3rd Generation Douchenator

[DX]

I tried that with the G2 Douchenator a long time ago and it didn't really work. Even barely opening the valve let too much air out to get a good second shot. So I thought that if there were a closed-off middle section, air could be let in and more shots could be fired. Hence the G3 Douchenator, which I meant to finish in September, but homework said no.

I just added an insurance coat of glue over the trouble spots. The glue should be totally dry by this time tomorrow, though I will be buried in work and probably won't be able to test it.

[WaterWolf]

I don't think people understand what I'm saying here. This is to be used on the G3 design for getting a consistent pressure in the middle chamber for each shot.

You pressurize the big PC to 100 PSI, then open the valve just enough to let air flow into the smaller PC at a controllable pace. watch a Pressure valve that is mounted on the middle PC until it hits 50 PSI, then close the valve.

Using this, If you have a 1:5 ratio on the PCs, then the big PC looses 10 PSI per shot, fire five shots, then on the last shot you can keep that valve open when you fire, resulting in the last shot being just as powerful as the first. See now?

And in my experience, I have been able to keep the air flow down to a controllable speed.

[SilentGuy]

We understand what you're saying. But it's unreliable. It's just like the interchangeable PCs--it's impractical because it can't be done easily on the field. How much time does it take? How much concentration do you need in the middle of a battle? If you had the time and if you weren't being engaged, why not just use the foot pump to pressurize while you can?

And by the way, those numbers aren't really correct. When you release some of the air to the middle PC, then the end one loses some of its pressure. The pressure is inversely related to the volume, whose change stays the same--from the end PC's volume to the combined PCs' volumes. ie, the big PC will loose a decreasing amount of pressure each time.

EDIT: You say you've been able to control the air-releasing speed. But assuming you haven't actually built this thing yet, you might have just been releasing air into the atmosphere. Which allows for no measurement of any kind. I could be wrong, though.

If you're looking for a cheap way to get consistent shots, I think there's a better way. Use the same design, but instead of the ball valve between the PCs, use a pressure release valve. Sure, it'll be at a fixed PSI or something, but it'll be cheap and you won't be paying for a (admittedly cheap) pressure gauge. Maybe you can switch the PSI of the pressure release valve, or switch valves or something if you want to. But either way, you'll want to fire and close the first ball valve quickly--maybe have a spring close it automatically, or the other way around for more performance.

EDIT again: What about a pull valve if you're going with an over-under design? Opens quickly, is cheap, closes automatically...but a solenoid is the best.



Edited By SilentGuy on 1163893529

[WaterWolf]

The numbers were just a generalization.

And No, I haven't built one yet, but I'm going to be getting the parts for my design on monday, then I'll test in on the real thing.

I have tested my theory by filling the tank of my simplified Douchenator with air, then seeing how slowly I could release it. It took something like 20 seconds to empty it, which I think is plenty slow enough to control. The tank is 12" long and was at 80 PSI.
I don't see how its "unreliable", you just load your round, open the valve a little bit, then shut it when the pressure is up to the PSI you want.
If your shooting it as fast as you can reload it, then either your accuracy will be bad or your target isn't very far away, in which case having a consistent pressure doesn't matter.

How does a "pull valve" work? What are the largest sizes they make them in? and how expensive are they?



Edited By WaterWolf on 1163898322

[SilentGuy]

I called it unreliable because there's minimal control of how much air you're releasing. You could overshoot the target, go too slow, rush it and mess it up in some way...so I would not depend on human control in the middle of battle.

A pull valve is the type of valve used most soakers, unless they're using ball valves or pinch valves. Like where there's a pin going into the valve that the trigger pulls on. Check out this thread at SM: http://z8.invisionfree.com/soakermedia/ ... wtopic=656. Bottom of the page.

If your shooting it as fast as you can reload it, then either your accuracy will be bad or your target isn't very far away, in which case having a consistent pressure doesn't matter.

Or you can just use those twenty seconds you mentioned to pump up the entire thing to a good pressure. :p

[WaterWolf]

I didn't say that it would take twenty seconds to get the pressure you want in the small PC, I said that that was how long it took to completely empty my Douchenator's PC.
Another possible method of getting consistent pressure in the small PC, would be to just make the big PC into a cylindrical CPS system, though I'm not sure if that would allow for the necessary pressure and It would make the design more complicated, thus possibly less practical.

[DX]

Why would you use a CPS system? They hold NO pressure, and are not designed to generate much, if any. The power behind CPS is the quick contraction of the rubber. You'd end up rupturing the tubing, as it is not meant for the purpose of holding 100+ PSI.

If you want constant pressure, then use a regulator. Makes the gun a bit longer, less durable, and costs a good $40, but works. I don't mind the drop-off since manual valves allow for faster firing times. Open the valve, load the balloon, close the valve and you're ready to go. A solenoid would be the best choice for the firing valve, but again I don't mind having a manual ball valve.

[WaterWolf]

Like I said in mine: "I'm not sure if that would allow for the necessary pressure"
Regulators are an option, but I like to keep my designs simple, strong, practical, clean and affordable, since I'm mostly designing these weapons to be used by my team.

I had been going to begin construction on my WBL design next week anyways, so now I can integrate your design into it. Then I can test my ideas on the real thing.

