Here's an interesting pump project I've been messing with. If you've been following my Atlanta build thread you know I'm building it to run at 24v. This is the pump that will probably make it into my Atlanta. It's a smorgasbord of parts with the lower half coming from an auto windshield pump and the upper, a 24v surplus can motor. This is pumping a solid 1GPM at 24v currently. Bought this a while back to fool around with ($8 at your local NAPA). As is, the pump lasted about 10 seconds under load at 24v (but it pumped like a banshee!). Taking it apart after the failure I found a little can motor inside that outer shield (I thought the shield was the motor). The little motor only had leaf brushes and they melted away (hence the $8 cost I guess). UPDATE: Trico 11-608 washer pump Rummaging though my motor collection I found a few of these that were initially purchased to test as main propulsion motors in my Mogador. It looked about the right size and is rated for 24v. Also, the shaft is the same diameter as the failed pump motor and even had the same D profile. Electronic Goldmine Item Number: G9332. Combine the two and Frankenpump! The pump and motor are stuck together with aluminum duct tape. Working well so far and I'll probably keep it that way until it comes unstuck. Just to prove it's a non-positive displacement centrifugal pump. The .5 unit nozzle was machined out of a 3/16" PTC cap fitting. As stated previously, this pump is doing a solid 1GPM at 24v (and the motor barely gets warm). If it's pulling two amps at load I'd be surprised. I'll be making a full unit nozzle to test so stay tuned. ...
More fiddling with this pump. In testing yesterday the pump wasn't priming very quickly. I took a closer look at the pump cavity and noticed a small gap above the output port. I thought this would tend to trap air in the cavity and inhibit priming. To address it, I machined a filler disk out of some fiberglass sheet and super glued it in place. So far in testing, priming is much better (insta-prime is a word that comes to mind). While fabricating a one unit nozzle for this pump, I remembered I had these tapered countersink drill bits. Taking a look at them I realized I could make a decent nozzle taper with them. Carefully tapering the nozzles So what are the test results with the spacer disk and tapered nozzles? Priming was instant! At half unit, the pump pushed a gallon in 56 seconds, four seconds faster than before. With the one unit nozzle, the pump took 40 seconds to push a gallon. Not to shabby for a 380 size brushed motor IMO. Some other considerations are that the half unit configuration was pushing a stream well above my second story gutter (20') and the pump had significant thrust. I may need to consider a horizontal inline discharge in the Atlanta to avoid any listing issues. ...
I like what you are doing to that pump. https://rcwarshipcombat.com/resources/half-unit-angle-mount-conversion-and-duca-outlet.91/ there is the horizontal discharge variant I am making for my Duca in there, along with an angled mount that primes well with the strike half unit pumps... I may have to make what you have above, as removing the internal air gap in the strike pump and the vent hole would really improve performance I think.
I kind of like the way this pump is turning out. When I decided to do the Atlanta at 24v I was a little concerned about getting a reliable well performing smaller pump that wouldn't burn up at 24v. Looks like this pump and motor combo will be just the ticket. Something satisfying about building a good pump. After this one, I've been saving a 24v RS775 motor for a new pump in my Barham. Hoping for 3+ gpm off that beast.
20' pump streams are so 2005, you need to get on the glug-glug train. 30% flow increase for free, no more rolling over the little cruiser. I've been happy with my flush-deck pump outlet tubes on two of my ships, it allows plenty of length of hose after the nozzle for the flow to fully develop and doesn't violate the rules for mounting angle
I only have about 2" of vertical height to work with. What's the shortest glug exit nozzle you've seen work?
one other trick with the diverging nozzle sections. Roughening the surface in the diverging nozzle regions can actually help in some cases. it is always more lossy than the ideal diverging nozzle but in practice, adding significant roughness can sometimes enable you to use a larger angle as it will impede flow separation at the cost of pressure drop. when and how to roughen the nozzle really comes down to application specifics. See Ch5 of the handbook of hydraulic resistance for more fun information.
I epoxy a brass tube through the deck at a slight incline, the outlet hose fits inside the tube, I cut the outer portion of the brass tube flush with the deck, it provides a way to get around the 2" vertical problem. There are a few pictures in this post of the tube installation, and then shots of it cut down. https://rcwarshipcombat.com/threads/uss-missouri-build-ircwcc.445059/page-3#post-515103 The pump hose with outlet goes into the tube just under deck level, and allows you 3-4" easy of tube after the outlet while still allowing measurement of the 3/32" from outside of the boat.
