Threads and Sails. at Langley

everal revolutionary advances in aircraft design and technology

emerged from NASA’s Langley Research Center in the 1970s as a result of the Aircraft Energy Efficiency program. Historian Roger Bilstein referred to them as “arcane subjects” that included “some unusual hard­ware development The first of them challenged the seemingly obvious assumption that the aircraft should be made of metal and aluminum. Most people took for granted that these were the best aircraft materials until a 1978 Los Angeles Tunes reporter speculated that “Large commercial and military jets of the future will probably be made not of metal but of thread.”[88] [89] [90] Machines with “gigantic spools of yarn” began making airplane parts with “threads” from new composite materials that promised tremen­dous weight savings, thereby making airplanes more fuel efficient.1

Another Langley development fundamentally changed the shape of the aircraft in two key ways. The first idea was an airplane wing that emulated a boat “sail" through a change in its shape at the wingtip. These first became visible in the 1980s, when the main wings on some aircraft, including the MD-11 in 1986. took an unusual upward or vertical extension at the end of the wing. This acted like a sail, taking advantage of a whirlpool of air that naturally occurred around the wingtip. The sail caught the swirling air. trans­formed it into forward thrust, reduced drag, and increased fuel efficiency.[91]

A second development, called the “supercritical wing,” was so unusual that when it emerged from a Langley wind tunnel, even its designer con­fessed, “nobody’s going to touch it with a ten-foot pole without somebody going out and flying it.”[92]

These striking new technological developments —threaded aircraft materials, wing “sails,” and supercritical wings—were the primary focus of two ACEE projects led by Langley engineers. They were airframe tech­nology advances with the primary goals of reducing structural weight and improving aerody namic efficiency as a means of decreasing fuel consump­tion.[93] The threaded aircraft materials were part of the Composite Primary Aircraft Structures (CPAS) program. The sailboat emulation, officially known as a “winglet,” and the supercritical wing were two of the most successful components of the multifaceted Energy Efficient Transport (EET) program. A central portion of Langley’s contribution to the ACEE program, these projects achieved significant savings in fuel economy.[94] [95]