## Summary

Software has been developed for the modeling, analysis and design of a fixed wing aircraft. The software is composed of a set of functions written in the Matlab® m language and is fully compatible with Octave. There is also a set of simulation models developed in Simulink® that include the simulation of the aircraft non-linear model with the flight control system. There are several versions of the simulation model, some more refined than others.

## Aerodynamic modeling

A method was developed for the aerodynamic modeling of a fixed-wing aircraft. It is based on an extended lifting line theory method that accounts for viscous effects using local non-linear coefficients for each wing section. The method considers the effective angle of attack and the changes in dynamic pressure in each wing section, based on the relative velocity and the relative angular velocity of the aircraft with respect to the sorounding air. Each part of the aircraft is modeled separately and the results are consolidated for the entire aircraft including the downwash effect of on the tail.

## Propulsion system modeling

Models have been developed for aircraft propulsion systems: models for reciprocating engines, electric motors and propellers. These models have been used to evaluate the performance of the propulsion system and the performance of complete aircraft with a specific propulsion system. They are also used in simulation models for specific aircraft, including small UAVs.

## Static stability and control analysis

The aerodynamic forces and moments produced by the wing-fuselage and the tail have been modeled and then consolidated in the static analysis, calculating the equilibrium conditions for steady rectilinear flight, steady turn flight, steady pullup/pull over and steady roll. The effectiveness of the aerodynamic control surfaces has been evaluated in these maneuvers based on the CG of the aircraft. The static margin has been evaluated to determine the proper range of aircraft CG positions that allows stable flight with sufficient control authority.

## Dynamic stability analysis

The non-linear model for the fixed-wing aircraft has been linearized and the dynamic modes have been calculated based on the values of the linearized model. This analysis makes it possible to establish the dynamic stability of the aircraft and evaluate the dynamic behavior parameters for the dynamic modes of the aircraft. Simulations have been developed to corroborate the dynamic modes with the behavior of the non-linear model.

## Performance analysis

Software has been developed to estimate the performance of a fixed wing aircraft. The estimation of the performance parameters is based on the complete non-linear model of the aircraft instead of using approximate formulas. Performance can be assessed at specified altitudes and with a specified aircraft weight.

## Simulation model for a fixed wing aircraft

A complete non-linear simulation model has been developed for a fixed-wing aircraft. The model has been used to evaluate the dynamic behavior of the aircraft.

## Aircraft flight control design

Software has been developed to help design the flight control system of a fixed wing aircraft. The design of a multi-loop autopilot has been carried out, and the subsequent simulation with the non-linear aircraft model has corroborated the effectiveness of the closed-loop control system.

## Aircraft flight control simulation

The closed-loop control system simulation model was implemented using the full non-linear aircraft model. The simulation results allow evaluating the performance and robustness of the designed control system.

## Aircraft models in Simulink®

A set of simulation models has been developed in Simulink® that include the simulation of the aircraft non-linear model with the flight control system. There are several versions of the simulation model, some more refined than others.