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a few miscelaneous ideas for projectile accelerators.

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hotcrazyfruit

Tue Mar 17 2009, 10:18PM

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ok so, iv had alot of time to myself lately and iv been thinking up some ideas. k so

number 1)
for a rail gun projectile, i dont know if this has been thought of , but having a non conductive projectile, with a peice or block of aluminum on the back, so when the whole projectile hits the rail, the aluminum vaporizes, creating pressure behind the projectile, creating an ETG/railgun. what do you think?

number 2 is more less of a project, i think i will upgrade my current 5kj bank to 10 kj (adding 16 more 3900 uF * 400 volt caps) and making a coilgun mortar system. a programmed ballistics calculator will calculate the needed angle of trajectory to hit the required distance/target at a specified muzzle velocity. air resistance will be taken into account. what i need to ask is how could i (electronically) control the angle of the barrel? if there are 2 fixed pivot points on either side.

my goals are to make a coil with 6 gauge wire, and have it hit a target at 300 m , obviously an angled shot.
but as i asked before, any ideas for the barrel angle? im kind of thinging stepper motors, but i would have no idea how to use or control them.
any help is appreciated.

Bjørn

Tue Mar 17 2009, 11:33PM

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1) The point of a rail gun is to reach extremly high velocities, the ETG part is not going to help a lot. So you would be fixing a problem that only exists when the gun is not working properly.

2) Elevation screws have been used for hundreds of years and is simple to make

Just count the rotations of the motor to get an accurate and repeatable angle.

hotcrazyfruit

Tue Mar 17 2009, 11:45PM

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BjÃ¸rn wrote ...

1) The point of a rail gun is to reach extremly high velocities, the ETG part is not going to help a lot. So you would be fixing a problem that only exists when the gun is not working properly.

what if i had a bimetallic block, one side with steel, the other with aluminum, so the aluminum vaporizes, and the steel or copper continues to conduct as it moves down. i dunno, lol i just kinda thought it up. xD

Bjørn

Tue Mar 17 2009, 11:52PM

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The plasma generated when the aluminium vapourise will be conductive and work as any other conductor. It is called a plasma armature, it is used on some rail guns.

big5824

Wed Mar 18 2009, 08:52AM

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I imagine you would get a build up of the aluminium on your rails, reducing performance

hotcrazyfruit

Wed Mar 18 2009, 02:17PM

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BjÃ¸rn wrote ...

The plasma generated when the aluminium vapourise will be conductive and work as any other conductor. It is called a plasma armature, it is used on some rail guns.

o right, i completely forgot*face slap
thanks man

aonomus

Wed Mar 18 2009, 04:03PM

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Another projectile I've heard of is using carbon/copper alloy (the stuff they use for motor brushes?). If you use copper rails you'll end up having the same metal buildup with irregularities, and carbon soot all over the place.... might make it easier on the rails if you use a different rail metal with a greater melting point (ie: just scrape the build up off).

hotcrazyfruit

Wed Mar 18 2009, 09:11PM

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aonomus wrote ...

Another projectile I've heard of is using carbon/copper alloy (the stuff they use for motor brushes?). If you use copper rails you'll end up having the same metal buildup with irregularities, and carbon soot all over the place.... might make it easier on the rails if you use a different rail metal with a greater melting point (ie: just scrape the build up off).

which is why it would be such a good idea to gave tungsten rails (3410 degrees celcieus melting point) with an aluminum projectile, there would near no rail erosion. lol. another thing i was thinking thinking of, instead of wasting time making a rogowski coil, what if you used a shunt. because the current from end to end of the shunt SHOULD be proportional to the full current, and giving us a readable voltage by a pc or occiliscope.

rp181

Wed Mar 18 2009, 09:51PM

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A shunt is more difficult if you have to make one. You have to know the resistance accurately. Also, it takes power away from the circuit, and is more intrusive. A tungsten rail would [probably] suck, due to the high resistance.

@aono
Those projectile have been tried before (read about it from Ebsco host), but the resistivity caused the projectile to explode.

hotcrazyfruit

Thu Mar 19 2009, 01:22AM

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rp181 wrote ...

A shunt is more difficult if you have to make one. You have to know the resistance accurately. Also, it takes power away from the circuit, and is more intrusive. A tungsten rail would [probably] suck, due to the high resistance.

but the resistance of a shunt is only a few milli ohms. i ust thought that there would be a small difference in potential because of the resistance in the shunt. thanks.

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