AT-4

[singularity]

i have shot c batteries a few times i normally would wrap them in a few layers of duct tape to give them a better seal. and the kick isn't that bad, now lunching full water bottles is another story (i have a 3" mortar and it has like 6 inches of kick every time i fire it) and once again thanks for the complements everyone

[spudbud101]

Wow. Just wow. Awesome, looks like the real deal!

[TwitchTheAussie]

Are you left handed by any chance? Great cannon mate. Nice to see people getting into bazooka styled cannons. Keep up the good work :thumbright:

[VH_man]

that piston is (GHASP) BEAUTIFUL!!!!!!

i want to hang that in a museum. its simply marvelous


the barrel spacer might be resisting flow a little. try modifying a bushing, you might get better results.

[Counterstriker]

Can you tell me the exact diameters and stuff?

[flamerz14]

Beautiful.... what kinda piston?

[Specialist]

wow. that is incredible ( actually very credible lol). the trigger looks like its in a wierd position but thats probably just me.

[robert23]

Awesome gun man. I feel inspired.

[singularity]

well the piston is a 1.5" cap wrapped in electrical tape shoved in a 2" cap wrapped in duct tape and its got some rubber i found at my local hardware (like 1/8" thick) CA glued onto the front of the 1.5" end cap. the barrel spacer is a modified 1" bushing (yay dremel) thats been flattened on 4 spots with flattened PVC glued to it i don't have a picture of the stopper but it was a piece of that rubber (on the piston) cut in a donut shape (about 3" OD 1/5" ID). i do realize its probably slowing down flow rate but at a 7:1 C:B ratio i doubt it will really increase preformance

[Counterstriker]

Ok.. I know people will laugh but.. How do you make the gun shoot multiple times instead on one shot and then you have to refill the air..

[Modderxtrordanare]

Ok.. I know people will laugh but.. How do you make the gun shoot multiple times instead on one shot and then you have to refill the air..

Use your imagination and come up with your own idea?

[noob of noobs]

Wait, you have a C:B ratio of 7:1? If you have a 3" chamber and a 1" barrel, than your ratio should be less than 3:1, right? Also, for ammo, try saboting mortar. I know that when you shoot it straight from barrel it explodes in a white cloud. So if you could make it so it explodes on contact, then it would produce a big white cloud of dust like a fake explosion!

[singularity]

noob of noobs no not so you actually have to do some math to find the ratio... to make this easy im going to say the air chamber and barrel are 40" (which is pretty close to the real length). the first thing we need to do is find the volume of the barrel (pi*r2*h) so pi*.25*40=31.42 the volume of the barrel, now the same equation is used to find the area of the chamber. pi*2.25*40=282.74 but we need to subtract the area of the barrel becuase its a coaxial. 282.74-31.42=251.32 now to find the ratio i divide 251.32 by 31.42 and we get a C:B ratio of 7.99:1 but i did not incorporate the wall thickness of the pipe so its a slightly smaller than 7.99:1 but still way overkill for a pneumatic

Counterstriker - well i doubt you'll be able to do it using a traditional piston or diagram valve but you might be able to with a sprinkler valve (of course the second shot will have servearly decreased power) your best bet would a be some sort of linked piston design or a circuit that would auto refill the gun after each shot

[Modderxtrordanare]

Or use CO2?

[jackssmirkingrevenge]

Wait, you have a C:B ratio of 7:1? If you have a 3" chamber and a 1" barrel, than your ratio should be less than 3:1

volume increases exponentially with diameter, this means that for a given length, 3" pipe will have 9 times the volume of 1" pipe.