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A Plan of Action

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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A Plan of Action

Unread postAuthor: mark.f » Tue Jun 05, 2007 8:58 am

Well, I'm sure most of you remember a guy named iusemyopensights a while ago posting a hybrid, 2" chamber, golfball barrel, simple construction?

Well, way back then, I was feeling kind of weird, and felt I needed to build something not just to show it off, but to use it.

Well, I'm that guy. I built that hybrid and I've still got it. It works great, but I'm ready to move on to something better.

I plan to use the same simple construction as the first. And endcap on the back, and a coupling in front of it so I can install the spark gap before capping off the back. There were some problems with the spark gap with the original, so I plan on using brass threaded rod for a better conductor, and an actual BBQ sparker instead of an aim n' flame piezo. I also plan on making the gap smaller, as last time it was too wide, and there's no adjusting the gap after the launchers capped because there are double hex nuts inside and out.

Also, I plan on making the barrel MUCH longer. I was limited by my 5' of 2" SCH-80 last time from McMaster, but I've finally found a retailer over in Pearl River where I can buy a 10' stick of continuous SCH-80.

I plan to have maybe a little over an 18" chamber of 2" SCH-80, and a barrel 96" long, (8'), with 1-1/2" SDR-21 sleeved inside for golfballs.

Same basic ignition and fueling system. I'm going to use a block and tackle pulley system and a string for remote ignition using the BBQ igniter. Only question now is performance.

I definitely feel confident in this launcher's ability to break the speed of sound. If anybody has any doubts, I would like to hear your reasons. I think the high-heat and pressures will allow the cannon to accelerate the golf-ball past the speed of sound, with this long of a barrel.

I would definitely like to hear your thoughts and comments on this. Thanks.
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Unread postAuthor: iusemyopensights » Tue Jun 05, 2007 9:01 am

And just in case anybody thinks I'm just trying to steal somebody else's work, I'm not.

Sorry to PCGUY and any moderators who disapprove of me creating another account. I won't use this one anymore and it can be deleted from the memberlist if desired.
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Unread postAuthor: flamerz14 » Tue Jun 05, 2007 9:12 am

Breaking the sound barrier would be SO cool but then again dangerous...the air/gas you want to use in the hybrind should be less dense than air itself(i.e.: helium).Although hydrogen is lighter, DO NOT USE! as it practically nees a a steel chamber.which might also not work dueto the force of the blast.
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Unread postAuthor: spudthug » Tue Jun 05, 2007 9:14 am

i am in the middle of building a hybrid to..well actually its done i jsut ned to get my stun gun..its in the mail.. instead of a spark gap that is too big why not use a spark plug? then u know that it will always work because spark plugs are the most reliable..even 2 spark plugs in a circuit...

what size union are you using? i suggest a union one size bigger than your barrel...so ur using 1 1/4 i would use a 1 1/2 union.

also for your size barrel isnt the chamber a bit small? im not an expert with chamber to barrel sizes though so i may be wrong... although isnt it unsafe to sue over 2 inch pvc for a hybrid?

what mixes are u going to be using? up to 4x? i may be using 6x in my hybrid...

oh and btw flamerz helium isnt flammable :wink:
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Unread postAuthor: mark.f » Tue Jun 05, 2007 9:25 am

The barrel size is 1-1/2 SDR-21. I will be using a 2" union for simplicity.

The C:B ratio I'm going to try to use is .25:1. I am also going to limit myself to a 4x mix.
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Unread postAuthor: spudthug » Tue Jun 05, 2007 9:30 am

oo 1 1/2 oops... i meant the chamber being small in size... but anyway...

what gas are u using? propane,mapp, or wat?
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Unread postAuthor: mark.f » Tue Jun 05, 2007 10:03 am

Most probably propane. MAPP can be used if propane doesn't have enough oomph.
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Unread postAuthor: spudthug » Tue Jun 05, 2007 8:23 pm

quick question for you guys.. can u use c02 in a hybrid or is it to dewnse and wont light with propane?
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Unread postAuthor: ShowNoMercy » Tue Jun 05, 2007 8:24 pm

Its an inert gas so it wont help the explosion at all, and I am pretty sure that you would not benefit from it being there, You would have to add even more flammable gas and air.
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Unread postAuthor: mopherman » Tue Jun 05, 2007 8:29 pm

spudthug wrote:quick question for you guys.. can u use c02 in a hybrid or is it to dewnse and wont light with propane?

I thought that the whole point was to have more oxygen so you could burn more propane. I dont think c02 has oxygen. so..... no
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Unread postAuthor: A-98 » Tue Jun 05, 2007 9:09 pm

@spudthug. im guessing you want to use c02 to acheive the pressures of a higher mix (not really that high for lower mixes, but lets say your going for a 10x mix). i would say use n2o paintball tanks, which are just compressed air. but if your reaching insane mixes like that, ill give you a cookie.
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Unread postAuthor: ShowNoMercy » Tue Jun 05, 2007 9:10 pm

But even if you start using this high pressure, wouldnt that require a new burst disk to hold that pressure?
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Unread postAuthor: Velocity » Tue Jun 05, 2007 9:57 pm

I liked that hybrid posted way back when... and this one should be even better. The simplicity leads to clean construction, and this is definitely a good thing.

I don't think the old one had a gen II fueling setup, so why not make one for this cannon? If you are worried about issues about portability, you could always get someone to machine you a piston, and then pump compressed air to the other side of the piston, which would then compress the fuel mixture... I have had this idea for a while, but I have never put it into practice.

I wish I could build a cannon with a 10' barrel; I have no where to store it though, and if I wanted to shoot the darn thing, I would need to transport the barrel, and right now I can't do that either.

Oh well
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Unread postAuthor: spudthug » Tue Jun 05, 2007 10:13 pm

1. i am not planning on using it i was jsut wondering if it would work..

I dont think c02 has oxygen. so..... no


well..thats one of the stupidest things i've ever heard...(not saying ur stupid but its simple) a question for u...what does c stand for on the periodic table and what does o stand for...carbon and oxygen. O2 is what we breathe mixed with nitrogen..and O2 is in CO2

CO2=1 part carbon 2 parts oxygen...what i was wondering is if the carbon would allow it to burn although it is very dense...
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Unread postAuthor: mopherman » Tue Jun 05, 2007 10:16 pm

rmich732 wrote:I liked that hybrid posted way back when... and this one should be even better. The simplicity leads to clean construction, and this is definitely a good thing.

I don't think the old one had a gen II fueling setup, so why not make one for this cannon? If you are worried about issues about portability, you could always get someone to machine you a piston, and then pump compressed air to the other side of the piston, which would then compress the fuel mixture... I have had this idea for a while, but I have never put it into practice.

Oh well

the only problem with that design is that if you got fuel behind the piston, it wouldnt move because it would blow on both sides. a very good piston with a check valve and o-rings could posibly remedy this, but sounds a bit fiddly to me.
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