Water Cannon Question.

[stev9960]

I'm designing my first boat, it's going to have a small water cannon mounted on the stern, can anyone recommend a water pump that would be good for long distance?

Also, I'm trying to design the cannon so it will be rapid fire (like a machine gun, but with water). Can anyone suggest how I could do this?

[patmat2350]

Lots of pumps to choose from, from model airplane fuel pumps (small) to windshield washer pumps (med) to recreational boat bilge pumps (large), and most will run on 12v.

Since the pump needs to spool up, you may not get the effect you want by switching the pump on and off. I'd activate it and leave it running, then engage a small solenoid valve (Clippard?) in the discharge... that could be toggled on and off with any number of fancy electronic circuits, or perhaps a mechanical device... like a servo with the stops removed, having a cam-wheel output which hits a lever switch.

Pat M

[stev9960]

thanks a lot Pat M, I'll try that!

[toesup]

I'm designing my first boat, it's going to have a small water cannon mounted on the stern, can anyone recommend a water pump that would be good for long distance?


I have used a car washer pump to pump water through a monitor and can reach a good ten feet or so. Have a look at the 'generic' washer pumps at your local auto parts store..
A word of warning though, car washer pumps put a heavy draw on your batteries and can drain them to a stage where you lose control of your boat.. :o

This was through a car washer pump and Graupner monitors..
http://www.rcgroups.com/forums/attachment.php?attachmentid=1101960

[patmat2350]

Also, avoid disappointment- test the unit before installing. Typical washer pumps put out a narrow discharge which can actually be pretty hard to see... sometimes victims don't notice anything except wet pants!

But see this example for what a higher volume pump can do... be prepared to carry a big battery.

http://static.rcgroups.com/forums/attachments/4/9/6/5/9/a1373825-13-aImg_5142.jpg

[patmat2350]

See http://clippard.com/store/byo_electronic/Default.asp for the "Mouse" solenoid valve. Not sure if this is the same type that the warship battlers use in their air cannons, but probably similar.

PM

[Umi_Ryuzuki]

The air valve might work, Something else that might work is some sort of piston pump.
It would need a one way valve on the out flow, but as the piston drew water the stream would be interupted and the result would be a machine gun like pulse.

What pump is the Judge McCombs carrying Pat?

[Brooks]

I have a car windshield washer pump in my vac u tug. I run it on a separate 7.2 volt NiCd battery. The distance the pump squirts is related to the size of the nozzle, smaller dia. => farther distance. For the 2 tugs I built, I get a 4' squirt with an 1/8" nozzle, and an easy 10' with the next size smaller nozzle (nested brass tubes per vac u tug site plans).

Today we used the 2 tugs with fire monitors to put out cotton ball and newspaper fires set in a tin can floating on a barge. As a practical matter, if you want to use the fire monitor to put out fires, a shorter squirt is easier to aim. Check out the vac u tug site for ideas on rigging the switch, etc. I used the "Philip S." type switch to run the cheapest pump from the auto parts store.

http://www.vac-u-boat.com/FireBoat.htm

[green-boat]

A piston pump would give you the machine gun effect you are looking for. Look for an old "Water Pick". They have the entire piston pump, you will need to adapt it to a DC motor though. Another thought is to use a paristalic tubing pump or sometimes called a tubing pump. A piece of silicone tubing is fitted inside a case where a set of rollers on a disc/wheel press against the tubing and squeeze the liquid thru.