The Gates Learjet family and Bill Lear's designs

[Apophenia]

Other Lear Aircraft Designations

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Lear Incorporated

Bill Lear Sr.'s first foray into commercial airframes was the Learstar programme to improve Lockheed 18 Lodestars (hence the Learstar name) as corporate transports. This work was initially done through the Aircraft Service Division of Lear Incorporated. That division later became Learcraft Conversions Inc. which was responsible for conversion work and marketing. In 1957, Learcraft Conversions became Pac Aero Engineering Corp.

Through a series of STCs, 6-odd Lockheed 18 airframes were cleaned-up aerodynamically with new nacelles, modified outer wings, nose and tail fairings, etc. Although not truly Lear aircraft, I include the Learstar Mark numbers as designations for completeness.

- Learstar Mk 1 : 2 x 1,425 hp Wright R-1820-76A, span 19.96 m
- Learstar Mk 1A: Learstar Mk 2 upgraded to Mk 1 standards
- Learstar Mk 1B: Learstar Mk 1 with RATO assist package
- Learstar Mk 2 : 2 x 1,325 hp Wright R-1820-56As, span 19.96 m
- Learstar III : FAA desig. for Learstar Mk 1A upgrade
-- http://1000aircraftphotos.com/Transports/258.htm
-- https://web.archive.org/web/20060209225506/http://www.burbanksbest.com/

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Gates Learjet Corporation

I have separated the Twinjet helicopter project from the main Learjet listings simply because the Model 112 designation bears no relationship to the the fixed-wing sequence.

Model 112 - (Project) 1969 Twinjet medium helicopter
- Model 112: Twin-engine helicopter, aka Gates Twinjet
- Model 112: 4-bladed main rotor (12.20 m diam), 2-bladed tail
- Model 112: 2 x 475 shp Garrett AIResearch TSE 231-P2400s*
-- * Mounted right-angles to the fuselage in high sponsons
-- * TSE 231-P2400 turboshaft derived from TPE 331 turbofan
-- https://www.secretprojects.co.uk/threads/lear-jet-projects-in-the-1960s.18024/#post-120924

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LearStar

The LearStar 600 was an independant 1974-1976 design. (I am unclear as to whether LearStar work was undertaken by LearAvia - see next entry.) The intended cruising speed for this bizjet was 600 mph - hench the designation.

Bill Lear, Sr. sold production rights for the LearStar 600 to Canadair Ltd late in 1976. After changes to the design, Canadair launched development of the CL-600 Challenger series.

LearStar 600 - (Project) 1974 'fresh sheet' medium bizjet
- LearStar 600: 'Wide-body bizjet' w/ supercritical wing
- LearStar 600: 1974, cruciform tailplane, span 14.02 m
-- c.1974: 2 x Garrett AiResearch TFE731 turbofans
- LearStar 600: 1975, 2+6-to-8 pax, cruciform tailplane
-- 2.23 m diameter fuselage, 5,000 miles range (6 pax)
- LearStar 600: July 1976, 2+14-to-30 pax+cabin attendant
-- July 1976: Longer fuselage, low anhedralled tailplane
-- 2 x 6,500 lbf Avco Lycoming ALF 502D, span 16.25 m
-- https://www.secretprojects.co.uk/attachments/learstar-600-july1976-3-view-jpg.84418/
- LearStar 600: Oct 1976, 2 + 10-to-11, (commuter) 30 pax
-- Oct 1976: Shorter fuselage, low-mounted flat tailplane
-- 2 x 7,500 lbf Avco Lycoming ALF 502-2L, span 18.22 m
-- Oct 1976: Canadair increases fuselage diam. to 2.69 m
-- https://www.secretprojects.co.uk/attachments/learstar-600-october-1976-3-view-jpg.84426/
- Canadair CL-600 Challenger: March 1977 format
-- * T-tail (0.31 m higher), longer (20.85 m vs 19.22 m)
-- 2 x 6,700 lbf Avco Lycoming ALF-502H,** span 18.85 m
-- ** C-GCGR-X, pending availability of the ALF-502Ls [1]
-- https://www.secretprojects.co.uk/threads/learstar-600.8158/

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LearAvia Corporation

LearAvia (occassionaly given as Lear Avia) sprang out of late 1972 work on aircraft noise suppression. This work was aimed at Learjets with GE CJ 610-5/-6 turbojets. The LearAvia Suppressor System was tested on Bill Lear's own Model 25 (N695LJ) resulting in an STC in March 1974. Other work was on a LearAvia Helicopter Muffler (aimed at the Bell 47) and the LearAvia Superwing - a supercritical wing originally aimed at Learjets. [2]

Doubtless, the LearAvia Superwing concept fed into the designs of the LearStar (above) and the Lear designs which followed - the Allegro bizjet [3] and the pusher-propeller Lear Fan 2100.


