XP GLJ Model 28 v4

Our Definitive Gates Learjet 28 Simulator for Lockheed Martin® Prepar3D®

This release contains many new features and improvements over previous versions, including revised exterior/interior high resolution 3D models with more details and additional animations, new PBR materials and textures, 20 new liveries, new aircraft interiors, instrument panel dynamic light effects, dimmable cockpit and cabin lights, 40 visual effects, more than 120 sound effects including new cockpit and cabin sounds, a new sound system, new Learjet custom aircraft systems including a fully simulated anti-ice system (with ice effects on the windshield, windows, and exterior aircraft surfaces), two different cockpit configurations with support for optional third-party GNS/GTN systems and radars*, and a completely revised and updated 320-page flight manual.

*: Optional third-party GNS/GTN navigation systems and radars are not included and must be purchased separately. Prepar3D GPS and demo radar are included.

What's new in version 4?

A Fighter in Civilian Clothing

Nicknamed “fighters in civilian clothing” because of their sleek design and amazing performance, the classic Lear Jet/Learjet 20 Series aircraft were the first true executive jets and redefined business aviation during the 1960s and 70s, flying high above the weather at transonic speeds. Their capabilities earned them a place among the extreme aircraft, setting record after record.

The Gates Learjet Model 28 along with its longer-range sister ship, the Model 29, represented the epitome of the straight-turbojet executive aircraft in the late 1970s and early 80s. With a fuselage based on the acclaimed Model 25, it had a new wing dubbed the “Longhorn” that replaced the traditional tip tanks with upswept winglets, the first ever on a jet, which provided a dramatic reduction of induced drag, therefore stretching range and enhancing climb performance. In February 1979, a Model 28 climbed from the ground to nearly 50,000 feet in about 12 minutes, setting five world records for altitude gain and sustained altitude in a business jet.

A Unique Addon for your Hangar

The Xtreme Prototypes GLJ Model 28 v4 is a next generation addon optimized for the latest versions of Prepar3D and designed to take advantage of the new and more powerful gaming computers and graphics cards that are available today. Nothing was spared in our efforts to reproduce the different instrument panels, carefully modeling and animating each mechanical device with all the necessary moving parts. Except for the LCD screens and the radio’s VFD displays, no flat 2D gauges are used in this model. Everything you see is in full 3D!

The result is a unique addon that strives to bring you not only the actual feeling of flying a high-performance aircraft now equipped with modern avionics, but also the spirit of maneuvering such a vehicle at times where large LCD screens and powerful computers didn’t exist, and where pilots needed to know how to fly and navigate with minimal resources and rely on their own experience, abilities, and judgment.

At Xtreme Prototypes, we consider our addons as real micro aircraft simulators rather than just games. Our products take months if not years to develop and test by a dedicated and passionate team of artists, technicians and pilots. We pay attention to every detail and we do our best to make sure that we provide our users with the best flight simulation experience they can get within the limitations of the current simulation platforms. We believe our GLJ Model 28 addon (and our GLJ Model 25, available separately) is the most advanced, detailed, and faithful classic Learjet simulation you can find.

Designed by Users for Users

Becoming one of our users makes you an important member of our development team. Version 4 of our GLJ Model 28 addon is the product of the many ideas, comments, and suggestions we received from desktop pilots like you from around the world since version 1 of our 20 Series business jet addons was launched back in 2009. We wish to express our gratitude to all our users, followers, reviewers, test pilots, ex-Learjet employees, partners, and friends for their contribution to the making and success of this extreme aircraft simulator. Thank you for your continuous support!

Download the Manual

Download the full 320-page flight manual
(132 MB, PDF format)

Manuals are updated frequently, make sure you have the latest version.

What you Need to Know

• Optional third-party GNS, GTN, radar and special transponder addons are not included and must be purchased separately. Prepar3D GPS, demo radar and transponder are included.
• The XP GLJ Model 28 v4 addon and the XP GLJ Model 25 v4 addon are two different products that must be purchased separately or together in a special bundle.
• You must accept the end-user license agreement before you can download, install and use this software.
• This version is not fully compatible with Prepar3D v6. A software update for Prepar3D v6 is currently in production. Please read "Minimum System Requirements", below.

The Xtreme Prototypes GLJ Model 28 v4 is an add-on software package that requires Lockheed Martin Prepar3D v5.4* to be installed on your computer. The software is not a stand-alone product and cannot be used without the underlying simulation platform.

IMPORTANT: Xtreme Prototypes next generation addons are designed to take advantage of the new and more powerful gaming computers that are available today. Increased performance will be noticed on more powerful systems. Before purchasing this product, make sure you have the minimum system requirements or better. For obvious reasons, downloads are not refundable.

