I-400 Project

This thread will cover the construction of an I-400 hull mold, operating systems and discussion of sub rules and tacttics for Washington Treaty combat.
Today Steve Hill, Jay Jennings, Dave Johnson and I met for several hours to discuss how to build a better I-400 model than the one I built from a modified Battlers Connection hull (now OOP). We studied a new set of I-400 plans and decided on hull mods to make a more stable and higher volume hull.
Compared to the plans the BC I-400 hull is too narrow from amidships to bow, with about 2/3 the volume it should have forward. Measurements showed my model's hull was 7/8" deeper than scale, meaning it was already 1/2" deeper before I added another 3/8" height to the lower hull.
We discussed different ballasting and battery options to get the center of gravity (CoG) further below the center of buoyancy (CoB) and increase stability. (Jay is a real submarine driver (Upholder/Victoria Class) so was a great source of info on general submarine theory and operation.) The conclusion was that the new I-400 hull needs to be only 3/8" deeper than the BC one.
The lines are being redrawn for a hull of scale length and beam but with a draft 1 1/4" deeper than scale. The new profile is the closest shape possible to the original profile and doesn't look bad. Above the waterline the model will be of scale appearance.
I already have an accurate mold for the conning tower and my hangar was a close match to the new plans. Unfortunately the hangar mold was damaged so I have to repair the hangar master and make a new mold. Construction of the plug will start next week and we expect to finish the I-400 hull mold in March.
More to follow!
Bob

 

Hi Bob, will you be selling the I-400 hulls? If so I would like a crack at getting one of your finished products, the last 2 I got from you were top notch.
If you get a chance, I posted a few pics of the new BC Iron Duke hull, the one that I made the plug for up in the new products section, I don't think I will be doing another, just too much work.

 

Hi David,
Thanks for the comments about my Krasni Krim and Sri Ayuthia hulls. The first three I-400 hulls will go to members of the project team. After that they should be available for sale and are short enough to be shipped with insurance by Canada Post.
One way we'll be getting the CoG lower is by making the box keel deeper and wider than scale to allow lead ballast to be glassed into the keel by the builder. This will have a secondary function of allowing the model to sit upright on the wider keel. If additional ballast is needed we think the best solution will be to fill lengths of box section brass with lead and attach them under the box keel.
Another way will be to dispense with the upright gelcell in the slot between the ballast tanks as in my sub and use long packs of rechargable AA cells laid on the upper side of the keel within the hull.
My I-400 was very close to being a success. With a deeper hull, more internal volume and lead ballast and batteries placed lower we think we'll have a stable submarine model that can be used as an armed dynamic diver, static diver, or surface runner. One of the class was converted to an aviation gas tanker to supply isolated island bases so the model can be used as a submersible convoy ship too.
Bob

 

Hey Bob, any idea what the crush depth is on the balsa?

 

I'm guessing a 3'-4' crush depth for 1/32" balsa, possibly less. Balsa crush depth doesn't apply to my I-400 model which was designed to test a different set of construction rules for subs. They were posted in full detail on the Yahoo IRCWCC site several years ago.
My I-400 has a central fiberglass pressure hull with free-flooding balsa sheathed bow and stern sections. Crush depth doesn't apply to those penetrable areas because they fill with water when the sub dives.The 2 ballast tanks are saddle type, to port and starboard amidships. They're penetrable and balsa sheathed. Again, crush depth isn't an issue because they fill with water during a dive.
Compared to an IRCWCC/MWC/Treaty hull about 20% of the hull length is penetrable vs the usual 85%. Given that subs are not allowed pumps for damage control this seems a fair compromise. A hit on one ballast tank will cause a capsize and possibly a sink. With the sub on its side, partly submerged, and unable to steer it's an easy target. Hole the other ballast tank and it goes down. I also proposed higher point values for hits above (25 pts.) and below (100 pts.) the waterline because the sub has no penetrable area on the waterline. (The waterline corresponds to the deck of the pressure hull and associated 1/4" deck stringer, with the upper hull's 1/8" deck stringer in contact with it.)
Bob

 

