514
P. Liu
Fig. 7.88 Turboprop engine
Fig. 7.89 Turbofan engine
7.11 High-Lift Device of an Aircraft
In addition to the albatross taking off from the ground, the swan can take
off on the water surface (as shown in Fig. 7.98). The takeoff attitude and
action, etc., of these birds are worthy of human-designed aircraft imitation. It
is conceivable that if the bird can speak, it may have to compete with humans
for the invention of the aircraft. When the aircraft is taking off or landing,
the pitch angle (also called the angle of attack) is relatively large, but the angle
of attack is relatively small when cruising. Why? This is because the speed of
the aircraft is fast when cruising. Because the lift is proportional to the square
of the speed, there is no need to increase the lift by increasing the angle of