Here's the modified bow. The Mogami hull's bow was too narrow for the first 4-5" - too narrow to install the forward pair of support beams for the flight deck in their scale position. I used a plan of Mogami's forecastle to make a new deck of the right size and shape from 1mm styrene and glued it to the fiberglass deck with contact cement. The new deck is 1/2" wider than the original at one point. Next I applied Bondo body filler, gradually working it into the correct bow shape and blending it into the fiberglass hull. Note the squarish bow tip compared to the more rounded bow tip on the Mogami Class cruisers. This shape is shown well in one of the few available photos of Ibuki. Bob
Here's a rather poorly lighted shot of the Ibuki's hull after having ~1,500 holes drilled in the fiberglass hangar substructure to reduce top weight. You can see the new styrene forecastle deck (glued to the narrower fiberglass deck underneath it) and the styrene hangar front wall glued to the hangar substructure with contact cement. Most of the holes are 3/16" diameter and are 3/16" apart horizontally and vertically. The lowest of the four rows begins 1/2" above the hangar/hull joint. Between the top 3 rows of 3/16" holes is another grid of hundreds of 1/8" holes. Note the opening in the starboard side. The side of the hangar has been cut away to allow the island's large support sponson to be molded to the hull side. That should be finished on Tuesday. Then the entire hangar can be sheathed in styrene and detailing will begin. Bob
Here's a closer view of the Ibuki's forecastle deck and front wall of the hangar. The black squares are where the styrene deck has been removed to make sockets for the second pair of flight deck support columns. Close to the bow you can see the other pair of squares marked for removal. The horizontal line across the front of the hangar below the W/T doors is where a catwalk will be located, extending around the corners and along each side of the hull. There will be a stairway from catwalk to forecastle deck. Side view of the bow, and better view of the holes drilled to lighten the hangar. (I see I missed one!)
Here are the prop shafts and rudders installed, with BC 'A' brackets to support the prop shafts. The resin BC brackets came with a rather rough surface and almost rectangular cross-section, so were sanded smooth and filed and sanded to an air-foil cross-section. A very useful product and much easier than soldering up 'A' brackets from brass tube and strips. The rudders are from two Robbe #1481 kits. Each included a nylon rudder with a long brass shaft, a brass stuffing tube with stainless steel washers, flared inner end and O-ring, and a 2-arm tiller with stainless steel collar and locking bolt. The rudders were originally 36mm (~1.5") long by 50mm (~2") deep. To get a rudder area of 1.5 square inches each they were shortened to 29mm deep, calculating for their taper. I've used Robbe rudder kits of various sizes for nearly all of my R/C combat models. After test fitting, the rudder stuffing tubes were shortened. The stuffing tubes protrude far enough below the hull for the rudders to just clear the keel at maximum throw and are short enough that the tillers will clear the underside of the quarterdeck. The rudder shafts were cut off level with the tops of the tillers. The tillers each had one arm removed (there were two arms at 90 degrees), and the remaining one shortened to clear the inside of the hull at full throw. The locking bolts of the two lower tillers are on the inner sides of the shafts and the bolts had to be slightly shortened to clear each other. The shafts are as close together as possible (28mm) to allow max. rudder throw. Prop shaft centers are 36mm apart to allow a 32 gm CO2 capsule and Palmer RTB regulator to fit in the 30mm wide space between the stuffing tubes. Note the two tillers on the port rudder shaft - the upper one will connect to the servo and the two lower arms will be connected to each other. Bob
Yeah, I was thinking of Swiss cheese while drilling the holes. Last night I made a wooden mold for the island sponson from 1/8" basswood, waxed it and CA glued it to the hull over the opening I cut in the starboard side. This evening I'll gelcoat it and will fiberglass it Tuesday. It sticks out really far and is simply the 45 degree angle formed by the base of the island and the flat outer side of the sponson sloping down to meet the hull. Bob
Thanks Mike. The main 45 degree angle part of the island sponson is done. Now I have to figure out how it was faired into the hangar at each end. One plan shows a flat rear end simply closing off the angle and the other shows a sharply inward sloping transition to the hangar wall . Both show the front sloping inward to the hangar and a gangway entering the front just below the flight deck so it must be flat there for a watertight door. before curving into the hangar side further down. It'll be tricky to mold. I hope to finish fiberglassing the sponson before my wife returns Friday PM. Next I have to decide whether to add the distinctive secondary bulges amidhsips. They'll increase hull beam about 1/4" but will be very difficult and time consuming to add. Max. beam is at flight deck level so the hull will be 'legal' without the extra bulges. They end well above the lower edge of the hull windows so can't be of scale shape along the4ir lower edges. I have no idea what they were for because they're too high on the sides of the hull to be effective against torpedoes. Bob
You ordered plans for the Unryu as well IIRC. I'd probably look at the superstructure area of that class carrier, and use which ever plan looks most like the other class of carrier. My thinking with that is the IJN would have applied some kind of design philosophy to all their ships and it's likely that Unryu and Ibuki would have been as similar as possible given the different designs. As for the bulges, I am personally a bulge hater. I don't like sheeting them, and my models certainly don't have the same level of detail as yours. That being said, as much detail as you tend to put on your models, I think they are too distinctive to leave off. As for purpose, I seem to recall reading somewhere they were for fuel, but I can't remember where I read that. They might have been added to help stability in some manner as well...I just dont know. The IJN destroyed so many records of things before the surrender, it's hard to tell sometimes.
