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9x mix and beyond Pneumatic cilinder

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: dongfang » Wed Jun 20, 2007 1:02 am

sandman:

That´s right, Powerlabs was the name.

I think he´s great too, but I don´t give a thing for his claims of -- how many miles of range were that -- with his final cannon.

PS: According to my calculations you can still do a supersonic GB with gas guns. Please stay with us - alive, out of jail, and on Spudfiles ;)

Regards
Soren
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Unread postAuthor: Hotwired » Wed Jun 20, 2007 4:03 am

Ahh, 6 miles with a golfball is nothing, I can hit one farther than that :D

I'd be interested to know how this goes. It will probably never explode even if the mixture did find it in itself to detonate but the results of a 9x mix should be pretty spectacular.
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Unread postAuthor: CannonBall » Wed Jun 20, 2007 7:41 am

spudthug wrote:
Now now spudthug just because he doesn't average 10 posts per day doesn't mean he can't handle himself or has never done this before...

I think your chamber can handle the pressure, but fining the rest of the parts you need rated at that kind of pressure is going to be costly. In the end, this will probably cost you hundreds of dollars to build.

You should do a lot of research on fuels, gasoline alone probably isn't enough. Something like jet fuel would be more appropriate under that kind of pressure, not that I know how the hell you are going to get your hands on any such thing.


jj how about u stop telling me to not say things to new people..he is new but he knows about things post count doesnt matter. u have tried to tell me off in like 5 threads yet u have no effing clue what you are talking about and u have built 1 functional gun...and one that u blow into...so u shut the hell up.....

@cannonball

i wasnt trying to get u down or anything i was jsut saying that i didnt know if u could get ur hands on parts that strong+ a compressor to get pressures that high..9x is around 110 psi is it not? a hybrid with 110 psi already in it before combustion happens is scary as hell...u do know about ddt right? because before u go anywhere near 9x u should test immensly from 5x up..like 20 tests+ at each mix above 4x...

and u probably know that remote ignition is a must for anything over a 4x hybrid...




I sure do know about ddt cause i build my own explosives.. icluding guncotton as sayd above...
But i only make powerfull explosives like MHN VOD = aproxx 8000 meters a sec.
So i know detonation.

As i have no camera i cant post a picture of the cilinder :( to bad but ill try to fix one to get a picture.

remote ignition is no problem i did a motor education as well so i know enough about car electronics ... im gone use the ignition coil.....

And yes gasoline is liquid at room.. but it gives of gas that u can compress to more then 20 bar. so a 20x mix is fairly possible. :twisted:
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Unread postAuthor: psycix » Tue Jul 03, 2007 9:11 am

Well if all parts are strong enough to resist the immense power, build it!
But will propane go liquid after a few bar then? Thought it could be compressed....

But anyways, goodluck on building it, we cant wait to hear the first results.
Be careful m8.
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Unread postAuthor: veginator » Tue Jul 03, 2007 10:05 am

HOLY S***!! We seriously need to keep track of the fastest projectiles fired from a spud gun.
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Unread postAuthor: CannonBall » Tue Jul 03, 2007 10:56 am

psycix wrote:Well if all parts are strong enough to resist the immense power, build it!
But will propane go liquid after a few bar then? Thought it could be compressed....

But anyways, goodluck on building it, we cant wait to hear the first results.
Be careful m8.




Read well my friend i use gasoline.... you can compress it more than 20x mix :wink:

Hope this cannon wil reach mach2 with 20x mix

Its in construction wright now.. its at my friend he is a pro welder. so i let him weld the whole thing.
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Unread postAuthor: psycix » Wed Jul 04, 2007 3:01 am

Cool i hope it works :)

You will be making a vid eh? ;) :P

When will it be done?
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Unread postAuthor: pyrogeek » Thu Jul 26, 2007 1:56 am

ok, a detonation is when an explosive burns at the speed of sound...mach.
So, how can you get something to burn at that speed, without detting? I'm just curious. I know you can get a round in a firearm to reach supersonic speeds (like .223 Rem), and that's why you can set off Tannerite.

Also, I think that propane is held at 100PSI (approximately at room temp). This has a lot to do with temperture though. So at a higher temperture, you could get propane to remain a liquid at a higher pressure.

If you can get the parts though, and have the land and equipment to do a 9 to 20x gun, DO IT! I really want to see it.
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Unread postAuthor: DYI » Thu Jul 26, 2007 11:16 am

Rounds fired from firearms can go supersonic because the gases pushing them are very hot, so they have a much higher speed of sound, allowing them to push a round to supersonic speeds without detonation occurring. This is also why some hybrids can fire things supersonic without detonations occurring, because the gases pushing them are so hot (>4000 degrees fahrenheit). A detonation is when the flamefront in a combustion exceeds the speed of sound in whatever medium it is in. In the hot gases combustion generates, the speed of sound is quite high.
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Unread postAuthor: pyrogeek » Thu Jul 26, 2007 12:55 pm

Ok, that makes a lot of sense. So theoretically, you could use a 9x mixture as long as it was hot enough. Would propylene work as the fuel?
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Unread postAuthor: DYI » Thu Jul 26, 2007 1:06 pm

I don't really understand what you mean
So theoretically, you could use a 9x mixture as long as it was hot enough.

Propylene would probably work as a fuel, but isn't propane cheaper?
The chance of DDT occurring rises when the mix is presurised before combustion, the more initial pressure, the greater the risk of DDT. Larger chambers (especially long ones) increase the risk even more. With a small enough chamber, DDT would be very unlikely at 9x (look at gasoline engines), but I still wouldn't want to be near it when it went off.
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Unread postAuthor: iknowmy3tables » Thu Jul 26, 2007 2:24 pm

it still doesn't make sense gasoilnie gives off vapor but gas won't change phase if its compresed so unless its heated to compensate for presure, this would mean any container that holds gasoilne must be rated to 20bar
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Unread postAuthor: DYI » Thu Jul 26, 2007 2:29 pm

The first part makes sense, but heating it would make the pressure even worse. You could always put gasoline in an airtight container with a pressure gauge and leave it for a while to see what happens. For some reason though, I think that there is more to it than that. You should ask someone smart like BLB or BC. They would probably have a good answer.
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Unread postAuthor: paaiyan » Thu Jul 26, 2007 2:44 pm

What you need to do is look up the phase diagrams for various gasses and find the one which changes to a liquid at the highest pressure. The one with the highest point of liquefaction will be the one that requires less heat to maintain a gasseous phase at 9x pressures.

EDIT: <img src="http://www.cbu.edu/~mcondren/water-phase-diagram.jpg">

This is what a phase diagram looks like. Point A is actually the point at which it is possible for all three phases to exist at once, this is called the triple point. Point C is the critical point, after you reach this point, liquid and gas are no longer distinguishable. Line CD is the border betwen solid/gas and liquid/gas depending on temperature. You want to find that gas for which this line is the highest in terms of pressure at temperature=0*C.
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Unread postAuthor: Jumpin Jehosaphat » Thu Jul 26, 2007 3:10 pm

I've never actually seen a good database of phase diagrams.
I've only seen them in textbooks, and they are usually phase diagrams for water like the one shown above. Do you have any good links to where we can look them up?
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