Aircraft Mission Planning with ModelCenter

STK Premium (Air) or STK Enterprise
You can obtain the necessary licenses for this tutorial by contacting AGI Support at support@agi.com or 1-800-924-7244.

Required product install: The Ansys ModelCenter® model-based systems engineering software and the STK Plugin for ModelCenter are required to complete this tutorial.

ModelCenter installation prerequisites: The ModelCenter software requires the installation of a 64-bit version of Java, a 64-bit implementation of Python 3.x, and the installation of the thrift and six Python packages. See the ModelCenter Installation Prerequisites for more information.

This tutorial was written using version 2026 R1 of the Ansys ModelCenter® model-based systems engineering software.

The results of the tutorial may vary depending on the user settings and data enabled (online operations, terrain server, dynamic Earth data, etc.). It is acceptable to have different results.

Capabilities covered

This lesson covers the following capabilities of the Ansys Systems Tool Kit® (STK®) digital mission engineering software:

  • STK Pro
  • Aviator
  • STK Analyzer

Problem statement

Aircrew and mission planners require a quick way to determine how wind will affect an aircraft's fuel consumption for a planned flight route. A military turboprop aircraft will: take off from an airfield in England, climb to an altitude of 20,000 feet MSL (mean sea level), navigate over three navigational aids (NAVAIDs) in France, and then land at an air base located in Germany. The aircraft has a fuel capacity of 200,000 pounds but will take off with 100,000 pounds of fuel. In total, the aircraft's weight with fuel is 380,000 pounds. The maximum landing weight is also 380,000 pounds. A weather system is moving into the area of the aircraft's planned flight route. Winds are predicted to change heading The direction that the aircraft is pointing., with variable speeds up to 25 nautical miles per hour. The aircraft is rated to land with a cross wind up to 30 nautical miles per hour, so you should not factor the cross wind into the problem. You want to determine how much fuel needs to be loaded on the aircraft prior to takeoff based on a worst-case scenario.

Solution

Use the STK software's Aviator capability and the Analyzer capability, which is part of the Ansys ModelCenter® model-based systems engineering software, to determine how wind speed and wind direction will affect the aircraft's fuel consumption over the course of the flight to help prepare for a worst-case scenario.

What you will learn

Upon completion of this tutorial, you will understand how to:

  • Change wind bearing and speed
  • Run parametric studies
  • Create carpet plots

Using the starter scenario

To speed things up and allow you to focus on the portion of this exercise that teaches you how to use the ModelCenter software, a partially created scenario has been provided for you.

Opening the starter scenario

The starter scenario is included in your install.

  1. Launch the STK application ().
  2. Click Open a Scenario in the Welcome to STK dialog box.
  3. Browse to <Install Dir>\Data\Resources\stktraining\VDFs.
  4. Select Aviator_Analyzer_Starter.vdf.
  5. Click Open.

Saving the VDF as a scenario file

Save and extract the VDF data in the form of a scenario folder. When you save a VDF in the STK application, it will save in its originating format. That is, if you open a VDF, the default save format will be a VDF (.vdf). If you want to save and extract a VDF as a scenario folder, you must change the file format by using the Save As feature. This will create a permanent scenario file complete with child objects and any additional files packaged with the VDF.

  1. Open the File menu when the starter scenario opens.
  2. Select Save As....
  3. Select the STK User folder in the navigation pane when the Save As dialog box opens.
  4. Select the Aviator_Analyzer_Starter folder.

    5. A scenario folder with the same name as the VDF was created for you when you opened the VDF in the STK application. This folder contains the temporarily unpacked files from the VDF.

  5. Click Open.
  6. Select Scenario Files (*.sc) in the Save as type drop-down list.
  7. Select the Aviator_Analyzer_Starter scenario file in the file browser.
  8. Click Save.
  9. Click Yes in the Confirm Save As Dialog box to overwrite the existing scenario file in the folder and to save your scenario.

When saving a VDF containing external files as a scenario folder, you must extract its contents to the scenario folder the STK application automatically creates for you in the STK User folder. This allows files packaged with the VDF, such as data files, reports, presentations, HTML pages, scripts, spreadsheets, and other files, to unpack to the scenario folder. If you save the VDF as a scenario folder in another location, these additional files will not be included. See the Permanently Extracting a VDF as a Scenario Folder and VDF Setup Considerations pages for more information.

Save () often during this lesson!

