Prestwick Dragonfly MPA Mk 1

The aircraft was developed with the specific goal of winning the £50,000 Kremer prize then on offer.[2] Its designer, Roger Hardy, previously had experience with three other HPAs; the SUMPAC, Jupiter, and the Mercury.[3]

An emphasis was placed on it being a practical, easily-built, machine, with the construction requiring a comparatively low amount of work hours.[2][4] It was intended to fly outside of ground effect, reaching an altitude of 60 ft (18 m) in 5 minutes, at what was described as "a small but realistic rate of climb."[1][3] If attempting the Kremer course, such altitude would permit greater room for manoeuvres without suffering from wing tip stalls.[4]

The Dragonfly was a wire-braced high-wing monoplane, with a pylon-mounted propeller, and had no unconventional features. The wing had an aspect ratio of 30, and a relatively high wing-loading. The wing could increase its dihedral under flight load, changing from 6° when static, to 10° in flight. Lateral control was achieved by differental ailerons.[1] The wing had a single wooden box-spar, with a secondary structure made from spruce, balsa and polystyrene. The fuselage was of the pod and boom type, a primary structure made using aluminium alloy, and a secondary structure of balsa. The empennage featured a small all-flying tailplane, or stabilator, and a large fin, half of was the rudder. The entire aircraft was covered in Melinex. The pilot was in a recumbent cycling position, and powered the plyon-mounted propeller.[1]

Construction began in February 1975, and was completed by July. Taxying trials took place in August 1975, however they revealed issues with the craft. It failed to achieve take-off due to the high thrust-line of the propeller and the small moment of the tail-plane.[5] During the following two months, changes made to the aircraft included the strengthening of the rear fuselage, increasing the moment arm of the tail-plane, and changing the pylon-mounted propeller from a pusher to a tractor configuration.[1][6]

Jane's all the world's aircraft 1976-77 wrote that further flight tests may take place from the Spring of 1977 onward.[1] An article in the February 1977 issue AeroModeller stated that Ron Frost had taken over development of the aircraft.[5]

Data from Jane's all the world's aircraft 1976-77[1]

General characteristics

• Crew: 1
• Length: 24 ft 1.50 in (7.3533 m)
• Wingspan: 80 ft (24 m)
• Height: 9 ft 7 in (2.92 m) with propeller horiztonal
• Wing area: 213.50 sq ft (19.835 m²)
• Aspect ratio: 30
• Airfoil: Wortmann FX63-137
• Empty weight: 95 lb (43 kg)
• Gross weight: 232 lb (105 kg)
• Max takeoff weight: 252 lb (114 kg)
• Propellers: 2-bladed fixed pitch, 9 ft (2.7 m) diameter

Performance

• Maximum speed: 23 mph (37 km/h, 20 kn)
• Cruise speed: 19 mph (31 km/h, 17 kn)
• Stall speed: 16 mph (26 km/h, 14 kn)
• Never exceed speed: 31 mph (50 km/h, 27 kn)
• Wing loading: 1.18 lb/sq ft (5.8 kg/m²) at maximum take-off weight

Aircraft of comparable role, configuration, and era

• Kohm Lady Godiva
• MacCready Gossamer Albatross
• MacCready Gossamer Condor
• MIT BURD II
• MIT Chrysalis
• MIT Daedalus

Related lists

• List of human-powered aircraft