Need nozzle Help!

[rainman]

After browsing these forums I got excited about building my own water gun. I have a working prototype, but it does not have the range I would like.

Design Goals:
1. Range
2. Range
3. Range
4. No pumping
5. Size/Portability

It is of my own design, so please point out any obvious flaws. It is a CO2 pressuried (CP?) system using some old paintball equip. and a regulator I bought online. A basic diagram is here: http://www.real-comp.com/temp/gun.bmp

A 3 liter water resovior/pressure chamber sits under the gun. A plastic hose with an inner diameter of .17 inches runs from the bottom of the water bottle to the nozzle. The pressure is provided by an external 12 oz. Co2 tank. The output pressure of the Co2 tank is 800 psi. I was able to find a pressure regulator to get it down to 0-60 psi (adjustable) so the PVC does not explode. I will wear the Co2 tank on my belt, with a hose leading to the pressure regulator. So the gun body and water tank are all pressurized driving the water down to the base of the water resovioir and then back up the hose to the nozzle. This all works great.

My current range is 40-45 ft, which is not acceptable. A $10 super soaker will get 35 ft, and I have too much time invested in this for 10 ft advantage, even though not having to pump is nice.

Correct me if I am wrong, but laminar flow is the key to a consistant stream, and as a result, range. It seems to me, that using a hose from the water tank strait to the nozzle is as laminar as I can get. This is basically one long 'straw', to use a term from other posts. Even without a nozzle or 'trigger' valve, basically using the end of the hose as the nozzle, I don't get great range.

I have tried several nozzles without much luck. The best so far is the nozzle off an 'arctic shock' super soaker. I have read other posts and have looked at several patents online as suggested by the forums. I have tried various hole diameters and screens.

So, gun gurus, what do you think? How can I increase the range of this gun.
Is 70 ft achievable?
Is 60 psi enough?
Are there design changes you would make?
What nozzle design do you think would provide the best range?

thanks!

[Ben]

Welcome to Super Soaker Central. I get an email every time someone joins, and while we don't require a real email address, we won't spam you. I hate spam as much as the next guy. You'll run into trouble in the future with password recovery or if someone tries to email you, so I'd suggest using a real email address.

Your main problems are not related to the nozzle.

To get even more than 50 feet of range, you'll need to increase the pressure, increase the internal diameter, use larger nozzles, and reorient the pressure chamber. Ideally you'll also use a conical nozzle and one of the proposed linear-flow designs. 70 feet hasn't been done efficiently yet, but I do know some have done it. This design is incapable of 70 feet.

The flow might be laminar with a tube, but it has tendencies to go one way or the other after released from the nozzle with bends. That's not always turbulence, but it's not wanted. That's why the general rule is that a straight continuous line should be drawn from the pressure chamber to the nozzle, and all water will follow that path and only that path. Easy to think about, and it creates no tendencies or turbulence.

60 PSI can work great, but you'd need a lot of surface area to get the force needed. Unless you are getting great range with a lower pressure, you should increase the pressure. However, don't increase it so much that you waste your CO2 supply quickly. Experiment.

Your 0.17 inch tube also is a major flaw. As I mentioned earlier, it's not linear. It also reduces the total amount of flow very greatly. I'm surprised you can get over 40 feet with a 0.17 inch internal diameter. Reorienting the pressure chamber so that it is above and removing the tube should get you a far higher internal diameter.

Some other pressure chamber designs such as the inverted-T and U designs will offer linear flow. I don't have images of them at the moment, but others certainly will shortly or eventually (heh).

Here's something similar I've done recently: http://www.sscentral.org/images/supercap/

This wasn't designed for range, but I know it gets more than 60 feet, which is plenty. It also gets legitimate >120X output, but that's another story. I use an air tank and regulate the pressure out. This works really well.

[Drenchenator]

Welcome to Super Soaker Central. It's great to see that some members are thinking of original ideas.

Correct me if I am wrong, but laminar flow is the key to a consistant stream, and as a result, range. It seems to me, that using a hose from the water tank strait to the nozzle is as laminar as I can get.

You are correct that laminar flow does decrease the breakup of the stream, but you are incorrect in assuming that a hose would create perfectly laminar flow. Bends of any kind create turbulence, the opposite of laminar flow.

The only real way to create true "perfect" laminar flow is with a linear design. A linear design is one where the path from the firing valve to the pressure chamber is a straight line. Ben's CPS homemade uses this concept. However, many compressed gas homemades (like regular air pressure Super Soakers) have one 90 degree bend from the chamber to the valve. This is because the gases would float to the top while the water would sink to the bottom.

Since you are using a regulated setup, I would recommend actually building a constant gas pressure homemade, like Ben's SuperCAP. Even though this kind of setup really isn't the best for range, it can be forced to overcome its problems with high pressures and other things.

[joannaardway]

I was thinking about low turbulence designs recently.

The idea was to have LRT with one end leading to the ball valve and a conical nozzle - if I can find one (or if I can manage it - that "fuzzy nozzle" concept) - With the LRT will being "charged" from the other end of the tube.

There will be a movable piece that feeds the LRT - with garden hose to allow the end to move. Obviously, the pump will be fairly standard.

I'm not really sure about this, but I think it'll be worth a try - especially if I collusus it.