10/31/2012. Remarks by Walter van Tilborg and Johan Visschedijk: "The unusual formula of a twin-engined machine carrying only two people was selected after George S. Wing, President of Hi-Shear Corporation at Torrance, California, had carried out surveys which indicated that more than 57 per cent of all flights in four- to seven-seat aircraft were made with only two people aboard; and that twin-engined types were 1.5 times as active "in trip frequency" as single-engined aircraft.
To market the type, Wing formed Wing Aircraft Company at Torrance in 1960, and the design of the Derringer was undertaken in June 1960 by the well-known John Thorp, who scaled-up his T-17 Twin Sky Skooter design (in turn a twin-engine development of his T-11 Skyscooter). It became one of very few light two-seat twin engine aircraft to attain production status. The prototype and the first two production aircraft were built at Transland Aircraft (also at Torrance, and also a Hi-Shear subsidiary).
The first prototype Derringer (N3621G) had two 115 hp Lycoming O-235 engines and first flew on 1 May 1962. The second prototype (N88941) was redesigned to production standard and was fitted with two 150 hp Lycoming IO-320 engines; it first flew November 19, 1964. The following month, December 12, test pilot Thomas Heffner (7,000 hr, 128 hr on the type) made a routine engine performance check flight, when the horizontal stabilizer failed and the aircraft crashed into a 220 ft (68 m) deep area of the Pacific Ocean near Palos Verdes; Heffner was killed.
A third aircraft was assembled for static testing, and the fourth aircraft (N7597V) was the second production version, fitted with two 160 hp Lycoming IO-320-B1C engines, it first flew on August 25, 1965. Since then, static and flight testing led to the Derringer receiving its Type Certificate on December 20, 1966. Six month earlier, Wing Aircraft Company had been incorporated on June 27, 1966, when it became completely separated from its parent company, Hi-Shear Corporation. By the time production ceased in 1971, a fifth aircraft was flown as a demonstrator, and a sixth was used to test a turbocharged engine installation.
From 1978 production was re-launched under the designation D-1 Derringer by the new Wing Aircraft Company which flew a pre-production aircraft and six production machines, while a seventh production aircraft was later completed from existing parts. When Wing Aircraft Company went bankrupt in July 1982, some seven aircraft were under construction, but not finished.
The Derringer design was revived in 1998 by the Derringer Aircraft Company LLC as a four-seater, with two 160 hp Lycoming IO-360 engines. A prototype aircraft was modified from an earlier aircraft and this flew in 1999. Plans called for production of several models, including the Derringer T for multi-engine training purposes and the Derringer GT, mainly intended as a four-seat sport and executive aircraft. Despite the plans, no additional aircraft were produced."