Silver Bullet - Putting on the final design touches

[WaterWolf]

Some of you here may know of my work on a new and more refined design for a "Silver-Bullet" CPH rifle, which had been in progress on the SSC forums, but were recently halted by myself.

Isoaker however has convinced me to open a similar thread here, so that we may put the finishing touches on the plans.
I am already accumulating the pieces necessary to build it, so construction may commence as soon as we have finished with a final polishing of the blueprints.

Here are three slight variations of the design, I would like input on them from the people here.
Please try to be as constructive as possible in your critiquing.
Thank you.

V 0.6.7:


V 0.6.8:


V 0.6.9:

[isoaker]

Can you provide also a pure sideview of the design? I'm also trying to get a feel for how long/large the overall blaster is as all these parts can theoretically be scaled up or down. Also, do you have plans to add in a strap or is this blaster being designed primarily to be held when in use with perhaps a strap for carrying when empty/used as a backup?

[WaterWolf]

The gun's approximate size in inches is 30" long, 8.5" wide and 11" tall. The current configuration is designed for superior balance while maintaining a good capacity.
However, to get a very compact gun, you could pull the whole thing back into itself and give it just one 2000-ml reservoir instead of two. (Imagine a Flash-Flood on steroids )

Strap placement is one of the things I had been going to bring up around this time.
After looking at it, I think the versions 0.6.9 and 0.6.8 would have difficulty with a strap, since the pump's placement would mean that it would hit the strap when you're holding it and trying to pump. So I may have to go with the conventional under-gun configuration as seen in 0.6.7.
Unless somebody here can think of a way to get around that?

[isoaker]

0.6.7, IMO, likely has more potential. Though I understand some of the idea behind having the top-mounted pump, from a pumping-force-direction-point-of-view, a under-barrel pump is more easily braced by one's other hand when the pump is in line with where the hand-grip area is. The tubing set-up in 0.6.7 looks like it may benefit from a slight tweak to me. If you could post up a side-profile of it, I could edit in a slight tubing flow modification that should make pumping a little easier, IMO. It would also help rigidify the overall structure, I believe. Of course, as you're building it, the final layout is up to you, but it looks promising thusfar.

[DX]

I also think the pump position works best under in this case, though I personally think that the pump handle should be shorter and clear the pc. PM'd.

[cobralex297]

All of that is looking very good. I've been watching the thread progress for a while on sscentral, and am excited to see and hear about construction, which is, IMO, long overdue. Nothing wrong with fully developing an idea though, and making sure you have it exactly right...

Any idea what the performance will be like? I'm sure it's hard to predict without building, however I'm just wondering.

[WaterWolf]

Here is the awaited side-view for the 0.6.7 design.



Something I have not added yet is that there will be garden-hose pipes leading into the reservoirs, (so you tilt the gun downwards slightly when pumping), and there will be held-open tire-valves in the reservoirs that will allow air in but not water out, to prevent a vacuum effect.

@Cobralex297:
Approximating off Ben's experience, this rifle should achieve ranges around 50 to 60 feet (17 to 20 meters).
Not as sure on shot-time, but I'm aiming for something around at least 4-seconds, which allows for plenty of tap-shots, without making the PC too big.

Even after this gun is built, all the sections are removable. So I intend to experiment with different PCs, reservoirs, pumps, etc, and battle-test them with my team.



Edited By WaterWolf on 1189822409

[cobralex297]

More importantly than the range, which is nothing to sneeze at certainly, is the practicality. The practicality of this is far better than others. I've never used or even seen in person a real homemade, but this one beats all others i've seen in pictures.

[isoaker]

@WaterWolf: thanks for the side image; it's easier for me to draw/photoshop in my thoughts without needing to try doing funky perspective manipulations. I'll post up my suggestion hopefully later today. Seeing the side-view helps a lot in terms of being able to gauge some of the tubing lengths and weight distribution a little better.

[WaterWolf]

@Cobralex297:
Yes, although practicality is more difficult to gauge on an unbuilt gun, that is what I am aiming for with this design. It takes many of the technologies that have been developed in past years and puts them all together in a battle-practical configuration.

Drenchenator has also recently developed a new trigger that I would like to add onto mine when I build it.



Edited By WaterWolf on 1189857768

[isoaker]

I don't quite recommend using Drenchenator's trigger unless you're willing to make changes to it. Use of the cylinder as the moving shaft is not good as it can rotate; it also is more limiting regarding how large a hole can be drilled to allow water to flow through. If a cylinder is going to be used as the gate, it should have a diameter much larger than the water flow pipe such that the drilled hole can have the same internal diameter as the water flow pipe. A better alternative would be to use a rectangular piston with the hole cut through it as it solves both the rotation problem as well as allowing larger holes to be drilled without over-compromising the strength of the piston.

