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Although development of turbojet engines had begun in the late 1930s, accelerated quickly during World War II and continued into the 1950s, the focus of engine manufacturers was primarily tied to military and commercial airframes, not business aviation. With the advent of the PT6A, however, gas turbine technology that was forged in the “Jet Age” was finally beginning to “trickle down” to the general aviation market. As far as Beechcraft’s senior engineers were concerned, the Queen Air airframe was a logical match for Pratt & Whitney’s powerplant. All that remained was to convince Olive Ann Beech. After a thorough investigation of the facts and input from her officials, she gave a green light to what would become known as “Project King Air.”
Originally conceived in 1961 as the 300-mph Beechcraft Model 120, the new airplane was officially introduced on July 14, 1963, and made its first flight on January 20, 1964. The company’s engineering department had grafted the PT6A onto the Queen Air airframe, which had been modified to allow the cabin and cockpit to be pressurized to 3.4 psid (pounds per square inch differential). Pressurization was not new in aviation, having been developed late in the 1930s and employed successfully on airplanes such as Boeing’s Model 307
Stratoliner airline transport. But in 1963, it was a novel concept for a small business airplane designed to carry four to six passengers and two pilots, yet the engineers and Beechcraft marketing officials believed it would put the company far ahead of the competition – exactly where Olive Ann Beech wanted it to be.
It should be mentioned that the first airplane built with PT6A engines, designated as the Model 87 and carrying serial number LG-1, had been undergoing rigorous flight tests at the Wichita, Kansas, factory since May 1963. Throughout the airplane’s nearly 10 months of intensive testing, company engineers gradually worked out the inevitable “bugs” associated with any new design, especially one that represented a major leap in technology involving not only an entirely new type of engine, but also a highly modified airframe that came with its own set of unique challenges from the pressurization system.
Designated NU-8F by the Army, the airplane was delivered to Fort Rucker, Alabama, in March 1964 when it began an in-depth evaluation by Army pilots, maintenance officers and mechanics. Prompted in part by the service’s success with the L-23F, of which
Cessna Piston Twins
FEBRUARY 2024
KING AIR MAGAZINE • 7