Come Fly With Me

Karlene Kurth                  Walther Lutheran High School
                               900 Chicago Ave.
                               Melrose Park, IL 60160
                               708-344-0404

Objective:

For intermediate grades through high school

1.  Students will state Bernoulli's principle which is "the pressure in a moving 
stream of fluid is less than the surrounding fluid." 
    
2.  Students will observe examples of Bernoulli's principle. 
    
3.  Students will apply what they have learned about guiding airplanes by 
designing and constructing a model glider whose direction of flight can be 
controlled. 

Materials needed:

For Demonstration:  notebook paper, shoebox, text book, medium sized ball, 
straws, water, beaker, vacuum cleaner with exhaust valve, ping-pong ball 

For Activity:  shoebox, styrofoam, thread, rubber bands, unsharpened pencils, 
straws, fan 

Strategy:

Through opening demonstrations students should be able to formulate a 
relationship between moving air streams and the effect they have on objects in 
the path of the stream.  The following demonstrations will be utilized:
   1.  Place two textbooks with a sheet of notebook paper on top on the table 
       top.  Ask a student volunteer to attempt to blow the sheet of paper off 
       the books by blowing under the paper.  (The paper should be forced down.)
   2.  All students hold their textbooks vertically and place a sheet of 
       notebook paper in the book so that the paper hangs over the edge away 
       from them.  Students attempt to force the paper down by blowing across 
       the top of the paper.  (The paper should be pushed up.)
   3.  A student volunteer blows through a funnel which has a ping-pong ball in 
       it.  He/she attempts to blow the ping-pong ball out of the funnel.  
       Attempt to blow when the funnel is right side up and also when it is 
       inverted.  (The ball should stay in the funnel regardless of the 
       direction the funnel is held.) 
   4.  Place medium sized ball on the nozzle of the vacuum cleaner exhaust.  
       Turn the vacuum cleaner on.  (The ball should levitate at some height 
       above the vacuum cleaner in the air stream.)  
   5.  Blow through a half straw across the top of another half straw that is 
       placed in a beaker of water.  (A spray of water should come out of the 
       straw.)
 
   After these demonstrations the instructor will lead a discussion of the 
events observed.  Stress where the high pressure regions and where the low 
pressure regions are.  Diagram this on the board, label the highs and lows.  It 
should be apparent that the low pressure areas are where there is a moving 
stream of air.  State Bernoulli's principle.  Relate the principle to air 
flight.  
   Introduce the activity of controlling direction of flight.  Define terms 
ailerons, elevators, rudders.  (Ailerons are flaps that can be raised or lowered 
on the wings, elevators are flaps on the tail, and rudders are on the tail.) 

1. Wings and tails are made of styrofoam meat packages.  Wings have dimensions 
   of 20 cm x 5 cm.  Ailerons should be rectangles on the back edge of the wing 
   and evenly spaced from the center of the wing.  Sides of the ailerons should 
   be cut and the front edge should be folded.  Tails are 15 cm x 4 cm with 
   elevators made the same way as ailerons but they will tend to be a bit 
   smaller.  About 3 cm from each end of the tail fold the tail up and place a 2 
   cm slit though the folded part to form rudders.  These should be folded to 
   the left and right. 

2. Attach the wing and tail to the pencil with rubber bands.

3. Adjust the wing and tail so that the plane balances when holding by a thread 
   attached to the front and rear of pencil.

4. Hold plane in front of wind tunnel.  The wind tunnel is made of a shoebox 
   that has sections inside made of poster board and the back cut out.  Inside 
   the sections are rows of half straws.  This provides a steady even stream of 
   air flow when placed in front of a low speed fan. 

5. Test each control by bending the ailerons, elevators, and rudders in all 
    combinations.

Conclude activity with a group discussion of concepts.  Results of the tests 
should show that ailerons cause one wing to dip to the right or left, elevators 
cause the plane to nosedive or rise up, and rudders control left or right turns. 
Relate these movements to air flow and high and low pressure.