Work with Fixed-Wing Aircraft Using Functions

To easily create fixed-wing aircraft in the Aerospace Toolbox, use the fixedWingAircraft function and its supporting functions. Use these functions to:

• Define aircraft dynamics.

• Define aircraft dynamics from DATCOM files.

• Perform static stability analyses using object methods.

• Generate state-space representation with linearization methods.

Suggested Workflow

Consider this workflow when designing and building your fixed-wing aircraft objects with these functions.

Objective	Use
Define a fixed-wing aircraft.	fixedWingAircraft — The aircraft object holds the main definition of fixed-wing aircraft. The aircraft has a main set of body coefficients, which you can manipulate with the fixedWingCoefficient function.
Define the condition (state) of a fixed-wing aircraft at an instance in time.	fixedWingState — Use this function when: Your calculations require a specific aircraft state, such as those for forces and moments. Gathering specific points of data from Simulink.LookupTable objects. This action requires a Simulink® license.
Define data for any and all coefficients that describe the behavior of the aircraft.	fixedWingCoefficient — Numeric coefficient objects hold the data for all coefficients that describe the behavior of the aircraft.
Define an aerodynamic surface on a fixed-wing aircraft.	fixedWingSurface — Control surfaces hold the definitions of the aircraft aerodynamic surfaces.
Define a thrust vector on a fixed-wing aircraft.	fixedWingThrust — Thrust vector objects hold the definitions of the aircraft thrust.
Define the fixed-wing aircraft state environment.	aircraftEnvironment — Aircraft environment objects hold the fixed-wing aircraft state environment such as air temperature, pressure, density, and gravity.
Define the properties for the fixed-wing aircraft.	aircraftProperties — Aircraft property objects define common properties to maintain and define aircraft. Use this object throughout the fixed-wing aircraft design process.

After creating these fixed-wing aircraft components, use object methods to work with them. For example, use object methods to perform static stability and linear analysis.

Static Stability Analysis

To perform static stability analysis of your fixed-wing aircraft, use associated object methods:

1. Create a criteria table against which to perform static stability analysis.

   To create a criteria table, use the Aero.FixedWing.criteriaTable method. This method creates a 6-by-N table, where N is the number of criteria variables.

2. To evaluate the changes in forces and moments after a perturbation as either greater than, equal to, or less than 0 using the matching entry in the criteria table, use the staticStability method. The method uses this evaluation process.

   • If the evaluation of a criteria is met, the aircraft is statically stable at that condition.

   • If the evaluation of a criteria is not met, the aircraft is statically unstable at that condition.

   • If the result of the perturbation is 0, the aircraft is statically neutral at that condition.

   Use this method only in the preliminary design phase. The staticStability method does not perform a requirements-based analysis.

For more information on object methods, see Analyze Fixed-Wing Aircraft with Objects.

For an example of static stability analysis, see Determine Nonlinear Dynamics and Static Stability of Fixed-Wing Aircraft.

Linear Analysis

To perform the linear analysis of the fixed-wing object at a given fixed-wing state, use the linearize method. This method linearizes a fixed-wing aircraft around an initial state and creates a state-space model for the linear analysis. To perform linear analysis:

1. Calculate the static stability of the fixed-wing aircraft using the staticStability method.

2. Linearize the fixed-wing aircraft using the linearize method.

For an example of fixed-wing aircraft linear analysis, see Analyze State-Space Model for Linear Control and Static Stability Analysis.

Linear analysis requires the Control System Toolbox™ license.