The Advanced Fixed Wing Tool allows you to define physical properties for the aircraft that you are modeling that drives advanced class performance models. The properties defined in this tool are saved at the catalog level, and each aircraft model is limited to one set of definitions for them.
Geometry
The Geometry properties group describes the dimensions of individual control surfaces of the aircraft. You can define the total Wing Area, Flaps Area, and Speedbrakes Area.
Aerodynamics
The Aerodynamics properties group describes the aircraft's aerodynamic performance using one of three broad strategies:
- External Aero File
- Subsonic Aerodynamics
- Supersonic Aerodynamics
- Sub/Super/Hypersonic Aerodynamics
- Four Points Aerodynamics
Click 
to open the properties window for the currently selected strategy. Click Create Aero File... to create an .aero file using the current property settings of the Advanced Fixed Wing Tool. Select Cache Aero Data to store intermediate results for aerodynamics calculations; this option can improve calculation speed at a small cost in accuracy.
Powerplant
The Powerplant properties group describes the aircraft's propulsion performance using one of several empirical models of aircraft engine systems:
- Electric
- External Prop File
- Piston
- Turbofan - High Bypass
- Turbofan - Low Bypass
- Turbofan - Low Bypass Afterburning
- Turbojet
- Turbojet - Afterburning
- Turboprop
- Thermodynamic Models ( Sub/Super/Hypersonic Powerplant, Turbofan - Basic w/AB, and Turbojet - Basic w/AB)
Click to open the properties window for the currently selected strategy. Click Create Prop File... to create a .prop file using the current property settings of the Advanced Fixed Wing Tool. Select Cache Fuel Flow to store intermediate results for fuel flow calculations; this option can improve calculation speed at a small cost in accuracy.
The No Thrust When No Fuel checkbox, if enabled, stops the aircraft when the fuel runs out. If the checkbox is not enabled, the aircraft travels the length you set despite being out of fuel.
Dynamics/Moments
The Dynamics/Moments tab allows you to specify control parameters for the aircraft. These allow calculation of aircraft performance characteristics, but are not used to calculate trajectory. Required Control Authority allows you to specify what angular rates are expected to safely control the vehicle. Control Surface Buildup allows Aviator to calculate control forces available in each axis and is used to compute flight profile Control Force Required and FullControl.
Aviator calculates control forces as torques throughout the flight. The max force available for the torque is determined from Surface Area, CLMax, and flight conditions based on:
| Item | Description |
|---|---|
| F | Force |
| p | Air density determined by aircraft altitude |
| V | Aircraft velocity |
| S | Surface area determined above |
The max available control torque along an axis is the product of this force and the proscribed Moment Arm Length.
Structural and Human Factors Limits
The Structural and Human Factors Limits properties group describes the performance limitations of the aircraft with respect to the structural integrity of the aircraft or the survival of humans flying in it. You can define the following properties that the aircraft or the occupants can bear:
- maximum altitude (Max Altitude)
- maximum Mach The ratio of the aircraft's speed and the speed of sound at the aircraft's altitude, with local atmospheric conditions. speed (Max Mach Number)
- maximum equivalent airspeed (Max EAS Equivalent Airspeed: the airspeed at sea level (International Standard Atmosphere) at which the dynamic pressure is equal to the dynamic pressure at the aircraft's current true airspeed and altitude.)
- the load factor limits (Min Load Factor and Max Load Factor)
The Max Mach Number cannot be greater than the Mach limits of the currently selected Aerodynamics and Powerplant strategies; if you modify a Mach limit in one of those strategies so that it is less than the Max Mach Number, STK's Aviator capability displays a warning message that it must reduce the Max Mach Number to a compliant value. You can click OK to accept the new value or Cancel to undo the change that you made to the strategy's Mach limit.
Temperature Limit
The Temperature Limit section can be used to limit the maximum speed of the aircraft so the specified temperature is not exceeded. Select the Enforce Limit check box and define the Max Total Temp to enforce this temperature limit.
Flight Aero
The option enables you to evaluate how parameter changes affect the vehicle's aerodynamics performance.
Flight Prop
The option enables you to evaluate how parameter changes affect the vehicle's propulsion performance.
Flight Envelope
The Flight Envelope tool allows you to graph the as-defined vehicle flight performance. The Contours and Levels drop-down menus allows you to control the data being displayed in the profile.
Click anywhere in the profile to view information about the aircraft's performance in the properties group. The Font Size and Show Colored Lines and Legend options allow you to adjust the appearance of the profile.
You can define the Weight, Drag Index, Load Factor, Delta Temp, Power, and Airspeed Type that you want to evaluate. Properties that you set in this tool are defined only within this tool, for analysis purposes; the aircraft's actual property settings remain unchanged.
The Flight Envelope tool can be used alongside the Flight Test tool and the main window of the Advanced Fixed Wing Tool so that you can make a change in any of the windows and evaluate the impact of that change across all three tools.
If you wish to compare different designs, create an Advanced Performance Fixed Wing Configuration (*.fwcf) as described below and load it with the Compare to Reference Envelope to display its data in the profile for comparison with the current property settings.
Create Performance Models
The "advanced" class of performance models is comprised Acceleration, Climb, Cruise, Descent, Landing, and Takeoff models based on parameters defined in the Advanced Fixed Wing Tool. Click Create Performance Models.... You can use the Create Advanced Performance Models window to create a full set of advanced performance model. You can use the Perf Model Name field to give each performance model in the created set the same name. Select the Overwrite existing performance models check box to replace any performance models with the same name that is in the Perf Model Name field. Select the Copy to clipboard check box to place a copy of the performance models on the clipboard, in addition to saving them to the performance models list for the aircraft. Select the Set as default check box to set the performance models that are created as the default performance models for the aircraft.
Exporting and Importing Configurations
The settings specified in the Advanced Fixed Wing Tool can be saved to an Advanced Performance Fixed Wing Configuration file, which has a *.fwcf extension.
Click Export... to save your current settings to a file. If the current configuration includes an external aerodynamics or propulsion file, the file will be embedded in the *.fwcf file when it is created.
Click Import... to populate the Advanced Fixed Wing Tool with the settings from a previously saved file. If the imported *.fwcf file contains embedded aerodynamics or propulsion files, these files will be extracted and implemented automatically.