Dismissed Ideas

[adronl]

I have been thinking about some ideas that I has that I thought would be great and had mentioned them on the forums and others had done the same. Ideas like CPH guns with pressurized bladder chambers, A small piston cannon style pump gun with a back pack reservoir maybe this is what Ben was talking about when he mentioned a hydraulic ram gun.

Regardless I came up with some interesting new concepts and I am going to try some concepts that haven't been done but talked about. 3 of which make me kinda giddy thinking about them.

[SSCBen]

If by "CPH guns with pressurized bladder chambers" you mean pressurizing the space between the bladder and casing, that is a silly idea. Doing so defeats the purpose of having the bladder--constant pressure--unless you use a system to keep the outside pressure relatively constant, which would basically be two systems in one where one system alone could accomplish the same goal. Maintenance will also be much more difficult. I can't see any advantages over simpler systems like bladders (particularly thick balloon bladders), regulated air pressure, or LPD air pressure.

As for the "hydraulic ram gun", I'd suggest reading the link I posted to Wikipedia's explanation of hydraulic ram pumps in my original post about the idea. The hydraulic ram idea is pretty simple; take a steady flow of water and turn it into higher pressure pulses of flow. Between each pulse energy is being stored (energy that normally would be used to shoot out water) such that once the energy is released the pressure will be higher.

Let me note that the hydraulic ram water gun idea is complicated and not likely to work well, but I think it might be fun to mess around with. It definitely will require tinkering to get working even decently well.

What other ideas do you have?

[adronl]

I actually tried the CPH with a pressurized Chamber It actually worked with great results but there were some drawbacks like it gets hard as heck to pump but the power is the same as my large APH type guns. I tried the CPH with an open chamber it was cool, it shot for quite a while but not anything special in my opinion as far as range and power go. The GRT actually performed quite well but I have to compare it to LRT before I can say which is better. From the video's I have seen of test fire's of LRT guns the range may have had a bit of improvement but nothing significant but I was only using 1/4" wall GRT I have some 1/2" wall GRT to test next

As for saying that it is a silly idea why not I ask? Maybe you should try it I think you will like the results. The fact is the rubber tubing is going to put what ever force it can on the water but if the chamber is sealed and you are adding water the bladder expands and the air in the chamber is being compressed it increases the force on the water. They use this principal on well pressure repeaters I am pretty sure that is not the correct term but this is exactly how they work so an Engineer with a degree somewhere thought it was a good idea employed it and made it successful.

http://forums.sscentral.org/t4669/

[Teh Moron]

Make a solenoid soaker.

Electrically fired (not the best idea)

[adronl]

I was actually looking at that a bit I watched a couple of auctions on e-bay for small compact low voltage electric pumps I am looking more for a 9v or something like that don't think I will be doing that for a little while

[SSCBen]

My main problem with pressurizing around the bladder basically is that you can get higher pressures other ways that are much simpler. I don't see any advantage to it over increasing the pressure of a normal air pressure chamber. There's a rule in engineering called KISS--"Keep it simple stupid". If a simpler idea does the same thing, use that one.

Bladder tanks are different. Some adjustment of pressure is necessary and they don't care if the pressure is constant (they are not meant for water guns). Bladder tanks are basically like LPD air pressure as far as I know. Higher pressures will make the pressure less constant, just like LPD air pressure.

I suppose if you want to use a bladder mainly to separate air and water, that'd be fine, but pistons would be a much simpler solution.

Sprinkler valves have complex flow paths that induce turbulence and wouldn't be a very good choice in my opinion unless you value a trigger and ease of building much more than performance.

As for electric water guns...

Don't expect much performance from electric pumps. I ran the numbers earlier and they'd really be impractical. You can use the simple steady state equations power = Q * P and power = I * V where Q is volumetric flow rate (i.e. m^3/s), P is gauge pressure (i.e. Pa), I is electric current (amps), and V is voltage.

Crunching the numbers, 100 mL/s at 25 psi requires about 17.5 W of power. At 9 V that's nearly 2 A, which is fairly high current. And that's with low performance and assuming 100% efficiency. I am not aware of actual electric pump efficiencies, but I'd imagine they are above 90%.

Most electric water pumps don't generate enough pressure for our use. Ones that do generate enough pressure with adequately high flow rates are generally expensive. A homemade pump might be worthwhile. Look into using drill motors for a cheap start.

Batteries with adequate energy storage exist (look at laptop batteries), but they're expensive, and to get the power output you'll need something like lithium ion batteries, which have a tendency to fail violently (they basically light on fire and explode). I don't think water and lithium ion batteries mix well. I'll admit I don't know much about this, so some online research would be best.

You could do it I suppose but I don't think it'd be worthwhile. A great deal of money and a good amount of design is required.

[adronl]

Here is the pump I was looking at there are others too

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... tsupported

haven't really thought there would be any real advantages like you said

[C-A_99]

It would be better to use a single balloon instead of LRT if there is going to be air pressure behind it. The balloon would then act as a substitute for a piston. However, this will result in odd PC shapes and probably isn't a good idea; pistons would work better. Or perhaps a long balloon could work in a cylindrical casing.

[cantab]

It would be better to use a single balloon instead of LRT if there is going to be air pressure behind it. The balloon would then act as a substitute for a piston. However, this will result in odd PC shapes and probably isn't a good idea; pistons would work better. Or perhaps a long balloon could work in a cylindrical casing.

This is the idea I've had. Instead of seeing it as a way to increase the power of a CPH, see it as a way to improve the firing angle and prechargability of an APH.

You and Ben both think pistons would be better. But some people have had trouble with pistons.

A single balloon would probably be too weak, but you don't need the same thickness as you would for a pure CPS.

Also, isn't what's being discussed here basically equivalent to the XPS mod?

[Teh Moron]

Pistons are still more durable. When you expand something, you lose elasticity. Not to mention both stresses from stretching and internal pressure. The balloons are likely to fail quickly.

I'm on the piston team.

[Silence]

cantab, yes, the XPS mod does come to mind. Although the fact that the name parallels "CPS" implies that the creator (I forget who) intended to get constant pressure in the end. I do know people used to discuss a version with just enough balloons to separate the air and water, though.

A few years ago someone suggested using a plastic bag to separate the two. This idea has grown on me, since a durable bag could be preferable to balloons or a piston. Still, mounting it could be problematic.

Teh Moron, the problem is that pistons are a bit harder to construct and require more expensive, mail-order materials. adronl has also had some problems with them warping, but he can tell you how to stop that better than I can.

[adronl]

Well actually on that Ben told me that the first piston gun was build by some guy and it was a solid piston. When looking for a good sabot I noticed that a small peanut butter jar fit in 3" PVC perfectly and formed a seal in 2 places and the rest was not making contact. A perfect space for a bunch of lithium grease.

You could leave it open without the cap and risk friction or fill it with water made it dense. another option fill it with soap or oil drill some tiny holes in the middle that do not contact the walls and bam a self lubing piston with some density. I started to test this but was torn Between testing that or sabot

as far as a durable plastic bag or elongated balloons for horizontal chamber I worry about the air pressure forcing the bag out if you try and do this by adding air outside the bladder/bag through a schrader/tire valve. You could find a way around this like putting a screen or a catch in there but I think that the best way around that is a pump gun where you pump in water into the bladder/bag compressing the existing air in the sealed chamber.

Also you could find something else. Refer to these links Ben provided plenty of things can be done with these links like finding a permanent sabot or a solid cheap piston

http://forums.sscentral.org/t5726/#post46791

P.S. ALWAYS think outside the box that is how new inventions are made!