This thread was started in the NATCF forum but due to interest in the hull we should continue it here. Having a real sub driver (Jason Jennings) in our local group of IRCWCC and Treaty battlers resulted in a new take on the I-400 sub. Steve Hill got a good set of I-400 plans and a group of us compared them to the OOP Battlers Connection hull that's been used for a few dynamic diving combat subs and my static diver that proved too unstable for use as an armed 1/144 sub. The plans showed the BC hull should have had about 1/3 more volume from amidships forward and also that the BC hull was deeper than scale. I'd deepened my BC I-400 by another 3/8", but even that wasn't enough to get the center of gravity low enough compared to the center of buoyancy. We went about 5/8" deeper than the BC hull, but then widened and deepened the box keel so sheet lead ballast can be glassed into it, at he lowest point in the hull. Dave used a CAD program to redo the hull lines and they turned out very nicely indeed. Note that what you'll see of the I-400 hull above the waterline will be of scale appearance and that the beam is unchanged, but the hull will have considerably more depth and internal voume than the BC version. This will make it more user friendly. Yesterday the frame-work of the upper and lower hull plugs was assembled by the 'team' and several photos were taken. Steve will probably post them. In 2 days we'll get together to complete the frame-work and inject non-expanding foam (to avoid distorting the frame-work, which can happen with expanding foam). By the weekend we should have the foam trimmed down to the frames and can begin plastering and sanding the hull plugs to their final shapes. Submariner Jay came up with a great suggestion: relocate the ballast tanks from amidships, where they are in my I-400 model, to bow and stern, which are already free-flooding in my model. A major problem with my model was lack of space for sufficient batteries to run more than 15 minutes. Getting rid of the amidships ballast tanks solves that problem and will allow the batteries to be installed much lower in the hull, lowering the center of gravity and improving stability. Bob
Steve and I got together ( the others were predisposed) and got a bit accomplished. I have been trying to post some pics and have so far been unsuccessful, so here we go. We are building a two piece plug, screwing the pieces together, dressing and shaping the entire thing and then separating the pieces. The bottom is larger but Dave did an excellent job with the auto cad and it looks good. Tried again, no joy with the pics. Soon I hope, J
Here are the pics of the frames. First the top plug... and then the hull plug frames... now both pieces... and now both pieces together. We are working on it again tonight so more pics to follow. J
Last night Jay, Steve and I spent a couple of hours working on the I-400 hull plug framework. The top and bottom halves of the plug were screwed together and the 1/8" thick basswood bases the frames and keel are glued to were carefully dressed to match with a small hand sander and sandpaper . The enlarged box keel (for ballast) was bevelled and tapered at the ends. A few small asymmetries in the hull sections will be corrected this weekend before the plug halves are injected with expanding foam and carved to approximate shape. We'll be applying the drywall compound early next week and sanding the hull plug to final shape, which should take several days. After that we'll glue on the carved wooden catapult at the bow and paint the plug halves with Zinser shellac/sealer prior to waxing and molding. We're a little behind schedule but should have the mold finished by the end of March. We hope to have hulls made in time for two local model shows in April, one at the Maritime Museum of the Atlantic where we occasionally recruit new club members. Jay took more photos last night and will be posting them soon. Bob
Will do David. I can't repair the damaged hangar mold so will repair the plug and make a new mold ASAP. The conning tower mold is fine. Bob
Steve, Dave, Jay and I worked on the I-400 hull plug again tonight and it was injected with expanding foam. That should be completely cured in a couple of days and Steve will start trimming it. There's a build session Sunday so we hope to apply plaster then and quickly proceed to final shaping. Jay shot more photos tonight prior to foam injection. Bob
Ok, have some more pics. I know how thrilled everyone is with frame pics , so here we go. A bit of shaping going on... Though we'ld put the fin on to check it out... Sorry all, my picture manipulating program crapped out, so the other pics are 10X too large. I will fix it and put the rest (no more frame pics!!  up tomorrow. J
What you're seeing in Jay's latest photos are the upper and lower hull frameworks fitted together with edges trimmed to match. The two pieces are held together by about a dozen short 3/16" dowels. Holes were drilled through the baseplates of the upper and lower hull halves where they meet at the waterline, then the dowels were glued into the upper plate, being a press fit into the corresponding holes in the lower plate. The expanding foam injected a few days ago was carved down to the hull cross-sections today and Steve Hill applied the first of several coats of quick drying plaster. When thick enough the plaster will be sanded to the final hull shape, the two halves of the hull will be separated and prepared for molding. Bob
