XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1
XP 20 Series v1

XP 20 Series v1


Our 20 Series Business Jets v1 addon contains seven variations of the GLJ Models 24, 25 and 28, designed for Microsoft® Flight Simulator X (compatible with Prepar3D®).

The addon includes three highly detailed exterior models and a fully functional 3D virtual cockpit. The package also includes a high-performance jet flight model, custom visual and sound effects, multiple camera views and a 84-page flight manual.

Please note that this addon is a legacy product offered for a limited time and for which we can no longer offer technical support.


A Classic Addon Available for Download for a Limited Time

Over the years, some of our products have become legacy due to the constant evolution of the simulation platforms or because they are being replaced by better, up-to-date products with much more features. By popular demand and for a limited time, we are now please to offer these products a very special price.

Please note that the 20 Series Business Jets v1 addon is a legacy product for which we can no longer offer technical support. It is offered to collectors as is. For an upgraded Learjet experience, please consider our GLJ Model 25 SE v3.0 for Prepar3D®, FSX and FSX Steam®.

Flying Dreams Are Made of This!

The classic 20 Series aircraft, nicknamed “fighters in civilian clothing” because of their sleek design and amazing performance, were the first true executive jets. Their capabilities earn them a place among the extreme aircraft, setting record after record while allowing shirt-sleeve comfort in their plush cabins.

The Xtreme Prototypes 20 Series addon contains seven variations of the legendary Models 24, 25 and 28. Each highly detailed exterior 3D model features over 500 parts and 40 animations. The fully functional virtual cockpit contains over 800 parts and more than 200 back and front-lit 3D gauges, lights, switches and flight instruments.

A custom flight model was designed to simulate the performance of a high-powered civilian jet aircraft in the simulator. The package also includes custom visual effects and sounds, multiple camera views and a detailed, 84-page flight manual.

Download the Manual

Download the full 84-page flight manual
(32 MB, PDF format)

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

What you Need to Know

  • You must accept the end-user license agreement before you can download, install and use this software.
  • Please read Minimum System Requirements, below.

This legacy addon was originally designed for FSX and is not compatible with FS2004. Boxed FSX requires SP2 with Acceleration Expansion Pack (FSX Gold fully installed). No FSX Steam® installer is provided. Installation in FSX Steam® requires changing the path to your FSX Steam® folder during installation. This addon can be installed in Prepar3D® but has not been thoroughly tested on this platform. No Prepar3D® installer is provided. Installation in Prepar3D® requires changing the path to your Prepar3D® folder during setup.

IMPORTANT: Xtreme Prototypes addons are complex and require better graphics cards and more processing power and RAM than other more conventional addons. 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: Microsoft® Flight Simulator X SP2 with Acceleration Expansion Pack (or FSX Gold fully installed). This product is not compatible with earlier versions of Microsoft® Flight Simulator. Compatible with all versions of Lockheed Martin® Prepar3D® and FSX Steam® Edition (please read notes below).
  • Operating System: Windows® 10/8.1/8/7/Vista/XP SP2 32-bit (64-bit recommended), depending on your simulator's requirements*.
  • Computer Memory 16 GB or better recommended*
  • Processor: Dual Core 3.0 GHz (Quad Core 3.0 GHz or better recommended)
  • Hard Drive Space: Downloaded ZIP file size approx. 300 MB, addon size approx. 500 MB when installed*
  • Graphics Card: A high-end graphics card with at least 8 GB GDDR5 or better is highly recommended*. Installing this addon in Prepar3D® requires a DirectX® 11-compatible graphics card*. Make sure you have the latest driver for your operating system.
  • Graphics: DirectX® 12, 11, 10 or 9 (depending on your simulator's requirements)*
  • Other: Wheel mouse, joystick (pedals optional), sound card and speakers, Adobe® Acrobat® Reader. A wheel mouse is required to actuate 3-position switches and some knobs.

*: Refer to your simulator's documentation for more information.

Note for Prepar3D® users (all versions): We have not thoroughly tested this native FSX addon in Lockheed Martin® Prepar3D®. However, we have been able to fly our 20 Series addon in Prepar3D®. Please note that there is no installer for Prepar3D® available for this addon. To install the addon in Prepar3D®, simply change the path to your Prepar3D® folder during installation. Select the "FSX with Acceleration Expansion Pack" option if asked.

Note for FSX Steam® users: Please note that FSX Steam® Edition is installed in a different way to the boxed version and occupies a different location on your computer. There is no FSX Steam® special installer provided with this native FSX addon. To install the addon in FSX Steam® Edition, simply change the path to your FSX Steam® folder during installation. Select the "FSX with Acceleration Expansion Pack" option if asked.

