I made a list and set out to gather the required pieces and parts. Turns out, the "big box" stores don't carry some of the things I needed... in fact, NONE of the things I needed. So I went to a independent hardware store we have here called Elliott's Hardware and found all of the things I needed for $10.
It really only took a very small amount of time to build the thing and we were ready for launch. I was pretty surprised at how well it actually worked. Here's some pictures:
It launched pretty high. It went OVER the house. I am guessing between 50 and 75 feet.
Then we decided if we could do that with two-liter bottle, how about a five gallon water bottle? I was a little concerned that it would be a little bigger than we really wanted but I couldn't resist. I rigged a cap that really wasn't fully sealed so I was guessing it wouldn't even work. I also didn't use much water to sort of keep the power down a little. We were here in the neighborhood and I didn't want to rocket that thing through anyone's window or car. I really didn't know what it would do. I also decided I would do the pumping just in case it went wonky and came at the person standing closest.
I got it all rigged up and started pumping. It wasn't holding pressure very well. I could see it leaking water and spewing air out as the pressure was trying to build. I was telling the boys with me that I didn't think it was going to hold enough pressure to launch it... when, of course, it launched. It actually didn't go as high as the two-liter for a few reasons. 1. it's a lot heavier of a bottle and 2. the lid wasn't holding much pressure before it popped and 3. there wasn't enough water to really send it up. It was pretty cool that it worked and I think we can make it really work to where this thing, in the right environment, could be a really big launch.
Maybe we'll see.