• Flight Simulation Platform: Lockheed Martin Prepar3D v5.4*
• Operating System: Microsoft Windows 10/11 or later, 64 bits (Windows 11 recommended)**
• Computer Memory (RAM): 16 GB or better recommended**
• Processor: Quad Core 3.0 GHz (Octa Core 3.7 GHz or better recommended)**
• Hard Drive Space: Downloaded compressed zip file size approx. 3 GB; addon size approx. 12 GB when fully installed
• Graphics Card: A high-end graphics card with at least 8 GB GDDR5 or better is highly recommended. Prepar3D requires a DirectX 12-compatible graphics card. Make sure you have the latest driver for your graphics card.
• Graphics: DirectX 12 (required by Prepar3D)**
• Other: Monitor, wheel mouse, game controller (joystick or yoke), pedals (optional), sound card and speakers, Adobe Acrobat Reader, Adobe Photoshop (optional, required for using the paint kit). A wheel mouse is required to actuate 3-position switches and knobs.

*: This version is not fully compatible with Prepar3D v6. A software update for Prepar3D v6 is currently in production. New addon versions may become available for future versions of Prepar3D. See "Software Updates", below.
**: Refer to the Prepar3D documentation for more information about minimum system requirements.

General Features

20 aircraft variations inspired by actual and fictitious models and liveries*:  

• (AUS) Gray, White and Black (fictitious tail number VH-GAXP)
• (BRA) Green, Yellow and Blue (fictitious tail number PR-VZAXP)
• (CAN) White (fictitious tail number C-DZXP)
• (CAN) White, Turquoise and Red (fictitious tail number C-FKVXP)
• (CHE) White, Red and Gold (fictitious tail number HB-VEAXP)
• (CHL) Blue, Gray and Yellow (fictitious tail number CC-PBVXP)
• (DEU) White, Gray and Turquoise (fictitious tail number D-BAXP)
• (FRA) White, Blue and Red (fictitious tail number F-BZXP)
• (GBR) White, Blue and Red (fictitious tail number G-KVXP)
• (MEX) White, Brown and Black (fictitious tail number XA-VCXP)
• (NASA Experimental) White, Red, Orange and Yellow (fictitious tail number N266XP)
• (NASA Research) White and Blue (fictitious tail number N816XP)
• (US Army) Green Camo (fictitious tail number 68095XP)
• (USA Charter) Red, White and Blue (fictitious tail number N142XP)
• (USA) Black, Orange and White (fictitious tail number N270XP)
• (USA) Gray, Green and Gold (fictitious tail number N233XP)
• (USA) Red, White, Blue and Gold (fictitious tail number N826XP)
• (USA) White, Black and Gold (fictitious tail number N46XP)
• (USA) White, Blue and Gold (fictitious tail number N128XP)
• (USA) White, Gray and Red (fictitious tail number N158XP)

*: All liveries are imaginary, though some may be inspired by actual airplane liveries. Any match with actual tail numbers is a pure coincidence. See appendix 8 in the manual.

Flight Model Features

Optimized, pilot-tested, 20 Series flight dynamics to simulate the performance of a high-powered civilian jet aircraft, within the present limitations and capabilities of the currently available simulation platforms: 

• Two General Electric CJ610-8A single-spool turbojet engines (2,950-pound static thrust at sea level)
• Service ceiling: 45,000 ft.
• Absolute ceiling: 51,000 ft.
• Maximum speed: 359 KIAS
• Maximum Mach: Mach 0.82 (at 24,000 ft.)

20 Series Aircraft Systems

The following Learjet 20 Series aircraft systems are simulated to conform as closely as possible to the operation of the real airplane, within the present limitations and capabilities of the currently available simulation platforms: 

• Flight controls
• Stall/overspeed warning systems with stick nudger/puller and stick shaker
• Electrical system
• Cockpit and cabin lighting systems with independent controls and dimmers, including emergency lighting
• Emergency batteries (not available in Prepar3D, APU used to simulate emergency batteries instead)
• Ground power unit (Prepar3D GPU)
• Hydraulic system (including functional electric auxiliary hydraulic pump)
• Landing gear, anti-skid system, differential brakes
• Fuel system (including cross-feeding)
• CJ610-8A power plant
• Fire detection and suppression system
• Pneumatic (high pressure), bleed air, pressurization, and environmental control systems
• Air conditioning and cabin temperature (H-valve) system
• Anti-ice system (fully simulated, with ice effects on the windshield, windows, and exterior aircraft surfaces)
• Automatic flight control system (AFCS) with autopilot, flight director, dual yaw damper, and speed/Mach hold systems modes (the Lear J.E.T. autopilot is retrofitted to be fully functional in GPS mode and compatible with the Prepar3D autopilot)
• RVSM system, complete with digital altimeters/altitude preselectors (ADDUs) with blue VFD display, analog standby altimeter, and control panel
• Caution and warning system (annunciator panel)
• Avionics, radios, and classic navigation systems: COM1, COM2, NAV1, NAV2, ADF1, ADF2, transponder, DME, marker beacons
• Programmable GNS 530, GTN 750, generic weather radar, and transponder 3D models (Optional third-party GNS/GTN navigation systems and radars are not included and must be purchased separately. Prepar3D GPS and demo radar are included.)
• Ground proximity warning system (GPWS)
• Emergency gear extension system
• Passenger and crew oxygen system
• Passenger and crew door (fully animated)

