M.Hardy. Gliders & Sailplanes of the world

Volpar-Spencer Drag-N-Fly

  This single-seat waterborne biplane glider is in the same class as the Explorer PG-1 Aqua Glider and, like the latter, is designed to be towed in tethered flight behind a conventional motor boat. It was designed ДальшеMore>>> at the instigation of Volpar Inc, better known for their various turboprop and other modified versions of types such as the Beech 18 and Grumman Goose. In February 1977 Volpar engaged Mr Percival H. Spencer, a pioneer pilot and amphibian designer whose Air Car amphibian had influenced the configuration of the Republic Seabee, to design a small but fully manoeuvrable water-based glider. This was to use modern plastics and foam materials for high strength and low cost, and to have simple controls that could be operated safely by an amateur or non-pilot. Mr Spencer himself made the first flight of the prototype Drag-N-Fly, on 20 April 1977 (nearly 63 years after his first solo flight!) and continued air and water trials have proved very satisfactory. Flight testing during 1978 resulted in the addition of a 1ft extension on each wing tip, to reduce the power requirements of the towing boat. When in flight the tether can be disconnected by the pilot in an emergency, and will disconnect automatically if the glider tends to overrun the tow boat. The fuselage is hinged so that the Drag-N-Fly can be transported on a light road trailer without exceeding a width of 8ft 0in.
  The structure makes extensive use of stryrofoam and other lightweight materials; the strut-braced biplane wings are of constant chord and covered in glasscloth laminate, bonded with epoxy resin; there are spoilers on the outer panels of the upper wing. The wings themselves are built up of aerofoil-shaped styrofoam blocks, with plywood spar caps bonded to styrofoam shear webs with epoxy resin. There are wooden blocks between the capstrips at each end to provide bolt attachments for joining the panels together. The fuselage and the twin floats which attach directly to the bottom of the lower wing are built up from plywood internal frames and bulkheads and are covered in polyester resin-bonded moulded glassfibre cloth laminate. The cantilever tail unit has a styrofoam core and glassfibre laminate covering; the vertical surfaces have wooden frame edges and the one-piece horizontal tail has plywood spar caps. The latter is hinged at the aft fuselage bulkhead and is statically balanced by means of a bob-weight; trim adjustment is by means of a bungee spring. There is a single open cockpit forward of the wings, an a water rudder is provided for control during towing, as well as the more conventional rudder.


Span: 17 ft 0 in
Length: 15 ft 11 in
Height: 5 ft 9 in
Wing area: 113.0 sqft
Aspect ratio: 2.56
Empty weight: 225 lb
Max weight: 425 lb
Max speed: 75 mph (in smooth air)
Required take-off speed: 40 mph