Aircraft Quiz #55

[Doug Robertson]

What complex twin engine aircraft was so radical in its construction that it was NEVER certificated by the US FAA?

1. Make of aircraft?

2. Model name?

3. Engines?

4. Date of first flight? (Nota bene-this date excludes ALL other possible aircraft you might otherwise consider. And, the official date is MOST unusual.

5. Name the radical thing about its engines.

6. BONUS for the user and use of the extra airframes built.

[SunvisorFlyer]

Hello Doug,

Can you speak to this aircraft being certified by a different aviation authority overseas?

[Doug Robertson]

No, the quiz aircraft was never certified/approved with any airworthiness certificate by any official aviation body, anywhere.

[Monsieur Zoom]

my search-educated guess would be the LearFan 2100.

[Doug Robertson]

As a new responder to these quizzes, I give congratulations on the right aircraft answer and will give you a pass (this time) for not answering ALL the questions.

Bill Lear of Learjet fame designed the Lear Fan Corp's. Lear Fan 2100 as a lower cost business aircraft than a bizjet with nearly the same performance. Original aircraft name was Futura. The Lear Fan was the first twin engine business aircraft constructed of carbon fiber/graphite epoxy/and Kevlar composite structure. This was radical in the late 1970s and posed certification problems with our FAA. They repeatedly rejected the LearFan design from certification (Approved Type Certificate) granting.

Lear died 14 May 1978 and his widow pursued completing the flight testing of prototypes, the first of three flew in 1981. The factory once had 130 orders and options for production aircraft. (Janes 1981-1982 states 203 orders). The company filed bankruptcy in 1984 with debts approaching $500 million.

Here are the answers:

1. Lear Fan Corporation

2. Lear Fan 2100

3. Two Pratt & Whitney PT6B-35F Turboshafts of 650 Hp each, coupled in gearbox.

4. First flight was officially recorded as of December 32, 1980-(this unusual oddity was to meet meet a deadline by the "end" of 1980. (Janes states Jan. 1, 1981 for the purists out there). Prototype flight was N626BL, which must have been Experimental class?

5. The radical thing about the two engines was that their output shafts were coupled via a gearbox to the pusher propeller. The gearbox performance was problematic, as was structural issues with the new materials for the sleek pressurized semi-monocoque fuselage, cantilever Y-shaped tri-tail and cantilever low un-swept wings. Costs escalated and bankruptcy ensued.

6. Bonus answer. NASA used the unfinished Lear Fans to test strength of composites in drop tests from towers under controlled crash conditions.

Specifications

Powerplant: Two P&W PT6B-35F Turboshafts, 650 shp each.
Length: 40'7"
Height: 11'6"
Wingspan: 39'4"
Weight: max takeoff-7,350 lbs
Max level speed: 425 mph
Service ceiling: 41,000'
Crew: 2 with 8 passengers

A manufacturing plant was started in Northern Ireland, but not building any aircraft. The plan was to build 42 first in America, then transfer production to Northern Ireland. Later, an Iraqi front company tried to buy the design for military usage.

[Monsieur Zoom]

I'll take the pass and run with it ! Seemed unfair to answer your questions by copying what I found online ...