Aircraft Exterior 3D Model Features

• Two high resolution, fully animated exterior 3D models, inspired by the real aircraft (optimized for the latest versions of Lockheed Martin Prepar3D): 
• 4096 x 4096 high resolution PBR textures (see definition of PBR below)
  • High resolution decals and markings
  • Unique livery for each aircraft variation
  • 20 liveries in total
• Movable aerodynamic control surfaces:
  • Movable horizontal stabilizer
  • Elevator
  • Ailerons with trim and balance tabs
  • Flaps
  • Vertical stabilizer/rudder with trim tab
  • Spoilers
• Fully animated landing gear, complete with flexible hoses, landing and taxi lights, anti-skid system, snubbers, and more
• Fully animated passenger and crew door (lower and upper sections)
• Detailed CJ610-8A power plant with animated (compressor and turbine) blades and inlet guide vanes
• Fully animated and highly detailed thrust reverser on both engines
• Dynamic lights with real projected light beams:
  • Independent left/right two-intensity landing and taxi lights
  • Animated rotating beacon lights (belly, tail)
  • Right wing inspection light
  • Navigation lights (wing, tail)
  • Strobe lights (winglets, tail)
  • Entry lights
• Animated stall vanes on the nose
• Optional nose boom with animated vanes
• Three user-selectable pilots (with headset and optional sunglasses)
• Functional ground power unit (GPU) supplying 28 VDC to the aircraft during maintenance, training, or preflight procedures (with animation, lights, smoke, and sound)
• Clickable hot spots on the exterior model (miscellaneous functions; see section 3, page 8, in the manual):
  • GPU visible/invisible (left winglet leading edge)
  • Crew present/absent (steps on the lower portion of the passenger and crew door)
  • Pilot selection (pilot’s shirts)
  • Pilot’s sunglasses (windshield defog outlets)
  • Cabin and entry lights (cabin wall switches)
  • Passenger and crew door open/closed (door handles)
  • Remove before flight items installed/removed (nose gear door)

Aircraft Interior 3D Model Features

• Two high resolution, VR-ready virtual cockpits** with different panel configurations, full-3D animated gauges, switches, knobs, levers, light indicators, and flight instruments with tooltips:
  • Basic Configuration: New radios with yellow VFD displays (COM/NAV/ADF/XPDR) are installed on the main instrument panel to replace the original sets with analog displays from the 1960s. A user-programmable GNS 530 and a weather radar are also installed*.
  • GTN750 Configuration: Features modern avionics including two user-programmable GTN 750 (GPS/COM/NAV/XPDR) multifunction display systems, a user-programmable weather radar, an ADF radio and a transponder with yellow VFD displays*.
• Full 3D integration of the GPS/GNS/GTN, radar and transponder. Screens, buttons, and knobs can be programmed by users to integrate most third-party addons*. Experimentation may be required (see appendix 2 in the manual):
  • Fully animated 3D model of a generic GNS 530, compatible with the Prepar3D GPS 500 and most third-party GNS 530 addons
  • Fully animated 3D model of a generic GTN 750, compatible with most third-party GTN 750 addons
  • Fully animated 3D model of a generic weather radar, compatible with most third-party weather radars, also compatible with the monochrome demo radar that comes with the Prepar3D SDK
  • Fully animated 3D model of a transponder with a front VFD display, compatible with the Prepar3D transponder and most third-party transponder addons supporting C mode of operation and other features

*: Optional third-party GNS/GTN navigation systems, radars and transponders are not included and must be purchased separately. Prepar3D GPS, demo radar and transponder are included.

