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Amateur Rocket Launch Assist (ARLA)

Newsletters and Random Thoughts

This page will include progress reports, notes, random brain farts, and other ramblings.


May 13, 2002

Butterfly Valves

I looked at a number of ways to build a valve for the six inch PVC ducting. While not a perfect solution, I settled on a butterfly valve. The prices for fast acting six inch valves start in the hundreds of dollars. So, I decided to build one. My first attempt at a butterfly valve with fiberglass laminated on plywood looked interesting but when I remembered the 1,200 lbf I decided that it wouldn't hold up. My second attempt was also plywood with fiberglass but considerably more stout. The downside was that I couldn't figure how to get a good seal. My third attempt is a sandwich with a steel tubular core, aluminum plates on either side, and a foam sandwiched in between. This one should be strong enough and the foam seems to seal well. Now I need to do an ops check with appropriate pressure. If this doesn't work I have a couple of ideas for improving and strengthening it.

Air Tank

I got nervous about using 55 gal drums for air pressure and so started looking around for options. Since I live well out of town there are many water-well pressure tanks around. These typically have a 70 psi working pressure, are not too heavy, and should be plentiful. Unfortunately, I could not find a used one. I thought I had spotted a big one laying next to a guy's fence so I stopped and talked to him. Turns out it was a 500 gal propane tank, good for 250 psi. I paid him $200. It's old but I'm guessing it only weighs about 750 lbm, a piece of cake for my front loader. I just won't be able to remove it from the trailer at the site. Now I need to cut a hole and weld in an adaptor to hook to the PVC. This should be interesting.


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This Page created May 13, 2002

Last Updated May 13, 2002