Long time people dreamed of flights. Handymen tried to copy wings of a bird, attached them for a back and tried to come off the earth. But simple imitation birds still allowed to rise to nobody in air. To overcome terrestrial gravitation it was possible when the plane with a motionless wing was designed.
Instruction
1. Still Leonardo da Vinci specified in the ingenious notes that for commission of flight it is necessary not to wave wings, and to tell them horizontal speed and to allow to move concerning air. In interaction of a flat wing with air masses there will have to be a carrying power which will exceed aircraft weight, the legendary inventor considered. But it was necessary to wait for several centuries before this principle was realized.
2. Experimenters quite successfully made experiments with flat wings. Having disposed such plate at a small angle to air flow, it was possible to observe how there is a carrying power. But appears as well resistance force which seeks to blow off a flat wing back. Researchers called a corner under which air flow affects the wing plane, an angle of attack. The it is more, the great values are accepted by the carrying power and force of resistance.
3. At the beginning of aircraft the researchers found out that the most effective angle of attack for a wing of a flat form makes 2-9 degrees. At smaller value it will not turn out to create necessary carrying power. And if the angle of attack is excessively big, there will be unnecessary resistance to the movement – the wing will simply turn into a sail. Scientists called the relation of carrying power to resistance force aerodynamic quality of a wing.
4. Observations of birds showed that wings at them not so flat. It turned out that only the convex profile could provide high aerodynamic qualities. Running on the wing having a convex top part and flat lower the air flow is divided into two parts. The top stream has more considerable speed as it should pass bigger distance. There is a difference of pressure which creates force directed up. It is possible to increase it, having adjusted an angle of attack.
5. Modern planes have considerable weight. But the carrying power arising at the time of take-off allows a heavy design to come off the Earth's surface. A secret is in correctly picked up profile of wings, in exact calculation of their area and an angle of attack. Be a plane wing absolutely flat, it is heavier to make flight on the device air it would be impossible.
6. Carrying power is used not only at take-off and deduction of the plane in air. It is necessary also for control of the aircraft in flight. For this purpose wings divide into a number of mobile elements. Such flaps at commission of maneuvers change the provision of rather motionless part of a wing. The plane has a horizontal plumage performing function of an elevator and vertical plumage which serves as a direction wheel. Similar structural elements guarantee to the aircraft stability in air.