Finally the resized pics. First the frames injected with expanding foam... After trimming, a bow shot... A couple of nice profiles... and finally the first coat of plaster. We are at it again on Wed. night. I will post more pics later in the week. J
Thanks Curt. We didn't actually work too much on it this past Wed. We had a snow storm, so it was a short session. A bit more sanding and some crack fills is all that was done. J
Well, Steve Dave and myself were at it again last night, Bob couldn't make it. Again, a little more sanding and shaping was done. I know everyone wants to see pics of a plaster plug but will post some pics when it is ready for the next phase, schelacking I think. J
I couldn't make it to last night's sanding session because I was on call for the hospital. I told Steve I'll work on the plug at my place early next week. Hopefully it'll be ready for separation into upper and lower hulls and sealing with Zinser shellac by the last weekend of March. The only remaining 'tricky' part will be making the molding flanges to fit exactly along the center of each hull half. We might be able to start the molding process during the first weekend of April. It'll take about 3 days to make the mold. Bob
Scott, Jay Jennings is a real sub driver and has some good ideas to improve on my earlier attempt at an I-400 using a BC hull. The new hull will be deeper than the BC one and have a fuller shape in its forward half as per the plans, so there'll be significantly more internal volume. My I-400 used amidships ballast tanks (port and starboard) but they greatly reduced the room available for a battery. I used a Panasonic 6V 1.2Ah which gave only 10+ minutes running with 2 Mabuchi 260 motors and less than 20 minutes when one motor was removed. Another problem was that the battery standing upright in the narrow space between the tanks did not help the stability problem. Jay suggested we use bow and stern ballast tanks, which could easily have been installed in the free flooding bow and stern spaces in my model. That gives a lot more room amidships for a larger battery or battery pack. Jay's trying to find a more efficient and compact type of battery, with the plan of making a battery pack from AA size rechargables that will sit on the bottom of the hull, partly in the overscale box keel, which was enlarged for that purpose. There's a lot of lead ballast in my I-400 so if that weight can be replaced by low mounted batteries both stability and running time will be improved. Even if we're delayed a week or two we should have the hull mold completed and I-400 hulls in production by the end of April. We've had a lot of discussion about sub tactics and necessary changes in construction rules. The pressure hull can't be sheeted with 1/32" balsa because it will crush in even a shallow dive. Based on the rule proposals I made to the IRCWCC several years ago, we're looking at an impenetrable pressure hull, penetrable bow and stern ballast tanks and a penetrable upper hull (but not conning tower/hangar) that's removed to get access the hatches into the pressure hull. Penetrating a ballast tank will cause at least that end of the sub to sink and the sub to assume a vertical position if still afloat. Even if one end is sticking out of the water it will be completely disabled and can be declared sunk, which is all that matters under Treaty rules. For other formats the points for penetration of ballast tanks or upper hull should be higher than for a conventional ship model, say 25 pts. above, and 100 pts. below the waterline (ie the ballast tanks). The waterline itself will be impenetrable because that's where the stringers for the upper and lower halves of the hull meet. Re tactics the I-400s will lack speed and running time to chase anything and will have either a stern firing cannon in the hangar (as in my model) or one inside the bow if a custom built cannon can be fitted into such a small space (doubtful). We see the subs sitting on the bottom in shallow water until a ship gets in trouble in close proximity, or loses propulsion, when the sub will surface and fire. They would be most useful as base defence ships in a Campaign Lite (IRCWCC) scenario, submerged perpendicular to where battleships have to stop to fire at the shore base targets. Any battleship firing at the targets will become a stationary target for the surfacing subs. I think the new version of the I-400 can win the old "Pitelli Challenge' which requires a sub to approach a stationary ship from one side, dive under it, resurface and fire at it. BOB
We were at it again tonight, I had no idea plugs take soooooo much sanding, almost done that part. It is hard to move quickly when we can only get together once a week. Here is a pic of the plug sanded, it looks pretty good, we think anyway. The plug Bob built for the fin sits on top. J
