Ben wrote:Great work CDMT. This data is very valuable to me.
Thanks for including the chamber length as well. That made me realize I forgot something which I might be able to calculate from the chamber length. Is the chamber length how far the piston moves? If so, then I can calculate the water volume. If you wouldn't mind, could you measure how much water each one takes when full just to be extra sure this is right? Should be pretty easy with a measuring cup. Sorry for neglecting this.
Using estimated chamber volume, the homemades have outputs of about 25X. This means their range-to-flow ratio is about 2.4 ft/X. The SS 300 gets about 6.7 ft/X. My SuperCPS design got about 6.4 ft/X. The CPS 2000 is about 1.2 ft/X. So the water guns measured are not fantastic in terms of this metric, but maybe if they had smaller nozzles, they might be. (I want to highlight that the SS 300, SuperCPS, and CPS 2000 numbers are very approximate, and the numbers measured in this thread are better.)
I am curious about the range increasing with chamber length in the Stream Machines. The flow rate of the smallest Stream Machine seems low, probably because it takes some time to accelerate the pump up to speed. The smallest two might not ever get up to maximum speed/flow. There might be another effect. In the past I hypothesized that stream length might be a factor in range, with longer stream lengths being better. This data might help confirm that idea. However, I am pretty unsure of this hypothesis, as there's one other possible explanation.
I'll do some more detailed analysis this weekend. No time to open a spreadsheet right now.
As for the seals, I'm not sure. I like piston cups myself, but I don't know if they are good for these sorts of water guns. The reliability is excellent in my experience, provided they are aligned correctly. The friction might be too high, but I don't have any data on this.
Sorry it took so long to reply I have been extremely busy. I have been studying for a servicewide exam, prepping for my transfer and working late with contractors to get the icebreaker I am stationed on ready for patrol. The chamber length is measured from piston seal to nozzle. If I get time today I will try measure the actual amount of water.