Aerospace Vehicle Systems Engineering and Analysis (AVSEA) Tools
M. S. Selig,* B. W. Fuesz
University of Illinois

AVSEA is a collection of engineering tools to support systems engineering and analysis of advanced aerospace vehicles. The tools currently support analysis of both single-stage-to-orbit and two-stage-to-orbit configurations. Object-oriented programming techniques are used in the core software (C language) to simplify the modification of existing simulation algorithms and provide for software reuse. The goal is to provide an object-oriented simulation environment that will allow area experts to contribute simulation modules to the system. In this way, users can configure AVSEA to support varying levels of fidelity and take advantage of models contributed by many users through the Internet.

The development of a flight simulator for navy unmanned aerial vehicle pilot training requires a model for the turbulent atmospheric environment encountered at sea. The current approach employs a 3-D Monte Carlo turbulence simulation code (SNLWIND-3D). The code correctly simulates the point-to-point correlation of 3-D gusts, both laterally (spanwise) and longitudinally (lengthwise). Thus, effects such as longitudinal swirl that can cause the aircraft to roll abruptly are being incorporated into the turbulence model. Integration of the model into the flight simulator has led to a more realistic simulation of the 3-D turbulence around the ship.

VSAERO, a computational aerodynamics code, is being used to predict the aerodynamic characteristics of the PIONEER and HUNTER unmanned aerial vehicles (UAVs) for integration into a flight simulator for use in pilot training. Concurrently, flight tests on these vehicles have been performed for verification and validation purposes. Parameter estimation techniques will be applied to the flight test data to extract aerodynamic characteristics that are otherwise difficult to obtain or predict. The approach employed is applicable to other existing or envisioned UAVs that are expected to play increasingly important roles in both civilian and military applications.

A flight vehicle modeling framework for real-time simulation of UAVs incorporating aerodynamic, propulsion, and mass characteristics along with flight control systems of actual vehicles is under development using object-oriented computer programming techniques. The framework is written in the C++ programming language and includes graphical representations of the UAV, terrain, and other entitites appropriate to a training exercise. Key issues under investigation are modeling of flight characteristics in the presence of steady winds, gusts and turbulence, and algorithm development for measurement of flight crew performance. This framework is being used to develop computer-aided instruction (CAI) devices for the navy's Pioneer UAV and the army's hand-launched (HL) UAV.

An aircraft simulator (which was obtained with support from NSF, the UIUC College of Engineering, and Frasca International) is being integrated into a Flight Simulator Laboratory for use in undergraduate education. Currently the work is focused on (1) developing computer-based utilities for extracting and post-processing flight engineering data from the simulator, (2) developing instructional modules for use in AAE courses, (3) building databases for both aircraft and propulsion systems, (4) integrating an external control system simulation module into the simulator system, and (5) validating the simulator performance.