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Hybrid Muzzle Brakes...

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 Muzzle Brakes...

Unread postAuthor: MrCrowley » Fri Nov 19, 2010 8:27 pm

...are probably not a good idea on large bore cannons.

I cut two slits at the end of the barrel on my Mjollnir hybrid canon to sort of act as a muzzle brake. I wasn't really interested in reducing recoil or such I just thought it would look aesthetically better and would have a cool muzzle flash at night. Basically, the slits look like a 2D version of the Sears–Haack body with a maximum diameter of about 11mm in the middle and a length of just under 90mm. One slit was on either side of the barrel and 25mm from the muzzle.

Yesterday my friend fired a blank 10x shot, no projectile, from the cannon and three cracks appeared at the muzzle brake. There was a crack each along the 25mm gap between the muzzle and the start of the slits and also a 30mm long crack at the opposite end of one of the slits.
Needless to say, i'm going to have to cut off a bit of my barrel.

My barrel is a 1.7m length of PN12 ABS, with 6mm wall thickness, so it's nothing to laugh at. I fear if I had decided to go with a typical 'tee fitting' muzzle brake the fitting would have exploded sending bits of plastic everywhere. I have no doubt that had I used PN12 PVC, the barrel would have exploded a long time ago.

Anyway just thought I'd share, i'll try get a picture up soon.
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Unread postAuthor: saefroch » Fri Nov 19, 2010 8:32 pm

:shock: Whoa...

What if you used a metal barrel, or added another piece of ABS to the end as a muzzle brake, instead of just cutting holes in the existing barrel? It might still tear up the additional ABS, but it's a suggestion.
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Unread postAuthor: jrrdw » Fri Nov 19, 2010 9:29 pm

Well we have a saying here in America, goes like this: "If it aint broke, don't fix it!".

You just had to play with it didn't you, now it's broken... :roll:
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Re: Hybrid Muzzle Brakes...

Unread postAuthor: Ragnarok » Fri Nov 19, 2010 9:43 pm

MrCrowley wrote:Basically, the slits look like a 2D version of the Sears–Haack body

To quote Adam Savage: "Well, there's your problem."

That's going to give you sharp corners and major stress concentrations around the "points". Even a round hole with no sharp corners drilled in pipe increases the stress around it by three times (which is why we usually recommend tapping through the double thickness of fittings) - sharp points for cracks to propagate from make it way worse.

For an analogy, the stress concentrations around cracks is why if you cut a nick in fabric, it'll tear down that line really easily - even though it's bloody hard to tear otherwise.

I'm not even vaguely surprised that happened if you chose such a shape. It'd be hard to pick something much worse to cut in a pressure vessel.
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Unread postAuthor: MrCrowley » Fri Nov 19, 2010 9:49 pm

It'd be hard to pick something much worse to cut in a pressure vessel.

Hahahahaha that's bloody great :D

Plain holes are simply to boring for me :roll:
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Unread postAuthor: POLAND_SPUD » Fri Nov 19, 2010 10:00 pm

Plain holes are simply too boring for me
Holes are all about boring anyway

(as in -> boring - noun - The act of drilling) :wink:


anyway
holes are too boring for me
Congrats! you've just passed the gay test
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Unread postAuthor: Technician1002 » Fri Nov 19, 2010 11:11 pm

English 101.. An action is a verb. I waited for someone else to be the grammar police.. A Noun is a person place or thing. A hole is a Noun. The act of boring a hole is a verb.

http://en.wikipedia.org/wiki/Verb
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Unread postAuthor: POLAND_SPUD » Fri Nov 19, 2010 11:44 pm

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Unread postAuthor: Technician1002 » Fri Nov 19, 2010 11:50 pm

The example given is fencing as a sport is a Verb vs White Fencing in your yard a noun. The act of boring a hole is still a verb.
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Unread postAuthor: jackssmirkingrevenge » Sat Nov 20, 2010 12:09 am

Putting the above grammar nazism aside, this is one occasion when I wouldn't object to you calling it a muzzle break :D

Plain holes but lots of them need not be boring, I like what the Ruskis did on their M46 for example:

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Unread postAuthor: POLAND_SPUD » Sat Nov 20, 2010 12:14 am

Verbal nouns (VNs) and deverbal nouns (DVNs) are both nouns formed from verbs (formally, lexicalized nouns derived from or cognate to verbs), but are distinguished syntactic word classes. DVNs differ functionally from VNs in that DVNs operate as autonomous common nouns,[1] while VNs retain verbal characteristics.

