water bottle rockets

[cannon monkey]

i going to make somthing to spend fun time with my little brother a few years ago a teacher made one and the students had to make their own rockets from soda bottle u fill 2/3 with water then pressurize it with air and it goes like 100 feet in the air
is there any thing i should know b4 i go off trying to make one of these?

[VH_man]

Nothing i can think of.

To release your bottle rocket, i reccomend using a Quick Disconnect fitting from a garden hose. Works like a charm.

[Insomniac]

Samelessly promoting my own threads, take a look here and here.

Launchers and rockets like this are really easy to make and work pretty well. The only difference I suggest you take to how I used to do it, is to make the nozzle like this. It's a bit more fiddly and harder to get it to seal, but it pays off. It is lighter, and there is no glue to crack from screwing it on too tight (I've done that a couple of times) The only other downside is due to the shorter nozzle length it can be harder to get it to latch onto the launcher properly.

[Lentamentalisk]

I read that replacing 1/3 of the water with soap greatly increases the performance, as you are effectively ejecting a very heavy expanding gas, rather than the incompressible liquid. The trick is figuring out how large of a nozzle to make, so as to have minimum drag, and maximum thrust.

[cannon monkey]

ok thanks my little brothers going to have a GREAT time

[nibbler125]

I used to have a pneumatic with a half inch pvc barrel so I filled the bottle 2/3 with water and stuck it on the end of my cannon and shot it like an RPG. but if you make it a handheld be prepared to get wet

[starman]

These will get a few wows at first for ones who haven't seen it but will get boring after not very long.

[cannon monkey]

ya well he is 7