Hi, All I have to add is that the fastest valve will not necessarily be the best valve for golf balls: The projetile is relatively dense, and it accelerates relatively slowly. There will be plenty of time for the valve to open before the golf ball has come very far. If you want to shoot golf balls, ...

Hi, Current projects: - Finish and present my DFTV golf ball accelerator - Prototype my old idea, the Jet Gun, and see if I can get it to ignite - At the same time, I have a scaled down experimental semi automatic in the works - Finish my stirrup pump (should be able to do most of that tonight, real...

Hi BtB,

Hmm, interesting what u say about the PP pipe.

I could try to pressure test a length of it (bolting PVC on end caps, and supporting it in the longitudinal direction with a clamp). My high pressure pump is soon finished...

Regards
Soren

Hi all, Maxus, what is a biatch? I just had a serious backache yesterday; until that is over I am NOT going to shoulder it at 10 bar ;) Yes, the pilot valve is very useful as a shoulder support. I will add a barrel support eventually - the static load on the tee is very very small. But of course the...

Hi,

OK, rubber cement; that sound plausible, haha. Problem is, I see all kinds of Loctite etc. products where I get my pneumatic parts, but nothing called rubber cement. OK I will ask.

Thanks for the answers.

Regards
Soren

Hi, Finally I got around to make a gun out of a valve that I had sitting around for a long time. It´s the larger one of the tees in my avatar. The set-up is a rather conventional 3000 cc barrel sealer, except: - The main seal is not on the front of the piston, but rather on its seat. It´s an O-ring,...

Hi, If you are researching in combustion of hybrid cartridges (a bottle with a pre-compressed fuel-air mixture in them, and a projectile at one end), maybe you can use the microwave as an ignitor for that. (Drop a paper clip into the cartridge, aim the magnetron through the chamber at the cartridge,...

Hi,

Does anyone know a reliable way to glue/cement rubber?

I know there is one Loctite product (name / number?) that is often used for making O-rings on the fly. Does that also work for larger surfaces?

Any other suggestions are also welcome.

Regards
Soren

Hi, A friend showed me a Danish website, http://www.appelsin-kanon.dk. There was a description of how to build a really primitive combustion orange launcher. IT wasn´t even glued together; it was supposed to pop apart at every shot. I decided to build one, but heck, I´d glue it together. With PVC gu...

EDIT: Hmm, someone else (Jack) already suggested this. EDIT: Just ignore this, then... Hi, Forgive me, but is this not rather simple: The momentum of the gun and that of the projectile are equal in magnitude and opposite in direction. That is: m_gun * v_gun = m_proj * v_proj Knowing the masses of yo...

Hi, Yeah OK induction will happen in the barrel and current will flow. But still I'd say, for the magnets that I used, that it is totally insignificant. I know I should support that by some kind of computation..... I did the shoot-through-the-wires thing, too. That was so cumbersome that I designed ...

Hi Larda, Sure you could shield the coils again electric fields, but my first guess it that it won't be necessary. And, hmm they run on the magnetic field. If the magnetic field from cannon interferes too much, there is not much to do but to move the chrono further away. My coils were just about 10 ...

Hi,

Yes it was posted.

OK keep hacking at it! Get some measurements.

Sonic speeds with cold gas is still rather unexplored (other than with very small calipers and very high pressures, maybe).

Tell us about the results..

Regards
Soren

Hi biggsauce, I have broken the sound barrier once, with a 15' barrel (46 mm ID) and a big plain-combustion chamber enriched with 40% oxygen. The projectile was very light. Joel of Spudtech claims to have broken the sound barrier with a pneumatic. There is (was?) even a picture of the gun on his sit...

Hi Larda Wow I am deeply impressed. May I see it if I come to Sweden this summer? I made an electromagnetic chrono once: The projectile is magnetic (doesn't have to be much; a few cubic mm of a magnet from a hard disk drive is enough), and it is fired through 2 coils (mine are 300 turns each I think...