:: theory of flight ||| activities ::

Demonstration Equipment :::

Lifting forces created through air speed and pressure differentials is difficult to visualize. To help the class understand this phenomenon, several different demos will be performed. Among these will be a wind tunnel to illustrate flow patterns over an airfoil, and a hands on “flying disk” demonstration.

The airfoil demonstration in the wind tunnel will reveal fluid flow around different shapes, which helps explain the reason behind the camber shape construction of standard wings compared to other potential shapes. It will also show how the angle of attack, if increased too much will cause a stall. The flying disk demonstration allows students to experience first hand the manner in which increased velocity causes a low-pressure area and generates lift.

Activity One:

::: Bernoulli’s Flying Disk

bernoulli's flying disk.

Ask if anyone can think of a way to use the vacuum cleaner to hold the disk in the air (probable answer will be to suck up the disk
Ask if anyone thinks that the disk can be suspended in the air by blowing air at it instead of sucking it up
Have all the students try the demo
Ask if they felt the resistance of the flow before the disk got “sucked” up
Ask if any one knows how the disk is being held up
Talk about the flow of a fluid over an object and the resulting low pressure – Bernoulli’s Principle
Attach the pressure gauges to quantify the lower pressure distribution over the area of the disk

Activity Two:

::: Wind Tunnel

wind tunnel.

Visualizing the flow around the wing
Angle of attack – increase to get more lift
Stalling – increase the angle of attack until the students can see the separation of the air from the wing and therefore the stall (see overhead #9)