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 57 users online :: 4 registered, 0 hidden and 53 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

Super Water Gun

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

Super Water Gun

Unread postAuthor: grock » Thu Dec 10, 2009 2:37 am

I was thinking of making some kinda of super water cannon, something along the lines of backpack mounted PVC tank > largeish diameter hose > modded sprinkler valve > maybe a footish of 1/2" pvc. i'll probably use about 60-80 psi. any reason that this shouldn't work? or any suggestions?
  • 0

User avatar
grock
2nd Lieutenant
2nd Lieutenant
 
Posts: 231
Joined: Mon Dec 29, 2008 2:59 pm
Reputation: 0

Unread postAuthor: psycix » Thu Dec 10, 2009 5:50 am

A ball valve will do, you don't need a sprinkler.

The reason it won't work well is because you forgot to add a nozzle.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: Biopyro » Thu Dec 10, 2009 5:56 am

60-80psi is unnecessarily high. You shouldn't need more than 40.
Too much pressure will result in turbulent water flow (more like a mist than a stream) and a painful close range jet.

This is the workthrough of the one I made. It started quite complicated, and I got very far before realising I could create an excellent cannon from only 4 parts. It's definitely better than any I've ever owned.
  • 0

Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety. -Benjamin Franklin
User avatar
Biopyro
Colonel
Colonel
 
Posts: 656
Joined: Fri Aug 04, 2006 5:32 am
Location: UK
Reputation: 0

Unread postAuthor: grock » Thu Dec 10, 2009 11:13 am

psycix wrote:The reason it won't work well is because you forgot to add a nozzle.


what shape would it have to be? like just a hole in an endcp or something?
  • 0

User avatar
grock
2nd Lieutenant
2nd Lieutenant
 
Posts: 231
Joined: Mon Dec 29, 2008 2:59 pm
Reputation: 0

Unread postAuthor: psycix » Thu Dec 10, 2009 11:23 am

Like... a nozzle. A hole, but smooth. Click here to see what I mean.

If you can, find a real firehose nozzle.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: btrettel » Thu Dec 10, 2009 11:50 am

Biopyro's right about the pressure. In addition, if you do some tests you'll find that doubling the pressure would increase performance less than doubling the diameter of the nozzle.

Conical shaped nozzles (like some fire hose nozzles) are best as they have the least losses. But holes in endcaps aren't bad if drilled cleanly. Most everything I use is a hole drilled in an endcap.

De Laval nozzles are for gas flow, specifically for trading pressure and temperature for velocity. Don't try something like that water as you won't see any benefit.

Using sprinkler valve would actually reduce your performance. Opening time is not important when the duration of the shot is on the order of seconds. Ball valves offer unobstructed flow, are readily available, and inexpensive. They unfortunately are not as easily adapted to triggered operation as other approaches, but I have not found this to be problematic.
  • 0

All spud gun related projects are currently on hold.

btrettel
Major
Major
 
Posts: 380
Joined: Sun Feb 03, 2008 4:40 pm
Location: Maryland
Reputation: 0

Unread postAuthor: psycix » Thu Dec 10, 2009 12:38 pm

you'll find that doubling the pressure would increase performance less than doubling the diameter of the nozzle.

That's because when diameter doubles, sectional area doubles twice...
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: btrettel » Thu Dec 10, 2009 2:22 pm

I think my point was clear, but I understand what you're saying. Look at area then. At steady state the flow of an incompressible fluid through a water gun follows an equation like Q = C * A * sqrt(dP / rho) where C is a constant, A is the nozzle orifice area, dP is the pressure differential, and rho is the fluid density. The influence of doubling the nozzle orifice area is greater than that of the pressure in terms of the flow rate.
  • 0

All spud gun related projects are currently on hold.

btrettel
Major
Major
 
Posts: 380
Joined: Sun Feb 03, 2008 4:40 pm
Location: Maryland
Reputation: 0

Unread postAuthor: SEAKING9006 » Sun Dec 13, 2009 5:55 pm

Personally, I was thinking of copying the prototype of the Super Soaker 50. There was a picture of it in either Scientific American or Popular Mechanics, pictured next to the re-released Super Soaker 50.

