Really Compact APH

Build a homemade water gun or water balloon launcher and tell us about it.

Should I change this to CPS?

Yes
2
40%
No
3
60%
 
Total votes: 5

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cantab
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Re: Really Compact APH

Post by cantab » Sun Mar 06, 2011 1:04 pm

You make sure you have a means for air to get in. The simplest way is a pinhole, the more complicated and perhaps more effective way is a check valve.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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soakernerd
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Re: Really Compact APH

Post by soakernerd » Sun Mar 06, 2011 3:07 pm

You can drill a VERY small hole in the top of the Reservoir to stop it collapsing.
Just build the PVAT in a 3/4" tee.
Pessimist: These blasters hold no water
Optimist: But their small output means they last just as long
Marketing: Huge blasts of water!
user: I shot it at an angle and it went a whole ten feet!

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strato_2r5
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Re: Really Compact APH

Post by strato_2r5 » Sun Mar 06, 2011 9:22 pm

soakernerd wrote:You can drill a VERY small hole in the top of the Reservoir to stop it collapsing.
Just build the PVAT in a 3/4" tee.
Is there any way to rearrange the PVAT so the intake is not perpendicular to the output?
Sorry if I'm not active much, busy on another forum and another project non-soaker related.

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soakernerd
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Re: Really Compact APH

Post by soakernerd » Sun Mar 06, 2011 11:20 pm

I don't think so. you could make the Tee screw on, rather than solvent weld. This would allow you to test various designs.
Pessimist: These blasters hold no water
Optimist: But their small output means they last just as long
Marketing: Huge blasts of water!
user: I shot it at an angle and it went a whole ten feet!

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strato_2r5
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Re: Really Compact APH

Post by strato_2r5 » Mon Mar 07, 2011 12:44 am

Okay, attached is the (hopefully) final blue print. Are there any problems?

Off Topic: Oops, I keep spelling reservoir wrong.
Attachments
water gun prototype.jpg
Sorry if I'm not active much, busy on another forum and another project non-soaker related.

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soakernerd
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Re: Really Compact APH

Post by soakernerd » Mon Mar 07, 2011 12:49 am

Well, you will need an intake tube for the reservoir.

I don't see how the PVAT is connected to the PC.
Also, where is the trigger? The biggest benefit to a PVAT valve is that you can easily attache a trigger. If you are just planning on pulling the pin at the back, it would be easier and quicker to just use a ball valve.
Pessimist: These blasters hold no water
Optimist: But their small output means they last just as long
Marketing: Huge blasts of water!
user: I shot it at an angle and it went a whole ten feet!

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strato_2r5
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Re: Really Compact APH

Post by strato_2r5 » Mon Mar 07, 2011 12:52 am

I'll add a trigger later once I know if the whole thing works. The intake tube would be right between the reservoir (yes! spelled it right) and the check valve. The PVAT is connected through the corner pieces. The PC is connected through the second tee.
Sorry if I'm not active much, busy on another forum and another project non-soaker related.

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strato_2r5
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Re: Really Compact APH

Post by strato_2r5 » Mon Mar 07, 2011 1:09 am

Any predictions of outcomes? Expected ranges? Will it epicly fail?
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C-A_99
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Re: Really Compact APH

Post by C-A_99 » Mon Mar 07, 2011 1:23 am

Just FYI, check valves bought in stores won't be quite that small. You'll want to use threaded fittings where possible to keep the design compact as well.

There are quite a few ways to let air into the reservoir to prevent it from imploding. The tiny pinhole is the easiest method, but can leak if its too big (should be no larger than 1mm, and probably even less), and even then, seems to be an unreliable method. The second method is to construct a rubber flap similar to the caps used in SS and WW blasters. This is tricky and I've never seen it done outside of stock blasters, as its not all that reliable either.

Anything spring powered is by far the best method. Check valves are the easiest, but most expensive method, but you can also build something for less. In any case, the idea is to have a rubber stopper seal up a hole which the spring holds in place. When the reservoir reaches negative pressure, outside air will come in. You can even use such a hole for quick refilling, similar to the quick fill caps that SS used to use.

The PC shape on your APH is still not too well optimized. Ideally it should be angled at 45°, or should be perpendicular to the barrel. Surface area dictates air pressure performance, and the current design seems to restrict how the air pushes the water. With a pipe thickness that small, performance will suffer badly.

Like I said, separate chamber APH is tricky to make compact designs out of. That reservoir may also end up with problems with size if you need a compact design.

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strato_2r5
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Re: Really Compact APH

Post by strato_2r5 » Mon Mar 07, 2011 1:41 am

Well, my resovoir will be just a 2L bottle. I know the valves are bigger. I think I'll just put a pinhole in my resovoir, I'll change it once I find out the performance of my gun. A vertical PC isn't that ergonomic. C-A_99, would you please draw how to attach the 45* angle?
Also, what is the recommended pipe diameter?
Sorry if I'm not active much, busy on another forum and another project non-soaker related.

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soakernerd
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Re: Really Compact APH

Post by soakernerd » Mon Mar 07, 2011 2:20 am

As large as practically possible. 3" works well, but if you can find pressure rated 4" pipe, that is better.

CA, you keep saying surface area increases power. Is this surface area of the water, or of the PC itself?

I'd always thought it was the area of the PC, but I could be wrong.
Pessimist: These blasters hold no water
Optimist: But their small output means they last just as long
Marketing: Huge blasts of water!
user: I shot it at an angle and it went a whole ten feet!

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C-A_99
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Re: Really Compact APH

Post by C-A_99 » Mon Mar 07, 2011 2:47 am

Well the main example is using a vertical 1/2" PC versus using 3" or 4". The 3" and 4" will perform substantially better because the air is able to push more water out at a time. Using multiple PC's also increases surface area.

One part I'm less sure of is whether or not positioning things at an angle improves this. My guess is that it does, a little bit. A 1/2" PC positioned at an angle may not perform quite as horribly as it would at vertical. I don't know for sure though.

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cantab
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Re: Really Compact APH

Post by cantab » Mon Mar 07, 2011 3:27 am

I imagine a 1/2" diameter pressure chamber will suffer simply from being small. A 3" diameter PC of the same length will have 36 times the volume. That's similar to the difference in reservoir capacity between the XP 220 and the CPS 3000.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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C-A_99
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Re: Really Compact APH

Post by C-A_99 » Mon Mar 07, 2011 4:00 am

Well, given a long 1/2" PC and a short 3" PC, lengths adjusted so that both PC's are the same volume, the 1/2" PC's performance will still be far worse. The water simply takes too long to push out.

Volume does play a role, but shape is also important though that is usually not a problem because no one makes messed up PC's shaped like that.

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strato_2r5
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Re: Really Compact APH

Post by strato_2r5 » Mon Mar 07, 2011 5:03 am

C-A_99, theoretically, the 45* angle should work better. When aiming at a 45, the PC will be straight up. OKAY, so what are the expected ranges, using 1" PVC for the works, and 3" for the PC.
Sorry if I'm not active much, busy on another forum and another project non-soaker related.

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