Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 45 users online :: 4 registered, 0 hidden and 41 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Army drinks bottle combustion chamber?

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
Sponsored 
  • Author
    Message

Army drinks bottle combustion chamber?

Unread postAuthor: ALIHISGREAT » Sat Dec 20, 2008 11:09 am

Image

would this make a suitable combustion chamber? i have one spare lying around and its made of pretty tough stuff obviously because its army issue so needs to be strong, i'm unsure of the plastic its made of though.

its 1000cc and i'd epoxy a 1.5" or maybe 28mm copper barrel to the cap and i'd have a ready made burst disc holder!

Thoughts?
  • 0

<a href="http://www.bungie.net/stats/halo3/default.aspx?player=ALI H IS GREAT"><img src="http://www.bungie.net/card/halo3/ALI H IS GREAT.ashx"></a>
Image
User avatar
ALIHISGREAT
Major General
Major General
 
Posts: 1779
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK
Reputation: 0

Unread postAuthor: pizlo » Sat Dec 20, 2008 11:33 am

Is it rigid plastic of sort of bendable?
  • 0

User avatar
pizlo
Brigadier General
Brigadier General
 
Posts: 783
Joined: Fri Dec 22, 2006 7:27 pm
Reputation: 0

Unread postAuthor: Ragnarok » Sat Dec 20, 2008 11:36 am

No, not a good choice.

I've tested similar shapes and materials, and they don't fare well.
Seriously, I've said it before, and will no doubt say it again, things that have a non-circular cross section are not suitable for pressure use.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: john bunsenburner » Sat Dec 20, 2008 11:41 am

How come rag? I have figured it because i have not seen many rectangular chambers but i never understood quite why...
  • 0

"Did you ever stop to think that out of the seven deadly sins envy is the only one which doesn't give the sinner even momentary pleasure"-George Will
User avatar
john bunsenburner
Major General
Major General
 
Posts: 1446
Joined: Sun Oct 19, 2008 5:13 am
Reputation: 0

Unread postAuthor: ALIHISGREAT » Sat Dec 20, 2008 12:12 pm

Ragnarok wrote:No, not a good choice.

I've tested similar shapes and materials, and they don't fare well.
Seriously, I've said it before, and will no doubt say it again, things that have a non-circular cross section are not suitable for pressure use.


ahh well...
  • 0

<a href="http://www.bungie.net/stats/halo3/default.aspx?player=ALI H IS GREAT"><img src="http://www.bungie.net/card/halo3/ALI H IS GREAT.ashx"></a>
Image
User avatar
ALIHISGREAT
Major General
Major General
 
Posts: 1779
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK
Reputation: 0

Unread postAuthor: Ragnarok » Sat Dec 20, 2008 12:53 pm

john bunsenburner wrote:How come rag? I have figured it because i have not seen many rectangular chambers but i never understood quite why...

It creates uneven forces around the circumference.

Take a balloon, and blow it up. It automatically takes a circular shape, because that's where the forces are balanced. Squash in the sides, it will spring back.

You might argue that's because the balloon's made that way (To which I say, if that's the case, then why don't they make oval balloons as well?), but if you take say a plastic milk jug, which is naturally near rectangular or square and blow into it (or alternately, fill it with water and freeze it), you can see the sides bowing out.
Any vessel with pressure in it naturally tries to expand out to a circular shape.

If that vessel was not originally circular, then this creates stresses on it as the forces try to bend the sides.
With a circular vessel to begin with, the only forces involved are the stretching of the sides under pressure, thus reducing the load the parts are put under.

It depends on the exact shape and dimensions of parts, but I've seen vessels very similar in shape, but with relatively thicker walls than army water canteens fail somewhere under 100 psi.

This vessel had walls about 3-4mm thick and was about 2" across it's widest diameter, and in a parallel hydro test against a PVC bottle for a non-carbonated drink, which had walls about 0.5mm thick, and a diameter of about 3", the PVC bottle won out, in spite of the much flimsier walls and higher diameter.

That gives you an idea of how much the strength of a non circular pressure vessel is compromised.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: john bunsenburner » Sat Dec 20, 2008 1:08 pm

That is what i like about you(and most spudfiles members) you sit down and explain things properly. Thank you that helped me!
  • 0

"Did you ever stop to think that out of the seven deadly sins envy is the only one which doesn't give the sinner even momentary pleasure"-George Will
User avatar
john bunsenburner
Major General
Major General
 
Posts: 1446
Joined: Sun Oct 19, 2008 5:13 am
Reputation: 0

Sponsored

Sponsor
 


Re: Army drinks bottle combustion chamber?

Unread postAuthor: jackssmirkingrevenge » Sat Dec 20, 2008 1:59 pm

ALIHISGREAT wrote:its made of pretty tough stuff obviously because its army issue so needs to be strong


Nope, it means it's made by the lowest bidder :roll:
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Re: Army drinks bottle combustion chamber?

Unread postAuthor: Ragnarok » Sat Dec 20, 2008 2:16 pm

jackssmirkingrevenge wrote:Nope, it means it's made by the lowest bidder

The man makes a fair point.

And that means that it's just (but usually by a loose definition) capable of what it was designed for, and little more.
Take assault rifles. They usually work just enough that the army doesn't bother to take the time and money replacing them.

I would use a smiley, but it's a rather more serious issue than deserves that.

@john bunsenburner: Not a problem. I quite enjoy explaining things.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: CasinoVanart » Sat Dec 20, 2008 9:51 pm

C'mon we have used plastic drink bottles for ever, it's not like its going to blow up in his face. It might shrink a bit but thats about all...
  • 0

User avatar
CasinoVanart
1st Lieutenant
1st Lieutenant
 
Posts: 281
Joined: Wed Jul 30, 2008 1:10 am
Reputation: 0

Unread postAuthor: Eddbot » Sun Dec 21, 2008 1:41 am

What makes you think it would shrink?

hehehe...that rhymed... :D
  • 0

:edfirst:
User avatar
Eddbot
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 434
Joined: Tue Oct 09, 2007 6:08 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Sun Dec 21, 2008 2:24 am

Eddbot wrote:What makes you think it would shrink?

hehehe...that rhymed... :D


mkay!
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Gippeto » Sun Dec 21, 2008 12:03 pm

Eddbot wrote:What makes you think it would shrink?

hehehe...that rhymed... :D



Have a heat gun? Try it on a PET (water, coke, etc.) bottle and see what happens.

It's a useful technique for making plastic parts using a plug mold. :)
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2393
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: Ragnarok » Sun Dec 21, 2008 5:28 pm

CasinoVanart wrote:C'mon we have used plastic drink bottles for ever, it's not like its going to blow up in his face.

We seen use of plastic drinks bottles for a long time, but generally advised against it.

And I assure you, the uneven shape of this canteen will make it a considerably less able pressure vessel than a normal plastic bottle.
I'm serious when I say that off circular vessels are not suitable for pressure.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: Hotwired » Sun Dec 21, 2008 5:53 pm

It'll be fine as long as that burst disk isn't to make it a hybrid chamber of any note.

I doubt it would shrink from heat, those bottles might well have hot liquid put in them during normal use. A fizzy drinks bottle on the other hand crumples as if it'd been punched in the stomach if you pour a kettle of boiling water into it.
  • 0

User avatar
Hotwired
Lieutenant General
Lieutenant General
 
Posts: 2599
Joined: Fri Oct 13, 2006 5:51 am
Location: UK
Reputation: 0

Next

Return to Construction Materials/Ammo Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'