The basic navigation concepts

NATIONAL AVIATION UNIVERSITY

AEROSPACE CONTROL SYSTEMS INSTITUTE

DEPARTMENT OF AVIATION COMPUTER INTEGRATED COMPLEXES

AIRCRAFT INSTRUMENTS AND INFORMATION SYSTEMS

LAB INSTRUCTIONS:

Dead reckoning computer АНУ-1

Teacher: Mukhina M.P.

Learning objectives:

Upon completion of this work you must be able to:

a to study the operating principle and construction of dead reckoning computer АНУ-1;

a to get practical skills for checking the performance of dead reckoning computer such as АНУ-1 before the installation on aircraft and during the flight operations;

a to study the methodology how to determine the instrument errors of dead reckoning computer to make a conclusion on the correspondence of inspected unit to the tactical and technical requirements.

Background

The basic navigation concepts

The dead reckoning computer АНУ-1 is designed to determine continuously the current coordinates of the aircraft in a conventionally chosen rectangular coordinate system, rotated with respect to the meridian at the map angle.

Coordinates are usually read by the reading of the pointers in kilometers of traveled path from the point of departure and using the cross-track error from the desired track.

АНУ-1 continuously produces the dead reckoning by integrating the components of the ground speed vector on the axis X and Y of a Cartesian coordinate system.

To obtain the components of the ground speed vector Wx and Wy of aircraft on the axis X and Y of Cartesian coordinate system, the airspeed V and wind speed U on the axes of the speed triangle are converted to the projection of the velocity Vx, Vy, Ux, Uy on the axis X and Y of Cartesian coordinate system with subsequent determination of Wx and Wy, and integrating them to get the coordinates of the aircraft.

Navigational speed triangle and its relationship to the rectangular coordinate system are shown in Fig. 1.

Fig. 1 Speed triangle

Navigation equations that show the relationship between the components of the velocities and coordinates of the aircraft in a rectangular coordinate system X and Y for the various modes of АНУ-1 are the following:

DN mode

MEMORY mode

AUTONOMOUS mode

X,У – axes of rectangular coordinate system;

- vector of true airspeed;

- vector of ground speed;

Y - map angle;

g - true heading of aircraft;

d - wind angle;

a - drift angle;

g+a - true track angle;

- vector of wind speed

OVERVIEW

Equipment of АНУ-1, the functionality of its component parts and assemblies.

АНУ-1 includes:

- Airspeed sensor НИ-50БМ ДВС;

- Selector of map angle ЗУК-1;

- Wind selector ЗВ-1;

- Counter НИ-50 сч;

- Temperature receiver П-1;

- Switching unit БК-1.

Functional diagram of АНУ-1 is shown in Figure 2.

Airspeed sensor НИ-50БМ ДВС is designed to determine the true airspeed V and to output the voltage proportional to this speed.

Selector of map angle ЗУК-1 is designed to enter the heading g automatically from the compass system, as well as to form the angle (g-y) when map angle is entered manually.

Wind selector ЗВ-1 is intended to enter the speed U and direction d of wind into the scheme of АНУ-1 during operation in autonomous mode. The expansion of the wind vector U is done with respect to the axes of the chosen coordinate system. The data needed to solve this problem is the wind speed, wind direction and map angle map that are introduced manually into the selector. For this the device has a handle and scale of wind speed U (0-200 km / h) with scale factor in 5 km/h and the handle and scale of the wind direction d (0-360°) with a scale factor 5°. The scale of the wind direction simultaneously serves to set the map angle y.

Fig. 2 1 – electrical circuit of АНУ-1, 2 – simulator of heading, 3 - simulator of track angle, 4 - ground speed simulator, 5 - simulator of temperature receiver, 6 - control display unit, 7 - switching unit БК-1, 8 – test jacks for voltage measurement, 9 - wind selector ЗВ-1, 10 – counter НИ-50 сч, 11 - selector of map angle ЗУК-1, 12 – indicator of airspeed НИ-50БМ ДВС, 13 – checkout equipment КПУ-3, 14 - switch, 15 - voltmeter, 16 - clamp of the pipeline.

The counter НИ-50БМ is the main indicator of dead reckoning computer. It gives the information about the current coordinates of the aircraft at any given time moment in kilometers of traveled path. With working АНУ-1 in the main mode (DN mode), as well as in the MEMORY mode the integration of DC voltage, proportional to the components Wx, Wy and ground speed, is done over time in a conventional Cartesian coordinate system. In autonomous mode of АНУ-1 the counter performs the algebraic addition of the components Vx and Vy of true airspeed and components Ux and Uy in a conventional Cartesian coordinate system. Integration in the counter is done by means of integrating motors.

The temperature receiver П-1 is used to measure and convert the outdoor temperature into voltage and feeding it into an electrical circuit of airspeed indicator.

The switching unit БК-1 is a set of same computing units that perform the generation of components Wx and Wy of ground speed of the aircraft in a conventional Cartesian coordinate system at any operation mode of АНУ-1.

The switching unit includes the following components:

- Heading unit УОК;

- Ground speed unit УОПС;

- track angle unit УОПУ;

- "memory of wind" unit УПВ.

At the same time the switching unit serves for connection of all units included in the kit of АНУ-1 into a single system. By the switching unit the АНУ-1 is matched with compass system KC, as well as with Doppler Navigator ДИСС.

Heading unit УОК is used to enter the value of heading g taking into account the map angle y in the computing circuit of АНУ-1.

The ground speed unit УОПС is independent computing unit and is designed for working out the signal proportional to ground speed W from the DN.

The track angle УОПУ is used to convert the sum of angles g-y+a into the voltage and to input this value into the circuit of computing unit of АНУ-1.

The "memory of wind" unit УПВ is designed to calculate and store the components Ux and Uy of velocity vector U in the conditional rectangular coordinate system:

U_x =W_x-V_x

U_y = W_y-V_y

Дата добавления: 2015-11-16