneuver. The approach trajectory to an obstacle of length S includes ground and air sections. At small climb angles, the length of the spatial trajectory is close to its projection. Then the predicted accumulated energy along the path is:

- сумма всех внешних сил: тяги двигателя, аэродинамического сопротивления, трения качения и торможения. Это уравнение непосредственно связывает энергетическое состояние объекта управления и длину траектории для достижения этого состояния. В предлагаемом методе результирующая сила естественным образом вычисляется через продольное ускорение a(t)Where

- the sum of all external forces: engine thrust, aerodynamic drag, rolling friction and braking. This equation directly links the energy state of the control object and the length of the trajectory to reach this state. In the proposed method, the resulting force is naturally calculated through the longitudinal acceleration a(t)

which is usually determined on board from the measured overload n _x

By equating the expressions for the required (1) and predicted (2) energies, taking into account the equivalent replacement (3) and measurements (4), during the takeoff, one can find the length of the ahead part of the trajectory necessary to accumulate the missing total energy:

Note that this expression is invariant under mass. At the point in the trajectory where the predicted length of this section is zeroed, the predicted energy value will be sufficient to fly over the obstacle at the required speed. This point is called the decision point (TPD) for a safe takeoff:

Coordinate of this point:

X _TPR (t)=X(t)+D _TPR (t)

A distinctive feature of the energy forecasting method is that the current forecast takes into account the total energy acquired by the aircraft in the air segment outside the ground section.

In contrast to the takeoff methodology prescribed by the flight manuals, the method of forecasting the total energy, taking into account its increase in the air segment, indicates the possibility of taking off not at the moment the decision speed is reached, but much earlier and in the range coordinates tied to the runway.

To improve situational awareness, it is considered very useful to know the margin, or reserve, of the distance to the edge of the runway at the decision point. The value of the reserve is also predicted during the run:

L _res (t)=L _runway -X(t)-D _TPR (t)

The energy forecasting method made it possible to obtain a predictive estimate of one more characteristic point on the takeoff trajectory. For each type of aircraft, there is a minimum takeoff speed V _r at which it is allowed to raise the front landing gear to turn the aircraft to the takeoff pitch angle. This speed depends on its takeoff weight, wing configuration and is regulated by the technical specifications for the aircraft. In emergency situations, the pilot must evaluate not only the possibility of continuing the take-off, but also the position of the aircraft on the runway, in which it is possible to start lifting the front pillar. The length of the distance from the current position of the aircraft until reaching the rate of climb is calculated by the formula:

An objective assessment of this range, in contrast to an intuitive one, improves the situational awareness of the pilot and reduces the prerequisites for erroneous actions. During the takeoff run, the pilot may be given a message about the range to the point of lifting the front rack. The moment of zeroing this range serves as a signal of readiness for the start of the aircraft turn to the takeoff pitch angle.

Range prediction correction

An aircraft movement forecast based on the current values of its coordinates cannot coincide with the real process, because all forces change either under the influence of disturbances, or in accordance with the regulatory requirements of the flight rules. During the takeoff phase, the main force is the engine thrust, which is most affected by the takeoff speed. To compensate for this influence, a multiplicative corrective term is introduced into the structure of the prediction algorithm:

где VP - скорость разбега; V₂ - скорость устойчивого горизонтального полета; k₀ и k₁ - настроечные коэффициенты, формирующие k_кор.The correction factor _kcor takes into account the drop in thrust with increasing speed, in the form:

where VP is the takeoff speed; V ₂ - the speed of stable horizontal flight; k ₀ and k ₁ - tuning coefficients that form k _cor .

Description. The input block 1 receives all the necessary signals from the sensors on the object, from its output part of the variables is fed to block 2, in which the predicted value of the distance to the decision point is calculated, the other part of the variables is fed to block 3, in which the correction factor is calculated, which is transmitted to block 4, at the output of which a corrected value of the distance to the decision point is formed, which in block 6 generates a signal to alert the pilot about the available reserve of rolling reserve to the edge of the runway, in addition, in block 5 the coordinate of the decision point is calculated, and in block 5 block 7 calculates the distance to reach the nose wheel lift speed.

The device for generating a warning signal for the pilot about the braking distance of the aircraft contains a block 1 for communication with on-board measuring equipment, a block 2 for calculating the predicted range to the decision point on the trajectory, a block 3 for calculating the correction coefficient at different rolling speeds of the aircraft, a block 4 for calculating the corrected range to the decision point , block 5 for calculating the coordinates of the decision point, block 6 for calculating the aircraft rolling reserve to the runway edge, while the outputs of block 1 are connected to the inputs of blocks 2, 3, 5, 6 and block 7, the outputs of block 2 go to the inputs of block 5, and the outputs of block 3 are fed to block 4, the outputs of blocks 4, 5, 6 and are fed to the checkpoint screen (Fig. 1).

To develop piloting skills with information support, a prototype of an indicator of aircraft movement in real time along the runway and on the air section was developed. An example of such an indicator is shown in Fig. 2.

In the indicator window, graphs of the given and actual values of the main flight parameters - altitude and speed - are formed. The altitude trajectory shows the aircraft symbol in its current position. The runway and the obstacle are conditionally depicted. Forecast marks of characteristic events are displayed, namely, the distances to the takeoff decision capability point (DTPP), the point of reaching the scheduled decision speed (DV1) and the nose wheel separation point (DVr). The numerical value of these coordinates is also shown. For the operational analysis of the results, the takeoff simulation can be performed in accelerated time.

Bibliography

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Claims (1)

A device for predicting the trajectory of takeoff and flight of an aircraft over a high-altitude obstacle, characterized in that it contains a block (1) for communication with on-board measuring equipment, a block (2) for calculating the predictive range to the decision point on the trajectory, a block (3) for calculating the correction coefficient for different aircraft rolling speeds, block (4) for calculating the corrected range to the decision point, block (5) for calculating the coordinates of the decision point, block 6 for calculating the aircraft rolling reserve to the runway edge, while the outputs of block (1) are connected to the inputs of blocks (2) , (3), (5), (6) and block (7), the outputs of block (2) are fed to the inputs of block (4), the outputs of block (3) are fed to block (4), and the outputs of blocks (4), (5), (6) and (7) are fed to the checkpoint screen.

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