Damage challenge

[Moonbogg]

I am going to make a damage video for my new cannon and I want to know what is considered to be a challenging target to penetrate. How much pine plywood can a typical cannon shoot through with golfballs? I don't want to get 1/2" plywood and find out it blows through it like paper, and combining sheets too many times would be a pain. Should I get some 1" or what?

[jmeyer1022]

My 2" piston can blow through 3/4 from 50+ feet now problem at 65ish PSI. I suggest posting your cannons specs before we tell you.

[Moonbogg]

My 2" piston can blow through 3/4 from 50+ feet now problem at 65ish PSI. I suggest posting your cannons specs before we tell you.

2x hybrid
4.125" ID chamber x 18" long
1.87" ID barrel x 6ft long
2 spark gaps and chamber fan
stun gun ignition
over under design
100% 6061-T6 aluminum construction
Camlock burst disc coupling & breech loading
using aluminum foil as burst disc for now (about 8 layers, will increase later for more power)




Oh, another question. Do you think this cannon would be more powerful than a PVC pneumatic? I honestly don't have any experience to compare the two.

[Technician1002]

I like using marshmallows. Did you know that marshmallows will dent a car door

I also discovered the hard way that a rolled up t shirt will go right through a carpet.

If you have high speed video, the obligatory fruit impacts are nice.

Some of my favorite ones are quite messy. Impacts on spray paint cans!

If you can penetrate 1/4 inch steel plate, I'll be impressed.

Oh, another question. Do you think this cannon would be more powerful than a PVC pneumatic? I honestly don't have any experience to compare the two.

Do you have chronograph results? I have an air cannon that launched an apple at 882 FPS.
The only side by side air to combustion cannon testing I have done was with 2 2 inch cannons the same length. The piston valve air cannon matched it at about 35 PSI. Sorry I have no hybrid comparisons.

[Moonbogg]

The piston valve air cannon matched it at about 35 PSI. Sorry I have no hybrid comparisons.

Damn man. 35PSI is really low and it sounds like it had power. The chamber pressure of my cannon will be around 200PSI with a 100PSI burst disc according to HGDT. I am struggling trying to compare chamber pressures between hybrids and pneumatics and its effect on performance. For instance, take my cannon for example. It is currently a hybrid with 200PSI chamber pressure. If I took this exact cannon and added an air valve and used it as a pneumatic with 200PSI chamber pressure, which would be more powerful?

[sniper hero]

haha marsmallows from a hybrid:D
I think you can buy some good wood for this one

If I took this exact cannon and added an air valve and used it as a pneumatic with 200PSI chamber pressure, which would be more powerful?

depends on the valve. can't you put pressure on the gun till the burstdisc bursts?

[Moonbogg]

depends on the valve. can't you put pressure on the gun till the burstdisc bursts?

Yeah I could do that. But that would be a lame way to shoot a cannon.

[Technician1002]

depends on the valve. can't you put pressure on the gun till the burstdisc bursts?

Yeah I could do that. But that would be a lame way to shoot a cannon.

Cycle time on burst disks sucks. The cannon these guys made has a cycle time in under 10 seconds. Watch a full load, fill, launch cycle here. The video is only 15 seconds long.
[youtube][/youtube]

The performance isn't too bad either. Here is a high speed video of an orange launched out of the design prototype for this.
[youtube][/youtube]

Have you figured your speed yet? What does the gun design tool come up with? The cannon is using a Quick Dump Valve as discussed elsewhere on this site.

Edit to prevent double post

Damn man. 35PSI is really low and it sounds like it had power. The chamber pressure of my cannon will be around 200PSI with a 100PSI burst disc according to HGDT. I am struggling trying to compare chamber pressures between hybrids and pneumatics and its effect on performance. For instance, take my cannon for example. It is currently a hybrid with 200PSI chamber pressure. If I took this exact cannon and added an air valve and used it as a pneumatic with 200PSI chamber pressure, which would be more powerful?

We spent an entire afternoon shooting apples. He wasn't using a meter, it was a propane spray N pray, so a better design would have done much better against the air cannon. The The air cannon is my first quick dump valve cannon. It used a rope pull on the valve. It is a coaxial with an 8 foot 2 inch barrel inside a 4 foot long 4 inch diameter chamber. Because of the valve design the barrel goes all the way through the chamber with the valve inside the breech of the pipe. Rectangular ports were cut in the pipe inside the chamber that the core sealed. The rope out the breech pulled it open.

This cannon is the ABS DWV cellular core pressure test cannon I refer to in some of my posts that failed to fail.

If I took this exact cannon and added an air valve and used it as a pneumatic with 200PSI chamber pressure, which would be more powerful?

Download Gas Gun Design Tool to see what the performance of both would be.

[sniper hero]

it's not about a lame way

take a piece of wood
shoot it at 2X (if that generates 200psi)
then shoot it with same ammo at same piece of wood at 200psi (just try some burstdisks till it's about 200psi burstpressure)
compare the results and write down your conclusion
now you now what's better

be creative and try something new

[Gippeto]

Tough targets eh?

I have a couple concrete blocks I'm saving for the co-ax "full pressure tests".

Their survival is highly doubtful.

1/4" steel plate has been done.(Albeit with a somewhat "less than portable" launcher, but still straight pneumatic, hybrids have done this too.)

Penetrating 1/4" steel with a portable launcher would keep me watching till the end. 8)

A hardened dart type projectile in a sabot is the way to "git 'er done".

Ricochet's can be nasty though.(Ask Spudfarm. )

[King_TaTer]

It would be interesting to try that with your cannon Moonbogg. Especially since you designed it as a hybrid. I agree with sniper hero's method. As far as the plywood goes I'm not really sure. If I were you I'd get a regular 4x8 piece of 3/4" ply and cut it in half then bolt them together. It's really not that much of a hassle. Good luck.

[starman]

For plywood and golfballs, you'll need to be in the 1 1/4" to 1 1/2" or greater range and doubled up sheets. Anything under an 1" blows out like butter bread.

[frankrede]

My mauler cannon will blow through over 5 sheets of 3/4" plywood...
Your best backstop would have to be multiple sheets of plywood sandwiched with sheet metal between layers.

[Moonbogg]

The sabot with dart sounds excellent. 1/4" steel plate sounds like a good challenge. I might pick up a couple arrows from a sporting goods store as well. Ohhhhh! I could use cross bow bolts They come in all aluminum with steel pointed tips. A balsa wood sabot would be easy enough to make. If the bolts aren't heavy enough to penetrate I will go with a solid rod with a point on the end.

About the pneumatic vs hybrid thing. I thought it would be different since pneumatics force the air through a narrow valve instead of a huge, instant dump.

[jackssmirkingrevenge]

The sabot with dart sounds excellent. 1/4" steel plate sounds like a good challenge.

Remember, sectional density is your friend