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Railgun begginings and questions

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rp181

Thu Jun 12 2008, 02:28PM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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Why not use the gunpowder in the bullet for injection? offcourse, this would only be practical with higher energies.

Quantum Singularity

Fri Jun 13 2008, 01:14AM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

Interesting idea, of course I have not studied railgun theory in depth but I worry that the round projectile would not work as efficiently from the electromagnetic perspective (might be better accurate and retain more energy at distance though due to aerodynamics of course).

Using an actual bullet for injection would take some special design considerations for sure... and probably require a hand loaded round. I'd imagine the lightest load 30 cal is way to much for a hobbyist class railgun. but if you were to hand load it with say only about 10% the powder charge now that might work. Of course you'd probably have to clean up the barrel after every shot due to gunpowder residue and buy the cleanest burning powder one can find. In any case, this just makes the hole project even more dangerous and deadly...

phil

Fri Jun 13 2008, 02:13AM

Registered Member #314 Joined: Mon Mar 13 2006, 03:12AM
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I was always curious as to why noone is making them with cylindrical projectiles. And i do not think gunpowder is such a good idea as the residue will definitely decrease efficiency.

rp181

Fri Jun 13 2008, 01:51PM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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Blocks can be aerodynamic, pretty much a regular bullet with flats on the back.

As for gunpowder, on my railgun, there is going to be a 1ft section of fake rail, so with hardly any gun powder, all the residue might be left behind.

badastronaut

Mon Jun 16 2008, 04:23AM

Registered Member #222 Joined: Mon Feb 20 2006, 05:49PM
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I don't really see the point in making things aerodynamic unless you plan to do range fired tests. The projectile isn't going to go faster once it's out of the barrel.

I think you shouldn't worry about getting the whole system working pefectly the first time. It's a common mistake in engineering to make the project as complicated as possible with every possible consideration from the get go. It's best to start simple. Once you get the overall system working, you could go to the next step and improve the projectile design. That's just my opinion though :P

phil

Mon Jun 16 2008, 04:51AM

Registered Member #314 Joined: Mon Mar 13 2006, 03:12AM
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No you are correct, i over complicate things by nature =). Today i soldered together the 12V regulator and 555 timer for the project. It's my best perf-board to date; once the prototype is up and working i'll order some professional PCB's and make it look nicer. Heres a pic, Green LED is the diagnostic LED for the power supply, and the blue one is for the timer circuit.

Not bad for a Mech E major eh?
EDIT: pics are WAYYY too big O_O sorry! heres a link instead

And heres a pic of the first layer of the inductor... I cracked my nail on the vice when i was removing the rest of that transformer so it better work ><.

Edit: same thing too big

I'll set up a website on my domain space when i get a chance, summer classes tend to take up all that spare time =)

My goal now is just to get one working whether it's my design or not so i can figure everything out. Now i need to track down some SCR's and an IGBT, maybe one of the circuit boards sitting in my de-soldering pile will have one.

A problem i'm having at school is the electrical engineering professors tend not to want to "waste" time with a MechE major =/ hopefully if i can get this working it'll change their minds.

badastronaut

Tue Jun 17 2008, 10:37AM

Registered Member #222 Joined: Mon Feb 20 2006, 05:49PM
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Yes... there is that problem between departments. Try to find a professor who would be interested in your line of work, maybe someone who deals with electromagnetics. Perhaps you could offer to build a demonstration device for said professor. Also, you can write a formal paper on the subject, and if you can write well enough, I'm sure you can convince the professor that you are genuinely interested in whatever you are trying to accomplish.

phil

Tue Jun 17 2008, 03:20PM

Registered Member #314 Joined: Mon Mar 13 2006, 03:12AM
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This is going to be the demonstration piece =D I figure if i can get this working i can prove to them it's not just a silly project.

rp181

Tue Jun 17 2008, 04:12PM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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When people hear "railgun" they think that its eaither a model of some fantasy gun, or a huge beast like the navy one.

phil

Wed Jun 18 2008, 03:17AM

Registered Member #314 Joined: Mon Mar 13 2006, 03:12AM
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It is actually quite amazing how (no offense to anyone) one can build these things from broken electronics. Most people think you need government backing to make something like this. The boost converter for my CG is made from some broken irons, an old computer battery backup, and a power supply for a laptop. I finished the comparator Circuit part of my design, trying to locate a IGBT for the boost converter and some SCR's for the bank. I'll post pics once i convert them so i don't anger the 4hv.org gods =D

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