Rubber Band Powered Airplane
Introduction
Energy is present in various forms all around us and is thus one
of the most important topics in science and engineering. In secondary schools, students learn the
basics of energy and energy transfer by studying potential and kinetic energy
of several systems. These concepts can
be taught through the use of rubber bands, as the energy stored in a
rubber-band is a form of elastic potential energy. Therefore, a rubber band powered airplane can
be a very interesting toy for demonstrating the fundamentals of energy and
energy transfer. The following are some
topics that can be taught about rubber-band powered airplanes.
The History
When the Wright Brothers were small children their father
gave them a rubber powered aircraft which resembled a helicopter. They played with it until it broke and then
they built several of their own. They
later claimed that their experience with the toy fuelled their interest in
flying, resulting in the invention of manmade flight.
In 1871, French scientist Alphonse Penaud, the same man that
built the toy the Wright Brothers played with, amazed people by flying a
rubber-powered aircraft called the planophore for 131 feet in 11 seconds. It was the first public demonstration of a
legitimately stable heavier-than-aircraft, making it one of the most important
inventions leading up to the invention of the airplane.
For the following 50 years, rubber-powered airplanes were an
important research tool for aerodynamic engineers, as it allowed them to test
numerous configurations of wings, rudders, elevators, and fuselages for
airworthiness without building full-size aircrafts.
Rubber-band powered aircraft, or then called torsion-powered
aircraft, became a popular toy in the late 1800’s and has remained popular ever
since, with people still building them today all over the world and entering them
in competitions.
How a Rubber-Band
Powered Airplane Works
An airplane moves forward when the plane’s engines push fast
moving air out behind the plane by propeller or jet. The propeller provides the thrust to move the
plane horizontally. In the rubber-band
powered airplane, potential energy is stored in the twisted rubber band which
powers the propeller. The propeller
provides the thrust, which pushes the airplane forward according to Newton’s
Third Law. The plane is able to move
through the air and fly by lift generated by the shape of the wings. During take-off and landing the speeds of the
aircraft are slower which in turn gives a smaller value for the lift, thus the
lift force acting on the airplane is at its weakest here. Extra lift can be achieved at slower speeds
by changing the shape of the wing using ailerons and flaps which increase the
surface area of the wing.
Energy and Energy
Transfer
Some concepts that could be taught or reviewed are potential
energy (U) and kinetic energy (K), as the potential energy that is stored in
the twisted rubber band is converted to kinetic energy which powers the
propeller. Next, work should be reviewed
as it is the amount of energy transferred by a force acting through a distance.
As well, the concept of power should be taught, as it is the
time rate of energy transfer. From
there, the idea of steady-state should be discussed and the notion of transport
cost could be introduced. Finally, we
could compare the transport cost of the model airplane with a real size
jetliner.
Some useful equations:
Gravitational potential
energy
Kinetic Energy
Power
Work
Transport Cost
Rough Lesson Plan (55-75min)
1. Introduce the topic and give a power point presentation to
the class (20-25min)
• Review the four forces acting
on an airplane- lift, gravity, thrust and drag.
• Review potential, kinetic
energy and work.
• Review Newton’s Second and Third
Laws of motion.
• Introduce power, steady-state
and transport cost.
2. Calculations (10 min)
3. Students will build their models (30min)
4. Testing the airplanes (10min)
Materials Needed
Model
airplane kit
Scissors
White
glue or fast drying wood glue and glue stick
Alphonse Pénaud. (2009). In
Encyclopædia Britannica. Retrieved October 20, 2009, from Encyclopædia
Britannica Online: http://www.britannica.com/EBchecked/topic/1312623/Alphonse-PenaudSerway,
R.
Serway, R. A., & Jewett, J. W. (2004). Energy and
Energy Transfer. In R. A. Serway, & J. W. Jewett, Physics for
Scientists and Engineers with Modern Physics 6th edition (pp. 181-205).
Belmont: Thomson Learning.
Serway, R. A., & Jewett, J. W. (2004). Potential
Energy. In R. A. Serway, & J. W. Jewett, Physics for Scientists and
Engineers with Modern Physics (pp. 217-236). Belmont: Thomson Learning.
White, D. (2009). Model airplane powered by elastic
rubber band. Retrieved September 27, 2009, from Model airplane powered by
elastic rubber band: http://www.rubber-power.com/
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