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Homemade Air Bladder.

Finished product. Video is up.

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#1 Fome

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Posted 25 March 2010 - 09:32 PM

Alright, so I'm in the process of making a low-pressure homemade air bladder for use specifically with my titan. I've rigged my titan to work with my homemade arrows in one of various efforts to make it safer and more war friendly (particularly indoors). I've found that using only about 5-6 pumps, I can get these homemade arrows to fly absolutely beautifully (straight, far, fast, awesome spiral)

This is the titan (3 barrel shotgun accessory still way too powerful for indoor wars):
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Using missile attachment and hooked up to my prototype bladder:
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My first attempt used a stock magstrike bladder. However, the psi required to expand the MS bladder exceeded the titan pump's OPRV so it couldn't hold enough air to provide additional shots. I do not want to plug the titan's OPRV.

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My second attempt used a PVC hard tank constructed out of 1.25" PVC and endcaps. It's my understanding that the titan tank operates at relatively low pressure anyways, so any risk of exploding was somewhat low. This didn't work, as I'm sure most of you would already have figured, but I wanted to try it anyways. I could get one very powerful shot, one shot at about half that power, and then a piddly-suck shot. Not worth it for 50+ pumps.

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It also fits nicely into a super sweet Old Navy drink bag. I'll probably use this for something that uses less air.

My third and current attempt uses a length of bike inner tube, PVC barbed plugs, PVC endcaps, and hoseclamps. It works at very low pressures but honestly scares me a bit, you'll see why. It's mostly comprised of stuff I had laying around and a quick trip to the hardware store so don't expect any finesse in the construction. It's a concept piece at best:

No air:
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Fuckin tumah! 50 pumps, barely registers on the titan's gauge. Still manages to fire homemade arrows 20+ feet.
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Please note that all PVC bits have been solvent welded and the bladder is going inside a large plastic container which in turn is going inside of a backpack. Safety first.


Does anyone know how the titan's "pressure" gauge represents its actual PSI? (ie. at what PSI is the titan "full"?) Bike tires supposedly explode anywhere from 80-160 PSI.
Basically, I'm sharing my progress so far because I'm somewhat stuck and frustrated and any ideas/input would be greatly appreciated. I still have a few ideas left and will be updating this thread as I try them out.

This thread has helped me during the process. I'm not quite sure if I'm ready to order 15 different sizes of LRT from Mcmaster yet, however.

Thanks for looking.

Edit: Just to be clear. Bike inner tube is much too thin. The bladder swelling up that big while maintaining such low pressure is a bad thing.

Edited by Fome, 23 April 2010 - 05:53 PM.


#2 Airsoftguy777

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Posted 25 March 2010 - 10:44 PM

This is great, I actually had the same exact ideas yesterday but still have yet to try them.
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#3 Doom

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Posted 26 March 2010 - 07:37 AM

http://www.sscentral...memade/lrt.html
http://nerfhaven.com...ndpost&p=269400

5234K53 from McMaster-Carr performs very similarly to the tubes Hasbro uses even though its dimensions are different. I used that tube for a Nerf gun in back in 2004.

Edited by Doom, 26 March 2010 - 08:25 PM.

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#4 meatballica

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Posted 26 March 2010 - 10:20 AM

If I remember right titans can hold up to 60 PSI. I am next to positive that is the maximum that they hold.
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#5 CA13

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Posted 26 March 2010 - 12:10 PM

Try finding some cheap bicycle tubes for clincher rims, like the ones used in beach cruisers. They are made to yield to lower air pressures, and I'm sure you could cut a section and glue it to endcaps for a suitable bladder.
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Doing this as I speak. I have no idea when I got it...my DAD got it some 15 years ago, but that doesn't matter. Anyways, it keeps jerking around all over the place. I try to hold it with a rag...It doesn't look like...much.

#6 Fome

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Posted 26 March 2010 - 03:45 PM

The little bands of more inner-tubing are a baby step, but in the right direction. You want layers of innertube. Probably more than just two. They don't have to start from tubes of different sizes, but it's much easier to assemble if they are. Only the innermost has to be air tight.



Awesome suggestion, Bob. I just made a new version using two solid layers of tubing and I'm getting much better results. It was a huge bitch to get on there but whatever works. I think 3 layers will be too much for what I'm looking at.
I'll get some pics of the new bladder soon.

Thanks for the info Doom.

#7 Fome

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Posted 02 April 2010 - 06:10 PM

Here's the new bladder which uses 2 equal layers of bike inner tubing and some bands on top to get the pressure I wanted. It's quite a bit sturdier looking and expands significantly less than the original.
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Here's the protective housing. I'm going to paint it to match the gun and then make some straps so it can either be worn on the belt or as a small backpack. It's simply an empty plastic bottle of whey protein. The plastic is surprisingly thick for a disposable container.
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Right now I'm getting 5-6 shots with about 40 pumps. The titan's gauge won't read over half-full until you pump it about 60 times. The last 2 shots are quite a bit weaker than the first couple but still propel arrows over 30 feet.
I'm pretty satisfied with it so far.

I'm going to make another one that operates at a higher pressure so I can get multiple shotgun blasts!
Also, hopefully I can get a video up by this weekend of the thing shooting my homemade arrows.

Edit: blurry photos, sorry. My apartment is dark.

Edited by Fome, 02 April 2010 - 06:11 PM.


#8 Fome

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Posted 22 April 2010 - 09:41 PM

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Alright, by adding more layers of innertube (real bitch to do), I've achieved some performance I'm happy with. The general construction is the same, except with more inner tube. I painted the container that's holding the bladder to match the titan, added an adjustable strap so it can fit on your hip or back, and put some tube protector over the vinyl tubing.

You could adapt this approach by adding or removing layers of innertube to get your external bladder to function within your ideal pressure range. Lengthening or shortening the bladder will also have unique effects. Keep in mind there still is a noticeable pressure drop as the bladder empties to a certain point. You can see this in my video, but still works well with my homemade arrows.

Video

If you're interested in the homemade arrows in the video then go here.


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