Flight has always been a subject of fascination for mankind. In fact, it was this very fascination that put us in the sky in our own flying machines. After Wright Brothers pulled off this seemingly impossible feat in 1903, it just got better. However, more than a century down the lane, the technicalities of flying continue to elude humans.
How Do Aircraft Fly?
When we see birds flying, we can clearly see them flapping their wings to soar in the air. On the other hand, when airplanes fly, no such physical activity is observed. That leaves many people wondering as to how is it possible for these heavy airplanes to fly. Basically, four forces play a crucial role in the flight of the aircraft: lift, weight, thrust, and drag―each of these are discussed below.
Lift: Lift is a mechanical force which is created by the interaction of any solid body with a liquid or gas. Basically, the molecules of air move freely in the surroundings and when any solid body comes in contact with them, it is deflected upwards. In this case, the lift pushes the airplane in mid-air when its solid body comes in contact with the gaseous surroundings.
Weight: Weight is basically the field force which pulls the airplane towards the center of the Earth. When it comes to flight, this field force is supposed to be countered by an opposing force, which―in this case―is the lift. It also plays an important role in balancing the entire airplane in the air. It is important to have a balanced weight right from the tip of the plane to its tail.
Thrust: Thrust is defined as the mechanical force which helps the body move forward. In case of an airplane, the thrust required by the plane to move forward is generated by the engine. This thrust helps the plane move ahead and at the same time, ensures that the air keeps passing over its wings―a necessity to keep the plane in mid-air.
Drag: Drag is the aerodynamic force which helps the airplane in flying. It basically controls the flight of the airplane by slowing down its speed. These airplanes are specially designed by taking into consideration the laws of aerodynamics. Like the lift, the drag is also a mechanical force generated when a solid body comes in contact with liquid or gas.
These four forces have to work in coordination for the airplane to fly; individually, they are of no use. The lift is created when the air moves around the wings of the airplane; courtesy, its shape and the movement of its wings. The lift of the airplane―to a large extent―depends on Newtons Law: Every action has an equal and opposite reaction. As the air moves beneath the wind, it is deflected downwards, which, in turn, lifts the plane upwards. The thrust, which triggers the forward motion, helps in increasing the speed of air and that, in turn, helps in deflection and lift.
Fly Upside Down
While the basics remain the same in this case, the directions change. The slight tilt induced by the pilot transfers the pressure to the opposite sides, thus making the airplane fly upside down for a brief period. Most airplanes can't fly in such a position for long, as it puts excess stress on their body and makes them vulnerable to disintegration in mid-air.
So the airplane can fly in mid-air only when the two most prominent requirements are fulfilled: (i) the thrust is strong enough to counter the drag and (ii) the lift is strong enough to counter the weight.