Obtaining situational awareness

Review the stater scenario in the 3D and 2D Graphics windows to visualize and understand the aircraft flight plan.

  1. Right-click on TurboProp () in the Object Browser.
  2. Select Zoom To in the shortcut menu.
  3. Look at the 3D Graphics window.

    4. TurboProp Taking Off from English Airbase

  4. Click Start () in the Animation Toolbar to obtain situational awareness of TurboProp's takeoff and location. An articulation file is being used to spin the propellers.
  5. Reset () the scenario after you have watched the animation.
  6. Look at the 2D Graphics window to obtain the overall view of the flight plan.

TurboProp's Flight Plan

Reviewing the aircraft's configuration

Before using the ModelCenter software to run trade studies, it's a good idea to understand the variables which will be changed and analyzed to determine how much fuel is consumed during the flight.

  1. Right-click on TurboProp () in the Object Browser.
  2. Select Properties ().

    3. TurboProp's () propagator is set to Aviator. The STK software's Aviator capability models real-world aircraft performance that accounts for variations in airframe performance characteristics, wind, atmospheric effects, and mission requirements.

  3. Click Configuration () in the Initial Aircraft Setup toolbar to open the Configuration window.

    4. The Configuration window is used to define the aircraft's fuel and payload configuration.

  4. Ensure the Basic tab is selected.

    5. The Basic tab is used to define the empty parameters of the aircraft, and displays the total values, based on the stations and fuel tanks defined for it. Note the Empty Weight, Max Landing Weight, and Total Weight.

  5. Select the Fuel tab.

    6. The Fuel tab displays a list of all of the fuel tanks defined for the aircraft, in their consumption order. The total fuel capacity and initial state of the aircraft are displayed below the list. You can see that though aircraft has a capacity of 200,000 pounds of fuel, it is taking off with only 100,000 pounds of fuel.

  6. Click Cancel to close the Aircraft Configuration window.

Reviewing the mission wind model

Wind bearing and speed will affect the aircraft's performance characteristics. Using Wind Models in the Aviator capability, you can change the ground speed, flight path angle, and altitude rate of an aircraft and produce a difference between the heading and course of an aircraft (also known as a crab angle).

  1. Click Mission Wind Model () in the Initial Aircraft Setup toolbar.

    2. Note that the Model Type is set to Constant Bearing/Speed. The Constant Bearing / Speed wind model creates a constant wind effect using a defined Wind Bearing and Wind Speed. In this scenario, the preset Wind Bearing (0 degrees) and Wind Speed (10 nautical miles per hour) will be changed and analyzed to determine their effect on fuel consumed.

  2. Click Cancel to close the Wind and Atmosphere Model tool.
  3. Click Cancel to close TurboProp's () properties.

Creating a new ModelCenter project

The Ansys ModelCenter software is designed for multidisciplinary analysis and design optimization. It allows you to automate complex workflows, integrate multiple engineering tools, and optimize designs within model-based systems engineering frameworks. Before opening the ModelCenter application, however, save your scenario and close out of the STK application.

  1. Save () your scenario.
  2. Close the STK application.
  3. Open the ModelCenter () application.
  4. Click Start a New Model in the Welcome to ModelCenter dialog box.
  5. Click Process when the What type of model would you like to create? dialog box opens.
  6. Navigate to your scenario folder (for example, C:\Users\<username>\Documents\STK_ODTK 13\Aviator_Analyzer_Starter.
  7. Enter Aviator_Analyzer_Starter in the File name field.
  8. Ensure the Save as type is set to the ModelCenter Model (Zip) (*.pxcz).
  9. Click Save.

Launching the STK Plugin for ModelCenter

The STK Plugin for ModelCenter imports a copy of the desired Scenario and opens it in an instance of the STK application. Launch the plugin by adding it to your workflow's analysis view from the Server Browser.

  1. Select favorites () in the Server Browser at the bottom of the window.
  2. Click and drag the STK component () into the dashed circle underneath "Drop items here to build the model" in the workflow's Analysis View.
  3. Select Aviator_Analyzer_Starter.sc when the Open STK Scenario file dialog box opens.
  4. Click Open.
  5. After a few moments, the STK Analyzer window will open.

The Aviator_Analyzer_Starter scenario file will open in the STK application in the background.

You can add any of the STK variables as ModelCenter input or output variables through the STK Analyzer window that appears. If you change the value of a variable in your scenario through the STK interface or the ModelCenter Component Tree, you should re-add the variable into ModelCenter or re-run the workflow before running any trade studies with the new value.

