[2] A development of his ATE-3 design of 1968, the JT-5 first flew in 1973,[2] and Tervamäki sold the prototype, its tooling, and its manufacturing rights the following year.
[3] The JT-5 features a streamlined fuselage pod that fully encloses its cockpit and a single, piston engine that drives a pusher propeller.
[5] This configuration was chosen to increase the area of the tail surfaces and therefore the static and dynamic stability of the aircraft.
[5] Tervamäki saw this as an important safety feature to reduce the possibility of pilot-induced oscillation, which had been implicated in fatal autogyro crashes.
[2][3] This feature was intended to facilitate inspection and maintenance of the instruments, nosegear, rudder pedals, and front side of the engine.
[9] He later reflected that this level of effort was contrary to one of the main reasons he had originally been drawn to autogyros: their simplicity.