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Railgun+Hybrid Cannon Science Fair Project

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.
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Unread postAuthor: strangers » Wed May 13, 2009 4:18 pm

@Ramses: I planned on having my friend(certified welder) weld the spark plug into the chamber along with the rest of the injector, so I don't have to worry about any threaded parts.

As for the fuel meter I don't have any parts, but I do plan on making it detachable(so I can use it on my other potato guns). I might post a diagram in a little bit for the design. Do you know if I can just buy a propane tank adapter?

If you know anything I could just find lying around that would make a sturdy enclosure please let me know, it would help very much, and I wouldn't have to buy any acrylic.

As for projectiles, probably .25"x.25x1"or.5" pieces of 6061 aluminum or plastic(teflon maybe?) wrapped on one side with aluminum foil, yay plasma. But if I could find where to obtain that copper/carbon alloy I would into that too. On the note of projectiles I was thinking of maybe using lubrication graphite powder on them to increase efficiency, I need to look into that. Maybe even graphite projectiles.

@rp181: The fiberglass is build the enclosure, which should measure 2.25"x1.25"x6', the smallest sheet of fiberglass for the top was 3", so I just decided on a 6" wide piece so I only had to buy one. And the teflon is for the injector rails, and 12" is the smallest width for the 36" of teflon I need, but I'm sure I'll find something to do with the extra teflon. I could make rounds out of the extra fiberglass and teflon.

Do you think the fllowing would make a good charger?
A variac, two radioshack transformers and a diode bridge?
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Unread postAuthor: rp181 » Wed May 13, 2009 5:13 pm

Back to the original point....
That is WAY too long, it will decrease performance from friction. A person I know used a 1 foot long barrel, with 20kJ, more than twice what you are using. Stick with 2 feet, or 3 feet. Your cross section is also overkill, try and calculate the forces, don't just guess.
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Unread postAuthor: strangers » Wed May 13, 2009 6:20 pm

The barrel of the railgun is 3', the injector barrel is 3', but they are both in the same enclosure.
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Unread postAuthor: rp181 » Wed May 13, 2009 7:07 pm

Still.... You need less than 6" of rails to empty all the energy. You are making the injector too powerfull, you will have a railgun agumneted cannon, not the opposite. For my injection, I use 60 PSI and a burst disc, with the friction, the projectile stops right at the end of the rails. Go with 1-2 foot injection, and 1 foot rail's. The mcmaster part 6" wide .5" x 3' GP03 is perfect.

What science fair is this for?

Frankly, I do not think you did enough research. I did research for nearly a year, and it helps. Hold off the project and do some research.
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