How Do Airplanes Fly

Flight has always been a subject of fascination for mankind, and it was this fascination that resulted in the first flight for the humans in their own flying machines in the beginning of the 20th century. After the Wright Brothers achieved this seemingly impossible feat in 1903, the voyage through the air just got faster and faster. 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 are flying, they don't demonstrate any physical activity, but still manage to fly. 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 case of an airplane, the lift pushes the airplane in mid-air when the solid body of the aircraft comes in contact with the gaseous surroundings.

Weight: Weight is basically the field force which pulls the airplane towards the center of the Earth. Weight also plays an important role in balancing of the entire airplane in the air. It is important to have a balanced weight right from the tip of the plane to its tail. When it comes to the flight of the airplane, this field force is supposed to be countered by some opposing force (the lift) which helps the plane fly.

Thrust: Thrust is defined as the mechanical force which helps the body to move forward. In case of an airplane, the thrust required to move the plane forward is generated by the engine. This thrust helps the plane to move ahead, and at the same time ensures that the air keeps passing over its wings, which is 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 various 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 were the four forces required by an airplane in order to fly. The proper coordination between all these forces is essential, as they are of no use individually. The lift is created when the air moves around the wings of the airplane. The shape and the movement of the wings is the key to this. 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, which 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 upon the craft 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 durations as it puts excess stress on their body, thus making them vulnerable to disintegration in mid-air.

The airplane can fly in mid-air only when the two most prominent requirements are fulfilled - first, the thrust is strong enough to counter the drag, and second, the lift is strong enough to counter the weight.