Drag and SRP sample plugins

« Go Back

Information

 
Notes/Code
The Plugins:
Attached are a few sample plugins that model drag area, drag coefficient, SRP area and SRP coefficient. Not all plugins vary all parameters. The plugins are:
  • CdFuncOfAlt . Varies the drag coefficient as a function of the altitude. Mostly designed for reentry. Open the .vbs file with a text editor and in the Evaluate function, edit the values you want to use
  • CdFuncOfMach . Varies the drag coefficient as a function of mach number. Mostly designed for reentry. Open the .vbs file with a text editor and in the Evaluate function, edit the values you want to use
  • CdFuncOfVel . Varies the drag coefficient as a function of velocity. Open the .vbs file with a text editor and in the Evaluate function, edit the values you want to use
  • DragAtTime . Simple 'If' Statement where drag coefficient is set depending on current epoch. Open the .vbs file with a text editor and in the Evaluate function, edit the values you want to use
  • DragSrpAreaFromAngles . Computes drag and SRP area as a function of Sun angle. It is assumes that the satellite rotates its solar panels so that they are exposed to the Sun as much as possible. The plugin then computes the equivalent drag and SRP area from the Sun angles. Once registered, go to the "Plugin Settings" and edit the values you want to change. Alternatively, change them directly in the header of the .vbs file
There are additional plugin samples that come with the STK install under <install folder>\CodeSamples\Extend\Hpop.ForceModels


Using the Plugins:
Instructions for registration of the .wsc type plugin are found at https://agiweb.secure.force.com/faqs/articles/Keyword/Register-wsc-plugin .

Once registered, the plugins will show up in the "Additional" tab in the HPOP Force Model settings. This is for satellites that use the HPOP propagator exclusively.
User-added image

For Astrogator satellites that are propagating using HPOP, the plugins can used in a duplicate of the HPOP propagator in the component browser. 
User-added image

After duplicating the HPOP propagator, double-click on the duplicate to open its properties, then add the desired plugin as a Propagator Function.
User-added image