Aircraft performance modelling for air traffic control simulation applications

Abstract

Existing Air Traffic Control (ATC) simulators have limited capacity to deal with current problems of traffic management and fuel economy. Software algorithms, such as table driven target generation, flat earth space simulation, and rudimentary weather model do not provide the required accuracy [I]. To improve the accuracy of aircraft modelling for ATC applications, a great deal of interest has been focused on the improvement of the quality of aircraft performance modelling and aircraft trajectory simulation. In this paper, we describe the approach taken by CAE Electronics in developing a generic aircraft model that simulates the performance of different aircraft types, and a simulation tool, Aircraft Construction Tool (ACT) that can be used to create any aircraft type. The ACT is used to efficiently generate any aircraft type based on a limited set of data easily obtainable from such sources as Jane's all the World, and from flight or operations manuals. The simulated performance of all aircraft generated using the ACT is within 5 % of the published performance data. INTRODUCTION One of the major deficiencies of existing ATC simulators is the fidelity, and the accuracy of the aircraft performance model. The accuracy of the aircraft model is very crucial for this kind of application, as it impacts the results of all the other functionalities of the simulator ( conflict alert, traffic management, etc..). Furthermore, ATC simulators must have the capability of simulating any aircraft type flying in the Copyright O 1995 by the American Institute of Aeronautics simulation exercise area. For example, CAMSIM [2] ( Canadian Airspace Management Simulator ) must be capable of simulating any aircraft type flying in the Canadian airspace. Around 150 different types must be realistically simulated, including civilian and military types. These requirements created the need for the development of a high fidelity generic aircraft model, and an Aircraft Construction Tool (ACT) which is built around this generic aircraft model. From a limited set of aircraft parameters, which can be obtained from such sources as Jane's all the World and flightloperations manuals, the ACT must be capable of generating different aircraft categories including: heavy, medium, and light jets, military and supersonic aircraft. This paper presents details of an approach in the design of both the generic aircraft model, and the ACT. The aircraft performance model is referred to as a class B point mass model where only the translational behaviour is taken into account. The translational behaviour is derived from the forces acting on the aircraft. A coordinated turn is assumed. Winds effects are included. During an ATC simulation, the aircraft performance model is adapted to the aircraft type being simulated using the performance characteristics of that aircraft. The ACT is built around the aircraft model. The main component of this tool is the trim algorithm, which is used to generate any aircraft type from a limited set of data. The ACT has a user friendly graphical interface that is used to enter all the input data. Both the aircraft model and the ACT were developed for CAMSIM. The simulated performance of all aircraft generated by this tool is within 5% of the manufacturer's performance. and Askonautics, I&. All rights reserved. 54 American Institute of Aeronautics and Astronautics Section 1 of this paper presents the details of the class B model. Section 2 discusses the software architecture, as well as the functionality of the main components of the ACT. Section 3 contains the simulation results, and Section 4 presents the concluding remarks. AIRCRAFT MODELLING The aircraft model considered is a class B model which is a point mass model. The translational behaviour of the aircraft is derived from the forces acting on the aircraft, these forces consists of lift, drag, thrust, and gravity. The moments of inertia are not taken into account. A coordinated turn is assumed with the pitch and roll degrees of freedom represented by simple lag. Wind effects (speed and direction ) are also taken into account. Only a limited set of pilot inputs is required such as vertical, horizontal speed and roll angle. Figure 1 shows a block diagram of the class B model. The three main components of this model are: Flight Dynamics Auto-Pilot Engine Dynamics Figure 1 illustrates the interface between these components. The trajectory generation module provides the autopilot with lateral and vertical commands that are required to follow navigational paths which are based on the given flight plans. The position keeping component computes the aircraft latitude and longitude by integrating the ground speed, the WGS84 elliptical earth model is used for position keeping. The weather module provides the temperature, pressure, wind speed and direction at the aircraft current position. In what follows, we briefly discuss the functionality of the main components of aircraft model..