Build an Overhead Water Rocket Launcher Part 3 valve pipe

does the lower 18" piece has a function ?
otherwise i'll don't attach it ..

RE the 18" of pipe--good question. When you mount a bottle half full of water on the launcher a bit of water trickles into the pipe. If the air pump hooked in right at the bottom of the launcher, the water will collect there and could back up into the pump--making it very hard to pump. Tire valves have a check valve (one way valve) but they often leak a little. Including that empty 18" of pipe bellow the valve lets the water pool there harmlessly.
Slater

Thanks =)

hey im going to do this for extra credit in science and i was wondering what type of valve should i use

Go to an auto parts store and get some cheap, common, pull-through stems. Long or short stem does not matter, but if there are two widths get the thinner.
Slater

In order to ease the re-opening and prevent the drying up of threaded containers of glues, paints etc., I coat the external threads with Vasiline. It works, even on superglue.

That is a brilliant tip! Thanks.
Slater

Excellent!