Origins turbojet is derived from the military
J85, pictured. During the early 1960s,
American businessman and inventor
Bill Lear successfully launched the
Learjet 23, one of the first light
business jets. This experience strongly influenced the decision to adopt a forward-swept wing for the new design, which became known as the
HFB 320 or the
Hansa Jet. A more spacious cabin could be achieved than that of the Learjet, while remaining just as fast by minimising
drag. The selection of the
American General Electric CJ610 turbojet engine to power the design was a straightforward choice; at the time, there were no other compact turbojets that had reached quantity manufacture yet. After a year of certification flight testing, on 12 May 1965, the first prototype crashed resulting in the death of Hamburger Flugzeugbau's chief test pilot; the cause was determined to have been the occurrence of an unrecoverable
deep stall which had been induced by the design of the
T-tail. As a consequence of the accident, various modifications were introduced to improve the aircraft's
stall characteristics, including the installation of a
stick pusher. Assembly of the first ten production aircraft commenced during May 1965, the first of these reportedly flew on 2 February 1966. The granting of
type certification by German authorities was achieved on 23 February 1967, certification from the American
Federal Aviation Administration (FAA) followed on 7 April 1967. Deliveries commenced during the following year. In 1969, the $840,000 HFB 320 was to be developed into the $1.7 million, Mach 0.76 HFB 330: flight-testing was to start in 1971 for FAR 25 certification by late 1972. It would have been stretched by and powered by
Garrett ATF3 turbofans with
thrust reversers for short-field operation. A fuel capacity would have given it a maximum endurance of over seven hours and a transcontinental range of with five people. ==Design==