• Learjet 23 By Franz Luftfahrt

    Review: Learjet 23 By Franz Luftfahrt

    By Bill Stack (6 July 2010)

    Screen shots by Franz Lufthahrt

    Introduced in the early 1960s, the Learjet 23 was the first in a long series of popular business jets developed in the succeeding decades. Its name "Learjet" is often used generically in reference to all business jets. The Learjet 23 pioneered a new market for aircraft used by corporate executives and the very wealthy that is still vibrant today. Until model 24 was introduced two years later, 105 Learjet 23s were produced.

    Conceived by a Swiss aeronautical engineer, the Learjet 23 found its financing, manufacture, and marketing through Bill Lear, an American inventor. Lear invented the automobile radio, the radio-direction finder, the autopilot, and the 8-track stereo system. The Lear Aircraft Corporation later became Gates Lear and was eventually acquired by Bombardier, which now makes Learjets.

    These specifications are taken from Airliners.Net:

    • Seating &#8212 two crew and four passengers
    • Maximum takeoff weight &#8212 12,500 pounds (5,670 kilograms)
    • Maximum operating altitude &#8212 51,000 feet (15,555 meters)
    • Cruise speed &#8212 460 knots
    • Range &#8212 1,436 nautical miles (2,660 kilometers)

    Franz Luftfahrt a group of flightsim enthusiasts with skills in game design and 3D modeling. In addition to the Learjet 23, their aircraft include the Caravan 675 and a motorized paraglider.

    The Learjet 23 was chosen for them to use among themselves with no commercial aspect in mind. "It’s mearly a hobby we all have in common and enjoy to try to get the most out of the fantastic Microsoft Flight Simulator," the developer said. "We really love the story and the design of the Learjet 23 as an aviation icon and Bill Lear the father of the Learjet, a true inventor."

    The developer highlights these among other features of its Learjet 23:

    • Detailed exterior with self-shadowing, specular, reflection, and bump maps
    • Animated control surfaces and animated door sequence
    • Custom aircraft sound package taken from a real Learjet
    • NASA, USA, Swiss, and German business jet paint schemes
    • Checklists, references, and aircraft information

    "The FL Learjet 23 uses the MSFSX Lear 45 VC cockpit but handles in no way like the bigger Lear 45," explains the developer. "It is more agile and harder to fly than its bigger brother."


    NASA USA Swiss German
    Screen shots by Bill Stack


    Instant download from the Pilot Shop


    Installation program


    License key required


    Copyright acknowledgment required


    Uninstall program included


    Manual included


    Checklists & reference included


    Visual Features

    Compared to the real-world photos I found, Franz Luftfahrt's Learjet 23 is visually accurate outside. Overall shapes, contours, proportions, and details such as landing gear, flaps, and spoilers all appear true to reality. I don't know if the paint schemes are based on anything real.

    The cockpit is a different story, however. Franz Luftfahrt's Learjet 23 uses the Learjet 45 cockpit, replete with glass instruments that were not available in the 1960s when the Learjet 23 was built. As a result, realistic simulation in this historic aircraft is not possible. The developer is working on this.

    USA NASA German Swiss
    Screen shots by Bill Stack

    Technical Features

    The archive file downloads quickly. The installation program quickly installs all needed files into the Microsoft Flight Simulator X folder.

    The custom sound package makes the Learjet 23 sound like a small jet &#8212 definitely different from the Learjet 45. I have no way of knowing whether this aircraft's sounds are realistic, but I'm glad it doesn't sound like the LJ 45. Borrowing sounds from other aircraft, as some developers do, makes the craft sound odd.

    The aircraft has 2D and 3D virtual cockpits. All the 2D subpanels are crisp and easy to read.

    Instructions for using the conditional items such as chock blocks, engine covers, and animated mechanic are in the product documentation in a subfolder of the aircraft folder in FSX. The conditional items are activated through the exit activation tags Shift+E, Shift+1, Shift+2, Shift+3, and so forth. After experimenting with various keyboard commands, I found that Ctrl+E and Shift+E open and close the main entry door.

