SpudFiles

Awesome video crowley!! I need to get a camera. I recently moved and have 46 acres of land to shoot my cannons!! I recently put a golf ball through both sides of a 55 gallon steel drum with my asco launcher!!

Good stuff MrC

With regards to stabilisation, at the ranges you were shooting at even a plain rod would likely have been adequate. Some testing I had done here showed that it took a couple of metres for the projectile to have tumbled significantly.

You really need some better support material for your darts though, I suggest a hole punch and some balsa sheet

With regards to stabilisation, at the ranges you were shooting at even a plain rod would likely have been adequate. Some testing I had done here showed that it took a couple of metres for the projectile to have tumbled significantly.

Well I tried 5m, as seen in the video, and I got good penetration. I think the dart was wobbling in the air from the turbulence as I pointed out it entered on an angle. The entry hole was no bigger than point-blank shots with the same projectile so I'm pretty sure it wasn't too badly affected. I can probably try 10m tomorrow, I would have done so first up but you can see there's a truck behind and to the left of the target.

I suggest a hole punch and some balsa sheet

And arrange them like baffles? Not sure how you meant for them to be arranged but if they're disks with the projectile going through the middle, wont they jam/break up inside the barrel?

I think the way I had arranged it, the cotton balls they weren't doing a bad job. I put one at the tip of the projectile and I assume this is the cotton ball that I always find intact after the launch whereas the cotton balls that surround the shaft are usually in tatters. It's actually surprisingly difficult to poke a hole through the cotton balls with the crossbow bolt and I think this is why it survives the launch.

Edit: Thanks for digging this up by the way. Me and DYI aren't alone

MrCrowley wrote:And arrange them like baffles? Not sure how you meant for them to be arranged but if they're disks with the projectile going through the middle, wont they jam/break up inside the barrel?

My suggestion would be to use a hole punch to cut out some disks, meat tray foam would also be a good candidate (of if you're feeling hardcore: http://www.depronfoam.com/ )

Punch out a barrel diameter disk, with a bolt shaft diameter hole in the middle. Then cut the disks in half, and slip them into the barrel as a pair. Make sure the split is perpendicular to the previous pair.

That should keep the projectile steady in the barrel and fly apart once it leaves the muzzle.

Thanks for digging this up by the way. Me and DYI aren't alone

I make no secret of my misadventures either

Actually meat tray foam would be good; especially if cut at a diameter slightly larger than the barrel so it folds inwards to form a cone and reduce the chance of the disk slipping out of place.

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jackssmirkingrevenge wrote:

Thanks for digging this up by the way. Me and DYI aren't alone

I make no secret of my misadventures either

Me Neither

hehe... I don't believe I've seen that before, backstory?

AAh, I should probably make a thread.

Long story short, we built a robot to throw the first pitch at a baseball game (using a 4" piston valved cannon)

Someone decided to test it in the school, I though 'meh'. He aimed about 4' above the top of our foam backstop at 60 feet and fired at about 30 PSI.

The baseball flew 300 feet down the hallway, bounced off the ceiling, went through two tempered glass doors, across 2 parking lots and into our athletic practice fields.

The Custodian on duty (this was Saturday) then gave us all pops and thanked us for the overtime.

hehe excellent bit of a mini-mythbusters event then

double tap, awesome

Here's one you guys might enjoy:

Nice one, Mr Smith any chance of putting a barrel on it?

There will be a barrel, but don't hold your breath. There's a lot of work left to do (including extensive modification to the chamber - there were a number of sealing issues). Probably two weeks or so, and I haven't even ordered the materials yet.

what velocity and energy figures are you expecting?

And about the rich mixture, what kind of performance increase is to be expected if you put a slighly richer (I have no idea about concentrations) mix in a butane-air hybrid?

seems a bit like a piece-of-string question to me, hope this is clear

I have tried gaseq, but I can't get it to work right