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 66 users online :: 4 registered, 0 hidden and 62 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

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

Sealing chamber/barrel revolving launcher

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.
Sponsored 
  • Author
    Message

Sealing chamber/barrel revolving launcher

Unread postAuthor: CS » Thu Aug 16, 2012 8:42 pm

I'm looking for ideas on how to seal the chamber and barrel on a revolving launcher.

Idea #1:
Spring load the chamber against the barrel with a gasket in between.
Image
Con- The spring mechanism needs to be engaged/disengaged everytime a chamber is moved into place.

Idea #2:
RevoSemi. The gasketed insert moves forward under pressure to seal the transition.
Image
Con- Not alot, but there may be a simpler idea.

Idea #3:
Similar to the last idea, a rubber gasket flexs under pressure to seal the clearance between barrel/chamber.
[picture in attachments]
Con- Rubber exposed directly to combustion. May not be a long term option.

Any other ideas?
  • 0

Attachments
flexibleRubberSeal.jpg
blah blah blah
flexibleRubberSeal.jpg (22.78 KiB) Viewed 1393 times
User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Unread postAuthor: Zeus » Thu Aug 16, 2012 10:32 pm

Look up the Nagant Revolver, might be useful.
  • 0

/sarcasm, /hyperbole
User avatar
Zeus
Major General
Major General
 
Posts: 1422
Joined: Tue Oct 27, 2009 7:34 pm
Location: 'Straya, C*nt
Reputation: 2

Unread postAuthor: CS » Thu Aug 16, 2012 11:36 pm

Image

Seems a lot like idea #1. link

Thanks.
  • 0

User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Unread postAuthor: jrrdw » Sat Aug 18, 2012 5:02 pm

Tongue and groove system. Set the grooves with a curve so that when the cylinder port starts to line up it pulls the ports together making a compression seal.

I think any kind of gasket will be problematic at best...
  • 0

When life gives you lemons...throw them back they suck!
User avatar
jrrdw
Donating Moderator
Donating Moderator
 
Posts: 6538
Joined: Wed Nov 16, 2005 5:11 pm
Location: Maryland
Country: United States (us)
Reputation: 25

Unread postAuthor: CS » Sun Aug 19, 2012 1:33 am

Now I'm thinking of the chambers and barrel being fixed distance from another with a gasket on the barrel. The chambers and barrel will be create a lot of friction, but having a strong spring to rotate the chambers. We will see...
  • 0

User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Unread postAuthor: ramses » Sun Aug 19, 2012 3:53 pm

If you made all the parts of the same material, you could probably get "good enough" sealing by simply maintaining a tight fit between them. Oil or grease could be added (and replenished) the bridge a looser tolerance gap. A total of maybe .010 should seal reasonably.
  • 0

POLAND_SPUD wrote:even if there was no link I'd know it's a bot because of female name :D
User avatar
ramses
Major General
Major General
 
Posts: 1679
Joined: Thu May 29, 2008 6:50 pm
Reputation: 3

Unread postAuthor: jackssmirkingrevenge » Mon Aug 20, 2012 12:05 am

A tight fit should be good enough - if you can get the parts in contact, you will have less leakage than if you have a slightly loose fitting projectile. If you do the math and calculate how much gas actually will escape from a simple close fit, it's not as bad as you think. This is why revolvers work quite happily even though most do not have the Nagant's gas-check design.
  • 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

Sponsored

Sponsor
 


Unread postAuthor: mark.f » Mon Aug 20, 2012 9:02 am

I agree with ramses and jack, but if it must use a seal I would go with idea no. two.
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3464
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: pneumaticcannons » Mon Aug 20, 2012 10:08 am

Assuming you don't have access to machining facilities, I'm all for idea 2. It would work a lot better though, if the insert had a fairly large diameter compared to the inside of your barrel, with a hole approximately the diameter of the barrel through it. Unlike the picture were the hole is almost the same dia. as the insert itself. This way, the air pressure and flow is keeping the breech sealed against the barrel :wink:
  • 0

ramicaza <- My Youtube Channel
User avatar
pneumaticcannons
Major
Major
 
Posts: 392
Joined: Sat Oct 30, 2010 9:45 am
Location: shite country in asia
Reputation: 0

Unread postAuthor: Gippeto » Mon Aug 20, 2012 11:23 am

Ever had a Crosman 1077 apart? There's a piece between the valve and mag..it's a cross between a piston and an orifice..uses a light spring to initiate contact with the mag and then the gas pressure provides the actual force for sealing.

Similar materials (plastics) and a flange/lip (if required) on the seal to ensure contact with the second barrel before the first moves completely away should work.

The system is simple and it works. Prt#106B036 is the part...moves in the housing prt#106A010 moved by spring prt#106A046

Image
  • 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: Brian the brain » Wed Aug 22, 2012 3:53 pm

The gap should be as small as possible.


Then:
take two pipes , one as an outer sleeve for the barrel.
On the other side ( cilinder?) you use the smaller inner pipe to make a piston that gets blown onto the inner barrel.

Now, if the piston can cross the gap it will most likely seal better.
You could bevel the edges so when you rotate the cilinder, the piston is pushed back.
Or use a spring to return it.
ideally, barrel and piston would fit together perfectly.

You won;t need the rubber seal, just straight cut pipe and a good fit.

Something like this:
  • 0

Attachments
blowforwardseal.jpg
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
User avatar
Brian the brain
Moderator
Moderator
 
Posts: 3494
Joined: Mon Dec 05, 2005 2:06 am
Location: Holland
Country: Netherlands (nl)
Reputation: 29

Return to Hybrid Cannon Discussion

Who is online

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

Reputation System ©'