Bill Lear Allegro - (Project) 10-seat business jet
- Allegro: Buried rear engines, T-tail empennage
-- (??) No other confirmed details
- Allegro: 2.74 m fuselage diameter (confirm?)
-- Allegro poss. unsuccessfully pitch to Canadair


Lear Fan 2100 - 1981 2+6 pusher-prop business a/c, x 3
- Lear Fan 2100: Composite constr., combined power
- Futura: (Project) 1977, inverted V-tail
-- 2 x Lycoming LTS101 turboshafts, combining shaft
-- https://www.secretprojects.co.uk/attachments/lear-fan-1-jpg.94989/
- Lear Fan 2100: (Project) 1978, revised Y-tail
-- Flush engines air intake revised to dorsal scoop
-- https://www.secretprojects.co.uk/attachments/xlear-fan-2100-3v-jpg.119384/
- Lear Fan 2100: Graphite/epoxy and Kevlar composites
- Lear Fan 2100: 2 x 650 shp P&WC PT6B-35Fs, span 11.99 m
-- Engines repositioned outboard into fuselage-side pods
-- Fuselage struct. weak and ext. shafts underdeveloped
- Lear Fan 2100: Further development abandoned in 1985

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[1] In his 2007 Canada Aviation Museum Aircraft monologue on the Challenger, Bill Upton implied that Canadair favoured the GE CF34 engine for the CL-600. However, use of ALF 502Ds was insisted upon by the launch customer - FedEx (which would later cancel its order for 25 CL-600s).

That story seems to be refuted in The History of North American Small Gas Turbine Aircraft Engines by Richard A. Leyes II and William A. Fleming (AIAA/Smithsonian Institution, 1999). On page 194, the GE CF34 and ALF 502 are seen in competition with Canadair choosing the latter (with Bill Lear's agreement). FedEx did indeed specify the ALF 502 but it was doubts about GE's ability to match the CL-600's production schedule which decided the engine choice.

[2] Source: A submission by LearAvia Executive Vice-President Kenneth C. Krammer to the US Senate committee on Aircraft Noise Control Programs, 16 May 1974, pp 112-114.

[3] The NASA Ames biography for William F. Ballhaus Jr. mentions that the Lear Allegro was designed using computer code created by Ballhaus and Ron Bailey (so too was HiMat and the Northrop B-2 bomber).[/B]

 

[Archibald]

Brilliant work. Very interesting, particularly the FFA P-16 connection.

FFA P-16 - Wikipedia

en.wikipedia.org

The Lear Liner Model 40 deserves additional comment. As already noted by elmayerle, this aircraft would have competed directly with the Gulfstream II as a bizjet, while also being pitched as a feederliner. Originally envisaged as a 28-seater (in airline layout) powered by two 8,750 lb-thrust Rolls-Royce Spey Juniors when first launched in 1965, the aircraft was subsequently upsized to a 40-seater (necessitating a 15 ft fuselage extension), powered by two 11,400 lb-thrust Rolls-Royce Spey 25s (Mk 511-14Ws).

The Model 40's first flight was targeted for the autumn of 1967, with certification and first deliveries to follow in spring 1968, Lear envisaging just under 500 sales over the subsequent decade. In the event, the cost of the Model 40's development, coupled with a fall in Learjet 23/24 sales, led to Lear Jet Corporation suffering a loss of $12 million in 1966 (compared to a profit of $54 million the year before), resulting in the company being sold to Gates Rubber Company in 1967. The Lear Liner did not survive the transaction, Gates preferring to focus on smaller models such as the Learjet 25.

Reminds me of Dassault Mystere 30 / 40 series. Same idea - stretching a bizjet into a feederliner. It happened in the 70's. End result: failure. That plus the Mercure even larger quagmire, nearly sunk the company.

That idea of stretching bizjets into feedliners is pretty interesting. Of course Embraer and Bombardier pulled it successfully in the 90's and this allowed them to get into the airliner business as a lower end to Boeing and Airbus. Now it is fascinating to imagine Dassault or Learjet achieving the same breakthrough some decades before...

 

[elmayerle]

In your history of the Model 24 and Model 25, you missed an important point. Sometime after the sale to Gates, they were redesigned for certification to fly at 51,000 ft.; the main externally noticeable effect of this was the oval windows being replaced by smaller rectangular ones which were carried over to the Model 35/36. IIRC, all subsequent Learjets have been certified to fly at that altitude (I know the 50-series was). Models 54, 55, and 56 all had the same overall length but differed in internal fuel tankage and number of passengers (most fuel, fewest passengers). There were originally supposed to be three extended range variants of the 50-series, ER, LR, and XLR with the additional fuel tanks placed outside the uncontained rotor burst zone.

