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Will I die a horrible bloody death?

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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Will I die a horrible bloody death?

Unread postAuthor: Necrosis » Thu May 22, 2008 7:15 am

I am using a 50 mm OD stainless steel pipe with a wall thickness of 1 mm.. (ID is 48 ).. How high of a mix can I go with it?

Thanks in advance.
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Unread postAuthor: sniper hero » Thu May 22, 2008 7:32 am

haha the name of this topic :D
I have no expierience with hybrids.
picture will help a lot.
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Unread postAuthor: Necrosis » Thu May 22, 2008 7:37 am

This is the pipe.. with an endcap in it.
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Unread postAuthor: jrrdw » Thu May 22, 2008 7:50 am

Necrosis, you need to research the strenth of the pipe you want to use, specs from the manufacture would be best. Sounds like you should also do some research on the fuel you want to use. Maby you shouldn't even try this because you admittingly don't know what your doing. Don't want to hurt yourself by making advoidable mistakes.
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Re: Will I die a horrible bloody death?

Unread postAuthor: D_Hall » Thu May 22, 2008 11:11 am

Necrosis wrote:I am using a 50 mm OD stainless steel pipe with a wall thickness of 1 mm.. (ID is 48 ).. How high of a mix can I go with it?

Thanks in advance.


ROUGHLY speaking.....

Figure with stainless you've got a yield stress of 60 ksi (could be more, but since we don't know what you've got that's the number I'm rolling with).

Yield = ID*Pressure / (2*WallThickness)

=>

2 * WallThickness * Yield / ID = Pressure

= 2 * .0787 * 60e3 / 1.890 = 5,000 psi.

But that's FAILURE. That is not what's SAFE to work with.

For safety, divide by 5-10 (depending on how safe you like to be).

So I'd say you're good for 500-1000 psi.


Note: That also assumes we're talking about seamless tubing. If there are welds, I'd split it in half. Call it 250-500 psi.
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Unread postAuthor: SpudFarm » Thu May 22, 2008 2:41 pm

remember it is hydraulic tube like that with walls just a little thicker so i think you are good.

to answer your question i would have sticked to 6x
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Unread postAuthor: DYI » Thu May 22, 2008 3:20 pm

Safety factors also depend on the consequences of failure; i.e. if you're planning on igniting it from 100 yards away behind a foot of steel, you probably don't need a safety factor of 10. If you plan on actually holding it in your hands... Then a factor of at least 5, preferably more, should be incorporated.
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Unread postAuthor: willarddaniels » Thu May 22, 2008 5:30 pm

The title "kills" me, Necrosis.
I can't add too much more to what has been suggested, as they seem to be right on.
To answer the question of your title: Probably not. You may die a bloody death, but you would most likely be knocked unconsious to realize how horrible the death is. So, from your perspective it would not be so horrible (asside from the whole death part); but from an observers perspective, I think it is safe to assume they would think "horrible" might be an accurate word to use in describing your bloody corpse convulsing on the ground.

Cheers!
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Unread postAuthor: joestue » Thu May 22, 2008 10:30 pm

get 2 more end caps, and a 4 inch or longer section and destructively test it.

no way else to be sure
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Unread postAuthor: Necrosis » Fri May 23, 2008 4:47 am

willarddaniels wrote:The title "kills" me, Necrosis.
I can't add too much more to what has been suggested, as they seem to be right on.
To answer the question of your title: Probably not. You may die a bloody death, but you would most likely be knocked unconsious to realize how horrible the death is. So, from your perspective it would not be so horrible (asside from the whole death part); but from an observers perspective, I think it is safe to assume they would think "horrible" might be an accurate word to use in describing your bloody corpse convulsing on the ground.

Cheers!


The title was a joke.. Somewhat.
That message cracked me up though. :)

I'll get some real good pipe on saturday.. that's been rated for 300-600 bar (depending on what's lying around).

Thanks for not getting me killed!
:wink:
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Unread postAuthor: jrrdw » Fri May 23, 2008 6:20 am

Thanks for not getting me killed!


Thats all up to you my friend, not the members of Spudfiles..... :wink:

No joke there, I'm glad you decided to be safe!
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Unread postAuthor: Necrosis » Sat May 24, 2008 2:04 pm

I got some 3mm thick steel pipe, rated for hydraulics applications now.

That would do the trick, right?

*edit* ID is 42mm

It's a bit small. But I'm now worried about the piston.
It's going to be quite heavy so it will only start moving when enough pressure is built..
this will cause tremendous kick..Wich is both awesome and dangerous
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Last edited by Necrosis on Sat May 24, 2008 2:40 pm, edited 1 time in total.
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Unread postAuthor: SpudFarm » Sat May 24, 2008 2:08 pm

that is the same as the barrel for my golf ball cannon.

that should be good for 20x. try to put a golf ball in to look if it is the same pipe
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Unread postAuthor: Larda » Sat May 24, 2008 8:47 pm

Spudfarm, your barrel is 50*3,5 so its 43mm ID
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