General Features

Contains seven variations of the 20 Series business jets:

  • Two variations of Model 24 (fictitious tail numbers XP-241 and XP-242)
  • One black variation of Model 24 (fictitious tail number N64JZ)
  • Two variations of Model 25 (fictitious tail numbers XP-251 and XP-252)
  • Two variations of Model 28 (fictitious tail numbers XP-281 and XP-282)

Flight Model Features

Custom 20 Series flight model to simulate the performance of a high-powered civilian jet aircraft on your simulation platform:

  • Two General Electric CJ-610, 2,950-pound static thrust, single-spool turbojet engines
  • Maximum altitude: 45,000 feet (51,000 feet for Model 28)
  • Maximum speed: Mach 0.82

20 Series Aircraft Systems

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

  • Flight controls
  • Electrical system
  • Hydraulic system
  • Landing gear
  • Fuel system
  • Power plant
  • Fire detection and suppression system
  • Pneumatic and environmental control system
  • Automatic flight control system
  • Caution and warning system
  • Radio and navigation system

Aircraft Exterior 3D Model Features

  • Native FSX 3D models
  • Highly detailed exterior models, with more than 500 parts and 40 animations
  • High resolution rendering of interior shadowing and accumulated dirt
  • Reflective high-resolution textures with bump maps
  • Emissive (night) textures
  • Unique markings and liveries on each aircraft
  • Movable aerodynamic control surfaces:
    • Movable stabilizer
    • Elevator
    • Ailerons with trim tab
    • Flaps
    • Vertical stabilizer/rudder with trim tab
    • Spoilers
  • Highly detailed steerable front gear
  • Highly detailed main landing gear with mobile landing and taxi lights
  • Fully animated engine turbine and compressor disks
  • Movable main cabin door

Aircraft Interior 3D Model Features

  • Highly detailed 3D virtual cockpit with over 800 parts and 200 full 3D animated gauges, switches, levers, light indicators and flight instruments with "tooltips"
  • Advanced fully functional back/front-lit 3D instrument panels with custom aircraft systems:
    • Captain's panel
    • Center panel
    • Electrical and radio panels
    • Co-pilot's panel
    • Annunciator panel
    • Center pedestal
  • Cockpit lighting
  • Cabin details

Visual Effects

  • Engine smoke and contrail effects
  • Aircraft lights, some animated (landing, taxi, recognition, navigation, rotating beacons)
  • VC/cabin lights
  • Wing vortices and vapor trails

Sound Effects

  • 20 Series custom sound package


  • Multiple camera views (external and internal)
  • 20 Series aircraft kneeboard reference tab and check list
  • Paintkit
  • A comprehensive 85-page user manual with complete instructions, flight planning, procedures and check lists, in a printable PDF format (English and French language versions)

Tony Radmilocich, PC Pilot Magazine:
"If you love hands-on, high adrenaline flying, the early Learjets should be your cup of tea. Xtreme Prototype's 24/25/28 models capture the essence of what it is like to pilot one of these little "rocket ships" in corporate jet guise."

Emmanuel Blanchard, Micro Simulateur Magazine:
"The numerous aircraft systems are realistic and plunge the virtual pilot in a pleasant environment of before the electronic era. Pleasant to control, offering feelings rarely encountered while flying a business aircraft, the 20 Series deserves the interest of the virtual pilots."

William Werrlein, FlightSim.com:
"For those of us who wonder how the basic jet feels I would recommend this aircraft (20 Series). I really do think that Xtreme Prototypes has done a great job in their level of detail on the exterior and interior, and the flight dynamics of the aircraft. As for the manual I must give a round of applause for the developer."

Proflig8tor, Avsim.com:
"Xtreme Prototypes has produced a most pleasing add-on Lear 20 Series jet. The design is a compromise that will be easy for new users to enjoy and has sufficient detail that more experienced users will not find it boring, or toy like. The flight model is good, with accurate roll and pitch response for the 20 Series Learjet. The Xtreme Protoypes Lear 20 Series is a lot of fun to fly."

PC Aviator (A Current Best-Of-The-Best List For Flight Sim Pilots):
"If there's a company that has impressed the heck out of us with their approach to quality and professionalism, it's Xtreme Prototypes out of Canada. They are nothing short of a world class act... Their latest addon emulates several models of the Gates Learjet 20 Series and is a must have addon to your hangar."

Joe Zerilli, 20 Series fan and ex-pilot:
"I must say, I simply love your 20 Series Lear collection. Truly a masterpiece series. I have real world experience with the 25D, and still have all the training manuals and documentation on the aircraft."

Mike Garner, 20 Series fan:
"Just curious, are there plans to release a paint kit for the Lear 20 Series Package. Absolutely love the package, the only thing I use now."

Pedro Barradas, 20 Series fan:
"Just got the (20 Series) and I just love it! Congrats on such a good product."

Raul Aubele, 20 Series fan:
"Your Lear is a masterpiece."

Joe Bush, 20 Series fan:
"Love the Lear 20 package, great job!"

Frank Schmitz, 20 Series fan:
"Greatest addon for FSX and even better than the original aircraft :-) I love the 20 Series birds, just wonderful aircraft"

Jose Otero, 20 Series fan:
"The Xtreme Prototype 20 (Series) is a beauty!"

Listed below are the latest available patches for your Xtreme Prototypes 20 Series Business Jets v1.x addon - for registered users only. To download these files, please login to your Xtreme Prototypes online account.

(2010-10-30) Version 1.01 (SP2) of the 20 Series Business Jets for Flight Simulator X (various improvements and fixes). If you have purchased the download version of this software after October 30th, 2010, you do not need to download this update. Free for registered users of previous versions.

(2010-10-30) Paintkit for version 1.01 of the 20 Series Business Jets for Flight Simulator X. Use this paint kit to create new liveries for your 20 Series aircraft. Free for registered users (all versions).