dang! nice! That is almost as fast as the High Speed Rocket Sled was travelling on an MythBusters episode where they smashed a car with 4'x6' 1" thick steel plate. It was going 948 FPS or 646 MPH, and your lil 7.2oz projectile was going 666.667 FPS or 455 MPH.

As I said in previous post, I have tested the wires twisted around one another, out of the chamber...100% spark between the ring terminals. Ever since I've added the fiber washers, all sparks have been between the screws. BTW the spark gap is about 1/4in or less, which is about the same/or less then...

I widened the gap just slightly, about 4~5mm gap now. I think I've solved my spark issues. I got some fiber washers on the inside of the chamber, then the ring terminal, then lock washer & wing nut. Before the ring terminal was in contact with the chamber wall. I've done 40+ dry fires, and they all ...

Well I thing the fiber washers on the inside is working best, the tape on the top just kinda squashed out and didn't get into the threads.

I've done 40+ dry fires, and they all sparked between the screws.

Not to thread jack, but my issue is with my design as described above. I've been getting spark failure, somewhere between the button & the screws I see sparks. Since my tape is blocking my view I am not sure if it's sparking from wire to wire, or from wire to PVC wall. I am guessing from wire to PVC...

Dang man that's a HUGE canon/howitzer! Wonder how far your ammo would go at 45* angle 8)

Had some ignition issues, so I put some PTFE tape on the very top of the screws where they are in contact with the PVC, and widened the gap about 1mm on each side. So far the dry firing is working 100%. edit: the extra PTFE tape didn't fix my issues. I seem to be getting sparks up behind the Gorilla...

Yeah that's it!

spark gap wider eh? it's prolly now about, 3~4mm wide

I am tempted to find this localy, or order one from Amazon just to see how it compares to Starting Fluid w/hair spray nozzle. http://ecx.images-amazon.com/images/I/21bI8%2Bhw3cL._SL500_AA280_.jpg http://www.amazon.com/COLD-SPRAY-FIRST-TREATMENT-AEROSOL/dp/B0006GE7B6 Topical skin refrigerant, cools s...

I used ACE Plastic Repair Epoxy (SKU 17394) for glueing a 65lb magnet to a 3in thinwall PVC cap.

MAN this stuff smelled so chemically when I was mixing it! But it works great, very very tuff, but not brittle. I'll be using it on my future launchers for attaching BBQ ignitors on PVC screw caps.

I was talking to a co-worker of mine about my spud canon, talking about this site & what all canons have been made. He asked me if anyone designed one for launching Golf Balls, I said "Yep! there's this really awesome chrome or stainless steel one I've seen at spudfiles.com" Sorry I don't remember w...

I get the Weber Ignitors, drill a 19/32 hole in a PVC threaded cap and glue it in place with PVC glue and some hot glue for extra help. I then drill (7/64) & tap (6-32) two holes in my chamber, and find correct length of 6-32 stainless steel screws for the gap. I use 6-32 locking washer & wing nut t...

Plastic paint drop cloths, or yard waste garbage bags. I think tarps would be too thick.

drop in a 120mm computer chamber fan with 9v battery taped to it or summat to mix it all, and one of those hobby rocket ignition things...BOOM

+1 for the Starting Fluid w/nozzle. Plus if you are going to go metered propane, you'll need a chamber fan. But a chamber fan in any combustion cannon is best.

Holly cow! a ~1500 in^3 chamber! I thought mine was huge (213 in^3). Cant wait to see the WIP pics & finished product.