Greets to all!
My son (like many boys his age) loves firefighting and wants to be one when he grows up.
Now, I thought that since he has a little motorized John Deere gator, I would build him a water cannon for the payload area he has. This water cannon would hold several gallons of water and allow him to shoot water, let's say 10 feet (15 would be way cool, but don't want the force of the water to be too forceful).
Sooo... I thought about ways I could do this easily. First thing is that I want him to be able to run the whole operation by himself, even though we will be out there with him.
For the primary water resourvoir - I have something like this: http://www.nextag.com/Igloo-Legend-Cool ... rices-html
it's NOT 72 quarts, it's prolly closer to 30 quarts. The key reason is that it has that spigot at the bottom that i can attach a hose to. And additionally, he could easily open the top and pour more water in.
Now I was thinking for the pressurized container, going with something like this: http://www.greif.com/packaging-systems/ ... efault.asp
good hard plastic, prolly can hold some pressure (let's hope)
k. that's where I get stuck. Now I need a way to pressurize the water and make it easy for him to release the pressurized water.
In reading forum posts here, and looking at the technical breakdown here:
http://entertainment.howstuffworks.com/ ... aster4.htm
I see that what I need is some kind of pump and I need a couple of valves. I wanted to see what ideas people had about this project and a kid friendly pump i should look for.
thx to all in advance for your help.
mj
Child safe - Fireman water cannon
-
Silence
- Posts: 3825
- Joined: Sun Apr 09, 2006 9:01 pm
Welcome to Super Soaker Central! The water gun is sure to be a fun toy for your son. 
Looks like you've done quite a bit of research, including the fine HowStuffWorks read. However, you should definitely read the APH article to see how homemade water guns have been done.
The biggest difficulty you'll have is keeping the power low enough. At 50-100 PSI, homemade water guns with good nozzles can hit over 60 feet (although it depends on how big the tubing is). And while even that isn't too dangerous, 10-15 feet is nothing. And it would probably take 1-5 gauge PSI (or pressure above one atmosphere). Perhaps 20 feet would be a reasonable goal?
Do you have one of those tiny squirt pistols that shoots every time you pull the trigger? Those can get maybe ten feet of range. Getting a beast of a water gun to shoot only that far would be difficult.
Anyway, back to the technical stuff...I guess you've considered 10-15 feet for a reason.
There are various types of pumps for homemade water guns, but most involve an O-ring held over a wooden dowel by strips of duct tape. Unfortunately, the actual size you'll use probably won't be the same as the regular 1/2"-tube size we use. If you want to keep the pressure down for a certain amount of applied force, you'll need more surface area for the plunger and a larger tube.
2.5 pounds of force is probably the most your son can comfortably apply to a pump. If your target is 2.5 PSI, then you need one square inch for the pump. Of course, such precise values aren't necessary as there isn't a set goal. PVC tubing from 1" to 1.25" in diameter should suffice for the pump tube.
I believe check valves, or your standard one-way valves, are suitable for the water gun. They're covered in the article I linked to, and you set them up like in the animation in the HowStuffWorks article.
For a nozzle, I would use a male adapter (a PVC fitting with male threads) and female-threaded endcaps. Glue the male adapter to the end of the water gun, drill a tiny hole (maybe 1/32" or 1/16") in the face of one of the endcaps, and screw on the endcap.
The other details are all in the APH article, as far as I know. If any problems or questions come up, please be sure to tell us! Good luck!
EDIT: Oh, just wondering, what were you planning to use for the trigger? Most homemade water guns use ball valves, but that's only because they need tremendous flow. For the small nozzles in your miniature firehose, pretty much any nozzle will work...so it's your choice. (Also, ball valves can be harder to turn than other types.) You could even use a hose handle for this experiment, although you might want to experiment to see if you can use epoxy to add a nozzle selector. The nozzles on hoses are fairly large.
I've been assuming you've wanted small streams...but large streams going smaller distances would also be neat. And now that I think about it, larger streams make more sense, judging from the tanks you've found.
Looks like you've done quite a bit of research, including the fine HowStuffWorks read. However, you should definitely read the APH article to see how homemade water guns have been done.
The biggest difficulty you'll have is keeping the power low enough. At 50-100 PSI, homemade water guns with good nozzles can hit over 60 feet (although it depends on how big the tubing is). And while even that isn't too dangerous, 10-15 feet is nothing. And it would probably take 1-5 gauge PSI (or pressure above one atmosphere). Perhaps 20 feet would be a reasonable goal?
Do you have one of those tiny squirt pistols that shoots every time you pull the trigger? Those can get maybe ten feet of range. Getting a beast of a water gun to shoot only that far would be difficult.
Anyway, back to the technical stuff...I guess you've considered 10-15 feet for a reason.
There are various types of pumps for homemade water guns, but most involve an O-ring held over a wooden dowel by strips of duct tape. Unfortunately, the actual size you'll use probably won't be the same as the regular 1/2"-tube size we use. If you want to keep the pressure down for a certain amount of applied force, you'll need more surface area for the plunger and a larger tube.
2.5 pounds of force is probably the most your son can comfortably apply to a pump. If your target is 2.5 PSI, then you need one square inch for the pump. Of course, such precise values aren't necessary as there isn't a set goal. PVC tubing from 1" to 1.25" in diameter should suffice for the pump tube.
I believe check valves, or your standard one-way valves, are suitable for the water gun. They're covered in the article I linked to, and you set them up like in the animation in the HowStuffWorks article.
For a nozzle, I would use a male adapter (a PVC fitting with male threads) and female-threaded endcaps. Glue the male adapter to the end of the water gun, drill a tiny hole (maybe 1/32" or 1/16") in the face of one of the endcaps, and screw on the endcap.
The other details are all in the APH article, as far as I know. If any problems or questions come up, please be sure to tell us! Good luck!
EDIT: Oh, just wondering, what were you planning to use for the trigger? Most homemade water guns use ball valves, but that's only because they need tremendous flow. For the small nozzles in your miniature firehose, pretty much any nozzle will work...so it's your choice. (Also, ball valves can be harder to turn than other types.) You could even use a hose handle for this experiment, although you might want to experiment to see if you can use epoxy to add a nozzle selector. The nozzles on hoses are fairly large.
I've been assuming you've wanted small streams...but large streams going smaller distances would also be neat. And now that I think about it, larger streams make more sense, judging from the tanks you've found.