Chapter 7, Problem 11A

How does a helicopter get its lifting force?

To determine

The way thehelicopter gets its lifting force.

Explanation of Solution

Introduction:

Landing and takeoff of helicopter is one of the best examples of aerodynamics.Newton’s laws of motion are the basic mechanism behind this.The main difference between the helicopter and airplane is the ability to fly vertically.

  

Lifting force is the perpendicular component of oncoming flow direction of fluid.If the fluid is air then this force is known as aerodynamic lift. In case of helicopter this lifting force used to encounter the force due to gravity.This force isalways perpendicular direction of the flow of fluid. In case of helicopter, air is flows in the horizontal direction.Main rotor of the helicopter rotates in the horizontal plane which is useful to apply the lifting force. Force exert on the air in downward direction,when main rotor blade rotates into the horizontal plane. Due to that equal amount of force exert by the air on the rotor blade in the upward direction, according to Newton’s 3^rd law of motion. This upward force is nothing but lifting force. Due to this lifting force helicopter fly vertically.

Conclusion: Due to the upward lifting force helicopter fly vertically.