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Random goings on before August 4: We have been mainly working on perfecting a G class PVC motor, and are looking into several options for nozzle construction, see the Nozzles page. The water rocket folks have been finding the rupturing point of many different types of bottles, go to the Pressure Testing page to see the surprising development. (It may not be up yet) Nozzles I have been surfing the net for new and better nozzle materials to use in the construction of PVC motors. Here are the findings: Durham's Rock Hard Water Putty Availability: Should be able to find it in a hardware store near you. Expense: about $5 per pound. Ease of use: fairly simple to use, mix with water, and pour into casing. The setup time is a little slower than optimal, but still good. Strength: not bad, but still need retention pins to make it hold well. Erosion resistance: poor Other notes: this stuff dries fairly slow, so give it a good week before casting the propellant in. Orthodontic Stone (Dental Stone) Availability: search for "Dental Stone" on Yahoo, don't expect to find it locally. Expense: really cheap, comes only in bulk. Ease of use: preparation same as water putty, but it dries much faster, so mixing with water should be the last step. Strength: better than water putty, but still need pins. Erosion resistance: not tested yet, however rumor is that it is much better than water putty Other notes: dries a nice white. Graphite Availability: People say it's easy to find, but it took me half an hour to find a good supplier online. Expense: for a 1" diameter, 12" long piece it's about $7.50, but prices go up exponentially from there. Ease of use: compared to dental stone, it's hard to work with, but if you have a lathe and a drill press, it machines like butter. Strength: gotta find a way to attach it! Erosion: not until you get into high impulse rockets Other notes: a page about machining these excellent nozzles will be coming soon! Conducts heat, which can be a problem Ceramic Not yet tested, check back soon Phenolic Availability: search the net. Expense: 1.5" diameter, 1.5" long for about $5 Ease of use: can be drilled and machined, but much harder to do than with graphite. Strength: needs to be held in place. Erosion: not very much at all, but more than graphite. Drylok Fast Plug Concrete Availability: http://www.ugl.com/ProdDRYlk.html Expense: N/A (but I'm sure it's not too expensive) Ease of use: needs to be packed, can't be poured, sets up in five minutes. Strength: poor, needs retention pins Erosion resistance: better than water putty, but still fairly poor questions? E-mail: wildmanben@rocketss.com |
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Rocketss 112 Thomashire Ct Richmond, Va 23229 (804) 741-2391 |
