NC triple sterns. Derf dual sterns, sidemount action, stranded on the rocks, was a rough few minutes for the Provence there
she is looking nicer still. although there was an added benefit of the vastly improved water channeling and waterproofing of electronics over last builds the following video was a staged re-enactment of the last few feet of a solid drag stern along bottom and return to shore under power after sink.
It did good this first year. No major refit planned other than re-sheeting. On that front, help has been conscripted. Pulled much of the internals open to make sure it is dry and started storage prep.
After several years of use, this ship is truly a nasty one. I have had to repair the bottom puck on the twin cannons (failed finally due to overtightened pipe thread, my bad). I never did like the midship sidemount and tried a bow side this summer. it never worked quite right. I decided to prototype up a half unit bow gun (sidemount angle not designed in yet). bench testing shows significant promise although it needs 1 more round to make it a full half unit gun. the lack of feeding issues with this gun gives me some interesting ideas for magazines.. in its current configuration, it easily punctures through both sides of standard amazon shipping boxes, and it is not heavily tweaked yet. I need to design one for some down angle but this is also the fastest firing cannon I have ever built, so I am happy with that functionality. I was afraid it would double shoot due to internal geometry but I have not seen any evidence of that happening, although a magnet would mitigate this risk entirely.
Once I figure out how to get down angle, I will probably publish the native cad files for the cannon. the second prototype worked as well as the first and also holds 50 rounds in the same footprint vs 30 for the first prototype.
Well, after one more season, I have to say it is an end of an era with this ship. I just pulled the last traditionally built cannon and the last machined hybrid cannon from the ship. they are being replaced with the 3d printed cannons (twins and side mount in the stern) that was first prototyped here and tested this summer by myself and another brave fellow in a Westfalen here locally. For the first time I will not have a single traditional cannon in any ship.
See image below. Don't plan to do much more on them for a bit, other projects will get in the way. stern side will get metal barrel soon enough. I may swap positions on them, but I wanted to make sure the twins fit at the lowest position. Will have to rebalast as this drops about half a pound of non centered weight...
Provence refit is underway.... after several years of futility as far as the bow sidemount is concerned... she is being refit from a 0.5U pump 4 gun ship to a 1U pump 3 gun ship, 75rnd stern side and twin sterns.... Also gives me the opportunity to test out a new pump design. promising so far in test, but we will see in practice new pump. Primes well, handles aerated flow well, poor NPSH but inlet port location and design mitigates that problem nicely. Long diverging section on 1/8" orifice converging - diverging nozzle at much lower speeds than I typically run a pump (only running it at ~12000 rpm). Design is still in its infancy as there is little good literature on base design rules for this type of pump (too many empirically defined constants), so a fundamentally experimental approach is necessary. 1.5 unit cannon on left, old dependable 1U on right...
got some pump testing in... need to redesign the diverging nozzle section... above ~3gpm the diverging section stops functioning, so while there is a significant difference in power consumption and height of jet between ~60% speed on the pump and full speed... there is little difference in pump flow rate, as all that extra power is making up for the now nonfunctioning diverging section. Got north of 3.2 gpm even in that case. Need to see what it goes to with changes to the diverging section...
Next iteration of the outlet nd pump... hit 2.7 ish gpm or more (column height measure, need to get actual flowmeter plumbed in line....) at around 6000rpm, ~20psi, and ~15A ish. More interesting is that the dead head pressure was 50psi.... Unable to measure flow by column method at higher speeds, went up to probably 12-14,000 RPM, hit 60-65 psi at the discharge thru C-D nozzle at 35-40 amps... Did not try to dead head it, as based on the previous curve, would have ended up at >120psi....
Ended up at ~35-40A, 4s lipi, 3.5-3.6 gpm with 1000kV motor. Definitely worth working on, as with some improvements I should be able to get that flow rate at 25-30A or less, so good first start for a turbine pump with less than excellent published correlation data (unlike centrifugal). Time to read more papers/journal articles and decide next steps.
Regenerative turbine? I have a industrial body eventually destined for a large ship. It needs to be flooded though. No self priming.
In this application built right they prime just fine. that was one of the first things I tested for because they do have a very low suction head, but unlike centrifical they work very well with two-phase flow.
I assume you went “priming hole-less” then? To maintain head? Also, picture of the body I have. 2.5” diameter impeller. It’s part of a Speck unit.
I am running about a 1-inch diameter impeller at this point, press fit onto a 5 mm shaft. I'll get some pictures it should get its first actual combat trials Sunday. I should note that most of the installation rules of thumb for this type of pump are wrong for the way we would use them