The 'I-400 Team' (Steve, Dave, Jay and me) got together yesterday and assembled the basswood hull cross-sections and keel sections for the upper and lower hull plugs. After a few hours everyting had gone together well and the frames were left for the glue to harden.
On Wednesday we'll screw the base plates of the upper and lower hull plug frames together at the waterline and dress the edgfes so they're a perfect match. The box keel will be enlarged to 1/2" wide vs the scale 1/4", and 3/8" vs 1/8" deep so sheet lead ballast can be glassed into the hull's keel. The deck catapult also has to be carved and glued topside. Then the base plates will be separated, tacked to masonite and injected with non-expanding foam (to avoid distorting the framework).
At the following session the foam will be carved to the approximate hull shape and we'll apply non-shrink, quick drying wallboard compound. From there on it's repeated plastering and sanding until we hae the right hull shape. If all goes well we should have the hull molds done by mid-March. In the meantime I'll have to repair the plug for the hangar, correct a couple of minor errors and make a new hangar mold. (We already have my conning tower mold.)
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

 

Finally, here are some pics of the beginning of the I-400 project.
This is the top plug frames...

and this is the hull plug frames...

and this the both of them...

and finally the two together.

We are working on it again tonight so more pics will follow.
J

 

Jay, Steve and Dave,
Due to other committments (including vacuuming the house to remove plaster dust from sanding the I-400 plugs - Kim gets home Thursday) I can't get together with you Wednesday night. This weekend I'll glue the 3 plugs to their bases for molding, add the catapult ramp and wax the plugs. At that point I'll leave them at Steve's to have the midline molding flanges made and attached with GE clear silicone. When the flanges are on and waxed we can start the molds, which will take 3-4 days to complete.
Bob

 

I will let the other guys know Bob. We are going to be working on Vanguard and the Newf.
J

 

Jay,
Re the Newfoundland, it needs to have the outer pair of prop shafts installed to be 'legal' under any 'small gun' rule set. As we discussed at the museum show the third turret should be on the main deck aft, not the superstructure, so the deck hatches aft and maybe the entire quarterdeck may have to be modified or replaced to install the aft turret and BB cannon. As it's a 2.5 unit ship Dave can install a 1 unit pump and 75 shot BB cannon or 1/2 unit pump and 2 X 50 shot BB cannons.
Bob

 

Thanks for the info, I'll bring it with me tonight.
J

 

Are we on for tomorrow night at Steve's? Plugs are waxed and on their baseboards. We need to make the catapult and the midline molding flanges. The hull plugs are not perfect but all defects are inward so can be sanded out of the mold.
Bob

 

I will check but as far as I know we are on.
J

 

I talked to Steve and don't think we are on for this week at his place, he is preparing for his trip. We may have to try another location. Maybe Dave's as he has the tools. Would another day be better I wonder? LMK what you think.
J

 

Jay,
Leave it with me. What's left is a one person job for someone who's made molding flanges before. I'd hoped Steve could do the catapult and flanges - I'm getting further and further behind on Ibuki due to spending so much time on the I-400.
I'll try to find time to make the flanges and catapult this weekend, though one day will be taken up by a vintage motorcycle run to the south shore and there's an increasing 'honey-do' list .
We're looking at another week or two delay in making the molds.
Bob

 

Bob, I talked to Dave and he sees no problem using his place. Thursday is better this week for me personally, little sleep Tues and Wed night due to Pam's shift. We can do the work if you want to supervise, Ralph explained the flange process, but it would be better to see/do it. This way it would also take some strain off of the weekend 'honey do' , I have one too. We didn' t want your own projects (Ibuki) to suffer for this project. LMK,
J

 

Thanks Jay,
I have fencing Thursday PM from 1900-2130 so that evening's out. The 'honey do' stuff resumes Friday and goes on through the weekend: gardening, exterior house cleaning, painting and installing quarter-round over the new hallway carpet, draining and cleaning the fish pond, shopping for new furmiture, etc. etc.
Somewhere in between those tasks I'll get the flanges and catapult installed and will start mold making next week. I do need the revised hull lines to cut the new bow and stern profiles into the flanges.
Bob

 

Bob, why not wait until next Wed to do flanges, we can go to Dave's or come here. Did you not get a copy of the revised plans? If not lmk and I can bring some into town tomorrow.
J

 

Jay,
Looks like there'll be rain all weekend so the motorcycle run and outdoor chores will be cancelled. That'll give me several hours to work on the flanges for the hangar and lower hull, which should be enough to complete them and maybe get the first layer of gelcoat on one side of each plug.
Dave called last night and will make the bow catapult from basswood. He'll deliver it when complete along with the revised plan. After the catapult has been glued on I'll do the upper hull flanges.
Bob