12-09-2012, 03:59 PM
Build a Hovercraft and float on air
hovercraft pdf 2.pdf (Size: 945.87 KB / Downloads: 90)
Experience frictionless motion!
Constructing a hovercraft adds exciting options
to your physics classroom and is lots of fun to
ride on too. It provides fun frictionless motion so
students can get a better grasp of the practical
implications of the laws of kinematics.
With the hovercraft you can vividly demonstrate
the First Law, accelerate different masses or
apply variable forces (Second Law) and easily
illustrate the Third Lawʼs action-reaction pairs.
We followed the classic design with a plastic
sheet attached around a 900 mm wooden
platform. The design allows for a mass of up to
100 kg to be supported.
How it works
A plastic sheet is attached below a circular wooden platform and securely stapled and taped
around the circumference of the platform. The center of the sheet is fastened with a wooden disk
to the platform. An air source such as a leaf blower is inserted through a hole at the top of the
platform. The air inflates the sheet and provides the air pressure needed to lift the rider, lifts the holes from the floor and forms an ʻair barrierʼ to the escaping air. The air trapped in the inner
ʻdonut-holeʼ slowly leaks between the ʻskirtʼ and floor and forms an “air cushion” that provides a
constant padding of air.
Materials required
• Wooden platform. Our diameter is 900 mm. We bought a piece of plywood 900 x 1200 mm from
a hardware store. Thickness: 12 to 17 mm. If you have access to a larger piece of wood, then
make a 1.2 m diameter hovercraft as it will produce a better lift.
• Plastic sheet. A thick plastic paint drop sheet, thick shower curtain or builders concrete underlay.
We used: 1.2 x 1.2 m Make sure it is 200 mm wider than the wooden disk.
• Leaf blower. Better to use a cordless rechargeable one. A vacuum / blower from a wood
workshop will work too.
• Small plastic disk and wooden disk of approx. 9 cm diameter. Check Craft shops for foam sheets
and thin wooden sheets.
• Bolt and nut to fix small wooden and plastic disks to the platform. Approx. 12 mm x 5 mm diam.
• Two washers to fit the bolt.
• Rubber tube connector to connect blower outlet to PVC pipe on platform. (It is best to start with
the blower nozzle diameter and work back from there to the platform. My blower simply fits tightly
into the rubber connector without any clamp). Check plumbing section at shop.
• PVC pipe to be glued into wooden platform. Approx. 65 mm long. It should fit into the rubber
connector. Check plumbing section at shop.
• Metal pipe clamp to secure rubber connector to PVC pipe.
• Electric jigsaw, hobby knife, drill & drill bit.
• Black duct tape
• Spray paint (optional)
• Staple gun & staples
• Foam rubber, pipe insulation. Our circumference was: C = pi x diam. = 3.14 x 0.9 m = 2.9 m
• Silicone sealant for PVC pipe inlet & pipe insulation
• Door handles (x2) (optional)
• Liquid level (optional)
Riding the Hovercraft
1. Place the hovercraft on a smooth, non-carpeted surface such as a vinyl, wooden or linoleum
floor. Gym floors work great!
2. Make a student sit in the center of the craft with folded legs (on the bolt).
3. Insert the air blower into the connector, make the rider hold onto the blower, then turn it on.
4. As the skirt inflates, the rider should center his/her weight to reduce friction.
5. Provide a brief push to the rider and observe the frictionless motion!
Safety
1. Close adult supervision is always required with this hovercraft.
2. Donʼt push it too fast. It can easily speed up in a large area such as a gym. Make sure the rider
knows how to stop it by turning the blower off or yanking it from the rubber connector.
3. Never get aboard while the air blower is running.
4. Do not turn the blower off when at speed. Newton I predicts that the passenger will continue in
a straight line while the craft stops dead.
5. Bystanders should stand off and watch their feet.
6. Remove all items at head height, such as tables, that may cause injuries to the rider.
7. Recommendation: A long rope can be attached to the craft to control the movement.