APH Design

[Ben]

Siphons (or "reentrant" pipe entrances in this case), have a high minor loss coefficient, which essentially means that there will be a loss in the pressure. The design also goes more against the design practice of linear flow more than the other PC location would. There would be pressure loss and turbulence, resulting in reduced performance.

We know what you're talking about because siphons are used in a lot of water guns. Andrew Mommsen's water gun wasn't designed for performance anyway.

I don't see any real advantage to having a siphon in this homemade water gun design. You always could mount the pump on top if you wanted to saved space or possibly make it balanced better. I never had a problem with the space or balance in my water guns, so I did not see any need to find a way to add a siphon.

Simply put, a siphon would be hard to make and decrease the performance.

[frankenbike]

I cede your points. The main advantage to a siphon is design flexibility. The APH designs I've seen are a bit unwieldly for all but artillery use.

As for water path and turbulence though, the current SSC APH design has the water jetting into the "barrel" at a 90 degree angle as well. With twin APCs, you also have two 90 degree streams creating independent stream turbulence.

I do, however, have a suggestion for increased power from the APCs. Put Shrader valves on top, and once pressurized, add additional air pressure from a bicycle pump for an added boost in power. The large diameter fill pumps I've seen so far in the designs make it much harder to add pressure beyond a certain point.

OTOH, you could add a "pump within the pump" which would have better hydraulic leverage. Of course, it would take a little better construction skill and maybe access to a lathe to make something that worked really well (butt hey, if you're in high school it's a good reason to take metal shop).

Let me try my hand at ASCII again:

.........._________________________________________......(1)
.............___________________________________|__|........(2)
.......///============================|--|...................(3)
.............___________________________________|__|........(2)
.........._________________________________________......(1)

(1) Pump casing
(2) Outer high volume pump shaft which is a tube
(3) Inner low volume pump shaft which fits within (2)

(3) would need to screw into (2) for volume pumping, then you'd unscrew it and continue pumping to increase pressure.

The | | represent your o-rings or electrical tape seals.

The ........ represent spaces because the interface parses out spaces.

[Ben]

As for water path and turbulence though, the current SSC APH design has the water jetting into the "barrel" at a 90 degree angle as well. With twin APCs, you also have two 90 degree streams creating independent stream turbulence.

Of course! I never said that was the best design (in fact I always say that it is a low performance design). Siphons are simply worse.

I was going to try out a schrader valve nozzle on one of my APH's actually. I didn't feel like adding one because that's just another point for stress and leaks.

That pump inside of a pump is a brilliant idea! Save total pumps while building up most of the easier pressure and built it greater when it is the hardest! That is pure genius in my opinion. B)

[Spinner]

Originally posted by Ben@Jun 30 2005, 12:22 AM
That pump inside of a pump is a brilliant idea! Save total pumps while building up most of the easier pressure and built it greater when it is the hardest! That is pure genius in my opinion. B)
[right][snapback]25583[/snapback][/right]

I doubt anyone will believe me, but I actually had that idea myself some while back. Just didn't have the opportunity to use it...after all, you know my experience with finding the materials for homemades... -_-

[RacerSoaker445]

Wow! A pump inside of a pump! Certainly a unique idea! I think I will go give this a shot.

[NiborDude]

That's a very interesting design, but how easily would it be to pump? Plus, the extension of both pumps may make it awkward to pump.

[frankenbike]

Originally posted by NiborDude@Jul 4 2005, 12:45 PM
That's a very interesting design, but how easily would it be to pump? Plus, the extension of both pumps may make it awkward to pump.

It might be hard to explain and make it kind of clear.

One pump fits inside the other pump.

A locking mechanism should be devised so that the larger diameter pump can be pumped up while the inner one is locked to it. This could be as simple as a thumbscrew and threaded insert in the pump handle. Or better yet, have too separate pump handles (you still need the lock, but I'll explain why separate handles might be advantageous).

So when you pump the larger pump, the inner one is locked and acts as if it is part of the larger pump.

The larger diameter pump would be the first to be used to move the largest amount of water into the APH chambers. When it gets too hard to pump, you unlock the inner pump, hold the handle that drives the larger pump so that it doesn't move in the pump housing, and pump the inner pump.

Because of the smaller diameter of the inner pump, it displaces less water and gives you better hydraulic leverage, making it easier to pump than the large one, but the tradeoff is that it pumps less water.

The problem this solution addresses is that you typically have a tradeoff between fast loading in a homemade (or any hand pumped pressurized water gun), that is pumping the largest volume of water in the shortest period of time, or high pressure. No matter how strong you are, you will always run into a pressure wall so long as your priority is speed loading.

By having a pump within another pump, you get both solutions in one device, though at a cost of additional design work and construction effort.

Also at the cost of maybe blowing your APC apart if you can increase the pressure significantly. It would most certainly put more stress on the components and require more diligence in construction.

[NiborDude]

Oh so you're saying you don't want to pump both at the same time, rather use the larger one in the beginning stages and the smaller one for the later stages. The design kind of reminds me of the plastic lightsabers.

[frankenbike]

Originally posted by NiborDude@Jul 4 2005, 01:21 PM
Oh so you're saying you don't want to pump both at the same time, rather use the larger one in the beginning stages and the smaller one for the later stages.* The design kind of reminds me of the plastic lightsabers.

Actually, first you use both at the same time, but without telescoping the smaller pump. The inner pump completes the displacement of the outer pump. Then you just use the inner pump alone to complete pressurization.

I mean, you could telescope the inner pump, but it won't increase displacement that much and your stroke is inconveniently long.

Hopefully the attached diagram will be more helpful in explaining what I mean.

[Ben]

Get that patented immediately frankenbike! I could really see Hasbro homing in on such a great idea. B)

[frankenbike]

Originally posted by Ben@Jul 5 2005, 08:14 AM
Get that patented immediately frankenbike! I could really see Hasbro homing in on such a great idea. B)

Really? I couldn't.

They really aren't interested in making more powerful guns, and I think part of their design limitation to avoid liability is to make guns too hard for little kids to pump so they don't hurt themselves.

Though some day, I should learn how to fill out patent forms. A mad scientist isn't worth his salt without a bunch of worthless-to-anyone-else patents to his name.

(This is no doubt why mad scientists turn to a life of crime to fund their doomsday devices...it all makes sense now)

Now I could see Big Bee using an idea like this. My licensing terms would be very generous. Documented credit, merch, swag, sponsorship of my wife's roller derby team, a job...

Though I think if they were really interested, I have some much better design ideas if they wanted to branch out to a paintball-style-adult/near-adult market.