it'll be cool to see how those drag props work out when you take it for the first test run. looks like they'll feed a flow of water straight into your props. So the rudder post will be slightly forward of the rudder's center? how much of the second prop's thrust cone will it block?
You can play with how to center the rudder for best effect, but you can never completely cover both props. This is why a single prop ship will never turn as well as a dual prop. And those single drive dual rudder boats…..
Bismark is a single drive dual rudder. Opposite spectrim from dual prop single rudder. "Woot" meaning that it would turn very good.
I'm sure you meant "This is why a dual prop ship will never turn as well as a single prop." Anywho, I'm going to mine Kevin's builds for ideas for my NM build in January and hope to at least make it challenging for @Panzer to sink me. I suspect that with enough brainpower, the American STBs can be made to hold their own in spite of their handicap
Photo dump. Hull 9 and rudder construction. Drag discs are something I don't comment on any more, but these are similar to Agincourt. Tried out a few rudder sizes, this one should be good. Generally my goal is to cover the hub of the outboard prop when rudder is at 45ish, this is slightly less but I think it will be good. And yes I think Keith mistyped, if you can't get a three prop two rudder ship to turn then its probably not the boat's only issue. Warning - the images your are about to see are not intended for all audiences. Those captains and keyboard commandos who are offended by non-100%-scale rudders should divert their eyes.
Few pics Trimmed rudders, cut out subdeck. Might get rudder slightly closer to hull, but this is generally the position Cut subdeck. I was very pleased with tape method, kudos to bob Back home, hull 9 Both Best first cut fit I’ve ever had. Bow will need tapering per usual, otherwise almost no grinding needed Made sure aft cross brace left room for rudder servo and the aft turret, should be good
So, questions abound. How big of a rudder did you manage--did you max out surface area for class 4 with that one? the tape method, I assume the subdeck is fiberglass sheeting of some kind, and that you put blue tape over the material you wished to keep--is this correct? How have you/how will you be bonding the subdeck to the hull? will you use some fiber to reinforce the bond? I have more, but am sure the answers will be in future posts. the above, if they'll be in future posts, feel free to let them lie and I'll just wait for the answer (complete with pics!) You're tempting me to do a fiberglass hull one day, Kevin.
Rudder is Class 4 size, limit is 3.75 sq in, area is projected area (length x height) vice a surface area. I use a spreadsheet to determine different length/height combinations to see what shape I like best, cut a few out of index cards and pick dimensions (picture shown in a post above). For this one with the angled top, I measured the change in height over 2.25in (rudder length), which came out to .75in, so I marked the height in the middle, then added 3/8 on one end and subtracted 3/8 on the other. I need to check them post build, since pieces can go together with small gaps which could increase overall size, so I will probably trim a sliver off the leading edge. Subdeck material is 3/16 aircraft grade birch plywood, 4 ply. The tape marked the inside contour of the hull (when pushed to correct beam) which accounts for variations in fiberglass thickness. I cut clean along the inside edge, so the tape is the material to keep. Then I marked the thickness of the rim on the tape for cutting, and location of cross members, drilled holes for jig saw access, and cut. To attach deck rim I usually put a layer of fiberglass mat between the inside of the hull and the outer edge of the plywood, and attach with epoxy. This fills up most gaps. Attaching subdeck can be a PITA depending on build size, but it is a milestone step. Once it dries, I will tape up any remaining gaps from the bottom and fill with epoxy and/or microfibers (filler) if the gaps are larger. For this project I might attach the subdeck and deck rim outside of the hull first, since I need to taper the edge of the subdeck for the places where the deck rim is only allowed 1/4" because of two stringers. Typically I epoxy in the subdeck to the hull first, then put deck rim on top of subdeck
Worked on deck rim and rudder servo mount yesterday Standard rudder servo setup, sprocket and chain from servo city Marked bow to sand the angle needed, guessed 1/8 off Underside, used index cards to mark contour at bottom of deck rim Sanded down, needed a little more off the front Done Showing fit Always check beam early and often Stern, working on pump outlet tube routing Now to servo mount Pretty simple Marked shape of vertical piece Assembled Now to mark deck rim Cut out. Just a U in the stern Bow piece the cut out will be deck. Used cutoff wheel to cut slots for blade entry Fwd rim Shout out to this bit, mini sandy drum was a champ. I hadn’t used one before out of ignorance, but far the fastest deck rim making process Will need to taper the edge of deck rim to get to 1/4 in some spots Marked aft deck piece, 1/16 fiberglass sheet from McMaster Cut out Epoxied pieces in, coated 100% prior to putting in Used mat cloth and filler to make up joint with hull, will be plenty sturdy Glued deck rim together to allow tapering edge prior to install
this "here's what I'm using, and here's where I bought it" you did just saved me a lot of time. That boat is looking fantastic.
More work today. Pump outlet tube routing, standard setup Tube from pump Added the step piece Tapered the underside of forward rim Prepped guides before opening epoxy Getting rim in wasn’t too bad. Added layer of mat between hull and rim, think it will come out good. A few clamps General idea is to use deck rim as alignment, cross pieces set the correct height when clamped Earlier in the day I marked deck pieces. Planning to use magnetic tape on the aft deck for a good deck seal. Each layer is 1/16, and 1/16 deck adds up to 3/16 which is the thickness of the rim Rudder servo mount came out good Marked barb holes And forward deck Cut holes
Hey so what are you using for a sprocket on the rudder post? Are you using a hub-mounted sprocket with a locknut hub, or are you using a press-fit?
This https://www.servocity.com/0-250-pitch-0-770-hole-pattern-acetyl-sprockets and this https://www.servocity.com/770-set-screw-hubs plastic .25" chain, servo mount sproket for the servo
Pulled clamps, layup came out good. Cleaned up the top for now with Dremel, it will need some more filling in a few spots Deck pieces Can't wait to cut the barbs out, that's always a nice step, and I'll get to feel out the gun layout more. Water channel will probably be next thing inside the hull once I finish finishing and sealing up the deck rim. Will use 1/4" magnets for the bow, strip magnet hold down in stern. Magnets have held up on my other builds I’ll be out of town for the holiday, so progress hopefully picking up Sunday. Also more traxxas motor mounts finally arrived, so I can start moving on #9 again to catch her up. Several places I tried to buy mounts from were sold out, finally was able to order 6x from traxxas website in case they go out of production. I (potentially) blame the tariffs. I should be set now for a few years of builds anyways
Thanks Greg, looks like they are slightly different in real life (12" vs 13.5"), a quick picture comparison shows that the turret body (?) is nearly identical (well within constraints of what passes for a turret). I'm not personally ready to make the jump to 3D printed guns, I still prefer the old reliable copper/brass guns. But Caleb (@Beaver) or Will (@bsgkid117 ) or Craig(@Panzer ) might be willing to try them out.
If anything, I'm printing some with the local High School Tech ed teacher as a cool experiment and @Panzer is welcome to test one of mine next year
I'm not sure I've ever seen a BB hole in another ship from a printed cannon. I've seen a lot of keystrokes, and have seen plenty of parts on the bench, or in the pits, but it sounds like the west coasters have made more progress/success
