The Upturned Wing Tip of Soaring Birds

     The Upturned Wing Tip of Soaring Birds

A JET plane in flight creates rapidly spiraling swirls of air at the tips of its wings. These vortices cause drag, increasing fuel consumption. They also buffet planes that may be following closely. Thus, flights departing from the same runway

must be sufficiently spaced to allow time for the vortices to dissipate.

Airplane engineers have discovered a way to reduce these problems. Their solution? Winglets, inspired by the upturned wing-tip feathers of soaring birds, such as buzzards, eagles, and storks.

Consider: During flight, the feathers on the wing tips of those large birds bend upward until they are almost vertical. This configuration balances maximum lift with minimum wing length. It also improves performance. Engineers have designed airplane wings with a similar shape. Using innovative wind-tunnel testing, they found that if the modified wings were precisely curved at the tip and properly aligned with the airflow, they improved aircraft performance—nowadays by up to 10 percent or more. The reason? Winglets minimize drag by reducing the size of the vortices. Moreover, winglets also create a form of thrust that “counteracts some of the normal drag of the airplane,” says the Encyclopedia of Flight.

Winglets thus enable airplanes to fly farther, carry a greater load, have shorter wings—which also facilitates parking—and save fuel. In 2010, for example, airlines “saved 2 billion gallons [7,600 million L] of jet fuel worldwide” and contributed to large reductions in aircraft emissions, says a NASA news release.

What do you think? Did the upturned

wing tip of soaring birds come about by

evolution? Or was it designed? ˛

LANDS AND PEOPLES - COSTA RICA

FIVE centuries ago, the Spaniards first visited this region. They called it Costa Rica (Rich Coast), thinking that they would find an abundance of gold —a quest that proved futile. This land is today known, not as a source for valuable metals, but as a country with one of the richest biodiversities on earth. 

Costa Ricans are known as Ticos, which comes from their custom of adding  “ico” to the end of words to form the diminutive. For example, instead of saying “un momento” (just a moment), they might say “un momentico” (just a little moment). In everyday speech they often say “¡pura vida!” (pure life!) to express their appreciation or their agreement or to say “hello” or “goodbye.”

One of Costa Rica’s favorite dishes is gallo pinto (literally meaning “spotted rooster”)—rice and beans cooked separately and then together with seasonings. Gallo pinto can be served at breakfast, lunch, or dinner. A traditional beverage is café chorreado—coffee brewed through a cloth filter hanging in a stand often made of wood.

There are about 450 congregations of Jehovah’s Witnesses in Costa Rica. Their meetings are conducted in ten languages, including Costa Rican Sign Language and two languages that are indigenous to Costa Rica—Bribri and Cabecar. ˛

   TEST YOUR KNOWLEDGE

Which of these do you think Costa Rica has?

A. One of the highest literacy rates in the Western Hemisphere

B. A highly developed army

C. An island to which more than 500 expeditions have been organized in search of buried treasure