    I asked the developer if there were any plans to replicate the original Learjet 23 cockpit from the 1960s. "There will be an update that will deal with the issues you mentioned below and some other small modifications suggested by some of our customers," they explained.


    3D Cockpit

    2D Subpanels
    Screen shots by Bill Stack

    Flight Modeling

    Franz Luftfahrt's Learjet 23 flies quite differently from the Learjet 45 we are so accustomed to. The Learjet 23 was loosely modeled on a Swiss fighter jet from the 1950s and did not benefit from the honing done in successive models. It is more agile as the developer says, but I didn't find it difficult to fly. Maybe that's because I have so much experience in so many aircraft types. I found it definitely different from the Learjet 45, but not difficult.

    The aircraft rotates at 130 KIAS as specified in the checklist and lifts off soon thereafter.

    Throttles should be pulled back soon after lift off, however, because this aircraft climbs steeply at high speed. The checklist says to climb at 1,800 feet per minute and no faster than 250 KTS. There is no way to accomplish those objectives under full power. For this reason, close attention to engine gauges, pitch, and power are requisite.

    It banks into turns easily, but it doesn't return to level flight as quickly. As a result, pilots must manage their ailerons carefully to begin, hold, and come out of the bank.

    It climbed easily into high altitudes, but it didn't like being up there. It wobbled on its longitudinal axis above FL300, and it stalled above FL350 even though its stated cruising altitude is 45,000 feet. This was true whether I used autopilot or flew manually.

    Descending was easy. It lost airspeed as expected (not too fast or too slowly) and it glided smoothly.

    Approaching for landing was a challenge, but that's true any time we're simulating in an aircraft that's new to us. I'm sure that I could find this aircraft easy to fly at low speeds after some practice.

    I had no trouble landing and stopping it.

    No flight manual is included. "We have designed the Learjet to be as realistic but at the same time as uncomplicated as possible at a very reasonable price," the developer explained. "It is not our intention to simulate every little procedure down to the bone like the hard core flightsim realist prefer. For us it was important that one can enjoy our product and have instant fun without having to go through loads and loads of manuals in order to start the engines."


    Screen shots by Bill Stack

    Checklists and Reference Data

    Aircraft performance data and checklists are included in the kneeboard, where I like to find them. They are uniquely done in black background and color text.

    A 10-page Product Documentation in Adobe Acrobat (PDF) format is included. Almost all its information is background and technical data about the aircraft.

    There are inconsistencies in data between the reference sheet and the checklists. As one example, the reference sheet says the landing speed is 125 to 131 KTS, while the checklist said the landing speed is 155. Based on my flight tests, the latter seems incorrect. The developer said an update will be issued to address such matters.



    Reference Sheet

    Product Documentation Page 7

    Product Documentation Page 8

    Screen shots by Bill Stack

    Nice Features

    The detailed reference sheet and checklist with color-coded data are unique and easy to use.

    A paint kit is included for those simmers who wish to customize their aircraft.

    Main Door Open
    Screen shot by Bill Stack

    More Information

    Information about the Learjet 23 can be found at these websites, among others:


    Franz Luftfahrt's Learjet 23 is a good visual representation of this historic and trail blazing aircraft. It is accurate outside, and its flight modeling is unique but not difficult. The paint kit is a nice extra for simmers who want to customize their LJ 23s. A realistic cockpit and instrument panel from the 1960s would make the aircraft truly realistic. If you can accept the modern glass cockpit in a 47-year-old historic aircraft, this item is a value for the asking price.

    Bill Stack

    Learn More About Franz Luftfahrt's Learjet 23

    Bill Stack is author of several books about flight simulation, a regular author in flight-sim magazines, and a contributor to Flight Sim Com. His website is www.topskills.com

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