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mini hybrid win!

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: ilovefire » Fri Nov 19, 2010 7:56 am

Insomniac wrote:Perhaps your particular piezo is just too shizenhousen to get the job done?


that is also a large possibility i just have to find somewhere thats sells cheep lighters with them, havent seen those disposable one around yet :(
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Unread postAuthor: Fnord » Fri Nov 19, 2010 12:51 pm

Just to back your hypothesis..
I have noticed that very small gaps tend to be unreliable for standard combustions. My hybrid refused to fire a 1x mix even when the ratio was perfect. The small gap only worked with pressurized fuel/air.

This was with a peizo grill ignitor.
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Unread postAuthor: jackssmirkingrevenge » Fri Nov 19, 2010 2:43 pm

Fnord wrote:I have noticed that very small gaps tend to be unreliable for standard combustions. My hybrid refused to fire a 1x mix even when the ratio was perfect. The small gap only worked with pressurized fuel/air.


I noticed the same with my combustions, a 6mm gap gave me reliable ignition while a 3mm gap gave no ignition at all, with a piezo. If I'm not mistaken it's about the spark arcing across a certain amount of fuel/air molecules, and by pressurising the mix in a hybrid you're increasing the density and therefore reducing the distance the spark needs to arc.
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Unread postAuthor: Insomniac » Fri Nov 19, 2010 5:29 pm

It's possibly got something to do with the air in a very small gap at a low mix not having a high enough resistance, causing the spark to jump without generating enough heat... Or perhaps it just reduces the number of molecules it affects, which reduces the chance of ignition.
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 21, 2010 3:48 pm

Some more experimentation, this time to see how much your average (though extremely funky looking, these are the best designed ones we're ever had :D) laboratory safety glasses would protect you in the event of being shot in the face by a hybrid :)

[youtube]http://www.youtube.com/watch?v=6RLpdGn6HzQ[/youtube]

First shot is a CO<sub>2</sub> capsule from the 0.75" hybrid at 12x, next was a 0.22" pellet from the mini hybrid at 14x.

In both cases, the projectile didn't technically make it through, but judging by the damage to the 1mm thick alloy witness plate, it would likely have made a clear hole through the glasses were it backed with something softer.
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Unread postAuthor: Insomniac » Sun Nov 21, 2010 3:56 pm

jackssmirkingrevenge wrote:Some more experimentation, this time to see how much your average (though extremely funky looking, these are the best designed ones we're ever had :D) laboratory safety glasses would protect you in the event of being shot in the face by a hybrid :)

Image


You're right... they are funky looking! :D

Very interesting however... I wonder how they'd react if they weren't allowed to move...
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 21, 2010 4:29 pm

Insomniac wrote:I wonder how they'd react if they weren't allowed to move...


I'm fairly certain that if it were rigidly supported without a hard backing, the pellet would have made it through with ease. The CO<sub>2</sub> capsule has a lot more kinetic energy but it doesn't have the benefit of velocity, meaning it would still bludgeon its way through as opposed to punching a clean hole.
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Unread postAuthor: ilovefire » Sun Nov 21, 2010 8:41 pm

well i guess all that proves is that safety glasses arnt made for the people with an intention of shooting themselves in the face :roll:
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Unread postAuthor: saefroch » Sun Nov 21, 2010 8:50 pm

Could you test something more like what I wear? It'd be interesting to see if that's really worth all the extra money (even if mine were free :D). I know the Flakjak series has test data out there, but probably not in direct comparison to your average lab series glasses.
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Unread postAuthor: jackssmirkingrevenge » Sun Nov 21, 2010 11:25 pm

ilovefire wrote:well i guess all that proves is that safety glasses arnt made for the people with an intention of shooting themselves in the face :roll:


No consolation for poor Marvinthen :roll: :D

Could you test something more like what I wear? It'd be interesting to see if that's really worth all the extra money


Send me a sample and I'll be more than happy to abuse it kinetically in the name of science, but I'm not going to spend $80 on something just to shoot at it ;)
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Unread postAuthor: ilovefire » Mon Nov 22, 2010 12:14 am

thought i would add some damage pics, damage is to a 8mm x maybe 15mm lead slug after hitting a brick at 27x with a 4ml chamber and a 1m x 8mm barrel
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 22, 2010 12:51 am

Fragmentation win! Any photos of the brick :D and also, since you were shooting at a hard target, I hope you were wearing safety glasses!

How loud is it at 27x?
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Unread postAuthor: ilovefire » Mon Nov 22, 2010 1:29 am

jackssmirkingrevenge wrote:Fragmentation win! Any photos of the brick :D and also, since you were shooting at a hard target, I hope you were wearing safety glasses!

How loud is it at 27x?


i didn't bother to take a photo of the brick because all that happend to it was it got a shiny metallic stain which was disappointing, but if you still want me to im sure i can make that happen and as for safety it had three sides surrounded by wood and for the front i had a newspaper to slow or stop shrapnel but did not effect the entry, i was wearing sunglasses but i know they wouldn't do anything so i looked in the other direction, and it is actually pretty good when i comes to sound because of the very low chamber to barrel ratio its pretty quiet i mean its not silent but its not bad
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 22, 2010 1:47 am

ilovefire wrote:i didn't bother to take a photo of the brick because all that happend to it was it got a shiny metallic stain which was disappointing


Hardly surprising given the frangible nature of the projectile, did you get lead fragments embedded in the wood?
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Unread postAuthor: ilovefire » Mon Nov 22, 2010 1:55 am

not in the side bits because they were solid hard wood blocks but a bit did get lodged in the bit of 1mm ply i had at the top that was covered by some other chunks scrap wood
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