There are also some interesting one-offs, like 24-218 which first flight tested the Longhorn wing and, at one time, also flew with tanks under the wings. The Model 25BGF was another one-off, with a GE engine on the port side and a Garrett TFE-731-2 on the starboard side with all the structural implications of two rather different mounting systems. If memory serves me correctly, this was S/N 25-064 and it was scrapped after this test program with the wings being saved for use in a fuel system ground test rig; which later helped develop the systems installations for the Longhorn wings.

I worked at Learjet from 1979 to 1982 when the recession caused them to temporarily close up (the shop was already laid off, leaving nothing but engineers and vice-presidents and you knew who was next). As 'twas, I got picked up fairly quickly by Northrop for the B-2 effort.

 

[TomcatViP]

As a matter of fact...

“With more than 3,000 aircraft delivered since its entry-into-service in 1963, the iconic Learjet aircraft has had a remarkable and lasting impact on business aviation,” said Éric Martel, president and CEO of Bombardier Inc. “However, given the increasingly challenging market dynamics, we have made this difficult decision to end Learjet production.” Martel announced the company would reduce its overall workforce by 1,600 positions.

Bombardier to end Learjet production, cut 1,600 jobs

WICHITA, Kan. (AP) — The Learjet, which became synonymous with lifestyles of the rich and famous, is about to fade into aviation history.

apnews.com

 

[elmayerle]

Damn, that's a real shame. The demise of the Learjet 85 was due to a variety of problems, including, IMHO, taking too big a bite of new technology at once ('twas supposed to be all composite). It was a good place to work when I was there and I still consider it a class ride.

 

[Ray]

I worked at Learjet in the late 60's. It was a great place to work. Gates had just taken over but Bill Lear was still there. Word was that he was still cooking his cheeseburgers himself. My place was fairly important in the Purchasing Dept. I bought things like toothpicks and toilet paper, and also gave occasional tours of the plant. One more thing. When I was there you could put your name on a list and you could go for a ride on a test flight. Those days a long gone.

 

[hesham]

I worked at Learjet in the late 60's. It was a great place to work. Gates had just taken over but Bill Lear was still there. Word was that he was still cooking his cheeseburgers himself. My place was fairly important in the Purchasing Dept. I bought things like toothpicks and toilet paper, and also gave occasional tours of the plant. One more thing. When I was there you could put your name on a list and you could go for a ride on a test flight. Those days a long gone.

Hi Ray,

please,can you tell us if there was unknown Projects you know it,
and never mentioned here ?.

 

[elmayerle]

I worked at Learjet in the late 60's. It was a great place to work. Gates had just taken over but Bill Lear was still there. Word was that he was still cooking his cheeseburgers himself. My place was fairly important in the Purchasing Dept. I bought things like toothpicks and toilet paper, and also gave occasional tours of the plant. One more thing. When I was there you could put your name on a list and you could go for a ride on a test flight. Those days a long gone.

Ray, I was there from early 1979 to mid-1982 when the Carter Recession caught them and they laid off the shop and then engineers. As one of the most recent hires, I was one of the first let go. Still, I quite enjoyed working there and did get a ride on 55-002 to run the instrumentation for a test I had written up. On a CAVU day, the world looks great from 48K feet in the air.

 

[Grey Havoc]

The Iconic Learjet Will Come To An End After Six Decades Of Defining Private Air Travel

Time is up for the classic bizjet as Bombardier announces the end of Learjet production at its Wichita plant.

www.thedrive.com

 

[GTX]

Bombardier Delivers Final Production Learjet | AIN

Northern Jet Management took delivery of the Learjet 75, which marked the end of Learjet production.

www.ainonline.com

 

[publiusr]

John Lear passed away recently.

 

[GTX]

John Lear passed away recently.

It was his father Bill Lear who is responsible for the Learjet though.

 

[Stargazer]

A few recent discoveries:

• Bill Lear considered at some point to do away with the name "Lear Jet 23" and call it the "Continental" instead. I guess the idea was dropped because it was too closely associated to the engine maker and prevented the use of another make.
  
  
• Bill Lear planned a derivative of the LearFan 2100 designated the LearFan 3100.
  
  
• The LearAvia "Allegro" design was also sold to Canadair, alongside the Lear 600. In fact, in a series of LearAvia 600 studies numbered SK-600-0002, -1000, -1002, -1006 and -1007, the "Allegro" was the latter.