Sound barrier

[MrCrowley]

Im probably gonna make a 10 foot golfball barrel too

Still around 800ft/s.

With such large diameter projectiles, it's very difficult to break 1000ft/s at a reasonable pressure with air.

I still highly recommend you dump the second chamber, almost pointless having it.

[Brian the brain]

still highly recommend you dump the second chamber, almost pointless having it.

just like this discussion....

[Gippeto]

How ironic is this topic?

I've been playing with this, and really THOUGHT I had done it.



BUT; (You just KNOW there's a but don't you!)



PROPER testing procedures show that, although I am getting close,... I'm not there yet.

I will update my thread accordingly.

It's going to be a lot tougher than you think, and I don't think it's going to happen with a plastic (?) launcher.

And tougher still using room temp air.

But, I'm nothing if not stubborn!

[MrCrowley]

still highly recommend you dump the second chamber, almost pointless having it.

just like this discussion....

Hmm it's his topic, the original topic is pointless as you said, but discussing his cannon still has a purpose I think. We're just helping him out, no point in him making another topic.

[rp181]

Just thought ide put this out there, but a golfball reaching supersonic will be MUCH easier that a TB. TB's are specifically designed with tennis regulations, and 1 of the regulations is how fast a TB can freefall a certain distance. That is the whole point of the fuzz, to slow it down.

Has anyone tried a multistage air gun 8)

[Ragnarok]

That is the whole point of the fuzz, to slow it down.

Outside the barrel. Inside the barrel, the drag of the tennis ball is completely irrelevant.

The other thing is that the fuzz actually improves it's drag over a regular sphere in a similar way to a golf ball's dimples - but it's deliberately kept from being as good as it can be.

[SEAKING9006]

Has anyone tried a multistage air gun

Give me some fast as hell photoreceptors and put them in some PVC or aluminum pipe and I'll put in QEV's to make it multi-stage. Timing is the key.


That was the system (albeit using rockets instead of QEV's) used by the nazi's to build the V-3 Cannon vengeance weapon.

[Hydra]

Wow youre really challenging yourself. Making a Supersonic Spudgun for your first!

[Tidbit77]

Hmmm......Im wondering if I should try helium as well, ive heard that if you use helium , its easier to go supersonic. Is there any truth to that? Also, if I build a larger piston valve with 3.5 porting or so, would i gain a significant amount of power. Sorry for the "n00b" question, but Im relativly new to spudguns.

[SEAKING9006]

First, try experimenting with simpler, smaller, less advanced (and difficult) goals. As a start, first gain a knowledge base with an initial launcher, not intended to do anything but throw things. Then, try to improve on it with better valves, better barrels, better chamber design. It's much better to start with a starting point, rather than the finish line.

[starman]

If supersonic is a hard goal for you, it would be much easier to just go the hybrid route. You don't state what kind of ammo you want to shoot supersonic and that will make a big difference on your design. However, golfball and smaller can go supersonic fairly easily in the hybrid world.

[Tidbit77]

thanks for all the info, but i have been wary of hybrids because i have heard the statement "if you mess up with a combustion, youre out $20, if you mes up with a pneumatic, youre out $100, If you mess up with a hybrid...youre dead." however, i have considered eventually building one.

[MrCrowley]

Hmmm......Im wondering if I should try helium as well, ive heard that if you use helium , its easier to go supersonic. Is there any truth to that? Also, if I build a larger piston valve with 3.5 porting or so, would i gain a significant amount of power. Sorry for the "n00b" question, but Im relativly new to spudguns.

Yes it's true. Because helium is lighter then air, it travels faster with the same amount of energy used. That's why if you pressurize water in PVC< if it explodes, the shrapnel will be travelling with far less energy then if it was pressurized air in the PVC.

3.5" fittings may exist, but I don't think any spudder has used or seen them before. They'd be expensive too. You may as well go 4" barrel sealing piston.

I just GGDT'd it with a 4" piston valve and the performance has no real change.

[starman]

thanks for all the info, but i have been wary of hybrids because i have heard the statement "if you mess up with a combustion, youre out $20, if you mes up with a pneumatic, youre out $100, If you mess up with a hybrid...youre dead." however, i have considered eventually building one.

If you're talking supersonic anything, you are automatically raising the bar significantly and associated risk on any platform. You will want to have built basic and advanced combustion guns AND a pneumatic model or 2 before attempting a hybrid.

However, the "mess up on a hybrid, you're dead" comment is a little over zealous and an over-simplification. Messing up with a pellet gun could also conceivably cause death as well.

[jackssmirkingrevenge]

If high velocity is your goal, consider using helium and a burst disk. I got close using compressed air