Setting up your analysis with Analyzer

Use the STK Analyzer window to configure the input and output variables available for further analysis with the Analyzer capability.

Selecting the input variables

Both the wind speed and bearing speed will have an impact on the amount of fuel the aircraft consumes. Add them as your input variables.

  1. Select TurboProp () in the STK Variables tree.

    2. When you select an object in the STK Variables tree, all possible input variable candidates for that object are listed under the General tab and the Active Constraints tab in the STK Property Variables panel.

  2. Expand () the Propagator (Aviator) () property in the STK Property Variables - General tab.
  3. Expand () the WindModel (Constant Wind) () property.
  4. Select WindBearing ().
  5. Move () WindBearing () to the Analyzer Variables list.
  6. Select WindSpeed ().
  7. Move () WindSpeed () to the Analyzer Variables list.

Both WindSpeed and WindBearing are listed as Inputs in the Analyzer Variables list.

Selecting the output variable

The same data providers that are available in the Report & Graph Manager are available in the Data Provider Variables tree.

  1. Expand () the Flight Profile By Time () data provider in the Data Providers list.
  2. Expand () the Fuel Consumed () data provider element.
  3. Select the Max () statistical function.
  4. Move () Max () to the Analyzer Variables list.

    5. Max is now listed under Outputs in the Analyzer Variables list.

  5. Click OK to confirm your selections and to close the STK Analyzer window.

    6. This will also close the STK application, which had been running in the background.

Determining the impact of wind bearing on fuel consumed

The first study you will perform varies wind bearing to determine its effects on how much fuel is used during the mission. The current wind speed of 10 nautical miles per hour will be maintained. You need to select input and output variables from the main STK Analyzer window to pass to the Parametric Study tool.

Using the Parametric Study tool

The Parametric Study tool runs a workflow through a sweep of values for some input variable. You can plot the resulting data to view trends.

  1. Expand () all the elements in the Component Tree.
  2. Click Parametric Study () in the Standard toolbar.
  3. Click and drag WindBearing () from the Component Tree to the Design Variable field when the Parametric Study tool opens.
  4. Set the following Design Variable values:
    5. Option Value
    starting value 0
    ending value 180

    Note that the step size is automatically set to 20.

  5. Click and drag Max () from the Component Tree to the Responses field.
  6. Click Run....

Clicking Run... will open the Data Explorer, which is a tool used by Trade Study tools to display data while they are being collected from the STK scenario. While data are being collected, the Data Explorer displays a progress meter, a halt button, and the data. The Table page displays trade study data in a tabular form. It is the default window that is present for all trade studies. Cells are shaded differently depending on the associated variable's state. Input variables are shown with green text, valid values are displayed with black text, invalid values are displayed with gray text, and modified values are displayed with blue text. From the table it is possible to view and edit all values in your trade study and even to add and remove whole runs. The first line shows wind bearing from zero (0) degrees through 180 degrees. The second line shows the maximum fuel consumed.

Viewing the 2D Scatter Plot

As the trade study runs and the data has been collected, a 2D Scatter Plot is automatically created. A 2D Scatter Plot displays an X-Y plot of variables in the model.

  1. Bring the 2D scatter plot to the front
  2. Hover over the design point with the maximum fuel consumption. The Design Tooltip appears.

    3. The Design Tooltip allows you to quickly examine individual design points.

    Wind Bearing vs Maximum Fuel Consumed

  3. Click Open Design View (...) in the lower right of the Design Tooltip to see more details about the design point.

    4. Design View

    You can see the maximum fuel consumption occurs around a wind bearing of 100 degrees. While you could perform additional trade studies with smaller step sizes focused around 100 degrees to narrow the range of the peak value, for the purposes of this exercise, this value is a close enough approximation for illustrative purposes.

  4. When finished, close the Design View.
  5. Close the 2D Scatter Plot and the Table page when you are finished.
  6. Click No when prompted to close your trade study without saving.
  7. Leave the Parametric Study tool open.

Analyzing the effects of wind speed on fuel consumption

Recall that the most fuel consumed with a wind speed of 10 nautical miles per hour was a wind bearing of 100 degrees. Update your model with this wind bearing to reflect the worst-case scenario.

  1. Click the WindBearing variable Value in the Component Tree.
  2. Change the value to 100 (degrees).
  3. Select the Enter key.

