Analyze Fixed-Wing Aircraft with Objects

To analyze fixed-wing aircraft in Aerospace Toolbox, use the Aero.FixedWing class and its supporting classes. These classes enable you to:

• Define aircraft dynamics

• Define aircraft dynamics from DATCOM files

• Perform static stability analyses

• Generate state-space representation with linearization methods

Suggested Workflow

As a guideline, consider this workflow when designing and building your fixed-wing aircraft with these classes:

To	Use
Define a fixed-wing aircraft.	Aero.FixedWing — Aero.FixedWing objects hold the main definition of fixed-wing aircraft. The object has a main set of body coefficients, which you can manipulate with the Aero.FixedWing.Coefficient object.
Define the condition (state) of a fixed-wing aircraft at an instance in time.	Aero.FixedWing.State — Use these objects when: Your calculations require a specific aircraft state, such as those for forces and moments. Gathering specific points of data from Simulink.LookupTable objects (requires a Simulink® license).
To define data for any and all coefficients that describe the behavior of the aircraft.	Aero.FixedWing.Coefficient — Aero.FixedWing.Coefficient objects hold the data for all Coefficients that describe the behavior of the aircraft.
Define an aerodynamic surface on a fixed-wing aircraft.	Aero.FixedWing.Surface — Aero.Aircraft.Surface objects hold the definitions of the aircraft aerodynamic surfaces.
Define a thrust vector on a fixed-wing aircraft.	Aero.FixedWing.Thrust — Aero.Aircraft.Thrust Objects hold the definitions of the aircraft thrust.
Define the fixed-wing aircraft state environment.	Aero.Aircraft.Environment — Aero.Aircraft.Environment objects hold the fixed-wing aircraft state environment such as air temperature, pressure, density, gravity, and so forth.
Define the properties for the fixed-wing aircraft.	Aero.Aircraft.Properties — Aero.Aircraft.Properties objects define common properties to maintain and define aircraft. Use this object throughout the fixed-wing aircraft design process.
To define the control states of a fixed-wing state.	Aero.Aircraft.ControlState — Aero.Aircraft.ControlState holds the definitions of the aircraft control surface deflection angles.

Static Stability Analysis

To perform static stability analysis of your fixed-wing aircraft:

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 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 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.

Examples

Aerospace Toolbox provides these examples to help you work with fixed-wing aircraft using the fixed-wing classes.

Action	Example
Create and analyze a fixed-wing aircraft in MATLAB® using Cessna C182 geometry and coefficient data.	Determine Nonlinear Dynamics and Static Stability of Fixed-Wing Aircraft
Convert a fixed-wing aircraft to a linear time invariant (LTI) state-space model for linear analysis.	Analyze State-Space Model for Linear Control and Static Stability Analysis
Construct and define a custom state for a fixed-wing aircraft.	Customize Fixed-Wing Aircraft with Additional Aircraft States