For example, gerunds are verbals, not deverbals; compare:

* Fencing is fun. (verbal – an activity; replaceable by the infinitive "to fence")
* The white fencing contributes to the neighborhood character (deverbal – a common noun, replaceable by other nouns like "bench")

and
As applied to English, it refers to the usage of a verb (in its -ing form) as a noun (for example, the verb "learning" in the sentence "Learning is an easy process for some").

and...
http://www.thefreedictionary.com/boring
:wink:


lol don't start this kind of discussion with someone who has better explicit knowledge of your own language than you do... sure your English is a lot better than mine but this kind of stuff is something that most of you don't know
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Unread postAuthor: MrCrowley » Sat Nov 20, 2010 12:49 am

I do have to say, Europeans school the sh|t out of me when it comes to English. Not because they can speak it better than I, which I don't think I have encountered, but because they are taught all the grammar and theory behind our language whereas we are merely brought up speaking it. Sure, we study it in English class but hardly to the extent of which some students in Western Europe study English.

Anyway, enough of that. :)

@JSR,

That does look nice but the reason behind why I attempted to build a muzzle break was more for effect (or is it affect, POLAND? I never can tell :D ) than an actual purpose. A tee muzzle brake would've been better as I wouldn't need to mod the barrel and it looks cooler haha. Maybe I'll try make another one :P
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Unread postAuthor: SpudBlaster15 » Sat Nov 20, 2010 1:10 am

Sharp corners do increase stress concentration, but I'm surprised that the pressure at the end of the barrel was sufficiently high to cause a failure, especially with only a tube of air as the projectile.

As for alternative designs, I tested a muzzle brake on my hybrid back in the summer. It essentially consisted of a double Y fitting held onto the end of the barrel by an octet of setscrews. It worked reasonably well, but the attachment method was always suspect. I think it has potential though.
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Unread postAuthor: jackssmirkingrevenge » Sat Nov 20, 2010 1:19 am

MrCrowley wrote:I do have to say, Europeans school the sh|t out of me when it comes to English. Not because they can speak it better than I, which I don't think I have encountered, but because they are taught all the grammar and theory behind our language whereas we are merely brought up speaking it. Sure, we study it in English class but hardly to the extent of which some students in Western Europe study English.


Couldn't agree more, and it does get slightly awkward when you correct someone on their use of their native language.

That does look nice but the reason behind why I attempted to build a muzzle break was more for effect (or is it affect, POLAND? I never can tell :D ) than an actual purpose.


If by "effect" (it is effect, by the way ;)) you mean "cool looking muzzle flash" then multiple holes will do it too.

By the way think of the pistol as a DCV piloted pneumatic and POLAND probably looks a little like David Mitchell :D

[youtube]http://www.youtube.com/watch?v=c3y0CD2CoCs[/youtube]
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Unread postAuthor: POLAND_SPUD » Sat Nov 20, 2010 1:23 am

well the difference between affect and effect is pretty well explained... in your context you should use 'for effect'

Though it seems that you can also use 'more for affect', but with different meaning
As in 'I yelled for her to stop but it was more for affect because she wasn't going to stop'
:wink:

@JSR
Hey I am not a grammar nazi. Technician started this pointless discussion by stating that 'boring' can't be a noun
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Last edited by POLAND_SPUD on Sat Nov 20, 2010 1:33 am, edited 1 time in total.
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