If you want to build a two-stage water rocket, Air Command Rockets has detailed build series over on YouTube[1], from simple soda bottle setups to a custom rocket that they got[2] to over 1600m (5000 ft).

That's air and water propelling a rocket a mile up!

[1]: https://www.youtube.com/@AirCommandRockets

[2]: https://www.youtube.com/watch?v=GCaiK3Zqs4M

It is great that people are going out doing stuff, having fun and learning. But this project seems like a disaster in the making.

-Making your own fuel.

-Using inappropriate materials (e.g. PVC)

-Poor storage of motors.

-People are standing quite close to the rocket when it launches.

-There seem to be buildings quite close to the launch in one of the videos.

-Night launches. How are you going to get out of the way, if you can't see the rocket?

2 stage rockets are particularly dangerous, because as the second stage can launch horizontally or downward if the first stage tilts (as shown in one of the videos).

I think they are being irresponsible with the safety of themselves and anyone nearby. I would strongly recommend they learn a bit of safe practices and make a single stage rocket that works reliably, before even attempting 2 stage.

> Turns out, PVC was never the move. It’s lightweight, yes, but also has the structural integrity of a soggy biscuit under pressure.

I believe that PVC is not considered safe for model rockets, as it turns into shrapnel if it ruptures. Happy to be corrected, if that isn't right.

When I was a kid I was into Estes model rockets and it always amazed me the preferred/documented way of glomming the multiple stages of engines together was a single strip of scotch tape.

From the blog post: "Pro tip: just take your time and design the O-ring system properly. Trust us — you don’t want to gamble with hot gases and bad seals."

I think NASA may have learnt that lesson in '86.