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 :: 5 registered, 0 hidden and 40 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Air pressure actuated QDV

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

Air pressure actuated QDV

Unread postAuthor: Labtecpower » Tue Jul 13, 2010 9:19 am

I made this design. do you guys think it will work?
I think the dead space may be too big.

The picture:

Image

Uploaded with ImageShack.us

The link:

http://yfrog.com/2gpneumaticqdvp

i hope to hear from you. If there are questions, ask me.
  • 0

User avatar
Labtecpower
Major General
Major General
 
Posts: 1267
Joined: Sat Feb 20, 2010 6:38 am
Location: Herb Island
Reputation: 7

Unread postAuthor: jackssmirkingrevenge » Tue Jul 13, 2010 9:57 am

Isn't an "air pressure actuated QDV" a piston valve :)

I didn't quite get your diagram :?
  • 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: Technician1002 » Tue Jul 13, 2010 10:09 am

Not in this case. It looks like the valve is blown forward to trigger it. I like it. The only downside is the double port required, one into the valve and one out to the barrel. This is an area of turbulence.

Is it possible to redesign it so the piston moves to the breech and directly opens the barrel? The trigger could be a pull cord and the reset would be a rod connected to the "pump" action to reset the piston.

Look at the drawing, the porting is a QDV spool valve. It is not a traditional piston valve where the barrel or chamber seal is smaller than the piston OD. The design is a 1:1 seat to OD ratio, a true QDV.

It is the first blow forward QDV I have seen designed.

Using air, I am playing with a blow back design to use in the 4 inch launcher. A sprinkler or other fast valve would port a blast of air between the piston and projectile moving both. The piston once unseated would behave like the mechanically triggered QDV and pop the rest of the way open. This is one way I am considering piloting the large 4 inch valve.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Lockednloaded » Tue Jul 13, 2010 10:42 am

I can't see your diagram, but I have been designing a pressure activated QDV too. I hope this helps. All your really need is a dual action air cylinder for it to work
Image
  • 0

I love lamp
User avatar
Lockednloaded
Major General
Major General
 
Posts: 1558
Joined: Thu Sep 03, 2009 9:38 pm
Location: Texas, USA
Reputation: 0

Unread postAuthor: Technician1002 » Tue Jul 13, 2010 11:54 am

That design I have been considering, but with one difference. I have a single action cylinder with a spring return. It returns extended (piston reset) and pulls with air pressure. Only a single air connection to the air cylinder is needed. ( it only has one )

Coupled with a custom pop off shuttle valve, the set up could be full auto. 8) Applying pressure fires it, after the chamber is vented, the air cylinder supply is gone so it is vented too and self closes.

The air cylinder is 1 inch. It will fit in the breech of the 2 inch cannon right behind the piston. A blowgun between the chamber and cylinder will pilot it.

I've been too busy to tear apart my 2 inch to build this inside the stopper. I may build it inside the 2.5 inch cannon.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Ranger » Tue Jul 13, 2010 11:58 am

I made something similar, the gun it self is a 3" chamber with a 1 1/2" sdr 21 golf ball barrel, QDV. Inside the stock is a 1/2" cpvc cylinder and a HDPE piston, a 3/16" steel rod runs through the stock and connects to the firing rid for the QDV piston. A blowgun connected to the chamber siphons a tiny amount of air and pushes the 1/2" piston, the firing rod moves building up momentum and then triggers the QDV piston.

Also inside the stock is a 1/4" ball valve for filling and a pressure gauge.

It works really good, so good that I'm having trouble finding a good bumper for the piston. It put a golf ball through 3/4" cedar plank at 50 psi, the highest I have taken to it 80 psi.

Image

Image

Image

Image

Image

Did I beat every body to an air pressure activated QDV?
  • 0


Ranger
Corporal
Corporal
 
Posts: 78
Joined: Thu May 27, 2010 10:01 pm
Location: Texas
Reputation: 0

Unread postAuthor: Technician1002 » Tue Jul 13, 2010 12:04 pm

Did I beat every body to an air pressure activated QDV?


I think so. Sweet. Nice cannon. I hope the main piston is decoupled from the rod so the rod isn't getting a beating. Good luck with a bumper. It will need it. Try the inside of a dense foam football such as a Poof brand. The one I use in the ABS cannon sheds a little from wear, but is holding up well.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Sponsored

Sponsor
 


Unread postAuthor: Ranger » Tue Jul 13, 2010 12:57 pm

Yes the main piston is disconnected from the rod. The 1/2" piston doesnt have enough power to move the main piston on its own, but when the 3/16" rod and 1/4" rod get moving it has enough force to unseat the piston. Right now I'm using knee pad foam for a bumper.
  • 0


Ranger
Corporal
Corporal
 
Posts: 78
Joined: Thu May 27, 2010 10:01 pm
Location: Texas
Reputation: 0

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'