Seattle-based Aviation Partners Inc estimates its blended winglets have saved customers worldwide an estimated 3 billion gallons of jet fuel, based on typical utilisation, since they were first installed on a Gulfstream II aircraft in 1993. They say this represents a reduction of over 32.2 million tons of CO2 emissions. By adding effective wingspan, the winglets reduce by around 6 – 7% the drag caused by wingtip vortices and result in increased fuel efficiency and boost range. The company’s winglets are now flying on more than 5,000 individual airplanes comprising more than 20 airplane types, mostly business jets but also commercial Boeing aircraft. The blended wingtips can be installed during production or retrofitted to existing aircraft, and they can be retrofitted to Boeing737-300 to -900, 757-200 and -300, and 767-300ER/F series aircraft.
Aviation Partners estimate its blended winglets have saved commercial and business aircraft around 3 billion gallons of jet fuel
Fri 27 Jan 2012 (Green Air online)
Seattle-based Aviation Partners Inc (API) estimates its blended winglets have saved customers worldwide an estimated 3 billion gallons of jet fuel, based on typical utilisation, since they were first installed on a Gulfstream II aircraft in 1993, representing a reduction of over 32.2 million tons of CO2 emissions. By adding effective wingspan, the winglets reduce by around 6 to 7 per cent the drag caused by wingtip vortices and result in increased fuel efficiency and boost range. The company’s winglets are now flying on more than 5,000 individual airplanes comprising more than 20 airplane types, mostly business jets but also commercial Boeing aircraft.
API expects the amount of fuel saved through its winglets to grow exponentially to more than 7 billion gallons in the next four to five years.
The blended wingtips can be installed during production or retrofitted to existing aircraft, and are certified on a range of Gulfstream, Hawker and Falcon aircraft types. Through its joint venture with Boeing, they can also be retrofitted to 737-300 to -900, 757-200 and -300, and 767-300ER/F series aircraft.
Back in 2009, American Airlines started to equip its 767-300ER fleet with API winglets and estimated the initiative would save it around 29 million gallons of fuel each year. Southwest Airlines is another that fits its aircraft with the winglets.
Winglets reduce wingtip vortices, the twin tornados formed by the difference between the pressure on the upper surface of an airplane’s wing and that on the lower surface. High pressure on the lower surface creates a natural airflow that makes its way to the wingtip and curls around it.
At last October’s NBAA convention, the company unveiled new winglet designs – the Scimitar Blended Winglet, Spiroid Winglet and Blended Split-Tip Scimitar Winglet – which promise a 10% improvement in the benefit provided by the existing technology.
API began discussions with Airbus in 2006 regarding the use of its blended winglets on Airbus A320 series aircraft, resulting in a memorandum of understanding in July 2011 with the intent, claims API, of forming a joint venture. API says that without notifying the US company, Airbus has filed a patent in Europe for its own Sharklet wingtip and has now also brought a lawsuit seeking to invalidate API’s own patent.
“API’s engineers analysed the Airbus materials and noticed the striking similarity between API’s Blended Winglet and the Airbus Sharklet design,” responded API founder and CEO, Joe Clark.
There is a lot of info on winglets on Wikipedia at http://en.wikipedia.org/wiki/Wingtip_device
Wingtip devices are usually intended to improve the efficiency of fixed-wing aircraft.There are several types of wingtip devices, and though they function in different manners, the intended effect is always to reduce the aircraft’s drag by partial recovery of the tip vortex energy. Wingtip devices can also improve aircraft handling characteristics and enhance safety for following aircraft. Such devices increase the effective aspect ratio of a wing without materially increasing the wingspan. An extension of span would lower lift-induced drag, but would increase parasitic drag and would require boosting the strength and weight of the wing. At some point, there is no net benefit from further increased span. There may also be operational considerations that limit the allowable wingspan (e.g., available width at airport gates).
Wingtip devices increase the lift generated at the wingtip (by smoothing the airflow across the upper wing near the tip) and reduce the lift-induced drag caused by wingtip vortices, improving lift-to-drag ratio. This increases fuel efficiency in powered aircraft and increases cross-country speed in gliders, in both cases increasing range. U.S. Air Force studies indicate that a given improvement in fuel efficiency correlates directly with the causal increase in the aircraft’s lift-to-drag ratio.
Boeing announced a new version of the 747 in October 1985, known as the 747-400, with an extended range and capacity. With that particular model, Boeing used a combination of winglets and increased span to carry the additional load. The winglets increased the 747-400′s range by 3.5 percent over the 747-300, which is otherwise aerodynamically identical but has no winglets. Winglets are preferred for Boeing derivative designs based on existing platforms, because they allow maximum re-use of existing components. Newer designs are favoring increased span, other wingtip devices or a combination of both, whenever possible.
In 2002, Boeing first flew a production Next-Generation 737 with its new Blended Winglets, six-foot extensions that decrease fuel consumption by about 4 to 6 percent. The airplane gained supplemental type certification in 2003, and the majority of 737s delivered today are equipped with the devices.
Winglets Save Billions of Dollars in Fuel Costs
long article, which includes this paragraph
APB winglets provide up to a 6% reduction in carbon dioxide emissions and an 8% reduction in nitrogen oxide, an atmospheric pollutant. The benefits of winglets do not stop there, Stowell explains. Reduced drag means aircraft can operate over a greater range and carry more payload. Winglet-equipped airplanes are able to climb with less drag at takeoff, a key improvement for flights leaving from high-altitude, high-temperature airports like Denver or Mexico City. Winglets also help planes operate more quietly, reducing the noise footprint by 6.5%.
Full article at http://www.sti.nasa.gov/tto/Spinoff2010/t_5.html