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XP GLJ Model 25/28 - What's New in Version 4?



New Features

  • New exterior/interior 3D models with more details and additional animations
  • New PBR materials and textures
  • 20 new aircraft variations, inspired by actual and/or fictitious liveries*
  • New aircraft interiors:
    • New interior colors
    • A detailed rear baggage compartment with curtain and props
    • Foldable cabin seats
    • Animated cabin tables with props
    • Animated cabin cabinet doors with props
    • A cabin refrigerator with light, animated door, and props
    • Animated cabin window blinds
    • A cabin TV (customizable)
    • A cabin toilet with animated seat cover, vanity, and door
    • Sheepskin pilot seat covers (optional)
    • New cockpit and cabin props: sunglasses, headsets, drinks and cups, snacks
    • New cockpit and cabin hot spots (miscellaneous functions)
    • New cockpit and cabin dynamic light effects**
    • New two-intensity ceiling lights (off/low/high)
    • New two-intensity map lights (off/low/high)
    • Dimmable backlit panels (0-100 percent brightness)
    • Dimmable annunciators and other panel lights (0-100 percent brightness)
    • Dimmable landing gear status lights (0-100 percent brightness)
    • New two-intensity instrument lights and post lights with independent controls for captain/center/copilot instrument panels (off/low/high)
  • A fully simulated anti-ice system with ice effects on the windshield, windows, and exterior aircraft surfaces
  • A revised annunciator panel (changes mainly related to the new anti-ice system and battery temperature)
  • A revised electrical system
  • A new cockpit and cabin lighting system*
  • A new sound system
  • 90 new cockpit and cabin sound effects (120 sounds in total)
  • 40 new and/or revised visual effects
  • A revised and updated 320-page flight manual (printable PDF format, requires Adobe Acrobat Reader)

*: All liveries are imaginary, though some may be inspired by actual airplane liveries. Any match with actual tail numbers is a pure coincidence.

**: Cockpit and cabin environment lights, panel instrument lights, panel post lights and flood lights are true dynamic lights, like in the real world - no textures with static light maps are used to artificially produce illumination effects, like in most legacy addons.

Modifications, Improvements and Fixes

  • A new Prepar3D “Add-ons” method of installation (makes addons easier to manage)
  • 2-position switches in the cockpit no longer respond to mouse wheel movements
  • The volume of the cockpit and cabin sound effects can be adjusted by moving the “Cockpit” cursor on the “Prepar3D > Top Menu Bar > Options > General > Sound” page, under “Volume Levels”.
  • The beta “SPD P” autopilot speed control mode from the previous addon version was removed from the AFCS because of unsolvable stability issues and software limitations in Prepar3D. “Speed Hold by Pitch” and “Flight Level Change” speed control modes are not natively supported in Prepar3D and were not available in most Learjet 20 Series aircraft.
  • A paint kit for users to create their own PBR aircraft liveries (to be released shortly) - Requires some knowledge of physically based rendering textures and of the paint tools needed to create them (see appendix 3 in the manual).
  • A revised and updated 320-page flight manual (printable PDF format, requires Adobe Acrobat Reader)
  • A revised method for installing optional third-party addons and gauges (GPS, GNS, GTN, radar and transponder, including the Prepar3D demo radar from the Prepar3D SDK)


Software features, prices and release dates are subject to change without notice. Some functionalities may differ from those in the real aircraft due to software limitations in Prepar3D.

The XP GLJ Model 25 v4 addon and the XP GLJ Model 28 v4 addon are two different products that can be purchased separately or together in a special bundle.

Optional GNS, GTN, radar and special transponder addons are not included and must be purchased separately from third-party vendors/developers (Prepar3D GPS, demo radar and transponder are included). Some third-party add-on software may no longer be compatible with the latest versions of Prepar3D. Please contact the developer for support. Xtreme Prototypes cannot provide technical assistance for third-party addons.

The GNS 530 3D model in the virtual cockpit is preprogrammed for the default GPS 500 that comes with Prepar3D. The weather radar model shows a dummy radar screen by default but is also compatible with the demo monochrome radar gauge that comes with the Prepar3D SDK (Prepar3D demo radar is included, see "Release Notes" in the manual). Navigation system and radar 3D models are user-programmable and are compatible with most third-party add-on software. Pre-configured panels for the most popular third-party addons are included. Detailed instructions are provided in appendix 2 of the manual for adding third-party addons and gauges to the cockpit of the GLJ Model 25/28 v4 add-on aircraft. Experimentation may be required.


The Xtreme Prototypes GLJ Model 25/28 v4 addon features all new PBR materials and textures. Physically based rendering (or PBR) is a method of shading and rendering that provides a more accurate representation of how light interacts with surfaces. The results are 3D models that look almost real under different lighting conditions. Refer to appendix 3 in the manual for information on how to create your own PBR aircraft liveries for your GLJ Model 25/28 v4 addon.