Spratt Model 107

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Controlwing 107[1]
Role Sport flying boat
National origin United States
Manufacturer homebuilt
Designer George Spratt
First flight 1967
Number built 60 sets of plans sold by 1977[2]

The Spratt Controlwing 107 was an unorthodox controlwing flying boat designed in the United States in the 1960s and marketed for home building in the 1970s.[2]

The aircraft featured a flat, speedboat-like[3] hull with a square bow and with tailfins blended into each side.[4][5] The fins were angled to form a butterfly tail and included no moving surfaces.[5][6] The wings were mounted on struts, parasol-style, and also contained no moving surfaces.[3][6][7][8] Rather, each of the two wings could pivot independently to vary their angle of attack.[6][8] The pilot and a single passenger sat side by side in an open cockpit with a converted marine outboard motor mounted behind them that drove a pusher propeller.[3][6] The flight controls consisted of a helicopter-style collective that varied the angle of attack of both wings simultaneously,[6][8][9] and a control wheel that varied their angles of attack in relation to one another.[6][8][10] The hull was constructed from polyurethane foam and covered with fiberglass, and the wing panels were fiberglass throughout.[6]

Designer George Spratt claimed that the Model 107 could not stall or spin, and that it was 75% less affected by turbulence than a conventional airplane design.[2] With friend Elliot Dalland, Spratt began construction of the prototype (registered N2236) in 1962.[3] During the 1970s, Spratt marketed plans for the Model 107 to homebuilders.[2][11]

Specifications (Controlwing 107)[edit]

Data from Markowski 1979, p.384

General characteristics

  • Crew: one pilot
  • Capacity: one passenger
  • Length: 17 ft 0 in (5.18 m)
  • Wingspan: 24 ft 0 in (7.32 m)
  • Height: 5 ft 0 in (1.52 m)
  • Wing area: 96 ft2 (8.9 m2)
  • Empty weight: 500 lb (226 kg)
  • Gross weight: 1,000 lb (543 kg)
  • Powerplant: 1 × Mercury 800 converted marine engine, 80 hp (60 kW)


  • Maximum speed: 98 mph (160 km/h)
  • Service ceiling: 3,000 ft (910 m)
  • Rate of climb: 800 ft/min (4 m/s)


  1. ^ "American airplanes: sk - ss". Aerofiles.com. 2009-03-16. Retrieved 2011-04-06.
  2. ^ a b c d Taylor 1977, p.563
  3. ^ a b c d Spratt 1962, p.25
  4. ^ Taylor 1977, p.565
  5. ^ a b Markowski 1979, p.384
  6. ^ a b c d e f g Taylor 1977, p.564
  7. ^ Taylor 1989, p.839
  8. ^ a b c d Markowski 1979, p.380
  9. ^ Spratt 1962, p.25–26
  10. ^ Spratt 1962, p.26
  11. ^ Gunston 1993, p.290


  • Gunston, Bill (1993). World Encyclopedia of Aircraft Manufacturers. Annapolis: Naval Institute Press.
  • Markowski, Michael (1979). The Encyclopedia of Homebuilt Aircraft. Blue Ridge Summit: TAB Books.
  • Spratt, George G. (July 1974). "The Controlwing Aircraft: Part 2 — Postwar Development". Sport Aviation: 24–30.
  • Taylor, John W.R. (1977). Jane's All the World's Aircraft 1977–78. London: Jane's Yearbooks.
  • Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions.

External links[edit]