Applebay Zuni II - (scan - 1997)

In early 70s, Soaring Society of America saw that lead in competitive sailplane design had passed back to Germany, despite dominance of US aerodynamicists and composite materials designers and manufacturers. Association attempted to create competition for best US design but, after several years, only ship completed was George Applebay's Mescalero, a 21 m (69 ft) span super sailplane. Ship had little chance of development, as competition had centered on the 15 m (49.2 ft) span racing class. Applebay solicited design help from some of best US designers and DuPont Corp and formed Aero Tek to produce a 15 m ship in Albuquerque NM. Zuni was one of few US designs to take advantage of composite construction largely developed by DuPont and Dow but primarily used by European sailplane manufacturers, especially the Germans. Careful design, control of molds, retractable gear and tow hook, and sealing of all openings allowed fully laminar aircraft. Tow-line force to maintain level flight at 60 mph is less than 25 lbs. Aerodynamic drag of the 40 ft of steel cable which holds the Zuni to the girders is more at the same speed! Initial ships used fiberglass cloth and epoxy resin for structure, and later examples made extensive use of carbon fiber for structural components and Kevlar for skins; this resulted in stronger, stiffer, and lighter construction. High performance sailplanes add substantial amounts of water ballast (often exceeds the empty weight of the aircraft--500 lbs for Zuni II) to increase high speed performance, but can be jettisoned if lift weakens. Uncommon feature is side-mounted control stick also used on BD-5, F-16, and A-320. When completed in late 70s, was equal to most competitors, but a fatal crash and lawsuit caused company to close at a critical time, and development stopped. When Applebay reopened, design was obsolete. Bowlus Albatross II, Arlington Sisu Ia, and Zuni II each represent state-of-the-art of wooden, metal, and composite sailplane design in their eras, with about 25 years between each.

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