Réalisation - Pet-Star water rocket car
Etape 1
Wrap two pieces of galvenized fixing band around the bottle. Use the longest at the front (bottom of the bottle).
Tighten the loops around the bottle with bolts and nuts.
Etape 2
Adjust the axes (metal rods) as shown on the picture. Screw axes on the metal bands as shown
The inclination of the bottle gives the rocket car its stability. To obtain the best result, you can experiment with different angles. To keep the rocket car on the ground, you can a fix a weight under the bottle.
Etape 3
Drill a hole in the centre of the jar lid, a little larger than the threaded rod.
To achieve a smooth movement, it is important to be precise . Attach the wheels on the threaded rods with cap nuts. Use washers so that the nuts are not directly in contact with the wheel. The wheels should be able to turn freely on the axis but not too loose.
If the rods are too long, you can shorten them up with a hacksaw.
Etape 4
The building quality of the valve system is very important.
Heat the largest plastic tube with a hot air blower to be able to pass the small plastic tube inside.
The thinnest tube will come off as soon as the pressure is too high, and the car will be launched.
Etape 5
Cut a piece of about 5 cm in length from a hollow threaded rod.
Drill a hole in the cap of the PET bottle.
The hollow threaded rod must just fit the size of the hole. Pass it through the bottle cap.
Pass on both sides of th rod rubber gakets and tighten with nuts.
Fix the larger laboratory (8 mm) tube over the threaded rod with a metal hose clamp. The hose should extend approximately 10 cm.
Do not attach the cap on the bottle with glue. The cap works as a pressure relief valve. Attach the bicycle valve to the smallest tube. Tighten with a metal hose clamp.
Use only PET bottles for soft drinks, because they are the only ones capable of withstanding the pressure.
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