If you walk around the static display here at MEBA 2012, a common theme emerges: there are hardly any airplanes on show that do not have upturned wingtip extensions.
Aviation Partners (U.S. Pavilion, Stand 575), a Seattle-based company established in 1991, pioneered the blended winglet design, in which the winglet forms a graceful curve up from the wing rather than turning up at a sharp angle.
Its initial application was an upgrade for the Gulfstream II, launched in 1993. Then came the big breakthrough as the company partnered with Boeing to provide blended winglets for the manufacturer’s aircraft, beginning with the 737 BBJ. The winglets were later adopted for regular 737NG airliners, plus some earlier versions. Aviation Partners winglet technology has subsequently been applied to the Hawker 800, Boeing 757 and Boeing 767, as well as being tested on the Airbus A320 and Boeing 747-200.
In 2009 Aviation Partners winglets were certified for the Dassault Falcon 2000, marking the first application of a high-Mach winglet. The Falcon 900 and, most recently, the Falcon 50, have also received the Aviation Partners treatment. The latter type was certified with API winglets in September this year.
Blended winglet technology significantly reduces induced drag, in which high-pressure air spills around the wingtip and forms a vortex. The winglets greatly reduce the amount of seepage, and thus greatly improve the wing’s efficiency. This translates into better longitudinal and directional stability, improved take-off performance and, most important, reduced fuel-burn. Aviation Partners calculates a 6-percent reduction for a 737, equating to about 100,000 gallons saved over a year with typical usage. The company claims that its blended winglets have already saved 3.4 billion gallons of jet fuel, a figure projected to pass 5 billion by the end of 2014.
Aviation Partners has refined its winglet technology over the years, leading to the development of the Blended Scimitar tip, which was first applied to the Hawker 800. This winglet has a refined tip with an extended section at the top. More recently the company developed the Blended Split-tip Scimitar Winglet, which adds a ventral fin beneath the upturned winglet. This is being tested on a Boeing BBJ, which first flew with the new tips in May this year.
Aviation Partners is also working at a more radical development, the patented Spiroid wingtip, which comprises sophisticated looped surfaces and was first tested on a Gulfstream II in 1993. Nearly two decades later the Spiroid took to the air again in July 2010, fitted to a Dassault Falcon 50. The intervening period has seen an improvement in computational fluid dynamics modeling that has led to improvements in the design. The recent trials proved a drag reduction of more than 11 percent.