My Hybrid!

[wyz2285]

Thanks DYI, My friend and I did a calculation, one layer of aluminium foil does hold around 1 bar, but two layer will hold more than 2 bar, not very linear, but kind close within the range of 1-5 layers.
I used a 3/4 male and a 3/4 female to 1/2 male adaptor to hold the disc, so I considered it as a 1/2 area for the pressure to exert.
My ignition source is a tazer, witch gives a 2-3cm spark in atmospheric pressure, 1mm should be enough in this case so.
Thanks

[CpTn_lAw]

I'd back up petitlu on soda cans, i use one layer and i need to score it a little for it to break at 10x. 12x however is no problem.
Soda cans can rupture badly. Only half of it can go out of the barrel and you need to consider it like a projectile on its own, at least for a few meters!

[Petitlu]

ThorJack with the cutting disc and total very well to MIX10.
As I glue on a washer, it stays in place and does not leave from the side

[wyz2285]

So I will need to start drinking canned sodas also convince my dad to drink canned beer as well
glue it to a washer every time ?! That will consume a lot of super glue for sure... Hope it's not necessary.

[Petitlu]

3 drops is enough!
you can take aluminum cans too!

[Moonbogg]

I noticed what your cannon did on your second video when it didn't fire. Sometimes mine does that also and I was wondering if it's from a bad mix, or too strong of a burst disc. What do you think? Mine makes that same kind of noise.

[wyz2285]

I would say too strong burst disc combined with slightly bad mix, because at mix 5, the highest pressure after ignition would be around 300 psi, before the mix the burst disc need to be strong enough to hold 75 psi safely, so lets say 100 psi min or when miss fire, even more, so the difference it´s only 200 or less, with a bad mix. I use strong burst disc so there won´t be any danger when I loading the projectile.

[Goats spudz]

I would say too strong burst disc combined with slightly bad mix, because at mix 5, the highest pressure after ignition would be around 300 psi, before the mix the burst disc need to be strong enough to hold 75 psi safely, so lets say 100 psi min or when miss fire, even more, so the difference it´s only 200 or less, with a bad mix. I use strong burst disc so there won´t be any danger when I loading the projectile.

a standard aluminium coke can rupturs at about 1000 psi when locked between a hydraulic nipple.

[wyz2285]

a standard aluminium coke can rupturs at about 1000 psi when locked between a hydraulic nipple.

What ?? so Petitlu´s hybrid at 10x produces >1000 psi??

[Petitlu]

At MIX10, according HGDT the chamber pressure is 76bar (1100psi)
the rupture disc steel cans, broken to 50bar (725psi)

[wyz2285]

wow, didn´t know that so mix 10 actually gives me a good number...
Now, adjusting the spark for mix 10

[Petitlu]

with flash ignition, the gap should not exceed 0.5mm (0.02 ")
Finally, I think you must know it...

[MrCrowley]

a standard aluminium coke can rupturs at about 1000 psi when locked between a hydraulic nipple.

Depends on the diameter of the nipple

I use 4 for a 10x mix in a 3/4" union.

[jackssmirkingrevenge]

As I glue on a washer, it stays in place and does not leave from the side

Odd... a good o-ring should suffice to hold it in place, but it depends on your threaded fitting.

[Petitlu]

I put a flat joint!