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Learjet 23

Every now and then something happens in the field of engineering and technology that marks a complete departure from that which the interested public has come to know as the recognized state-of-the-art. When such an event occurs we like to speak of milestones.  One of these was the appearance of the Lear Jet 23, pioneered and developed by William (“Bill”) P. Lear Sr.

 

The Pioneer and his Concept

In the early 1960s, Bill Lear, now known as “the father of corporate jets”, began an adventurous project that changed the face of aviation forever. Bill Lear dreamed of a jet that the average human being could own, that could traverse the continent in reliability and comfort. His new design would be called the LearJet, later Learjet or simply “the Lear”. It was to become the world's largest, fastest, best selling and best known series of business jets. It was to be the origin of what in aviation circles has come to be called a “family”, starting with the original six to eight seat Lear Jet 23 which first flew on October 7 1963.
Lear was a charismatic entrepreneur who had settled down in Switzerland, after having spearheaded a number of innovative technologies, among them the 8-track sound recording system. Although not entirely an aviation man Lear was what one could call air-minded. His interest in business aviation had been aroused at some stage and he first entered the market by converting Lockheed Lodestars, surplus to requirements, into elegant, streamlined, high-speed private aircraft, offered under the name Learstar. Although they were an instant commercial success, Lear was not satisfied, as their top speed was limited by the fact that they used piston engines. Two occurrences came together that provided the basis for what was to become Lear’s unique achievement:

Lear recognized that the business traveler was ready for the highest cruising speeds and altitudes possible. To achieve that he proposed minimizing aircraft size and weight while maximizing engine power to produce a lightweight aircraft with performance similar to that of a military fighter, keeping the weight under 12,500 lb (5,670 kg). This would place such a design in the light aircraft category (Part 3) of the Federal Aviation Regulations (FAR). This would also reduce development time and costs.
Lear toyed with the idea of manufacturing his new aircraft, to be named Lear Jet 23, in Europe, where labor and material costs were lower. In 1960 he set up the Swiss-American Aircraft Company (SAAC), based in Switzerland, but subsequently opted for moving the project to the United States, where Lear had founded Lear Jet Corporation. Coordinating the various sub-contractors in different European countries had proven to be somewhat challenging.
Bill Lear enlisted a group of the most talented individuals in the field to spearhead his program, including Hans-Luzius Studer, father of the P-16, as program director, and Henry Beaird as his head test pilot, a young World War II fighter pilot, who in the Lear established several time to climb, speed, and altitude records.
The Lear Jet’s performance was made possible in large part by the design's strong, thin, high aspect ratio wing. One drawback of this very thin wing was the lack of internal volume for fuel, which made necessary the permanent wingtip fuel tanks that came to distinguish the design.

 

History – Model Development Overview

The very successful Lear Jet 23 pioneered an entirely new market segment for business jets. The first production 23 was delivered in October 1964. This model version was replaced by the Model 24 in 1966 after 105 Model 23s had been built. The most significant upgrade of the 24 was that it became the first business jet to be certified under the stringent criteria of FAR Part-25, moving the Lear Jet, whose name at some stage changed to “Learjet”, into the realm of commercial flying activities.

 

Further development into the model 24

Altogether 259 Model 24s received their certificate under this model designation. However, it should be noted that an upgrade of Model 23s to Model 24s became available at an early stage, so that the total number of 24s comprises several upgraded 23s.
The 24 had up-rated engines for higher thrust and incorporated several technical detail changes. It first flew in February 1966, and was delivered to customers from the middle of that year. The model range of subsequent developments of the 24 included the 24D, E, and F, introducing improvements such as increased weights, thrust, and range. The design of the Learjet 24 made use of the full 13,500 pounds (6,100 kg) gross weight permitted under FAR-25 standard; the Learjet 23 was limited to 12,500 pounds (5,700 kg) gross weight.
The first flight of a Learjet 24 took place on January 24, 1966. Only four months later from May 23 to 26, 1966, a Learjet 24 flew around the world in 50 hours, 20 minutes flying time as a demonstration of its capabilities.
The next distinctly different new model was the Learjet 25. It had a fuselage stretch of 1.27m (4ft 2in), which increased seating to up to eight passengers. It was first flown on August 12 1966, and same as in the case of the Lear 24, a number of subsequent variants were built, including models B, C, and D.
In 1966 the name of the manufacturer changed to Lear Jet Industries, and in January 1970 Gates Rubber Company, who had bought a controlling interest, changed the name again, to Gates Learjet Corporation.
Finally Canadian aviation heavyweight Bombardier bought Learjet, continued their production lines, and continued developing the Lear by adding sophisticated avionics packages, and even further increasing speed and range of the Lear.
Today, variants of the Lear can be found in militaries around the world, air ambulance services, numerous corporate aviation departments, and even at the National Aeronautics and Space Administration (NASA).
In the forty years that Lear has been producing aircraft, the basic design of the aircraft and the principles that it was founded on have been sustained. The state of the art Lear 45 can fly passengers higher, faster, and farther than all other aircraft in it's class. The Lear jet is easily the most recognizable business aircraft in the world and exudes elegance and demands respect everywhere she goes.

 

Operating and flight Safety Aspects

Many people say that the Lear looks, sounds, and handles like a fighter jet, that's because that is exactly what the Lear is. The aircraft design was based on a Swiss fighter called the P-16.

The original LearJet, though an instant success , had shortcomings that became painfully obvious to aviation consumers. The original wing on the Lear 23, and some of the Lear 24s, earned the nickname "Flash" because of it's stall characteristics. In most aircraft an impending stall is felt by an aerodynamic buffet on the controls, due to the slick wing of the early Lear, stalls came with no warning at all, often ending tragically. Additionally, many military pilots coming from the fighter jets of the time had the mentality that since the Lear design was based on that of a fighter, it should have the same limitations. Before people could grasp what was happening, an alarming number of LearJets would simply disappear from radar screens with signs of alarm, they would later be found in many pieces scattered across a field. Pilots were taking a corporate aircraft into near supersonic speeds and producing a shockingly severe control flutter that would eventually tear the aircraft apart. After discovering the abrupt stall tendencies and erratic over speed characteristics, designers altered limitations of the aircraft and began the first of many improvements to the standard wing.

Altogether 39 LJ24s had been lost through accidents.

 

The Learjet as a Cult Object

Many aviation enthusiasts will admit that somewhere in the depths of their memory banks they lovingly harbor a favorite aircraft, that makes their eyes shine when they see one and that they want to fly more than any other they can think of. At the top of our list there are two: The Douglas DC-3, affectionately referred to as the ‘Dakota’, and on the list ‘the mother of all business jets’, the Learjet 23, which many seasoned old dogs just call ‘the Lear’ (whereby we wish to reserve this term for our favorite, the ‘23’). They both have in common that each in its respective field marks the beginning of an era in what concerns aircraft technology and design, customer base, and continued market acceptance.

Enjoy your flight in the Lear!

 

Some interesting links about the Learjet23:

 

Learjet 23 photos on airliners.net

 

on Youtube:

Learjet 23 take off

Learjet 23 landing

Learjet 23 acrobatics (amazing, must watch!)

Gear up landing!

 

FFA P-16 the inspiration for the Learjet 23

 

The Learjet in motion pictures:

Cap Cover

Another inspiration for us to build the Learjet was it's depiction in the motion picture "Capricorn One". Great movie with great flying scenes.