THE MARK II LEARJET FROM CONCEPT TO CERTIFICATION 760471
Advanced technology in aerodynamics, both highspeed and lowspeed, are being applied to new airplane designs proposed by Boeing, Douglas, Lockheed, and other large aircraft manufacturers. New military aircraft employ the results of many years of exploratory research and development dealing with aerodynamics.
Such items as supercritical airfoil technology, sophisticated high lift devices, and the optimum integration of various individual airframe components to increase the overall productivity of the larger jet and military aircraft are just now finding their way into the business jet design community.
The Mark II Learjet, embodying advanced design features such as blunt wing leading edges employing supercritical aspects, trailing edge flap optimization, and overall wing aerodynamic clean-up was first envisioned by the Raisbeck team in 1973. The Mark II concept, taking the basic Learjet of the 50's and bringing it to true competitive status in important areas of productivity has been the result. These areas include payload/range, cruise speed, low continuing operating costs, and airport operational flexibility.
Mark II Learjet conceptual design was followed in early 1974 with “Boiler Plate” leading edge configurations which were tested on a typical Learjet Model 25. Subsequent detail design and flight testing, both under contract to Gates Learjet in late 1974 and early 1975, and final tailoring and certification in cooperation with The Dee Howard Company in mid-to-late 1975 complete the initial Mark II effort.
Certified results of the Mark II Learjet are detailed, including reduction in approach speeds, takeoff speeds, and certification to FAR Part 36 without the use of sound suppressors. Fallout gains such as improved stall characteristics and reduction in cruise drag on the order of 10% or more are also discussed.
The general overview of the application of advanced technology to today's fleet of several thousand jet aircraft is emphasized.