Creating a new Parametric Study

With the worst-case wind bearing set in your model, create a new parametric study to analyze the effects of wind speed on fuel consumption.

  1. Click and drag WindSpeed () from the Component Tree to the Design Variable field when the Parametric Study tool opens.

    2. This will replace WindBearing as the Design Variable.

  2. Set the following Design Variables:
    3. Option Value
    starting value 0
    ending value 25
    step size 5

    Note that the number of samples is automatically set to 6.

  3. Click Run....

Reviewing the results

Review the 2D Scatter Plot when the trade study is complete.

  1. Select the 2D Scatter Plot window.
  2. Review the plot.

    3. Wind Speed vs Maximum Fuel Consumed

    There are no real surprises. There's a steady increase in fuel consumed with an increase in wind speed. What's interesting to note is how much of a difference there is between 0 nautical miles per hour and 25 nautical miles per hour. The difference is over 4,200 pounds of fuel consumed.

  3. Close the 2D Scatter Plot and the Table page when you are finished.
  4. Click No when prompted to close your trade study without saving.
  5. Close the Parametric Study tool.

Analyzing the effects of wind bearing and speed together

A Carpet Plot is a means of displaying data dependent on two variables in a format that makes interpretation easier than normal multiple curve plots. A Carpet Plot can be thought of as a multidimensional Parametric Study. Setting the design variables in a Carpet Plot is similar to using the Parametric Study tool, except you can study two variables simultaneously instead of one.

Creating a new Carpet Plot

You know that wind bearing and wind speed had an impact on fuel consumed. For the purposes of this study, keep the number of steps low for time. However, on your own, you can perform as many runs as you desire. For the purposes of illustration, you'll assume the peak fuel consumption occurs at a wind bearing of 100 degrees.

  1. Click Carpet Plot () on the Analyzer toolbar to access the Carpet Plot tool.
  2. Click and drag Windbearing () from the Component Tree to the first Design Variables field when the Carpet Plot tool opens.
  3. Set the following Windbearing Design Variable values:
    4. Option Value
    From 99
    To 101
    Step Size 0.5
  4. Click and drag WindSpeed () from the Component Tree the second Design Variables field.
  5. Set the following WindSpeed Design Variable values:
    6. Option Value
    From 10
    To 25
    Step Size 5
  6. Click and drag Max () from the Component Tree to the Responses field.
  7. Click Run....

Configuring the Carpet Plot's axes

Your found with your first parametric study that the most fuel is consumed when the wind bearing is around a constant 100 degrees. Using the Carpet Plot, you refined this by focusing on 99 through 101 degrees using 0.5 degree increments. Set the Use the Plot Options menu to set options for the axes.

  1. Bring the Carpet Plot to the front.
  2. Click Axes in the Plot Options menu.
  3. Select the Ticks tab.
  4. Change the Max # value to 40.
  5. Click anywhere on the plot to close the Plot Options menu.

Constraining the Carpet Plot

You can constrain the Carpet Plot for better visualization when looking for specific variable data. For the purposes of illustration, constrain the carpet plot to a wind bearing of 100 degrees and a maximum wind speed of 19 nautical miles per hour.

  1. Click Constraints in the Plot Options menu.
  2. Set the WindBearing maximum value to 100.
  3. Set the WindSpeed maximum value to 19.
  4. Click anywhere on the plot to close the Plot Options menu.

    5. constrained Carpet Plot

  5. Review your now-constrained Carpet Plot.

The area of the plot in white shows feasible values. The point where your two maximum values meet shows the maximum amount fuel consumed for your constrained scenario, which in this case is about 57,300 pounds.

Saving your work

Save your work and close out ModelCenter application.

  1. Close out any open plots, tools, and the Data Explorer window.
  2. Click No when prompted to close your trade study without saving.
  3. Click Save () to save your ModelCenter workflow.
  4. Close the ModelCenter application.

Summary

Your aircraft mission was scheduled to fly from an airfield in England and land at an airfield in Germany. The weather forecast in the area called for variable wind speed and bearing. A large, pre-configured turboprop aircraft model and it's flight plan were already loaded into a prebuilt STK scenario using the Aviator capability. Using the ModelCenter application, you ran parametric studies which determined the effects of wind bearing and wind speed on the aircraft's fuel consumption. You then used a Carpet Plot to evaluate wind speed versus wind bearing to determine a worst-case scenario for the mission, which will help you to ensure there was enough fuel on board the aircraft prior to takeoff.