APH backpack design

Build a homemade water gun or water balloon launcher and tell us about it.
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Specter
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APH backpack design

Post by Specter » Sun Jun 29, 2008 6:26 pm

About 5 minutes ago I was thinking back on the PVC backpack I designed up.
I used my TI 84+ Silver and Google to do the calculations.

I thought up 3 different ideas. One uses 3" PVC, another uses 4" PVC and the 3rd idea (which is less likely to be used) uses 6" PVC. It doesn't have to be Schedule 40 pipe or whatever since it's just the reservoir.
Here is what I came up with.
I used the cylinder volume equation. The actual volume of water in the backpack may be slightly larger because I did not include the fittings.

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3" PVC pack:
π * 1.5^2 * 12 = 84.82300165
Ans * 3 cyl = 254.4690049 cubic inches 
that = 4.16999987 liters which = 1.10159742 gallons

4" Pack:
π * 2^2 * 12 = 150.7964474
Ans * 3 cyl = 452.3893421 cubic inches
that = 7.4133331 liters which = 1.95839542 gallons

6" Pack(bit overboard lol)
π * 3^2 * 12 = 339.2920066
Ans * 2 cyl = 678.5840132 cubic inches
that = 11.1199997 liters which = 2.93759314 gallons
If it were 3 cyl
1017.87602 cubic inches
which = 16.6799995 liters  or  4.4063897 gallons

But who would carry 6" PVC on their back??? lol
For the homemade backpack, there would be 3 cylinders (or 2 with the 6" pipe) consisting of 12" long. Connected with a + and 2 90* angles at the bottom and a + and 2 90* angles at the top with the top of the top + going to a cleanout plug to be filled.
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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cantab
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Re: APH backpack design

Post by cantab » Sun Jun 29, 2008 8:52 pm

Don't exclude the capacity in the elbows and crosses, that could add a fair amount.

And yeah, the 3cyl 6" design will be seriously heavy when full (over twice the CPS 3000 or 3200), so I'd say that's only for if you're pretty strong.

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Specter
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Re: APH backpack design

Post by Specter » Sun Jun 29, 2008 10:54 pm

cantab wrote:Don't exclude the capacity in the elbows and crosses, that could add a fair amount.
Its hard to include that because I don't know the space that would be between them. In reality its just 2 more cylinders on their sides so that would need to be figured out of the thing was actually built. :)
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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SSCBen
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Re: APH backpack design

Post by SSCBen » Mon Jun 30, 2008 12:37 am

If you're making a simple backpack just use drain pipe. It's available in 3 and 4 inch sizes for cheaper and lighter than even cellular core PVC pipe. Great stuff.

The only other suggest I have is to make the pipes longer in the backpack. 12 inches seems rather short. 18 inches should work better, but if the water capacity is already adequate for you then 12 inches are fine.

Take some pictures of your finished product and maybe make a guide. I've been told about how well pipe backpacks work but never saw a guide, so I'm sure some people would appreciate some help/ideas about making them.

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Specter
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Re: APH backpack design

Post by Specter » Mon Jun 30, 2008 12:45 am

Take some pictures of your finished product and maybe make a guide
I didn't actually make one. It's just ideas I came up with
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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SSCBen
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Re: APH backpack design

Post by SSCBen » Mon Jun 30, 2008 12:51 am

I wasn't completely clear. If you do make a finished product let us know about it.

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Specter
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Re: APH backpack design

Post by Specter » Mon Jun 30, 2008 2:21 am

Oh ok. The way you worded it, it sounded like you thought I made it.
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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