- 2 hours
Parental supervision required
Try out these kits, they're cracking!
Build a car driven by air currents, just like the one Jem drives in the TV show.
When a round object like a ball or tube spins fast, a small layer of air clings to the moving surface. If the object is moving, or if it is windy, this means the air on one side is moving faster than the air on the other. The difference in speed leads to unequal pressures, which pushes the object sideways.
The Magnus effect is responsible for footballs curving when kicked with spin. It gives golf balls longer flights when they’re struck right (and hook/slice when hit badly). It can give paintballs longer range, and it can make this model car drive along the ground powered by a side-wind.Instructions below
If the motor stops (or stalls) it could short-circuit the battery. Make sure you turn off the power or the wires will get hot hot hot!Download and extra parts to make your kit look great! PrintOff these instructions and get making!
Cut out all the printed parts. Glue the main chassis template over the bottom half of the pet food box as shown.
2 Cut along the lines on the printed guide to create the chassis.
3 Find two straight skewers and poke them through the chassis where indicated. Wiggle the skewers in the holes until they can rotate freely.
4 Neatly cut the bottoms from the bottles.
5 Drill holes as close to the centre of the bottle caps and the bottle bottoms as you can. Pick a drill size that will create a tight fit to the skewer axles.
6 Poke a skewer, pointy-end first, through the centre of one of the wheels. Push it all the way through as shown.
7 Thread the wheel and axle through the chassis holes and attach the other wheel. Build up the second axle in the same way. Once complete, test that the wheels turn freely and the chassis rolls easily when pushed.
Most motors have an adaptor on the shaft. You need to take this off, but save it for later.
9 Glue the printed guide to a piece of cardboard from the pet-food box. Cut to shape and fold along dotted lines.
10 Make a hole for the motor with a skewer where indicated. Check the motor fits neatly.
11 Cut another hole for the switch. Draw around your switch to find the size, and place it where indicated on the guide.
12 Hot-glue the switch and motor into place.
13 Work out what batteries your motor needs. Most are either 3 Volts or 12 Volts. Unsure? Try connecting 3V first (two AA batteries). If it doesn't turn or turns weakly, try connecting a 9V PP3 battery instead (the square type).
14 Build the electrical circuit. Solder is ideal for connections, but it’s hot, so take care!
15 Test your circuit works.
16 Place the motor assembly in place in the chassis. Don't glue it in as you may need to take it out to adjust it. Use sticky tape or blu-tac to hold it in place. Fix the battery in place in a similar way.
Hot-glue the stiff cardboard tube into the chassis as shown.
18 Glue the remaining pattern to a piece of card. Cut to shape, fold and hot-glue into place.
19 Take the adaptor that came off your motor and put it back on the shaft. This will act as a spacer to hold the drum up.
20 Draw round your cardboard tube on another piece of card. Cut it out and stick it into place as shown. Pierce the end.
21 Create another wheel hub from a plastic bottle bottom, like you did for the wheels. Tape this to the other end of the drum to close it.
22 Glue the card end of the drum to the motor shaft. Pierce a skewer through the top support and fix it into the top of the drum. Trim to size.
23 The Magnus Effect requires a bumpy surface to create the boundary-layer effect. Stick a sheet of patterned kitchen roll to the drum.
Put the car on a smooth level surface and turn it on. If the drum vibrates a lot, adjust it until it runs fast and smooth.
Set up the desk fan or hairdryer to the side of the car. Turn it on.
Turn on the car's Magnus drum. Wait a second or two for it to spin up, and the car should race off by itself!
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