Students will explore the action of an airplane propeller.
Large plastic lid top (margarine or powdered drink)
Large spike or nail
2 small nails
Cord or heavy string
1. For construction of the propeller use a plastic top from margarine or a powdered drink mix that's about 6" in diameter.
2. Find the center of the disc and draw diameter lines dividing it into 2 parts. Draw lines on the disk to make a propeller shape. To get the proper shape, copy the sketches made while at the Franklin Institute.
3. Cut out propeller with scissors.
4. To make a rotary: (a) pound a nail part way into a wooden rod. This wooden rod is the handle; (b) place the spool on the nail so that it can spin freely.
5. Remove the heads from the 2 small nails and set them into the top of the spool. Make sure they are directly opposite each other.
6. Punch 2 small holes in the center of the propeller so that it will fit loosely over the 2 nails and rest on top of the spool.
7. Give each blade of the propeller a twist in the same direction, similar to the vanes of a windmill. Make them of equal pitch.
8. Wind a few feet of strong cord around the spool. Be sure the cord is wound evenly to avoid tangles. This makes a smoother, more successful flight.
9. Hold wooden rod vertically and pull out briskly on cord.
10. The propeller should spin rapidly and rise into the air.
11. The pitch or bend in the tin makes the propeller exert change of pressure in the air as it spins. This air pressure causes the propeller to rise.
These two activities are used by permission from Science is Elementary, by Museum Institute for Teaching Science. They appeared in their May 1988 (Vol. 2, No. 6) issue. For more information on MITS, write them c/o New England Aquarium, Central Wharf, Boston, MA 02110; tel. 617-973-6587.