The other design I really want to try and reverse-engineer is the water cannon they have at Schlitterbahn. They seem to have a piston mounted in the barrel and use a fairly wide nozzle to create an effect not unlike an airzooka (more accurately a vortex gun, but different terminology than we use). It ends up firing an almost coherent ball of water (which has quite a bit of KE to it, if you ask me) about 30 feet up to the decks of a fake ship, which tells me that on a level plane it will get a good 50-60 feet on a high angle lob. It was dang impressive, and really freaking fun.
  • 0

Completed projects:
CA1 SMSS Basic Inline
CA3 PDAB Airburst Cannon

Current Project: Bolt action rifle (25x140mm + 1in shot)

SEAKING9006
Colonel
Colonel
 
Posts: 734
Joined: Mon Jun 23, 2008 3:20 pm
Location: Texas
Reputation: 0

Unread postAuthor: Biopyro » Sun Dec 13, 2009 6:07 pm

That would be incredible seaking, but can't imagine what it might look like? Surely in two such different fluids it wouldn't work?
  • 0

Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety. -Benjamin Franklin
User avatar
Biopyro
Colonel
Colonel
 
Posts: 656
Joined: Fri Aug 04, 2006 5:32 am
Location: UK
Reputation: 0

Unread postAuthor: MrPed » Sun Dec 13, 2009 6:14 pm

D_Hall already made a beast one, long ago.

http://thehalls-in-bfe.com/UberSoaker/ubersoaker.html
  • 0

User avatar
MrPed
Private
Private
 
Posts: 13
Joined: Tue Mar 17, 2009 2:09 pm
Location: East Coast, USA
Reputation: 0

Unread postAuthor: SEAKING9006 » Sun Dec 13, 2009 6:15 pm

It just looks like an M1919 With a barrel the size of a softball gun. It's quite impressive. And even if that's NOT the effect it uses to achieve a water ball, it still works, whatever they did. And well enough to send a 180 pound teen staggering back four feet from the impact. :D
  • 0

Completed projects:
CA1 SMSS Basic Inline
CA3 PDAB Airburst Cannon

Current Project: Bolt action rifle (25x140mm + 1in shot)

SEAKING9006
Colonel
Colonel
 
Posts: 734
Joined: Mon Jun 23, 2008 3:20 pm
Location: Texas
Reputation: 0

Unread postAuthor: spudtyrrant » Sun Dec 13, 2009 8:42 pm

SEAKING9006 wrote:It just looks like an M1919 With a barrel the size of a softball gun. It's quite impressive. And even if that's NOT the effect it uses to achieve a water ball, it still works, whatever they did. And well enough to send a 180 pound teen staggering back four feet from the impact. :D

Image is this what you speak of :D
  • 0

I ♥ ♣'in baby seals
User avatar
spudtyrrant
Colonel
Colonel
 
Posts: 550
Joined: Fri Jan 02, 2009 6:10 pm
Reputation: 0

Unread postAuthor: SEAKING9006 » Sun Dec 13, 2009 9:32 pm

VERY close to it. But a bit longer on the beak and it had a barrel shroud. Not to mention an actual 1919/Maxim/M2 type grip+trigger. There was also a release valve under the aluminum shroud on the controls that you use to clear a jam.

But I'm sure they offer different models. So yes. That IS what I refer to. :D
  • 0

Completed projects:
CA1 SMSS Basic Inline
CA3 PDAB Airburst Cannon

Current Project: Bolt action rifle (25x140mm + 1in shot)

SEAKING9006
Colonel
Colonel
 
Posts: 734
Joined: Mon Jun 23, 2008 3:20 pm
Location: Texas
Reputation: 0

Return to Pneumatic Cannon Discussion

Who is online

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

Reputation System ©'