# How is lift created?

Lift is created through the combination of Bernoulli’s principle and Newton’s 3rd law.

Bernoulli’s principle states that as air speeds up its pressure reduces.  An airfoil is used to create increased air flow on one side of the airfoil, which creates a lower pressure.  In an effort to equalize itself, the airfoil moves to the lower pressure, creating lift.

Newton’s 3rd law states that for every reaction, there is an equal and opposite reaction.  With an airfoil at some angle, there will be airflow impacting the bottom side of the airfoil.  As such, the airfoil is pushed in the opposite direction, producing lift.

To see these two forces in action, complete the following experiment.  While holding a piece of paper horizontally from one end, blow air over the top of the paper from the end being held.  The increased airflow should draw the paper upwards.  This is an example of Bernoulli’s principle.  Now, blow air underneath the paper.  This airflow should push the paper upwards.  This is an example of Newton’s principle.

Reference(s):

FAA-H-8083-21A – Helicopter Flying Handbook pg. 2-3
Principles of Helicopter Flight, 2nd Edition, pg. 17

Other Helicopter Aerodynamic Principles

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