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 46 users online :: 4 registered, 0 hidden and 42 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Big Stuff

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

Unread postAuthor: Jimmy K » Tue Feb 22, 2011 8:32 pm

The pipe nipples are already welded in place.
I did a lot of research on large PVC pipe fittings and found no pressure rated wyes (true wyes or manifolds) of the desired size, unfortunately.

Also, according to Toro, the manufacturer of the two main valves, using the valves as elbows actually minimizes losses due to friction.

Here's the product literature if anyone is interested:
http://www.toro.com/irrigation/com/down ... 0sheet.pdf

And regarding the connections, I planned on making the (slip socket) connection to the tee last.

It all worked out on paper, but we all know how that goes. Something will get screwed up, almost guaranteed... :D
  • 0

User avatar
Jimmy K
Master Sergeant
Master Sergeant
 
Posts: 173
Joined: Wed Jan 20, 2010 9:17 pm
Reputation: 0

Unread postAuthor: Jimmy K » Fri Feb 25, 2011 3:15 pm

I got the 3" nipple welded in place. Not too shabby. Despite what it may look like, it is actually in there almost perfectly perpendicular.
  • 0

Attachments
2011-02-25 15.01.31.jpg
2011-02-25 15.01.57.jpg
User avatar
Jimmy K
Master Sergeant
Master Sergeant
 
Posts: 173
Joined: Wed Jan 20, 2010 9:17 pm
Reputation: 0

Unread postAuthor: Labtecpower » Fri Feb 25, 2011 3:23 pm

Looks like you have lined them out pretty well.

Are you leading the pipes all the way around the tank?
(not the most efficient design)
  • 0

"ñøw mÿ šįg šüçkś!"
User avatar
Labtecpower
Major General
Major General
 
Posts: 1267
Joined: Sat Feb 20, 2010 6:38 am
Location: Herb Island
Reputation: 7

Unread postAuthor: Jimmy K » Sat Feb 26, 2011 7:27 pm

With 1 tank, 2 valves, and a tee, the shortest path would include 2 elbows (including the valves themselves). The tee is going to be parallel to the two ports, just about 6" above the tank. It would be a lot more efficient if I had a pressure rated wye or manifold, but they are nonexistent.
  • 0

User avatar
Jimmy K
Master Sergeant
Master Sergeant
 
Posts: 173
Joined: Wed Jan 20, 2010 9:17 pm
Reputation: 0

Unread postAuthor: aEx155 » Thu Mar 03, 2011 10:29 pm

It's great to see a large project like this nearing completion. As Fnord said, not many project like this are as well documented.

If you ever plan on redoing this (I doubt you will), maybe you could try an air-driven butterfly valve? Correct me if I'm wrong:

A 4" butterfly valve and a small pneumatic cylinder seems to me like it would be the simplest solution needing the least amount of turns from chamber to barrel (and the least dead space). The fact that you have a 20' barrel balances the speed of a butterfly valve (making it air actuated would be even better)

This is all speculation, as I have no experience with the physics of this stuff. If I'm correct, while it may not help you, future readers of this thread my have a simpler option available to them if they're doing something similar.
  • 0


aEx155
Private First Class
Private First Class
 
Posts: 38
Joined: Tue Oct 13, 2009 9:52 pm
Reputation: 0

Unread postAuthor: Jimmy K » Thu Mar 03, 2011 11:02 pm

It might be the simplest and efficient, but probably not as cost effective.

My understanding is that with larger and heavier projectiles, the speed at which the air dumps is not as important as it is with smaller projectiles (inertia of projectile, time spent in the barrel in relation to the opening of the valve). So everything kinda balances out.

I chose the valves that I am using for this project because of their relatively low cost and ease of use. Had i found any valve with full 4" porting at a similar price I would have gone that route.
  • 0

User avatar
Jimmy K
Master Sergeant
Master Sergeant
 
Posts: 173
Joined: Wed Jan 20, 2010 9:17 pm
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Thu Mar 03, 2011 11:04 pm

Jimmy K wrote:My understanding is that with larger and heavier projectiles, the speed at which the air dumps is not as important as it is with smaller projectiles (inertia of projectile, time spent in the barrel in relation to the opening of the valve). So everything kinda balances out.


