Friday, December 15, 2006

What's With the Winglets?

Since no one has asked a question recently, I thought I'd come up with my own.

Lately there has been a rash of modifications to planes, adding those large winglets. This isn't necessarily new. The 747-400 has had winglets since it was first produced as has the Airbus A320. So why are airlines suddenly spending considerable sums to equip their fleets with winglets? What do they do, other than look pretty cool?

As a wing moves through the air, the shape causes there to be higher pressure on the bottom than on the top. At the end of the wing that pressure escapes and tries to make it to the top. This causes small, horizontal tornadoes off the tip of each wing. These are known as "vortices." In high humidity conditions, you can sometimes see them. The thing about it is that, especially at slower speeds, these vortices cause a tremendous amount of drag, which in turn causes a much higher fuel consumption because the engines must compensate for the extra drag.

The addition of winglets interrupts the creation of these vortices. You can't stop them altogether, but you can reduce them...and any reduction in these tornadoes reduces the drag on the airplane...and any reduction in drag reduces the fuel consumption...and any reduction in fuel consumption reduces costs, and increases the range of the plane. A couple of airlines have added the winglets to 757's in order to increase their range to the point they can fly across the Atlantic.

I am going to try to get a couple of pictures of winglets to post for those who are still scratching their heads about what I am talking about.

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