As for my tubing suggestion, see image below:


This would shortened the distance from the reservoir to the pump as well as strengthen the frame. Of course, it requires more T-connections as well as plugging some pipes internally.

[Drenchenator]

I don't quite recommend using Drenchenator's trigger unless you're willing to make changes to it. Use of the cylinder as the moving shaft is not good as it can rotate; it also is more limiting regarding how large a hole can be drilled to allow water to flow through. If a cylinder is going to be used as the gate, it should have a diameter much larger than the water flow pipe such that the drilled hole can have the same internal diameter as the water flow pipe. A better alternative would be to use a rectangular piston with the hole cut through it as it solves both the rotation problem as well as allowing larger holes to be drilled without over-compromising the strength of the piston.

First, it is a valve. Trigger mechanism was not built yet. Secondly, please read the topic or this post. The cylinder can't rotate because it has guides that limit its motion to only vertical motion.

The valve is limiting in that the hole can't be as wide as the pipe. But given that is closes automatically, opens quickly, and offers completely linear flow, a small reduction in flow is worth it. If you really are worried about flow, just use a ball valve. They perform the best anyway. In the end, most people don't use the pipe's diameter as the nozzle size anyway. As long as a nozzle is attached, the valve offers more cross section area than the nozzle does.

@WaterWolf: To add to what iSoaker recommended, I would recommend that you also shorten some pipe lengths. The pipe from the first check valve to the tee by the reservoir could be shortened as well as the pipe above it. Right now it just forms dead space. This would make the gun more compact.

[isoaker]

@Lt. Col Drench: ah, never saw the guide in the previous valve picture and only saw some posts with rotational concerns. If there's a guide, yeah, no rotational issue. As for the hole through the cylinder, if it is smaller than the feeding tubing, it will further restrict flow to the nozzle. I suppose if the hole drilled through the cylinder is at least as large if not slightly larger than the tube between it and the nozzle, it shouldn't be much of an issue.

As for shortening tubing, the design could have some tubes shortened, but how short they should be also depends on how the overall soaker feels when filled and/or empty as some of the lengths so contribute to the front-to-back balance.

[WaterWolf]

@Isoaker:
Ya, I like it. One thing I would change is that I think that we only need one pipe plug, the upper one you put in. That way once can still fill the reservoirs from that cap piece in the corner.

@LT. Col. Drench:
I would like to get it more compact if possible, but It would make the whole thing less balanced. You would have a majority of weight on that spot just ahead of the middle handle. In addition to this, the pump would be harder to use or have to be made to be longer.

V0.7:
I've made the changes Isoaker mentioned, as-well as adding the feeding pipes in the reservoirs and the tire-valves to let air in.





Edited By WaterWolf on 1189877154

[isoaker]

That way once can still fill the reservoirs from that cap piece in the corner.

I wondered about that part. Makes sense, though if you're going to try to fill using the rear, vertical tube into the reservoirs, you may consider either making the back tubing larger in diameter and/or adding some sort of sealable vent hole on the reservoirs. Otherwise if you pour in water too quickly, the air that it needs to displace won't have a place to go thus stopping flow.

[WaterWolf]

Thats what the bike-tire valves are for, they are held in an open position so that suction is prevented and so is the issue you mentioned.

I would have liked to use 1" PVC pipe for that area as-well, but if I did then the reservoirs were farther away from the PC and adding supports would be more difficult.

[isoaker]

Thats what the bike-tire valves are for

Doh! I missed that part of the diagram. I seem to be doing that a lot these days. Ok, then.

[Rook]

Neat design!

The only problem I see (at the moment) is your choice of reservoir. 2-Liter bottles aren't the most structurally stable of materials. They crush and bend really easy. I'd try 4" thin-walled PVC. It's usually used for drain pipe. It's really light, too.

[cobralex297]

I agree with Rook on the above. Especially considering how generally stable the rest of the gun design seems to be, it seems to me to do an injustice to the design to use 2L bottles, when everything else seems so high quality.

The possible downfalls - bending, crushing, breaking of the threads, they all greatly outweigh the upsides, which are convenience and lightness.

[isoaker]

While I see the concerns with using 2L bottles, they are light and, well, easy to come by and easily replaceable, too. As they are only being used for the reservoirs, they won't experience as much stress on them apart from perhaps hitting the side of one's body when running with the soaker. Part of me wonders how difficult it would be to move the venting air valves onto the attachment assembly and leave the 2L pop-bottles completely unmodded allowing easy swapping. Of course, moving the air valve would involve making a modification to the bottle attachment point to allow water to enter and exit through the intake tube while allowing air to enter or be released through an upper hole.

Then again, if the reservoirs are not meant to be swapped, using a more durable contained would definitely be recommended. Not sure what WaterWolf had in mind when he suggested the 2L bottles.