Indeed, heavier projectiles almost always result in higher muzzle energy for a given launcher.
  • 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: Gaderelguitarist » Thu Mar 03, 2011 11:05 pm

This is all speculation


There's a definite seperation between members who do the math, and those who say, "Well it looks like it should work." I'm proud to say I'm smack in the middle.


The chamber looks good, Jimmy. I feel as though the next time you take any more pictures, you should throw in some sort of reference-able size comparison object. I'm reminded of DHalls picture of a person laying inside Vera's barrel, though obviously not to such an extreme.
  • 0

so many muchness
User avatar
Gaderelguitarist
Colonel
Colonel
 
Posts: 580
Joined: Sat Aug 16, 2008 9:56 pm
Location: Columbia, MD
Reputation: 0

Unread postAuthor: aEx155 » Fri Mar 04, 2011 1:42 am

Jimmy K wrote:I chose the valves that I am using for this project because of their relatively low cost and ease of use. Had i found any valve with full 4" porting at a similar price I would have gone that route.


How much did the two valves cost you? The link to the eBay auction no longer works.
  • 0


aEx155
Private First Class
Private First Class
 
Posts: 38
Joined: Tue Oct 13, 2009 9:52 pm
Reputation: 0

Unread postAuthor: Jimmy K » Fri Mar 04, 2011 6:16 am

I bought both of them, brand new, for about $80. Not bad considering Toro's retail price is about $350 per valve.
  • 0

User avatar
Jimmy K
Master Sergeant
Master Sergeant
 
Posts: 173
Joined: Wed Jan 20, 2010 9:17 pm
Reputation: 0

Unread postAuthor: Technician1002 » Fri Mar 04, 2011 8:03 am

The 3 inch nipple is a good reference for me.

The chamber looks good, Jimmy. I feel as though the next time you take any more pictures, you should throw in some sort of reference-able size comparison object.
  • 0

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

Unread postAuthor: Gaderelguitarist » Fri Mar 04, 2011 11:02 am

The 3 inch nipple is a good reference for me.


I was thinking more along the lines of a soda/beer can or bottle. I don't normally work with large pipe like that. Everyone can relate to soda/beer cans however.
  • 0

so many muchness
User avatar
Gaderelguitarist
Colonel
Colonel
 
Posts: 580
Joined: Sat Aug 16, 2008 9:56 pm
Location: Columbia, MD
Reputation: 0

Unread postAuthor: Technician1002 » Fri Mar 04, 2011 11:16 am

A soda can fits a thin wall PVC 2.5 inch barrel


For reference his 3 inch pipe is the same size as the black barrel with the red an blue paint and white reflector tape. The 3 sizes of black ABS in the photo are 2 inch, 3 inch, and 4 inch. His barrel is 4 inch.

Image

I found a good reference on a prior page.. The valve that fits the nipple is this one. It's big stuff.. :P He included a pencil and blowgun for size comparisons.
Image
  • 0

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

Unread postAuthor: Jimmy K » Fri Mar 04, 2011 3:30 pm

Here is the tank with the valves.

That is not the final position of the valves - they are on there simply for the ongoing pressure tests.

And I included a root beer can for comparison this time.
  • 0

Attachments
Air Tank with Valves.jpg
User avatar
Jimmy K
Master Sergeant
Master Sergeant
 
Posts: 173
Joined: Wed Jan 20, 2010 9:17 pm
Reputation: 0

Unread postAuthor: Gaderelguitarist » Fri Mar 04, 2011 5:32 pm

And I included a root beer can for comparison this time.


:D

It definitely puts things in perspective.

Have you thought of putting some sort of wedge shape in the center of your Tee to help direct the airflow towards the barrwel and minimize turbulence?
  • 0

so many muchness
User avatar
Gaderelguitarist
Colonel
Colonel
 
Posts: 580
Joined: Sat Aug 16, 2008 9:56 pm
Location: Columbia, MD
Reputation: 0

PreviousNext

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'