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Aviation History
1963
1963 - 1346.PDF
170 FLIGHT International, 1 August 1963 FLEXIBLE WINGS AT WORK Largest Flex-Wing aircraft so far built, the Fleep is a prototype of a manned transport for battlefield use. Standing beside it during the handing-over at the Ryan factory is Mr M. M. McDaniel, Flex Wing programmes manager IN 1961 the Ryan Aeronautical Co, of San Diego 12, Calif, • started full-scale flight tests with the first Flex-Wing aircraft, to demonstrate the feasibility of the idea. The idea was not new, but Ryan was the first to put it into practice: to build an aeroplane with a wing consisting of a delta-shaped flexible, plastics- covered sheet attached to a rigid leading edge and centreline. Under load the sheet billows out into port and starboard planes each forming part of the surface of a cone. Such a wing has no proper aerofoil section; in fact it is essentially two-dimensional. But it is light and cheap, and for many specialist tasks appears superior to a conventional "rigid" aerofoil. Aircraft control is accomplished not by aerodynamic reaction on movable surfaces but by displacing the suspended-body e.g. position relative to the wing. During the latter part of 1961 Ryan were content to carry on proving the principle, which the company call the Flex-Wing. This journal asked Ryan to outline the origin of the idea, and the company replied, "I guess this Flex-Wing concept was originally toyed with by Leonardo da Vinci—it seems he had a hand in every revolutionary concept. There are also evidences that Otto Lilien- thal had a hang glider concept which was close to the Flex-Wing idea. "However, the modern man credited with the wing is Francis Rogallo. Now chief of a wind-tunnel branch of the National Aeronautics and Space Administration, he has served NASA and its predecessor NACA for 27 years, and 18 years ago began an intensive study into what Ryan has since developed under the registered name of Flex-Wing." Ryan have used light-alloy structures and a variety of covering materials. Ordinary rip-stock parachute nylon is common, or nylon or Dacron covered with a plastic film to increase strength and reduce porosity. These materials weigh from loz to 6oz per square yard, and stand up excellently to repeated folding and general use. The control mechanism shifts the position of the hung body relative to the wing by reeling in and out the suspension lines on electro mechanical winches. The original free-flight, full-scale test vehicle was a manned one. It was piloted by company chief engineering test pilot Lou Everett, who found little difficulty in acquiring the special tech niques needed to obtain the best results from such a concept. Once Everett had shown that the Flex-Wing could be flown, he undertook an intensive test programme for the US Army Trans portation Research Command (TRECOM), at Brown Field, just south of San Diego. The same craft was then shipped to the Nat ional Aeronautics and Space Administration Langley Research Center, in Virginia, where tests in Mr Rogallo's big open-jet tunnel confirmed data obtained in free flight. Ryan have thought of many Flex-Wing applications. Some appear improbable, or at least not capable of immediate realization. But during the past year a very encouraging number of these potential applications have become the subject of US Government contracts, including the following:— 1. Atmospheric recovery, following re-entry, of the NASA/Depart ment of Defense Gemini two-man Earth orbiter (responsibility for this part of the Gemini programme was not assigned to Ryan). 2. PDG (precision-drop glider) system for the US Army, using Flex-Wings to support cargo containers released from transport aircraft and remotely controlled to land on preselected spots. 3. ACD (air cargo delivery) system for the US Army, using Flex- Wings to support gliders towed by helicopters. 4. Fleep (a corruption of "Flex-Wing" and "Jeep") for the US Army TRECOM, using Flex-Wings to carry payloads in support of forward troops. 5. Flex-Bee (a name stemming from the company's very successful Firebee), for the US Marine Corps, using Flex-Wings to support an unmanned reconnaissance package. The last-named appears of doubtful value, since at first sight A Ryan secretary provides scale to the diminutive Flex-Bee drone, an example of which is seen in flight on the right
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