Modding SC 600 Nozzle

For questions, articles, and discussions regarding water blaster modifications.
User avatar
marauder
Posts: 3821
Joined: Tue Jul 20, 2004 9:29 pm
Location: Clayton, NC
WWN League Team: Havoc
Contact:

Modding SC 600 Nozzle

Postby marauder » Mon Nov 03, 2014 12:38 pm

Hey everyone. In preparation for Frozen Fury I've decided to increase the nozzle size on one of my SC 600s to get more power.

The biggest complaint about the 600, going back at least as far as I can remember (which is a year after it was initially released) was that it just wasn't powerful enough. You can see this in reviews on GNG, Duke Soak 'Em, and old comments on SSC. It didn't take long for people to notice that there seemed to be 2 different marks or version of the SC 600, a lesser powerful release with black trim and a more powerful release with grey trim. For over a decade the majority consensus was that the grey trim mk2 had a more powerful rubber bladder than the black trim mk1. I surmised, about a year ago, that this was not the case, but that it was purely due to the fact that the mk2 had a larger nozzle size than the mk1, something no one had bothered measuring until recently. In fact, I compared the nozzle size of the lower ranged mk2 to that of both WWF models and found that they were all equal, with all three having nearly identical range, output, and shot time. Furthermore, I modded one of the WWF guns by increasing the nozzle size to that of my mk2 and ended up with range and output comprable to that of the "more powerful SC 600 mk2.

I'm assuming that increasing the nozzle size to that of the Zook/PPB/Devastator will also relate to an increase in range. Dux and I have discussed "range curves" in the past, which is basically a theory that range vs nozzle size can be plotted as a negative quadratic equation, basically an upside down parabola, where range increases with nozzle size up to a certain point and then begins decreasing downward. For example:
Image

This assumes that all other factors (beside nozzle size) are kept equal. In plain terms this means no messing with or modding firing valve size, type of bladder, type of firing valve, psi of the pressure chamber, etc.

The current stock range for my mk2 is 36-37 feet with a nozzle size of 1.6 mm / 1/16" / 0.0625". I am making a prediction that I can up the range a few feet if I increase the nozzle size to be in the Devastator/PPB/Splashzooka range which is about 2.4 mm. The only problem with my assumption is that all other factors aren't equal. The PPB, which has a max stock range around 39 ft, has nearly the exact same firing valve size but is air pressure, the Splashzooka has a different pressure chamber, and the Devastator uses a ball valve. Nevertheless, I think we will see an increase in performance by increasing the nozzle size. I will be using this post to update you on the process and to get feedback and ideas from everyone.
https://hydrowar.wordpress.com/

SEAL wrote:If you ain't bloody and muddy by the end of the day, you went to a Nerf war.

User avatar
marauder
Posts: 3821
Joined: Tue Jul 20, 2004 9:29 pm
Location: Clayton, NC
WWN League Team: Havoc
Contact:

Re: Modding SC 600 Nozzle

Postby marauder » Mon Nov 03, 2014 12:51 pm

*double post*

First Step

Today I'm disassembling the 600's nozzle. To my knowledge I don't think anyone's ever done this before, or at least they never bothered to post about it if they did.

Here's what's inside:
Image
So that's how Super Chargers work! There's another little valve inside the nozzle, made up of a plastic piece with a rubber washer on top backed by a spring. The pressure of the water from the QFD pushes the plastic piece down on the spring and opens up the firing valve. This allows water to flow in at a much greater rate since the area inside the nozzle is greatly increased. Without this piece you'd be forcing water in through the little 1.6 mm nozzle aperture.
Sorry for the crappy quality, I don't have a camera at the moment, and my phone isn't that great.

Image
Here's another look at that plastic piece and rubber washer from the valve. Note how small the nozzle aperture is (you can see it with the rubberwasher around it) compared to the piece it fits into.

Image
Here's a picture of how it all fits together. This look is from behind, as if you are looking at it from the direction of the firing valve and pressure chamber.

Image
The nozzle has a mini laminator behind the QFD port valve. This is very similar to the mini laminators found in the Monster series. Sorry for how dark the picture is. I will try to get a better picture of this piece later. The plastic between the openings in the mini laminator is actually quite thick. I imagine that this does a great deal to slow the shot down, which gets even further slowed down by the QFD port. There has got to be a lot of turbidity inside the nozzle. Oddly enough, the 600, along with other Super Chargers, seems to have one of the least turbulent shots out there. I guess this has to do with the fact that the stream speed is slowed down and only allowed to exit through a small opening.


To be continued...
https://hydrowar.wordpress.com/

SEAL wrote:If you ain't bloody and muddy by the end of the day, you went to a Nerf war.

User avatar
SSCBen
Posts: 888
Joined: Sun Jul 16, 2006 9:06 am
Location: Austin, TX
Contact:

Re: Modding SC 600 Nozzle

Postby SSCBen » Sun Nov 09, 2014 2:13 pm

maurader, thanks for bringing this topic to my attention.

"Range curves" are an important idea in water gun engineering. I recognized the concept back in 2004, though my understanding was flawed. I don't think a parabola is the right shape now. Something like the following is probably more realistic:

Image

The numbers in the plot above are made up, but I have reason to believe the general features of this plot are realistic. For example, my mathematical theory suggests that as the diameter goes to zero, the range should go to zero (this seems obvious enough because no water will have no range). But what's not obvious is that the slope of the curve is zero there too; this is due to the effect of stream breakup. Then, as the diameter increases, the range will increase until a peak is reached, and then decrease, potentially gradually, potentially sharply.

What's most interesting about range curves is that it's not clear precisely why the decrease in range happens at all. My computer model from earlier predicts that range will continue increasing as you make the nozzle diameter larger. I call this the "ideal nozzle paradox".

I've developed a hypothesis that might explain the paradox. The simulation is based on the assumption that the shot time is effectively infinite. This clearly is not true in reality. The reduction in range could be caused by the duration of the shot being too low. I hypothesize that this contributes to stream breakup.

One way to characterize this is what I'll call the stream aspect ratio: V_w/d^3

V_w is the water volume of the shot and d is the diameter of the nozzle. This is one way you can compare water guns of different size, to see if the range could possibly be improved by increasing the size of the shot.

I've been meaning to test this hypothesis with a carefully made homemade water gun, but I haven't had the time, and won't for many months. If anyone reading this wants to do the test themselves, let me know and I can help you set up a rigorous test. Alternatively, you could compare the range of tap shots and shots with long durations, though this won't be as rigorous.

Originally, I thought the decrease in range was caused by larger streams being slower, but if you do the math, you see that's not true. In fact, the opposite is true. Larger streams are slightly faster than smaller streams.

Some other possible explanations are that my model doesn't include the effect of air entrainment (air being pulled along with the water), that the drag on the stream before breakup is wrong and should also include shear stress, that the drag coefficient I am using for the spray is not accurate, that the droplets are assumed too large (adjusting this did not seem to help my simulation), and that the droplet size distribution is not considered (this is not easy to do, but it's on my to-do list).

Anyhow, I'd be interested in seeing the results of the modification. Looking forward to your reply.

(Oh, and if anyone is interested in the algebraic function used to make the plot, it's this: a0 * (exp(a1 * d) - a1 * d - 1) ./ (1 + a2 * d^a3). This function is not based on any theory, aside from the mentioned constraints, i.e., that the range is zero when the nozzle diameter is zero, etc.)


Return to “Modifications”

Who is online

Users browsing this forum: No registered users and 1 guest

cron