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Posted: Thu Jul 10, 2008 11:00 am
by SpudFarm
i just got one more strange shot. once more with a golf ball.
this one was the loudest i have ever had and i turned around because i thought the gun has exploded..

i did not measure the shot but it split up 6" of wood to just small particles and the ends of it because it broke on the middle.. the people who gathered around to look at the shot did not see the ball, even after it hit the wood.

and just to let you know i also shot through a 1/4" stainless plate, i will do as DYI did and make a thread about it with details.
the next step would be 1/2" stainless and it should not be a problem

Posted: Thu Jul 10, 2008 11:26 am
by daberno123
:shock: :shock: :shock:

Any pics?

Really, you need to start videoing all the shots you make.

Posted: Thu Jul 10, 2008 11:50 am
by SpudFarm
i will get you damage pics but i will only show them to the people i have on MSN since i won't show it all before i make a good topic about the gun.

the steel plate thread will have pics tho and i will update it with 1/2" plate when i do it

Posted: Thu Jul 10, 2008 1:00 pm
by Xerxys
Hey, mabe if you have a really powerful spark it could of turned some left-over aluminium dust into a plasma, and boom! Just like a Electro-thermal gun.
That would make it a triple Hybrid!(pneumatic/combustion/electrothermal).

Probably impossible though.

But maybe the pressure changes electrothermal properties.

Posted: Thu Jul 10, 2008 3:15 pm
by SpudFarm
OMG you just said something!!

i am going to get Larda to make it, a ETG with a burst disk, chamber fan and aluminium powder!
the fan spreads the powder in the air and he can "ignite" the powder and it will explode super heating the gas to make a detonation!

if this work you have made a new generation of guns!

Posted: Thu Jul 10, 2008 3:32 pm
by Ragnarok
SpudFarm wrote:if this work you have made a new generation of guns!
My suspicion is that it won't (work, that is) - and if it does it'll just be a suspended dust combustion/hybrid, burning the aluminium dust.
There won't be any electrothermal power involved at all, because for that, you expressly need to vaporise the aluminium to a gas, and then ionise it, which creates huge pressures and temperatures.

It wouldn't really be possible to make such a "3 way hybrid", and even if it were, the combustion pressures would be insignificant compared to the plasma pressures.

A 10x hybrid would only just about reach 1000 psi at peak pressures.
Larda's own ETG - around about 20,000 psi (AVERAGE, not peak!) IIRC.

In theory, you could however pass the currents through the combusted gas mixture more effectively, but save under perfectly engineered laboratory conditions, I think the effect would be too hard, and too ineffective to be worth the effort.

Posted: Thu Jul 10, 2008 4:04 pm
by SpudFarm
it should work if you get enough current.. (i am not good in this stuff )

Posted: Fri Jul 11, 2008 12:44 pm
by psycix
SpudFarm wrote:it should work if you get enough current.. (i am not good in this stuff )
Which makes the combustion insignificant compared to the ETG effect.

Posted: Fri Jul 11, 2008 12:46 pm
by SpudFarm
hmm you might be right...

Posted: Mon Jul 14, 2008 4:26 am
by Gunner
Hmm...it would be interesting to see what is the effort if you first shoot just with a normal spark and then next shot with a few kilojoule spark :P.

Posted: Fri Jul 25, 2008 9:12 am
by SpudFarm
i bet Larda can do a test on that when i send my hybrid to him for burst testing

Posted: Fri Jul 25, 2008 10:00 am
by DYI
I believe that, if you want a decent ETG/gas gun-hybrid effect, you'd want to use very high voltage pulse capacitors that discharge directly through the fuel air mix, thus preserving the stoichiometric ratio of gases, rather than discharging them through aluminum or something.

Considering the relationship between pressure and breakdown voltage of gases, you would probably need something in the tens or hundreds of kilovolts. Capacitors like that are expensive (the best deals I've seen on such things so far is a site selling 20kJ, 20kV pulse capacitors for $900 each) even if you get them second hand, so you'd better be damned sure the thing was going to work before you went and invested about 10 grand on a high voltage pulse cap bank.

Perhaps some benefits could be achieved simply by uniform ignition of all the fuel through a larger spark? Say, 1kJ or so discharging through a thin aluminum wire running the length of the chamber. I believe I could probably test that myself in a few months.

Posted: Fri Jul 25, 2008 11:07 am
by SpudFarm
hey you have a pretty decent cap now DYI mabe you can make some tests?

and now that i have my universal fuel and air meter i may consider to do the DDT test with 1/4" steel pipe and a short section of rifled pellet gun barrel.

and if i have the money i can do it with a larger diameter pipe to find out how that effects runup distance