Wiltshire / Thruxton ES.101/102 / HDW-1 "Gadfly"


Latest project to come from the Wiltshire School of Flying at Thruxton is the E.S.101 Gadfly, a general-purpose two-seat autogyro designed by Eric Smith. The machine will be powered by a 165 h.p. Rolls-Royce Continental IO-346-A and is expected to be sold for £2,600 (including course of flying instruction). Maximum gross weight is 1,500lb.

Performance data for the type are quoted as: cruise speed, 110 m.p.h.; maximum speed, 125 rap.h.; ICAN sea-level rate of climb, 1,500ft/min; tip speed, 500ft/min; service ceiling, 14,000ft; endurance, 2hr; range, 220 miles (with long-range tanks, 5hr and 550 miles); minimum continuous straight and level speed, 25 m.p.h.; take-off distance to 50ft, less than 100ft; landing distance from 50ft at 25 m.p.h., less than 150ft. 

According to Sqn Ldr J. E. Doran-Webb, managing director of Wiltshire School of Flying, "The Gadfly is intended as a private owner's runabout, as a crop-spraying vehicle, and as a spotting aircraft in its military role. It combines simplicity of design with excellent performance, low initial cost and ease of maintenance."

Almost all the airframe is of welded, square-section T.45 steel tube, the reason for using square section being quoted as its greater simplicity in joining. The backbone of the airframe comprises two members running fore-and-aft, from which stem most of the other members. Although a great deal of welding is used, this is effectively for sub-assemblies, and the final assembly is by bolted joints. The reason for having a bolted final assembly is to provide easier packaging and to make the replacement of damaged members easier than with a fully welded structure.

"Flight International", May 7, 1964

The Thruxton Aviation Co. of Andover, England, began design of their two-seat cabin ES 101 Gadfly autogyro in 1964, using a conventional two-blade teeter rotor system with a fixed-pitch pusher propeller driven by a 165hp Rolls-Royce Continental engine, and a twin boom tail structure. Ground tests of the sole prototype began at Thruxton airfield in 1967 but this autogyro failed to fly and was abandoned.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

TYPE: Two-seat general-purpose light autogyro

ROTOR SYSTEM: Two-blade rotor. Blades of laminated spruce and balsa

FUSELAGE: Welded square-section steel tube

TAIL UNIT: Twin fin and rudders on tail booms

LANDING GEAR: Non-retractable tricycle type

POWER PLANT: One 165hp Rolls-Royce Continental IO-346-A four-cylinder horizontally-opposed air-cooled engine, driving a two-blade pusher propeller

ACCOMODATION: Two seats side-by-side in fully enclosed cabin


Technical data for Thruxton HDW-1 Gadfly

Engine: Rolls-Royce Continental IO-346-A, 165hp, rotor diameter: 11.28m, length:6.70m, height: 2.90m, gross weight: 725kg