Much awesomeness.

[video]https://www.youtube.com/watch?v=Q1eQw4ycgQM[/video]

*mashes “like” button on new forum*

wow !

As a kid I always wanted to build stuff like this, but realised that I had as much chance as a slow worm with a hammer of achieving it with my spannering skillz

Ben (the little fella) and I are intending to build a “coke bottle” water rocket with a Pi launcher control system soon though 🙂

Not as cool as the trike, but here is a slow mo video of a water rocket I made for a children’s holiday in camp in the summer.

It’s constructed from 3 lemonade bottles. I made a zip tie launcher which is attached to an old tripod.

that’s very cool Simon.

Any chance you could send some details of the launcher ?

this maplin kit works well
https://www.maplin.co.uk/p/4m-science-green-rocket-a49xj

just a bottle/air launch system, but when I stamp on the bottle I can get the rocket to go a good 100′ in the air.

Sure, i will take a picture of it later. I used a pressure of about 90 psi and about 2l of water. The zip tie launcher is a safe way of preventing a premature firing. I didn’t follow these instructions, but you get the idea.

rocket launcher

The ziptie method works surprisingly well.
Think the biggest we made was 8x 2 litre bottles, but I suggest to keep it simple and use single 1.5 or 2.0 litre bottles.
90psi is a fair amount. 30-40psi can be fine for a single bottle.
Things start going awry when you go much over 100psi. Major bottle warpage at 180psi, and things like car valves blowing of the fill tube. PS it makes your ears ring for ages when a coke bottle explodes.
Roughly 30% filled with water is about the sweetspot.
Prepare to get soaked 🙂 😈

We may or may not have found that the standard Euro PET bottle size is an exact fit for a CO2 canister used to pressurise beer kegs. Do not try that at home.

All rockets are good. Especially ones attached to modes of transport.

Coooooool.

Not as cool as the trike, but here is a slow mo video of a water rocket I made for a children’s holiday in camp in the summer.

Lot of cows in the background…. hope they didn’t put you off 😉

8 bottles, that’s a big rocket! The children on our camp love the water rocket activity. It’s great fun. We use estate agent sign boards to make the fins. Waterproof,light and will tolerate the abuse of crash landing.

yeah, but trying to make it not flop like a flying banana was a pain. think we used 2 dismantled brooms and a couple of chairs to make a kind launch ramp, and it still practically folded in half.
gaffer tape and estate agent board for fins is perfect. card, gaffer tape and some modelling clay for nosecones (optional, but makes them fly much better).
used to have competitions to see who could get them to go the furthest.

we also used them to launch huge delta wing RC gliders that were not feasible to hand launch.

I use a tennis ball for some nose weight held in place with gaffer. The 3 bottle rocket used lemonade bottle sleeves (top and tail bottle) to provide support between bottles which worked reasonably well. I wanted to strap small coke bottles on like boosters, but I couldn’t manage to get an air tight seal.

Thanks for the info Simon – I think we’ll have a go at something like that

With the multiple bottle rockets, are you somehow joining the bottles together to create a single pressure vessel?

yup, drill the base of a bottle, and screw the next bottle in with lots and lots of araldite and any other adhesive/sealant you can lay your hands on.

i wouldn’t do more than a 3 bottle though – 1/3rd of the total volume of water is “about right”.

Brilliant, it’s reminded me that the oab household need to do some more rockets again.

I joined the bottles together with suction tubing. As the tubing is tapered, it a good seal pulling it through a tight hole. Plus a good helping of sealant.

Cool thanks – will have to try a multi bottle one then.

Once they get the range issue sorted out that’s a competitor for electric cars.