“Blended ‘winglet’”

[Not very imaginative, but it was a travel day: shot 2 frames all day; threw out the other one. But I learned some stuff as a result of this, single frame. In particular, airline tickets would probably be even *more* expensive without these curved wingtips!]

Up at 4:30 a.m. Driven to the airport at 5 a.m. by our wonderful, wonderful son-in-law — Thank you, Steve!! This is descending into rainy St. Louis. While it was a horrible time to get up, it was pretty cool arriving in St. Louis before 10 a.m., since we still have a 3-hour journey home from the airport.

I'd be curious about the costs and engineering characteristics of these curved wingtips, which have been around for a few years. I'm sure they provide more lateral stability, particularly for take-offs and landings.

WRONG! Apparently it is not about handling. It's about reducing "drag." In particular, reducing "induced drag."

From Air and Space Smithsonian, http://www.airspacemag.com/flight-today/how-things-work-winglets-2468375/ » “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 upward around it. When flow around the wingtips streams out behind the airplane, a vortex is formed. These twisters represent an energy loss and are strong enough to flip airplanes that blunder into them.

“Winglets produce an especially good performance boost for jets by reducing drag, and that reduction could translate into marginally higher cruise speed. But most operators take advantage of the drag reduction by throttling back to normal speed and pocketing the fuel savings.

“Several airliners use them. … Aviation Partners, a Seattle, Washington company, has a new design it calls a ‘blended’ winglet. The Boeing Business Jet …, a derivative of the Boeing 737, has a set of the firm’s eight-foot winglets with a curving transition from wing to winglet that is characteristic of the company’s design.

“In 1976, shortly after an energy crisis sent fuel prices skyward, Richard Whitcomb, a NASA aerodynamicist, published a paper that compared a wing with a winglet and the same wing with a simple extension to increase its span. As a basis for comparing both devices, the extension and the winglet were sized so that both put an equal structural load on the wing. Whitcomb showed that winglets reduced drag by about 20 percent and offered double the improvement in the wing’s lift-to-drag ratio, compared with the simple wing extension.”

Even more —
» https://www.quora.com/Aerodynamics-Why-are-the-tips-of-some-airplane-wings-bent-upward
» http://www.aviationpartners.com/blendedwinglets.html

1 year ago (“2-frame day” [also a travel day]): http://365project.org/rhoing/365/2015-04-11
2 years ago (“Big yawn!”): http://365project.org/rhoing/365/2014-04-11
3 years ago (“3-frame day”): http://365project.org/rhoing/365/2013-04-11
4 years ago (“Floral ‘Russian dolls’?”): http://365project.org/rhoing/365/2012-04-11
5 years ago (“Rainy Days and Mondays…”): http://365project.org/rhoing/365/2011-04-11

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