Good tip on the O-Ring. The buna ones I picked up from Home Depot are a perfect fit, but I'll keep that in mind in the future! Depression. I've put a lot of thought in to it, and have a plan for how it'll fit into my design. Basically, the gun mount will be much shorter, and will have a pivot point inside where the cartridges will rock back/forth. However, I decided to prioritize getting a ship on the water first; so what you see is a muuuuch simpler geometry. Most of my fellow NTXBG have given up on depression; so I don't feel I'll have an immediate disadvantage. She does have a little bit of a list with one turret rotated, so we'll see once the second one comes off the printer this week. I do think I'll eventually have a configuration for metal barrels at some point. I already proved them out on the Surcouf cannon; so I know how to make it happen. Velocity - good question! I ran some tests this past weekend; and was getting pretty consistently 1.5" into the foam with 7/32" bearings. I didn't think to try out the BB caliber guns, so I'll add it to my list this weekend. I wanted the extra 0.5" penetration, so I tweaked it to the point where the 7/32" round would just get stuck in the cannon most of the time. I was trying to figure out if the cannon had any significant leaks, or if it was really at 150PSI. After a while, the magazine wall just gave out. The next cannon revision have thicker magazine walls; so I'm hoping that problem is behind me. That said, I've pretty much concluded the blow-by on the barrels is what's limiting me the most now. After a point, the tweaking just had very little benefit. These 7/32" barrels are built so I don't have to do any post processing, which means there is room for improvement. If that doesn't give me 2" of penetration; I will eventually add a metal barrel. That all said; I think I'm going to call 1.5" of foam penetration good enough for now; and continue to work toward getting her into a real fight. -- One of the things I'm most happy with in this design is I can quickly swap big gun for fast gun cannons. Everything is just attached to the deck; so just swap to a new deck & I can fight whatever ruleset I want.
Update! Aft turret deck, mk1 finally came off the printer!! …and as you would expect, it’s pretty rough. It has a lot of “hitches” to work out yet. You can see it in the video as the aft cannon does not rotate as smoothly as the front cannons. However, I can finally show off the gun director logic! It tracks a single point from two offset turrets. It does have convergence for closer distance, but I forgot to show that off… and I haven’t yet updated the code for @Kotori87’s observations. Lastly I tried to video the firing mechanism. The blue lights represent a single cannon firing. (Note, I haven’t purchased the 3rd firing board yet, for all 6 cannons. I tried to show a couple of single trigger pulls, as well as the full auto. The idea here is to make every shot count; until it’s time to dump lead.
I’ll get you some pictures of my set up. But it looks like your rudder covers a little bit more of your outside prop. Based on your short video, mine does seem to turn just a bit sharper. I think that has to do with the different rules. I have a 3sq in rudder with this horizontal fins to help keep the wash on the rudder. I’ll get you some video and pictures this weekend when we are at the pond.
New Pump Design! The biggest thing I wanted to see out of this design was to easily field strip it. SO I'm re-applying what I've learned from the cannons about 3D printed threads & O-Ring seals. When I want to field strip the pump, I'll simply have to twist the seated motor & clear the block. --- I designed this for a 550 that I bought on Amazon today. Unfortunately, all told, the 550 is just too tall for the Deutschland. I'm going to print this revision out as it is tonight, because I'm sure I'll find some improvements. However, I will need to reduce it for use with a 380 or similar.
Huh. Thank you! Never heard of one of those before…. I guess that’s what happens when you are making this stuff up as you go! Quick googling gives me the general idea of what I need to add. Is there any guidelines or rules of thumb for the Volute? (Or any other tips you can share?)
Most pumps I've seen just offset the pump outlet so its outer edge is tangent with the circle of the impeller. Better than nothing, but still not great. In my pumps, the volute extends about half-way around the impeller. I have no idea how much or even if my volute improves performance at all. At our scale and without common motors, it doesn't seem to make a huge difference.
Pretty good fit for a first try! I think I’m starting to get the handle of this Fusion thing!! 550 Motor is just a tiny bit too tall. I’m starting to consider just making space for it in the SS?
Pump RESULTS!!! @Beaver is 100% correct, pumps need Volutes! Detail: everything was the same between the pump geometrically, except the volute.
Well, I learned some more stuff about pumps. I learned that IRCWCC pumps have an 1/8" restrictor, not a 1/4" like I have attached to my pump right now. Next I learned from @Kevin P. 's amazing pump videos, that having the restrictor in the middle of the pump pipe yields "20% more waterflow" than when the restrictor is at the end. So, I have both designs in the printer right now & will give them a try soon! I also burned out the brand new 550 motor I got from Amazon. So, it's in a box ready to go back tomorrow; and the next least expensive motor is on its way to me! Detail: Kevin says this is vastly more efficient: Than this:
That will be better but it would be even more efficient with an aggressive taper into the restrictor and a gentle taper out.
Did you burn up the motor, or wear out the brushes? DC brushes experience significantly more wear when run underwater, and I notice your test rig was almost completely submerged.
Brush wear due to water is ridiculous. At 2021 Nats, my brother lost a brand new 550 pump motor because his radio failsafe locked the pump ON. He sank in deep water, and declined to interrupt the fleet battle for a swimming recovery. Fifteen minutes later, when we retrieved his ship, both brushes had worn completely away and the metal brush holders snapped off when they contacted the commutator. It can happen that fast.
Update - I have 1.5 weeks before the next battle. So today was a test day for all electronics and programming. Upgrades - — OVERDUE - added dialectic grease for all my electronic connectors. — Installed the pump on the ship. It tried all the pump shaft designs that had printed, except the last design than beaver recommended as I just didn’t get the time to print it. I was quite disappointed with all of them. Fortunately, I remembered my next battle is big gun! So I just installed the “long distance” pipe from the first tests. (Yes, I know I’ll need to slow down the motor…) Added (simple) pump programming, every 10 seconds the pump runs for 3 seconds. It’s enough for me to see if the ship is sinking to turn on full pump. TODO: I need to post a question to the forum about pumping strategies… I tried MULTIPLE “dual” prop-drive ESC algorithms, trying to get better turning. Reversing one, slowing one down. None of them has turned as tight as both motors at full throttle. I’m honestly disappointed. Both turrets are rotating based on the “target computer”. It’s pretty awesome to see it live. I wish I was able to take video, but it was just too dark by the time everything was working correctly. I do have to say, for @Kotori87, the user experience of my stick-positioning system is being called into question. I do know I’m not yet a good Big Gun driver. However, there is a large cognitive load to drive the ship relational to where you stand AND move the guns relational to the orientation of the ship.
Your experience with turning makes a lot of sense. The inboard propeller, which you would reverse to turn, is also the one providing most of the propwash that the rudder is redirecting. It *might* make a difference on a four-shaft ship like Iowa or Yamato, as long as you keep the inboard propellers rotating ahead. That's a great idea to automatically run the pump every few seconds. I know my brother has sunk numerous times because he forgot to check his pump. I try to check my pump every 30sec or so, but I am highly susceptible to time dilation effects during battle. I wonder if it's possible to include an automatic pump circuit, so you toggle off/auto/on. Cognitive load is a significant consideration that many captains underestimate. I think that's why so few people use rotates in Fast Gun. I am considering ways to incorporate a rotate without frying my brain. I might try something on a future build. Good luck at the battle! Sink a convoy ship for me.
