Well, if you haven't figured out by now, a Littorio caught my fancy. due to a current lack of tooling (in storage, no space) I've been doing design/research work on it, with a plan of scratch building the hull/superstructure. I plan to post progress here as the design progresses, hopefully, that will show a bit of a design -> hardware -> build. I expect this to be a very slow/time consuming build. The fun begins in research. I have the Moriske plans and the book "the littorio class" by Bagansco and de Torro. For future reference there are a whole lot of internal and between document discrepencies and things that just don't line up in both texts, but both are of great value. The bulk of the "that just ain't right" discrepencies are in hull form. That being said, there is a point where perfect becomes the enemy of "good enough" and I am at the good enough stage. One of the more interesting (to me) discrepenies was with the rangefinders on the 381mm main battery. The drawings in both texts looked good, but when you actually draw them out, they become impossible (two lines overconstrain a plane) when compared with pictures of the turrets in regions that are almost obviously flat. some tweaking fixed that up good enough. Then the rangefinders... the drawings show one thing, that looks ok, but then I came across two pictures that showed the back side of the rangefinders/AA deck.. drawings fairly obviously wrong on the back side and for AA deck.. more tweaking to get closer to pictures later, and I have what is shown below... Which goes nicely with the rest as it currently stands... After the rest of the details are drawn up, it will be time to figure out propulsion and steering, then the hull ribs and keel can be layed out...
and the insanity continues... rather than work on what I should, I spend my time detailing... rangefinders and 152/55's have been added... along with more detail on the tertiaries...
Finally got the hull sorted out. the region in red is the area that is more than 45 degrees down (and hence solid in all known formats) the rest of the hull hits 1.25 inches below the waterline (1in required plus a quarter inch of conservativisim) so I didn't show it. Next steps will go something like this: Preliminary rib layout, 1/4" wide ribs. Internal equipment layout, drivetrain design/layout, rudder train design and layout, followed by detailed rib and deck design...
So I have been playing around with the rudders. given the hull and rudder shapes, I decided what I wanted was the following functionality from the rudders: Input is +/-45 degrees (standard servo) Main rudder swings +/- 90 degrees. secondary rudder A swings +45/-90 degrees, secondary rudder B swings +90/-45 degrees with the additional restraint that when the input is at 0 degrees, all three outputs have to be at 0 degrees. I wanted to see if it could be accomplished with a single servo. the linkages below are the parts needed to do that, using a chain for the main drive and to achieve +/-90 on the main rudder, with a secondary gear set (clocking this so it doesn't bind was extremely difficult to figure out but it can be done at least with 32 pitch gears using 1x 12 tooth, 2x 18 tooth, and 1x 24 tooth gear) that has different gearing depending on which direction of travel it is going. Now I put this here to show what could be done. after costing out the gears, chains, misc. hubs, etc, it actually is more expensive to have a single servo than to have three different servos and just mix them (even if using a stand alone mixer) along with more alignment issues. this being said, this path will not be pursued in this build, I will be going back to a 3 servo setup, with the plan being 3x identical traxxas waterproof servos and servocity servo gears driving the outputs.
not when you can make a rudder that's max side force is at 70-80 degrees. It is also nice to have the break on occasion.
Why not just go with a linkage system with the servo between the 3 rudders. I seen this done and it worked well.
Thats easy with linkages. Im not gonna say he can get the exact throws he is looking for. Just that he can get the asymmetric factor by crossing the linkages to the outside rudders and not running them perpendicular to the tiller arms. Das Butts
you can get the throws I want (theoretically) with linkages. the issue is that the geometry necessary for said linkage produces a truly unworkable linkage.
You could layer it height wise with multiple 90deg bell cranks to tighten up the footprint. That would increase the "slop" in the system depending on your attachment method. More failure points too. Personally I would rather have more mechanical things than electronic and would risk it. Das Butts
unfortunatly, from the 4 bar linkage solutions, that would not work, one linkage needs to be 3-4 times as long as the distance center to center, hence the no way in heck does it fit. Honestly, by the time I put in all those linkages, I am not convinced that the electronic solution is too much less reliable. But I plan to design a drop in setup to do either 3 servos or one servo and a chain/belt drive without the asymmetric throws, just in case.
I agree with Mike on this one. Solid state electronics are one thing: I can paint them with skotch-kote or epoxy and throw them in the bilges and forget about them. I'm not a big fan of having more servos than necessary. Good to hear you've got a back up plan. Is there perhaps a cam system that would work?
Hmm ... how about ... Rudder servo geared to the main rudder using something like BC gears. Mount a flat bar metel across the top of the servo gear and run crossed linkages to each of the outer rudders. The linkages can be mechanically adjusted to reduce throw to the side rudders while keeping the main rudder's full movement. That should fullfill all of the rudder requirements you are looking for.
