I had an idea to fire steel darts in a foam sabot made from polyurethane foam. Other than that i liked the burnt latke guy's idea to fire wooden slugs with rubber gaskets.

Well assuming that still means me, and since D_Hall hasn't replied yet, here's my understanding of the situation: You're reached a sort of balance between the pressure behind the projectile, atmospheric pressure, and the friction in the barrel. By increasing the projectile's friction, you decrease ...

Ok I've been toying with HGDT this weekend and Ive found a bit of an anomaly that has left me scratching my head. With a chamber length of 8 and diameter 3 I seem to get significantly more power in the simulation from a 1.5" bore compared to any other size bore. I have the barrel length set at 48 ...

Thank you that is very helpful. This project would be my first over/under so I was unsure of how to account for that portion of the gun.

alright.

Ah another question:

When calculating the volume of the combustion chamber on an over/under configuration, do you include the 180 degree portion of the barrel (the length of the barrel between the chamber and the projectile.

absolutely, I just don't have high hopes.

Also, HGDT is supposed to be able to model simple combustion guns as long as you set the burst disk pressure to 0 so that's helpful for seeing the potential of different barrels. I found a website that sells a pressure rated schedule 40 U bend pipe (the ...

Yes, but the page hasn't been active since '04. I doubt that those emails are used by them anymore.

That is small, but too small.

Looking to build basically this: http://www.burntlatke.com/mini.html
except in an over/under configuration with on board propane.

I just cant really tell what the dimensions are.

Edit: the article mentions that the chamber uses a cpu fan, which are typically 70mm ...

ok by bang I mean power, but relative to its size. I feel that I should be able to launch a small projectile as fast as a larger gun launches a larger projectile. I'm not trying to "set the world on fire" with this gun. I want good power for its size.

To really lay out what I'm looking for:

How ...

Hi all, I'm breaking into the forums with a new projects over the course of the next few weeks. I'm designing a not-quite-mini combustion.

I'm thinking of an over and under 1.5" barrel with an d=3" by 8" combustion. However, Id like to shrink that even more. I'd like something around the size of ...