Research: A hovercraft is a vehicle that glides over a smooth surface by hovering upon an air cushion. Because of this, a hovercraft is also called an Air-Cushion Vehicle, or ACV. How is the air cushion made? The hovercraft creates vents or currents of slow-moving, low-pressure air that are pushed downward against the surface below the hovercraft. Modern ACVs often have propellers on top that create the air currents. These currents are pushed beneath the vehicle with the use of fans. Surrounding the base of the ACV is a flexible skirt, also called the curtain, which traps the air currents, keeping them underneath the hovercraft. These trapped air currents can create an air cushion on any smooth surface, land or water! Since a hovercraft can travel upon the surface of water, it is also called an amphibious vehicle. How does the air cushion beneath the hovercraft allow the vehicle to glide to freely? The key to the ease of movement is reducing friction. A simple way to think of friction is to think about how things rub together. It is easier to rollerblade on a smooth sidewalk than a gravel path because the sidewalk has less friction. The wheels of the rollerblade do not rub as much against the sidewalk as they do all the pieces of gravel on the path. Similarly, the air cushion beneath the hovercraft greatly reduces the friction of the vehicle, allowing it to glide freely upon the land or water below.
In this aerodynamics and hydrodynamics science project, you will build your own mini hovercraft using a CD or DVD, pop-top lid from a plastic drinking bottle, and a balloon. The balloon will create the air currents the hovercraft needs to work. These air currents will travel through the pop-top lid and go beneath the hovercraft. You will fill the balloon up with different amounts of air to test if more air will cause the hovercraft to travel for longer periods of time. A balloon blown up with a lot of air will provide a large volume of air, and a balloon blown up with less air will provide a smaller volume of air. Will a balloon with a large volume of air make the hovercraft travel longer than a balloon with a smaller volume of air?
Hypothesis: The greater the friction, the faster the hovercraft.
Apparatus: coldrink top lid from a plastic drinking bottle, An old CD or DVD that you do not mind destroying
Craft glue or wood glue
Medium-size balloons (should be able to inflate up to at least 11 inches
Optional: Balloon pump
Large flat surface for testing the hovercraft
Method: First construct the base of the hovercraft, so gather supplies and prepare a craft space.
Remove a pop-top lid from a plastic drinking bottle
Glue the base of the lid or valve to the CD (or DVD) so that the lid covers the hole in the center of the CD.
If glue or epoxy dries on the bottom of the CD, this may make your hovercraft not work because it could have increased friction.
Allow the glue to dry completely.
Get ready to test the hovercraft with your balloon inflated to different sizes.
Make sure the pop-top lid or valve is closed.
Blow the balloon up as large as you safely can without popping it, then pinch the balloon’s neck so that no air can escape.
Stretch the neck of the balloon over the pop-top lid or valve, being careful not to let any air escape.
Carefully center the balloon’s opening above the pop-top lid opening.
0bservation: when I pushed the balloon it did not take a few seconds to land on the ground and when I picked it up from the ground there was friction.
trial Large balloon Medium balloon Small balloon
#1 3,80s 1,63s 2,87s
#2 2,89s 0,80s 2,74s
#3 2,43s 3,96s 1,09s
#4 1,98s 2,22s 1,27
#5 3,43 1,03s O,98s
Interpretation of results:
Application: my findings can benefit the environment if we know the amount of friction a hovercraft uses.
‘ Different cultures might view this as useful and can make their own hovercrafts if they know how it works
‘ It is not applicable to geographic limitations and is not made out of a lot of raw materials
‘ It is a pollution problem because the materials that it is made out of are not raw materials
Conclusion: the more the friction the longer it will take to move across the water.
Bibliography: Xinventions. (n.d.). How does a hovercraft work? Retrieved August 23, 2012, from http://www.xinventions.com/main/hovercrafts/work.htm