Robert W. Mellette
TOPIC: The forces of flight—LIFT
Rationale All aircraft that fly within earth’s atmosphere rely on a force called LIPT that acts in a predictable and upward direction against the downward force of the earth’s gravitational field. The understanding of the concept of LIFT is key to the basic forces involved in the study of aerodynamics.
Objective After instruction the student will be able to explain how the movement of an air-stream over the curved surface of an aircrafts wing, provides the LIFT that allows an aircraft to rise up and remain in the air.
Materials Required
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Strip of paper that is 3 inches (7,5 cm) wide and about 82 inches (21 cm) in length.
Pencil or pen
Procedure Glue or tape the ends of the paper strip together as shown in the diagram fig. 1. Insert a pencil or pen into the open loop of the model wing. Blow a strong, blast of air across the top surface of the “wing”. Observe what happens.
Fig. 1
(figure available in print form)
Conclusion The paper wing is shaped in such a way that the air blowing over the top surface has to travel a longer distance than the bottom surface. The air traveling over the longer top surface has further to go so it is speeded up. Bernoulli’s principle states that an area of low pressure will develop on the top surface of the “wing”. The atmospheric pressure pushes up on the bottom of the wing trying to fill the place where the air pressure is not as great. This force called Lift makes the wing rise.