• Highly detailed full 3D instrument panels:
  • Captain’s panel
  • Center panel
  • Copilot’s panel
  • Annunciator panel
  • Thrust reverser control panel
  • Center pedestal
• 4096 x 4096 high resolution PBR textures (see definition below)
• Advanced cockpit lighting system:
  • Two-intensity ceiling lights (off/low/high)
  • Two-intensity map lights (captain’s, copilot’s, controlled independently, off/low/high)
  • Two-intensity glareshield yellow flood lights (captain’s side, copilot’s side, controlled independently, 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)
  • Two-intensity instrument lights and post lights with independent controls for captain, center, copilot instrument panels (off/low/high)
  • Emergency lighting
• Animated control columns and yokes (hidable, user-selectable), with functional autopilot remote buttons
• Stick nudger/puller and stick shaker with animation and sound
• Animated rudder pedals with differential brakes
• Retrofitted radios with yellow digital VFD displays and standby frequencies: COM1, COM2, NAV1, NAV2, ADF1, ADF2, ATC/XPDR
• RVSM system, complete with digital altimeters/altitude preselectors (ADDUs) with blue VFD display, analog standby altimeter, and control panel
• Automatic flight control system (AFCS) with autopilot, flight director, yaw damper and speed/Mach hold systems modes (the Lear J.E.T. autopilot is retrofitted to be fully functional in GPS mode and compatible with the Prepar3D autopilot)
• NAV1 or GPS/GNS/GTN navigation modes
• DME head
• Ground proximity warning system (GPWS)
• Lear engine sync spinner
• Analog and digital clocks with stopwatch
• Lear Jet Stereo “Jetstar 8” 8-track tape player that can play up to four user’s personalized stereo music tracks (a tribute to the inventive genius of Bill Lear)
• Side controls (light dimmers, fan control knob, oxygen valves)
• Pilot seats with adjustable/retractable armrests
• Optional sheepskin pilot seat covers
• Animated sun visors (foldable, slidable)
• Hidable throttle quadrant
• Thrust reverser subthrottles
• Gray leather interior with light gray birch wood cabinets
• Front and rear cabin curtains (open or closed, switchable)
• Rear baggage compartment with props
• Foldable passenger seats (animated)
• Animated cabin tables with props
• Animated cabin cabinet doors with props
• Cabin refrigerator with light, animated door, and props
• Animated cabin window blinds
• Cabin TV (customizable)
• Cabin toilet with animated seat cover, vanity with animated drawers, and door (open or closed, switchable)
• Cabin lighting system (ceiling lights, signs, entry lights, refrigerator blue light, passenger reading lights with individual switches)

**: Xtreme Prototypes next generation addons no longer include 2D panels found in legacy products. They are replaced by full 3D virtual cockpits. No flat 2D gauges to represent 3D flight instruments are used in this model.

Dynamic Lights and Visual Effects

• Cockpit/cabin lights: panel yellow flood lights, ceiling lights, map lights, instrument lights, panel post lights, passenger reading lights, entry lights, refrigerator blue light, signs*
• Aircraft lights, some animated: landing, taxi, navigation, strobes, rotating beacon, wing inspection
• Engine startup flames and smoke
• Engine contrail
• GPU lights
• GPU startup smoke
• Wing vortices and vapor trails
• 40 dynamic lights and/or visual effects in total

*: Cockpit instruments and all interior objects are illuminated with real dynamic lights for a more natural look (no static light maps are used to simulate cockpit illumination; see section 6, page 7 in the manual).

Sound Effects

• 20 Series 3D sound set, including starter and engine sounds recorded from a real 20 Series aircraft and positioned in the 3D space
• Over 80 additional cockpit stereo sound effects, many from a real 20 Series aircraft: switches, knobs and levers, pneumatic valves, blower fan, alerts and horns, Learjet unique brake sounds, GPU engine, cabin tables, cabinet doors, toilet seat, curtains and doors, foldable seats
• More than 120 sounds in total

Miscellaneous

• Prepar3D “Add-on” method of installation (makes addons easier to manage)
• “Cold and Dark” cockpit reset cycle and “Auto Start” sequence
• Custom sound system for playing cockpit sounds and music
• 15 interior camera views
• 5 outside camera views
• A 320-page flight manual (printable PDF format, requires Adobe Reader)
• A paint kit for users to create their own aircraft liveries (to be released later) - Requires some knowledge of physically based rendering (PBR) textures and of the paint tools needed to create them (see appendix 3 in the manual).

IMPORTANT NOTICES:

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 28 v4 addon and the XP GLJ Model 25 v4 addon are two different products that must 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 28 v4 add-on aircraft. Experimentation may be required.

WHAT ARE PBR TEXTURES?

The Xtreme Prototypes GLJ Model 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 28 v4 addon.

Reviews about our GLJ Model 28 v4 addon will be posted here when available. Refer to our  GLJ Model 25 v4 addon for previous XP GLJ 20 Series reviews.

Listed below are the latest available patches for your Xtreme Prototypes GLJ Model 28 v4 addon for Prepar3D - for registered users only. To download these files, please login to your Xtreme Prototypes online account.

New software update for Prepar3D v6 coming soon.