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another hybrid...

Built a hybrid cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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another hybrid...

Unread postAuthor: MrCrowley » Thu May 12, 2011 2:58 am

...well someone has to keep this showcase section alive :D

Nothing really interesting here just my old M480 hybrid put back together and changed up a little bit after I disassembled it when making the Mjöllnir cannon.

This cannon uses the same fuel metering setup as Mjöllnir. I really love using manometric fueling, makes things like this much easier plus i'm having more success with this cannon compared to when it used to have volumetric fueling.

Chamber is 1.25" with some 1" fittings. Union is 3/4". I use MAPP gas up to 10x mixes and use 4 orings to seal the modified union. I have 15mm and 20mm copper barrels and a 44mm aluminium barrel that will be used for golf balls and the likes. I should still see supersonic golf balls even though the barrel is only a meter long so the cannon still packs a punch.

Anyway I hope this shows the doubters how easy it can be to build a hybrid. $50 of plumbing fittings, couple of gauges and a MAPP bottle. I feel safer firing this than any of my PVC cannons funnily enough.

P.S. I don't care that it looks like sh|t, the beauty is on the inside :wink:
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Unread postAuthor: Labtecpower » Thu May 12, 2011 7:43 am

well, it looks like sh|t. :roll:

I don't think it is difficult to build a hybrid... It just seems very complicated with fuel metering, and pressurisation... i'm currently designing one, but hybrids are still creepy things to me. :P
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Unread postAuthor: jackssmirkingrevenge » Thu May 12, 2011 7:51 am

Labtecpower wrote:well, it looks like sh|t. :roll:



Pretty is as pretty does, and so far we haven't seen it in action ;)

I don't think it is difficult to build a hybrid... It just seems very complicated with fuel metering, and pressurisation.


I used to think the same, butit doesn't have to be complicated.
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Unread postAuthor: Labtecpower » Thu May 12, 2011 8:17 am

I read that part before :)

I found some 30 mm aluminium tubing with 2 mm walls in my local hardware store. Would this be good for a 11x mix hybrid? calculated burst pressure is 146 bar.

P=(2t*S)/O

P=pressure
t=wall thickness in inches
S=tensile strength in PSI
O=outside diameter in inches

t=0.0787
S=15954.1512
O=1.18

P=(2*0.0787*15954.1512)/1.18=2128 psi=143 BAR.
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Unread postAuthor: Doctore » Thu May 12, 2011 8:22 am

Awesome
I love it!!!!
We want to see damage pictures!!!
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Unread postAuthor: jackssmirkingrevenge » Thu May 12, 2011 8:26 am

Labtecpower wrote:I found some 30 mm aluminium tubing with 2 mm walls in my local hardware store. Would this be good for a 11x mix hybrid? calculated burst pressure is 146 bar.


That sounds about right. Will you be using epoxy endcaps?
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Unread postAuthor: Labtecpower » Thu May 12, 2011 8:29 am

jackssmirkingrevenge wrote:That sounds about right. Will you be using epoxy endcaps?


well. what do you think yourself? I have a lathe within reach :D
But, an important pro-epoxy claim is that it won't weaken the chamber.

before going with aluminium I will call a pipe manufacturer for cold-drawn hydraulics tube, wich is much stronger, and easier to weld.
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Unread postAuthor: jackssmirkingrevenge » Thu May 12, 2011 8:33 am

Labtecpower wrote:I have a lathe within reach :D
But, an important pro-epoxy claim is that it won't weaken the chamber.


I would definitely not thread a 2mm wall thickness pipe. You could compromise and machine ali endcaps then epoxy them in place :)
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Unread postAuthor: Labtecpower » Thu May 12, 2011 8:53 am

I think I will go with steel pipe, with sufficient wall thickness. In that way I can just thread the inside, and keep the whole thing serviceable.

The only problem is that nice steel pipes are mostly distributed by companies that are not interested in selling to individuals, especially not when they don't need more than 1 meter. I had the same problem with O-rings for my QDV.

Another thing is that I would like to take the gun to 20x mix eventually, if I make myself a nice pump.


oh, and MrCrowley, Any chance of some damage pics? (or vids)
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Unread postAuthor: jackssmirkingrevenge » Thu May 12, 2011 9:31 am

Labtecpower wrote:I think I will go with steel pipe, with sufficient wall thickness. In that way I can just thread the inside, and keep the whole thing serviceable.


If you can, go for it, though really with no moving parts you don't need it to be "servicable", unless you're using an ignition source strong enough to wear out the electrodes.
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Unread postAuthor: Labtecpower » Thu May 12, 2011 10:02 am

It will be a piston hybrid. I don't feel like putting in new burst disks every shot :roll:

I want to be able to clean and check the inside of the chamber.

I sent a mail to a pipe company near my house, so i'll wait for a response.
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Unread postAuthor: MrCrowley » Thu May 12, 2011 10:52 pm

I don't think it is difficult to build a hybrid... It just seems very complicated with fuel metering, and pressurisation.

It requires very basic math and that's about it. All I have to remember is that 0.71PSI of MAPP gas in the chamber per mix (n). A 5x shot has 3.55PSI of MAPP for example.

So: (0.71 x n) + (14.7 x (n-1))
Takes about 10 seconds to figure out in my head and the rest is reading a gauge. I think it's easier than volumetric because the chamber volume is irrelevant and the fueling is simplified where you are only dealing in fuel pressures from 0-10PSI.

oh, and MrCrowley, Any chance of some damage pics? (or vids)

Perhaps this weekend. I made this cannon to take up to my friends bach (holiday house) in early June. If you've seen the video for my Mjollnir cannon, that was filmed up there.
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Unread postAuthor: irisher » Thu May 12, 2011 11:09 pm

The only problem is that nice steel pipes are mostly distributed by companies that are not interested in selling to individuals

I would do some more looking online, Try speedymetals or onlinemetals, I was able to get a 18" segments of aluminum with .25" wall thickness for only $20 and that was 3.75" diameter so with 30mm it should be pretty darn cheap.
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Unread postAuthor: Labtecpower » Fri May 13, 2011 12:21 am

irisher wrote:I would do some more looking online, Try speedymetals or onlinemetals, I was able to get a 18" segments of aluminum with .25" wall thickness for only $20 and that was 3.75" diameter so with 30mm it should be pretty darn cheap.


Thank you for your suggestion.
I want strong steel tubes,however, because they can take about 4 times more pressure, and if I thread them, the threads are less likely to fail.
Aluminium is also harder to weld for me, and the welds need to be perfect, because I want to fire this thing from my shoulder.
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Unread postAuthor: irisher » Fri May 13, 2011 8:13 pm

I would still take a look though. They carry a wide a variety of steel and iron pipe as well.
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