Aeroplanes fly and reach to a height by using two things. One is the Bernoulliâ€™s effect and other is the simple momentum transfer in the flow of air for the lift.
Daniel Bernoulli stated a principle which says that with the increase of speed of fluid the pressure decreases. Here the air over an airplane works as a fluid.
For the lift of airplane the cross-section of wings are made in a way that the lengths between the leading side to the trailing side is greater along the way that moves above the wings as compared to the below part of the wings. When the airplanes move air starts flowing both under and over the wings. The air pressure above the wings is less because the distance that air has to move is more as compared to the distance that air has to move under the wings. We can say that the air flow has to cover more distance above the wings and the air expands in volume hence creating low pressure while air below wings expands less and have more pressure than above air. So a difference is created on the upper and lower parts of the wings which happen to give more force from the bottom and the aircraft lift upwards.
One more force acts in the process of deflection which says that the air below the wings is forced downwards which pushes the wings upward with same force (according to the Newtonâ€™s law that says that every action has equal and opposite reaction). Hence the airplane is forced upwards. The faster is the speed of wings through air the more is the force for the lift of airplane.
Weight is the force that acts on airplane and the plane is built in such a way that its weight is distributed from the front to the back side which keeps the balance of the plane. Another thing helpful in lift is dynamic momentum i.e. the angle at which the wings strike to the air with relation to the overall direction of the plane makes the air to strike on the lower surface of wings to be turned or downward deflection.