jgrepps

Anyone one know if someone sells water cannon systems for RC boats. I wanted to put a water cannon on one of my boats so I could squirt on-lookers.

enyaengine

The only ones I've seen are the cheap ones built onto toy fire-boats and the like. You would probably have to make a simple pump (out of an old, small glow engine perhaps? Find a scrap one - it may be able to be converted to work as a pump, with a motor turning it).

scubyfan

Just use one of those cheap electric pumps from Edmunds Scientific. You can use more if one is not enough.

Umi_Ryuzuki

Most people use windshield washer pumps from cars.

We are making up our own pumps from a discarded pump housing.
The mounts will fit a standard RC car motor. From preliminary tests, the pump will be able to move about three gallons a minute. We are going to run two to three of these in [link=http://www.rcgroups.com/forums/showthread.php?t=77749&page=1&pp=15]models of the LA Fireboat #2.[/link]

There was quite a bit of machining to make the necessary adaptations for the impeller mounting and water seal, but we are confident that the pumps will be able to move up to 350 gallons an hour. Of course by that time the motors will probably have overheated.


The second image is a jet pump design. As designed, the two intakes should be able to supply enough water to create a 60mph jet of water. The force should give us a 20mph boat.

LtDoc

Most 'water cannons' are probably made from a windshield washer pump. Not difficult at all. Just need a pump, plumbing, a power source, nozzle, and a switch. The plumbing can be plastic/rubber tubing, the power source the boat's battery, and the switch a micro-switch activated by a servo. The size and range of the stream depends a lot on the nozzle (and the amount of water moved by the pump). That can take some searching for the right size of tubing to make the nozzle.
Here's a picture of one installation. The pump is the black 'blob' in the bow of the boat. The switch is from Radio Shack, and a servo turns it on at full throw. Power supply is the battery running the boat. Sorry for the quality of the picture...
- 'Doc

PS - If you can find a self-priming pump it's a lot easier. If not, just prime it before getting underway. The most traumatic part is punching a hole in the bottom of the boat!

jgrepps

Thanks for the help guys. I have a few more questions.
How big are the windshield washer pumps and I am assuming I can get it at a local auto parts store?
Will the pumps run off of 7.2 volt battery?
Are the windshield washer pumps self priming?
Also do you know how much wter them can pump per minute?

Umi_Ryuzuki

The windshield washer pumps should pump enough water to squirt like,.. well, your windshield washers.
Maybe a little less, as you will be running it on less than 12 volts. I think most of the guys I know have just picked them up at a junkyard someplace. As for self priming, that would depend on the make of the car.
If you mount the pump below the water line of the boat it shouldn't be much of an issue.

Otherwise consult with your local auto parts dealer.[8D]

Foggy Bottom

If you REALLY want a pump (and have 12volts) Use a bilge pump I put one on my tug with a 3/8 inch port and it would squirt 15-18 feet and push the boat around( Finally had to aim it dead ahead so I could control the boat with the throttle)

LtDoc

jgrepps,
The automotive parts houses usually carry at least one or two types/styles of generic WS washer replacement pumps, and they vary quite a bit in size. Something on the order of 2" in diameter and maybe 3 - 4" long. Just depends on what the thing was supposed to fit on to start with, but that's about the 'average' size.
The amount of water they move per minute isn't very much. How quick can you emprty your WS washer tank? But you don't need a very large flow rate. You do need to experiment to find the 'right' size of outlet, or nozzle (it ain't gonna be very big, so think small!).
A 12 volt pump will operate on a reduced voltage, the difference is going to be in the amount of water flowing (not a problem). Higher voltages mean greater flow rate, but since it's going to be for "looks", not putting out fires, you just don't need much flow.
A self priming pump is nice but not absolutely necessary. Mounting the pump below the water line will prime it (depends on the size of the model, there's not much 'below water line' room in some). Or, use a sirynge/syringe(sp), or a 'turkey baster' (put the thingy over the nozzle to suck water through it). The 'turkey baster' makes for a handy 'bilge pump' too!
Something to remember is that the inlet needs to be larger than the outlet (nozzle). That's mot usually a problem though. The pump weighs something, so you'll have to adjust the ballast of your boat to compensate for the extra weight. Keeping the pump on the center line of the boat is a good idea, don't want the boat to lean one way or the other (also not a huge problem, just someting to remember). Just like house plumbing, you don't want any leaks, so a tight fit, or sealing the tubing is a good idea. Mounting the nozzle straight forward or straight aft makes 'living' withit much easier. It will move the boat, takes a while, but it's just like a rocket motor, equal and opposite reactions, etc.
Have fun...
- 'Doc

PS - Be selective in 'who' you squirt! Some people can't take a joke LOL.

jgrepps

Wow, that was very helpful LtDoc, thanks. I just found out the boat I was going to use was thrown out by my parents a while ago. I was going to use a simple plastic hull boat that I had when I was a kid and I was going to use it for this water cannon and as a kind of tug boat for my RC sailboat. I guess I have to find a cheap electric to use first, but I still want to make the water cannon.

Thanks

subsinker

My Feedback: (61)

Hello,

All good options. Another option that no-one has mentioned yet is to use a fuel pump for glow fuel. I used one on a Midwest Patriot Fireboat and together with a simple on-off ESC worked quite well. It was able to squirt water thru 2 cannons, more properly called "monitors" without any trouble. I feel that I did have to use a separate battery pack as to not deplete the main drive battery so quick. If you do opt to go for this you may want to consider using a six volt model instead of the more popular 12 volt simply as it is less cells. Another interesting option, and I have yet to try it is to use a Sullivan Pro series Smoke Writer pump. They are made for R/C airplanes for pumping smoke fluid into the exhaust to create smoke. These little pumps are essentially fuel pumps that are contained with battery. You simply plug them into a spare receiver channel and you would be able to turn them on and off as well as adjust the flow from your transmitter. The downside I can see to them is the cost (about $125-$150.00) but they do look promising. I am currently scratch building another fireboat and have purchased one of these units for trials. I will post an update after I get her to sea and give the pump a workout.


Best regards,
Pete Olson

There are two types of ships: submarines and targets

Sarges_heroes2003

My Feedback: (6)

u could use combat builge pumps, they squirt water out of a 1/8 " outlet high into the air, some times all the way accross the pond!!

Tachikaze

Car water pump. Will work and at that price order a dozen
[link]http://www.allelectronics.com/cgi-bin/category.cgi?category=search&item=PMP-2&type=store[/link]