[SilentGuy]

Fine, it's your call. But whether such a system is usable on the field is a good question. It would be simple (except for the pressure gauges, and I presume you'll want two), strong (except for the narrow tubing connecting to the pressure gauges, once you find it), practical (once you've mastered the art of hiding and slowly leaking air in the middle of a battle), clean (although not any more so than a different system), and affordable (asides from the extra cost of the gauges and the tubing, and the hassle of getting both). Good luck!

[WaterWolf]

Gauges are pretty cheap. and what extra tubing are you talking about?
Pressure gauges are also quite easy to install.
My local hardware store has everything I'll need, so it should be an easy one-stop for all my parts.
I believe that with a little practice, I could get a consistent pressure in the middle chamber in only a few seconds. (4, maybe less)

[SilentGuy]

Hmm...I haven't really seen the gauges, but most usually use 1/4" or 1/8" connector tubing. Maybe there are some that fit right onto 1" or whatever PVC.

IF you can reliably and effectively get the correct PSI...then by all means do so! I'll concede that.

[WaterWolf]

The two ways that I would attach a gauge would be to:

A. Put in a schrader valve then thread a female gauge onto that. (I'd prefer to do this If I can get the right gauge)
or
B. Drill a very tight fitting hole then thread a male gauge in with plumbers tape.

[WaterWolf]

I just did the math on the drop-off for a 1:5 ratio, and here are the results.
Pressurized at 120 PSI.

1st shot: 120 PSI (Because you pressurized the small PC at the same time as the big one)
2nd shot: 96
3rd shot: 76.8
4th shot: 61.5
5th shot: 46.2
6th shot: 34.7
7th shot: 27.8

In my opinion, its pointless to calculate after that, because the PSI is so low.
Though on one of the later shots you could keep the "Pressurization valve" open when firing, resulting in a larger volume of air for your last shot.

[SilentGuy]

I would haeve thougt a Schrader valve would be complex because of how the air flows through, but I'm not sure. Both options really aren't great for a high-pressure system, so just hope the seal stays. Good luck with the design!

BTW, you could just graph an exponential function to show the pressures...exponential decay, asymptote at 15, that sort of thing.

[wetmonkey442]

*gah, tiredness=inability to comprehend posts*



Edited By wetmonkey442 on 1164072287

[SilentGuy]

@ wetmonkey442: Who are you addressing? I said Schrader valve because that's what's in WaterWolf's post. I don't see how it could effectively connect a gauge to tubing, so maybe you're right. Thanks for pointing it out.

[wetmonkey442]

Sorry SilentGuy, I didn't read your post well enough, I could have sworn I read "solenoid" valve.

In the case of what you guys are talking about, you wouldn't need a schrader valve to attach a gauge. First of all, unless you bought a gauge that came with an attachment that depressed the release rod of the schrader valve, your gauge wouldn't work. Second of all, it'd bee quite a bit easier to simple drill an undersized-hole (like WaterWolf's method B) and screw it in. I've done this once, for my first WBL. However, I don't recommend it. IMO, a pressure gauge is just another area for potential leaks and something else to snag or get bumped around while you're carrying and moving the actual WBL. However, if you don't have a bicycle pump with a gauge built in, then a pressure gague might be needed depending upon how consistent you want your shots to be.

[SilentGuy]

Oh, no problemo...just a bit confusing. I was really tired yesterday as well.

That's what I was trying to say about the Schrader valve, but I don't know much about them so I wasn't sure. I think that with the proper connections, the pressure gauge might not leak as much; but drilling a hole probably isn't the best idea, same for filling. A gauge is needed here because you're probably pumping into the back chamber, not the constant middle one.

On second thought, WaterWolf, did you mean to plug in a footpump to the Schrader valve in the middle instead? That's not a bad idea.

[SSCBen]

However, I don't recommend it. IMO, a pressure gauge is just another area for potential leaks and something else to snag or get bumped around while you're carrying and moving the actual WBL. However, if you don't have a bicycle pump with a gauge built in, then a pressure gague might be needed depending upon how consistent you want your shots to be.

Personally, I never would ever trust those schrader valves that are threaded into a hole drilled in the tank, even on the thick parts.

No one really takes a look at how I do things, but on Supercannon II, SuperCAP, Dr. Nerf's homemade Nerf gun (he's my brother), among other things we have used air couplers and 1/2 inch X 1/4 inch reducers. The reducers are brass or steel. They allow you to thread on a 1/4 inch fitting and the seal is as good as it gets. Air couplers are better than schrader valves for most of what we do. But, schrader valves are in 1/4 inch varieties as well and you can do the same thing. In fact, I had bought a schrader valve in case I wanted to take Supercannon II somewhere without an air compressor.

The pressure gauges can be threaded into these reducers as well. Pressure gauges are essential in many creations in my opinion.

I don't know why people are so keen on drilling holes in their air tanks, especially with more reliable options available. It's probably because that method is the only one known, but it should be known that it's not a good idea and there are definitely other options worth consideration.

[WaterWolf]

The Schrader valves I use have a black rubber outer skin, and are cone shaped so as to prevent air leaks.
I have never had any problems with them, they are easy to install and are the one part on my simplified Douchenator that has never failed me over the years of use.