|Role||Ground effect vehicle|
|National origin||United States|
|Manufacturer||Collins Radio Company|
|Developed into||RFB X-113|
Design and development
Lippisch's development of his Aerofoil Boat, a ground effect vehicle for use over water, began whilst he was working in the aviation division of the Collins Radio Company in Cedar Rapids, Iowa, US. The Collins X-112 was built to test the concept.
The Airfoil Boat was an inverse delta aircraft, that is it had a wing which was triangular in plan but with a straight, unswept leading edge. Combined with strong anhedral, this layout produces stable flight in ground effect. Specifically, it is claimed that it is stable in pitch and also that it can fly in ground effect at altitudes up to about 50% of its span, allowing it to operate over rough water. This contrasts with the lower aspect ratio square wing of the Ekranoplans which leaves ground effect at only 10% of span, limiting them to the calmer waters of lakes and rivers.
Its fuselage was conventional, with flat sides and rounded decking. The nose-mounted single engine was of very low power, only 25 hp (19 kW). Two open cockpits were arranged in tandem, both over the wing. Aft of the trailing edge root the bottom of the fuselage rose strongly to carry a tall, broad fin and rudder. The X-112 had a T-tail, carrying elevators. Its thick airfoil wings were low mounted, each with a tip float which, in combination with the strong anhedral kept the fuselage well clear of the water surface. Each float carried a steeply sloped short aileron for roll control. A retractable water-rudder, fuselage mounted at the point at which the lower fuselage rose upwards, provided directional control on the water surface.
Tests made during 1963 began with the Airfoil Boat operated like any fast motor boat, planing on the surface. With speeds increased to around 36 mph (58 km/h) the X-112 rose clear of the surface as a ram-air air cushion or ground effect vehicle. Solo free flights at up to 77 mph (124 km/h) were made; tests with two occupants were also conducted. "Entirely satisfactory" stability and control characteristics were reported under all these conditions. With The Airfoil Boat proved, the X-112's mission was completed and Lippisch, suffering from cancer, left Collins Radio. He recovered sufficiently to design and build its successor, the fibreglass, more powerful X-113 with Rhein-Flugzeugbau GmbH in Germany.
Data from Jane's All the World's Aircraft
- Crew: One or two
- Length: 25 ft 0 in (7.62 m)
- Wingspan: 14 ft 0 in (4.27 m)
- Wing area: 110 sq ft (10 m2)
- Empty weight: 370 lb (168 kg)
- Gross weight: 710 lb (322 kg)
- Powerplant: 1 × unknown, tractor configuration , 25 hp (19 kW)
- Maximum speed: 77 mph (124 km/h; 67 kn) in free flight, flown solo
- Take-off speed: 35-38 mph (55-61 km/h)
- Taylor, John W R (1964). Jane's All the World's Aircraft 1964-65. London: Sampson Low, Marston & Co. Ltd. p. 207.
- Taylor, John W R (1974). Jane's All the World's Aircraft 1974-75. London: Jane's Yearbooks. p. 98. ISBN 0 354 00502 2.
- Lee Qihui (2006). "Stability and Control of an Inverted Delta Wing In Ground Effect Aircraft". Retrieved 25 September 2013.
- "Ekratoplan vs. Lippisch". Retrieved 25 September 2013.