Page 91 - Understanding Flight

CH03_Anderson 7/25/01 8:56 AM Page 78

78 CHAPTER THREE

One might wonder why the winglets of some of the jets
Northrop invested $1.2 billion in
cover only the last part of the wingtip, as in Figure 3.18. This
the early 1980s to develop the
is because, at cruise speeds, the air flowing over the first part
F-20 Tigershark. Despite
of the wing is going at or near the speed of sound. A winglet
outstanding performance, not a
here would cause a shock wave and increased drag, which is
single one was sold.
discussed in Chapter 6.

Canards
The Wright brothers designed their airplanes such that the horizon-
tal stabilizer was forward of the wing. This configuration is called a
canard, which is the French word for a type of duck. But the
canards soon disappeared from the scene, until their recent revival.
Today, canards have become popular, much like wingtips, because
of their sexy appearance. A dramatic example of a canard is the

Fig. 3.18. A winglet on a K-C135A. (Photo courtesy of NASA.)