Rubberband Airplanes: Physics for Takeoff, Flight & Range

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In summary, the conversation discusses the need for knowledge of physics related to rubberband-powered airplanes for a project. The focus is on creating two free-body diagrams, one for the plane accelerating on the ground and another for the plane flying, and writing equations to show the relationships between forces, acceleration, velocity, and distance traveled. The conversation also mentions equations for endurance and range, as well as tips for finding the takeoff distance and speed and the maximum height and gliding angle of the plane. The speaker also suggests using aerospace engineering texts or doing a Google search for more equations and information.
  • #1
vvoo7vv
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I'm working on a project relating to rubberband power airplanes. I need to know the physics related to it. For my project I need to. Sketch two free-body diagrams: one for the plane accelerating on the ground and another one for the plane flying. Show all the forces in each case and write simple equations to show the relations between these forces. Include equations which show the relation between these forces and the acceleration, velocity, and distance your airplane travels on the ground before becoming airborne. Show also equations for the endurance and the range.
- takeoff distance
- takeoff speed
- maximum height attained in flight
- gliding angle from the maximum height to the touch-down point
- time aloft (endurance)
- range (distance traveled)

If you can help me, I would appreciate it. Thanks a lot.
 
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  • #2
FBD Guide

Perhaps there should be a guide for posting problems to the help section.

Specifically regarding FBD's, if you don't know where to start, try listing all of the forces that are acting on the airplane.
 
  • #3
Well, essentially an aircraft is subject to the following four forces:

1. Thrust
2. Drag
3. Lift
4. Weight (gravity)

During take off, the thrust of the engine causes the aircraft to move forward (thanks to its wheels it really does move). The drag at this point is offset by this large thrust. At the optimum speed (at which the thrust is optimum) the elevators assist in directing a portion of this thrust at an angle with respect to the horizontal, to balance the gravitational force. The aircraft takes off just when the thrust is greater than the weight.

When in air, all the four forces listed above are still acting, though differently depending on the motion of the airplane. With these facts in mind, you should be able to make a FBD for the aircraft. The force equations can be easily written by applying Newton's Second Law (F = ma) once you have convinced yourself about the FBD. Depending on your needs, you might want to consider more complex situations involving center of gravity and center of pressure.

The takeoff distance is the minimum distance required to develop enough lift (or acceleration if you use F = ma, assuming negligible mass change) to counter the weight. You can use kinematics to find this out. The takeoff speed is similarly computed.
Maximum height attained in flight really depends on the net vertical force and parameters such as fuel left, mass, etc.
For other equations you might want to check out some aerospace engineering texts...or do a google search.

Cheers
Vivek
 

1. How do rubberband airplanes work?

Rubberband airplanes work by converting potential energy from the stretched rubber band into kinetic energy to propel the plane forward. When the rubber band is released, it quickly contracts and transfers its energy to the propeller or wings, causing them to move and generate lift.

2. What factors affect the flight and range of a rubberband airplane?

The flight and range of a rubberband airplane can be affected by various factors including the design of the airplane, the tension and length of the rubber band, the weight of the airplane, and external factors such as wind and air resistance.

3. How can I increase the flight time of my rubberband airplane?

To increase the flight time of a rubberband airplane, you can try using a longer and thinner rubber band, reducing the weight of the airplane, and adjusting the angle of the wings for optimal lift. You can also experiment with different designs and materials to find the most efficient option.

4. Is there a limit to how far a rubberband airplane can fly?

There is no specific limit to how far a rubberband airplane can fly, as it depends on various factors such as the design and materials used, the strength of the rubber band, and external conditions. With the right combination of these factors, a rubberband airplane can potentially fly long distances.

5. Can I use physics principles to improve the performance of my rubberband airplane?

Yes, understanding the principles of physics such as potential and kinetic energy, lift and drag, and center of gravity can help you design and adjust your rubberband airplane for optimal performance. By applying these principles, you can improve the flight and range of your airplane and even perform experiments to further enhance its performance.

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