Propeller airplane: thrust and lift

What the experiment shows

The engine spins the propeller and it pushes the plane forward. At high enough speed the wing makes a force equal to the plane’s weight and it lifts off.

How to run it

1. Run and hold W: the plane accelerates along the runway.
2. When it is fast enough press the up arrow — the nose rises and the plane takes off.
3. In the editor raise the wing’s “lift” or reduce the mass — takeoff gets easier.

Questions to discuss

• Why does an airplane need a run-up before takeoff?
• What happens if you switch the engine off in the air?

The science

Wing lift grows with the square of speed: F ≈ k·v². While the speed is low, the force is smaller than the weight m·g and the plane rolls on the ground. Once F > m·g it takes off. Thrust comes from the propeller: it throws air backward and the air pushes the plane forward.

Try it at home

Make a paper plane and compare how it flies with different throw strengths. Hold a sheet of paper under your lip and blow over it — it rises.

What to change in the editor

• Change the wing span (size Z).
• Add a second engine with a propeller.