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Hybrid Q's From Crowley

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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Hybrid Q's From Crowley

Unread postAuthor: MrCrowley » Thu Jan 31, 2008 2:27 am

Starting to get bored and thought I might make a hybrid to kick school of with a bang :)

Anyway, just got a few Q's for the more knowledgeable.

I'm planning on shooting .177" metal BB's, projectiles around .3" and maybe 3/4" marble sized projectiles.

1) Chamber size, what sized chamber do you think I should go with for decent results. I was thinking maybe 9" of 1.25" steel pipe. Tad over-kill for the BB's but oh well.

2) Union, should I have multiple unions for each barrel, or just have one? If the latter option, what size should I make it?

3) I'll probably be using MAPP gas, would a spark plug with it's pre-set spark gap be fine for this? Or will I need to make the gap smaller?

4) Would tapping and epoxying a spark plug into the chamber be fine for mixes up to 6x? It's not going to be remote-ignition, so I just want to make sure.

5) I understand some have trouble getting burst disks to seal in their unions. I saw SB15's thread where he modded his, anyone else have their own way dealing with this problem?

Thanks, and yes SB15 it'll probably end up being similar to yours, the one many others have copied :wink:
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Unread postAuthor: Novacastrian » Thu Jan 31, 2008 2:36 am

I so want to help MrC however all of my parts (excluding ball valves-gauges) have been machined to my specific needs. As such when it comes to pre bought items i am lost.
Your sparkplug should be fine- as long as you tap it in.
I would go against multiple unions- just get it to work first. The French member we have would be able to help you i think.
I really wish i could be of more help- if you need any parts machined i can do that :P It's only a stones throw to kiwi land!
I wish you every success :)

BTW a 100ml chamber would be awesome for bb's.
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Unread postAuthor: MrCrowley » Thu Jan 31, 2008 2:41 am

Haha thanks anyway. I shouldn't need any machined parts if all goes to plan, which it never does but hey sh|t happens.

I've just been stuck at 120psi for far too long, it eventually gets to you and eats away at you from the inside. :)

BTW...

What do you call 15 people sitting around a TV watching the Rugby World Cup Finals?













The All Blacks! :D

God that is so wrong for me to laugh at.
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Unread postAuthor: jackssmirkingrevenge » Thu Jan 31, 2008 2:43 am

God that is so wrong for me to laugh at.


So much for Kiwi pride :roll: good one though :D
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Unread postAuthor: Novacastrian » Thu Jan 31, 2008 2:44 am

Hehe, lucky you are from Auckland- the rest of your country hates you already! :D
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Unread postAuthor: rna_duelers » Thu Jan 31, 2008 2:48 am

It's so true!The Auckland bit any way.

I to have the sting of 120psi,always wanted to build a hybrid but. . .I don't think it's going to happen I even have my chamber out there but something is stopping me from doing it,possibly the fact that they take to much time and money.

Go for it,but I do think the 9" of pipe is overkill and longer thinner pipes are more likely to have DDT.Try and have a Spherical chamber if you can the best performance is achievable through that.
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Unread postAuthor: MrCrowley » Thu Jan 31, 2008 2:48 am

Novacastrian wrote:Hehe, lucky you are from Auckland- the rest of your country hates you already! :D


Hahaha :lol: So true.

rna_duelers wrote:Go for it,but I do think the 9" of pipe is overkill and longer thinner pipes are more likely to have DDT.Try and have a Spherical chamber if you can the best performance is achievable through that.


Yeah I know, I just didn't want a choad for my chamber :D
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Unread postAuthor: Eddbot » Thu Jan 31, 2008 2:51 am

wow, are rugby championships the same time of year as american football superbowls, i'm assuming that joke was brought up because it has to do with current events in...New Zealand? i don't know what kiwi land is...
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Unread postAuthor: MrCrowley » Thu Jan 31, 2008 2:57 am

Eddbot wrote:wow, are rugby championships the same time of year as american football superbowls, i'm assuming that joke was brought up because it has to do with current events in...New Zealand? i don't know what kiwi land is...


Rugby World Cups are during Winter, so depending on what country they are in, the month changes.

Yeah we lost to France in the Rugby World Cup, don't think we even got in the semi's and we're supposed to be the best team in the World.

Kiwi-Land = New Zealand. A Kiwi is a NZ flightless bird, and sometimes NZ'ers and referred to as Kiwi's.

Spose I gotta await for SB15 to get out of school so I can get some more advice :)
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Last edited by MrCrowley on Thu Jan 31, 2008 3:00 am, edited 1 time in total.
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Unread postAuthor: rna_duelers » Thu Jan 31, 2008 2:57 am

Eddbot has a valid point,it should be re-named kiwiland.

Please don't refer to your game as football. . .It's an insult to all other codes of real football.

Nova-You could machine a spherical chamber could you not?Joined in two halves some how,I wonder the power increases with using a spherical chamber are actually noticeable in velocity compared to a cylinder chamber of the same volume.
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Unread postAuthor: Killjoy » Thu Jan 31, 2008 3:18 am

Please don't refer to your game as football. . .It's an insult to all other codes of real football.


You do realize that american football is called....wait for it...football. How else are we supposed to refer to it if not by its name? And since when is it an insult to "other codes of football"?

Anyways crowley,
1)1.25" pipe would probably be fine, even for a bb barrel. Overkill maybe, but who cares. It would also allow you to use larger barrels so it would probably be a good bet to use that to allow the hybrid to be versatile.

2)You should also be able to use just one union, except for maybe the bb barrel. In that case you would probably ahve to make one such as jsr did with his attempted mini hybrid a while back. There also might be a problem with the burst disk material getting caught in the barrel if the union is a much larger size then the barrel, btu if you use tinfoil you'll probably be fine.

3)You could epoxy a spark plug and it would probably be fine, but to be sure its pretty damn safe, you may want to consider making you own spark gap. All you need is a threaded plug, wire, and a little epoxy and just bend the wire so it has a small spark gap and then seal evrythign with epoxy.

4) I'm not sure about spark gap size for mapp gas, I would assume the gap on a spark plug would probably work fine.

5)I have yet to use a union on a hybrid, I prefer using layers of duct tape to form a seal with something strong (like wood, foil, or soda can metal), and then clamp it down by tightening bolts connected to a coupler. I use this method on FEAR as well as another hybrid with great success and a perfect seal everytime.
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Unread postAuthor: MrCrowley » Thu Jan 31, 2008 3:22 am

Okay thanks alot for that Killjoy. :)

Edit: I see what you mean with JSR's design, might look into that.
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Unread postAuthor: Killjoy » Thu Jan 31, 2008 3:28 am

Sure thing, jsut trying to help.
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Unread postAuthor: MrCrowley » Thu Jan 31, 2008 3:33 am

Oh and RNA was meaning because in NFL you hardly kick the ball compared to Soccer, or even Rugby for that matter, it doesn't deserve the name of American Football. :)
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Unread postAuthor: Killjoy » Thu Jan 31, 2008 3:50 am

Ah ok got it, but still it's a little late to change the name now haha. The name "American Football" seems to be alright, helps seperate the real football from the "fake" I guess.
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