Hi! 🙂
In the past, I’ve made water bottle rockets, rubber band cup rockets, blowpipe-parachute-rockets, baking soda lid launchers and combustion cans, but here’s another fun and inexpensive rocket project!
Hardware-store-pipe-bottle-stomp-rockets! 🙂
There are several great stomp rocket projects, but here in Germany, hardware-store parts (and tube diameters) differ. So I came up with my own solution. It’s also rather cheap (as the students should be able to take their build home).
Here are links to English sources:
– This was the main inspiration, but I did not get the exact parts and reduced my cost; https://www.exploratorium.edu/snacks/bottle-blast-off
– Another one: https://www.jpl.nasa.gov/edu/teach/activity/stomp-rockets/
I used:
– Pipe: M20 wire installation pipe 20cm: 8 Eurocents (Works with 15cm as well)
– Angle: Flexible pipe 50cm: 9.5 Eurocents (Works fine with 40cm as well) – or 90 deg angle piece
– Connection: Coupler… or a lot of tape 🙂
– Bottle: PET. Small rigid bottle worked better than the big thin flimsy bottle.
– Stick: Shashlik-Skewers are a bit weak but only cost a fragment of a cent. Cotton candy sticks 3.5 Eurocents work well but do break. Coat-hanger wire is another idea. Attach with tape or zip-ties!
With the angle-piece and connectors it looks better, but doesn’t necessarily fly better.
– Rockets: Paper, perhaps plastic as the edges will wear out quickly. Reinforce with tape, keep scissors ready.
Make sure to sand off the edges of the cut pipe pieces! Ideally use thicker paper.
Tightly wrap a fourth of a A4 page around a piece of M20 pipe. Thicker, glossy paper doesn’t wear as fast. Tape the roll. Fold the top over and tape it shut. Ad fins and such if you’d like. Note: Perhaps use thin plastic instead in the future.
And that’s about it. Stick it into the ground, and stomp! Make sure to blow air into the bottle before the next launch (wrap your hand around it to avoid contact with other kid’s drool 🙂 )
Edit: Duckt-Tape to fix things and patch ruptured bottles. Paper, tape and spare bottles are useful, too. 🙂
Perhaps I’ll glue the flexible tube to bottle-caps for a quick and easy swap.
Ideas for the future: Wrap rockets slightly conical in order to more easily get them onto the tube?
(Not easy to see on this image, but the right one is a symetrical tube. As the end is flattened it looks broader. The left ones look symetrical, as the flattened end and their smaller end-diamter kind of even out visually. The bottom lefto ne works best, as it’s conical nature is more subtle. It still fits snug on the tube, but the larger opening is easier to slide over the tube).
Update 2:
(30.05.2018)
In order to be able to swap the bottles more easily, and to avoid using expensive adapters, it’s best to cut a hole into a bottle cap and attach the hose:
