Section 6 EO C231.01 – OPERATE AN EXPERIMENTAL WING

Resources needed for the delivery of this lesson are listed in the lesson specification located in A-CR-CCP-802/PG-001, Chapter 4. Specific uses for said resources are identified throughout the Instructional Guide within the TP for which they are required.

Review the lesson content and become familiar with the material prior to delivering the lesson.

Create slides or copy handouts of Figures A-1 to A-4 for each group.

Gather cardboard boxes suitable for constructing a wind tunnel as described in TP2.

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An interactive lecture was chosen for TP1 to introduce wind tunnels and give an overview of them.

An in-class activity was chosen for TP2 to TP4 as it is an interactive way to provoke thought and stimulate an interest among cadets.

The review for this lesson is from EO M231.01 (Identify the Four Forces That Act Upon an Aircraft) and will include:

By the end of this lesson the cadet shall be expected to have helped to assemble a wind tunnel and to have operated an experimental wing in the wind tunnel.

It is important for cadets to operate an experimental wing so they can experience the change in lift that follows a change in angle of attack.

The objective of this activity is to have the cadets, organized in groups but working as a coordinated team, assemble a wind tunnel for flying experimental wings.

Place a table large enough to hold the wind tunnel and fans in an area that will provide room for groups of no more than four cadets to work comfortably, with access to power for the fans.

Have the cadets make a wind tunnel out of five boxes taped together with all ends open. The wind tunnel should be large enough that both hands will fit into it easily. For both the settling chamber and the drive section, use boxes that include cardboard separators for shipping glass bottles. The cardboard separators will “honeycomb” or straighten the swirling air currents from the electric fan.

D Cdts 3, 2007 Ottawa, ON: Department of National Defence

Figure 2  Parts of a Cardboard Wind Tunnel

The parts of the wind tunnel can be divided between groups of cadets but, when completed, the wind tunnel components must fit together so that each section fits tightly inside the next section.

1.Shape the contraction zone and diffuser sections by cutting out triangles of unwanted cardboard as shown at Figure A-2. Make cuts straight and smooth so the resulting joint can be made airtight.

2.Cut “windows” in the test section and cover over with OHP slide material.

3.Tape all edges and holes airtight and ensure the inside of the wind tunnel is smooth to allow the air to pass through without turbulence. Seal all box joints with duct tape.

4.Place an electric fan so that it blows into the cardboard honeycomb of the settling chamber. The fan must be run at a speed that does not produce unreasonable turbulence, yet fast enough that it pushes a large volume of air through the glass bottle separators. Place another fan at the exit of the drive section facing away from the wind tunnel to pull air from the wind tunnel.

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The cadets’ participation in the activity will serve as the confirmation of this TP.

The objective of this activity is to have the cadets create their own airfoil shapes for testing in the wind tunnel.

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If locally available materials, such as balsa wood, knives etc., are used for constructing experimental wings instead of file folder airfoils, ensure safe practices are followed. Careful supervision will prevent unsafe use of materials or unsafe actions.

The cadets’ participation in the activity will serve as the confirmation of this TP.

The objective of this activity is to have the cadets suspend experimental wings in the operating wind tunnel and make changes in the wing’s angle of attack, observing the change in lift.

Place the wind tunnel created in TP2 in a location that provides room for groups of no more than four cadets to work comfortably, with access to power for operating the wind tunnel fans.

1.Have the cadets poke tiny holes in the roof and floor of the wind tunnel test section where the trailing edge of the experimental wing will be located.

2.Poke tiny holes in the window walls where the leading edge of the experimental wing will be located.

3.Run dental floss from window wall to window wall of the test section, passing through the interior of the experimental wing to be tested, at the wing’s leading edge. This will suspend the experimental wing in the centre of the test section where it can be controlled and viewed.

4.Run dental floss from roof to floor of the test section, attaching the string to the trailing edge of the experimental wing with staples. This will allow the angle of attack to be changed by pulling on the dental floss under the test section to increase the angle of attack, or pulling on the dental floss above the test section to decrease the angle of attack.

5.With two cadets holding the ends of the horizontal string and two cadets holding the ends of the vertical string, turn on the fan.

6.Ask the cadets with the vertical string to increase the angle of attack. The cadets holding the horizontal string will detect an increase in lift.

7.Have the cadets trade positions.

8.Repeat with each group of cadets.

As a concurrent activity, while cadets are waiting for their turn on the wind tunnel, they will improve their experimental wing or develop different shapes for testing.

Ensure the fan has a safety guard around the blade and turn fan off when not testing a wing. Ensure that the fan is not located where a cadet might touch it accidentally during the activity.

The cadets’ participation in the activity will serve as the confirmation of this TP.

The cadets’ participation in the activities will serve as the confirmation of this lesson.

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A wind tunnel provides an inexpensive opportunity to test an airfoil design and compare it to other designs, without being exposed to the dangers of a test flight.

If room permits, the wind tunnel can be preserved for future use instead of being discarded. If a glider is available from lesson C231.02 (Fly a Paper Colditz Glider) cadets can suspend that in the test chamber and perform control surface experiments with it.

C3-091 (ISBN 1-55652-477-3) Carson, M.K. (2003). The Wright Brothers for Kids: How They Invented the Airplane. Chicago, IL: Chicago Review Press.

C3-093 NASA. (1996). NASA’s Observatorium Teacher’s Guide. Retrieved 12 February 2007, from http://observe.arc.nasa.gov/nasa/aero/tunnel/tunnel_parts.html.

C3-116 A-CR-CCP-263/PT-001/(ISBN 0-9680390-5-7) MacDonald, A. F. & Peppler, I. L. (2000). From the Ground Up: Millennium Edition. Ottawa, ON: Aviation Publishers Co. Limited.