Airheads
Generating Lift
Today we will learn about how airflow can produce lift and make things fly.
Before we start, let’s reflect on these questions:
What is the force of LIFT?
Lift is one of the four forces of flight, the others being gravity, thrust, and drag, but let’s just concentrate on lift.
The USS Intrepid is an aircraft carrier that served from 1943-1974
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The force of lift directly opposes the force of gravity - the force that pulls everything within the Earth’s atmosphere toward the center of the Earth. Without lift, things cannot fly!
The USS Intrepid is an aircraft carrier that served from 1943-1974
Thrust
Lift
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How does airflow generate lift?
Air is considered a fluid with many characteristics in common with other fluids such as water. Daniel Bernoulli, a Swiss scientist who lived in the 1700s, observed that the faster a fluid travels over a surface, the lower the pressure it exerts on that surface..
For example: As an aircraft moves forward into a stream of air, the wing deflects the air. Some of the air moves to flow above the wing while some of the air moves to flow below the wing. The wing is curved to help the air that flows above the wing move more quickly than the air that was able to flow below the non-curved bottom of the wing. The resulting lower pressure above the wing, pulls the wing, and therefore the aircraft up. This is lift!
This can be easily demonstrated by taking a strip of paper and blowing air over the top of it. The resulting area of low pressure will pull the paper strip up, creating lift.
The USS Intrepid is an aircraft carrier that served from 1943-1974
Many of the things we have learned, we have learned by observing or studying nature. Bernoulli’s Principle can be seen in action by observing how birds fly. It is no coincidence that an aircraft’s wing is modeled after a bird’s wing. This curved shape is called an airfoil.
As the picture shows, the curved shape of both the bird’s wing and the aircraft wing are curved on top, allowing the air to flow faster over the top then on the bottom. The resulting reduced air pressure pulling up creates lift!
The force of lift makes it possible for all things to fly, including our aircraft here at Intrepid. Yes even the helicopters!
If you look closely at a helicopters rotors, you will see the tops are curved while the bottoms are flat just like an airplane’s wing. A helicopter’s rotors act as its wings to create lift.
What are some different ways to generate lift?
Sometimes, Bernoulli's Principle is the sole explanation of lift, however Isaac Newton's Laws must also be considered.
Sir Isaac Newton was an English scientist who lived in the 1600s. He is famous for creating three laws of motion, which actually inspired Bernoulli. Newton’s 3rd law states that a force applied in one direction will generate an equal force in the opposite direction.
For instance, although an airfoil’s shape creates lift by “pulling” a wing up, some of the air flow over the top sticks to the curve and is directed down. According to Newton's 3rd Law, the reaction of the air being pushed down is that the wing is pushed up. This can also be demonstrated by blowing air over the strip of paper as before.
Another example of Newton’s 3rd law is called the “magnus Effect”. This is most commonly associated with a spinning object such as a ball. As with the airfoil above, the air flowing over the top of a spinning ball will be forced down behind it causing the ball to be deflected in the opposite direction. This is why a soccer player can “bend” a soccer ball around a 5 player wall to score a goal or a baseball pitcher can make a baseball curve to strike out a batter.
Let’s Visit Intrepid!
Press play on the next slide to travel to the Intrepid Sea, Air & Space Museum and learn about how aircraft generate lift.
Create a magnus glider!
Follow the visual instructions on the next three slides to create your own Magnus glider
Materials: What you need
Step 1: Build the glider
Step 2: Make a rubber band chain
Step 3: Wrap the rubber band
Create a Magnus Glider!
FOR MORE INFORMATION
To learn more about Bernoulli and Newton, click here
For more about the Museum and to plan your visit, click the link below
Intrepid Sea Air & Space Museum