SpudFiles

I fired off a shot today, and had quite bad results. This was probably due to the fact
[1] projectile fit could have been better (see pics)
[2] error in measurements, I was unable to measure the voltage on the bank after firing, so a full 400 volts was assumed. In this pictures, you can see the arcing lasted all the way to the end of the rails, leading me to believe there was a charge left.
The projectile was not found (will be shot at the bullet resistant plastic next time).
The data:
-chronograph:
distance of wires: 10"
voltage charge: .667 volts
calculated projectile speed: <b>864.7 FPS</b>
-rogowski coil:
no data collected. Suspected to be signal diminishing due to long leads.
-rails:
projectile contact was made midway through the rails.

And the grand total of <b>273.4 joules</b> on kinetic energy, and <b>.02%</b> efficiency. <i>Keep in mind this is most likely a lot higher, as I was unable to measure the voltage after firing. </i>
See the whole project at: http://rp181.wordpress.com
Without further ado, a video and pictures:

[youtube][/youtube]
<a href="" title="100_4942 by rp181, on Flickr"><img src="http://farm3.static.flickr.com/2789/429 ... b08362.jpg" width="500" height="375" alt="100_4942"></a>
<a href="" title="100_4941 by rp181, on Flickr"><img src="http://farm3.static.flickr.com/2712/429 ... 420669.jpg" width="500" height="375" alt="100_4941"></a>
<a href="" title="100_4940 by rp181, on Flickr"><img src="http://farm5.static.flickr.com/4041/429 ... 882fec.jpg" width="500" height="375" alt="100_4940"></a>
<a href="" title="100_4952 by rp181, on Flickr"><img src="http://farm3.static.flickr.com/2760/429 ... a27186.jpg" width="500" height="375" alt="100_4952"></a>
<a href="" title="100_4948 by rp181, on Flickr"><img src="http://farm5.static.flickr.com/4049/429 ... 0cefc2.jpg" width="500" height="375" alt="100_4948"></a>
<a href="" title="100_4946 by rp181, on Flickr"><img src="http://farm5.static.flickr.com/4036/429 ... 6e3d8b.jpg" width="500" height="375" alt="100_4946"></a>

Sweet, I want one!

very interesting looking at the rails, just after 1 shot?

yes, after one shot. As said, it was a very bad shot. You can see the projectile didn't make contact with the rails until it was well into them.

When you get the projectile sorted out how many times do you think you'll be able to clean off a set of rails and use them for another shot?

Looking forward to more updates

For serious shots, I wouldn't go more than 2 per set of rails.

Very Nice! That's an impressive set of beancans you have to run that thing. 12 KJ is a boatload. How much of the projectile energy could the injector account for?

Never thought I'd see rogowski coils mentioned on spudfiles!

The numbers are given without the injector energy, forgot to mention that.

How much power were you expecting?

Nice, shame there wasn't a target.

Do you have a 4hv thread for this. Also very nice, 12000J is a [insert expletive here] load. Have you considered this with your ETG.

Neato

Isn't there any way to recycle used rails by sanding them or something?

I give this two thumbs up.

Nice. I can't wait to see a better shot from this. When I made my first penny switch, the bank would occasionally dump through the metal vapor deposited on the wood base. For this reason, you may need to clean your Garolite enclosure from time to time.

Rails are difficult to recycle, as deep pits develop.

I am considering an ETG, Im almost sure it will be my next project.

I am going to try to setup a target for the next shot, possibly a piece of the bullet resistant plastic in a steel angle frame.

Cool, ok, can anybody explain how these things work, I know there is something to do with an electromagnet, but I really don't understand what's going on there...