Student Data Sheet: Energy for Flight
Powering Up the AMA ALPHA with Potential Energy! ______________________________________________________________________________
Background: When you wind the rubber motor of a model plane, you are storing potential energy. This energy is transformed into kinetic energy when you launch the plane. In general, planes with more turns on the rubber motor will generate more thrust, will accelerate faster, fly higher and fly longer than models with less turns on the motor.
Directions: You will study how increasing the turns in a rubber motor will affect how high a plane will fly and its time aloft. Work with your partner or group and choose one plane to study. Adjust your wing position to establish the correct
center of gravity (CG) for good flights. Mark the wing position with a pen. Make flights with three different numbers of turns wound into the motor. Record the flight times with a stopwatch. Estimate the maximum height of the airplane. You can estimate the number of feet altitude or you can estimate height as a percent of height to the ceiling if you are flying indoors. Show which method you used; record feet like this: 18′ and record % like this: 45%. Also catch the plane right as it lands and unwind the motor, counting the turns remaining on the motor.
1. Finish this hypothesis: If turns increase, then…
2. List three things to keep the same every time you fly the plane for these tests.
a.
b.
c.
2. Use a winder to put 600 turns into your motor. Record the time of flight, estimate the maximum height reached by the Alpha and note the number of turns remaining on the motor. Record your observations here. Time Height Turns remaining
3. Use a winder to put 800 turns into your motor. Record the time of flight, estimate the maximum height reached by the Alpha and note the number of turns remaining on the motor. Record your observations here. Time Height Turns remaining
4. Use a winder to put 1000 turns into your motor. Record the time of flight, estimate the maximum height reached by the Alpha and note the number of turns remaining on the motor. Record your observations here. Time Height Turns remaining
5. Plot your data on graphs.
6. How did changing the number of turns on the rubber motor affect time aloft?
7. How did changing the number of turns on the rubber motor affect maximum height?
8. How did changing the number of turns on the rubber motor affect turns remaining on landing?
9. Is it possible to put too many turns into the motor? Explain.
10. Look at the example Flight Trajectory graph.
This shows the height of a rubber powered airplane at different times during its flight. This plane’s motor was wound just short of the breaking point and ran out of turns just when it landed. Your airplane was not fully wound. What does this graph suggest about the flight of your airplane with an incompletely wound motor? (Hint: The airplane on the graph had no turns when it landed. Each test airplane had some turns when it landed. Work back from there. Each airplane reached a highest altitude. Include that point. Remember that your airplane still had turns on the motor when it landed. It would have still been flying if it had not hit the floor. Your airplane used up some turns before it came down from its highest altitude and hit the floor before it ran out of turns. It used turns on either side of the apogee. Think of each horizontal line on the graph as a floor.)
Read Energy of Flight for a better understanding of the relationship between the motor torque curve and the flight trajectory.