Since they are above the forecastle deck, even if a BB goes in one it does not count, of course that's in the MWC, IRC may or may not be the same, I have not looked at their rule set.
I'd wondered if those odd secondary bulges were for extra fuel storage. They were below forecastle deck level but not by much amidships and were relatively short fore and aft. I may have a go at them though it will mean an extra week of work. I'd reached the same conclusion that there would be similarities between the Unryu Class and Ibuki. I used plans of Amagi (Unryu Class) and a photo of Amagi capsized showing the island and its sponson in great detail to work out a likely design for Ibuki's sponson fore and aft of the 45 degree angled central part. The front angle of the sponson was been molded this evening and I hope to mold the aft angle into the hull tomorrow night. I doubt very much that the back wall of the sponson was flat as shown in the plan on Wikipedia, simply closing off the 45 degree angle outboard. Photos to follow. Bob
Ibuji's island sponson is finished. To add the curved ends to the 45 degree angled main section I marked the outlines where the sponson ends met the hangar wall and cut away the fiberglass hangar side inside the lines. Then I glued short pieces of 1/8" x 1/8" balsa outside the lines, leaving a gap of about 0.5 mm. The aft end of the sponson was to curve smoothly into the hangar side. I cut a piece of 0.5 mm thick sheet styrene to fit against the hangar side, braced against the sections of balsa, curved it over the edge of the main part of the sponson, trimmed it and CA glued it in position. The front end was more complicated, being a compound curve. Plans indicated the upper gangway along the hull side ended at a watertight door in the sponson facing forward. (A similar door was on the Amagi's island sponson.) The front end of the sponson would need a flat area facing forward and just below the flight deck for this door. I cut a piece of 1/8" thick basswood 16mm deep and 10-11mm wide, allowing for the slanted hangar side. This was slightly wider than my H&R pewter W/T doors and was glued edge on to the hangar side with the top at flight deck level and 1/8" x 1/8" pieces of balsa along the line below it. I glued a piece of 0.5mm sheet styrene to the aft side of the piece of basswood and curved it over onto the front of the 45 degree angled part of the sponson. Then I shaped another piece of styrene to fit below it at a sharper angle to the central sponson. The rest was easy: a thick application of gelcoat on the inside of the styrene sponson end 'molds', then fiberglass on the inside of that, let it cure, peal off the styrene and sand the line where the two pieces of styrene on the front end met. The sponson looks great and very similar to that on other Japanese carriers. Next step is to sheath the hangar sides in styrene and start detailing them (AA gun galleries, large air intakes, funnel, etc.). Bob
Curt, The 3/16" holes are slightly larger than a BB and the 1/8" holes are slightly smaller. The grid pattern will provide a lot of support for the styrene sheathing and the fiberglass hangar sides are still rigid despite 1/3 of the material being removed. I got the idea from the 'pepper-pot' wheels on my 1986 Jaguar Sovereign - the mag wheel weights were reduced by having dozens of holes of different sizes and looked like the end of a salt or pepper shaker. When sections of styrene eventually get too damaged they can be pealed off the hangar side (attached with contact cement) and replaced. Bob
Sheeting the hangar substructure with 0.040" styrene started last night with the starboard side which was a little tricky because the curves of the island sponson had to be matched. The port side is simple and will be done tonight. Steve Crane said contact cement may shear off like CA glue when hit by BBs, but I'm not sure the guys in the MWC were using the same product. The starboard side styrene was glued on with Lepage's contact cement, which when dry is still a stretchy film. I may use Goop for the port side and see how they stand up in combat. I've decided to add the strange secondary bulges to Ibuki's sides - this will have to be done before the amidshps windows are cut out.. Doing more research revealed that the Ibuki had the same hull as the last 2 ships of the Mogami Class (Kumano and Suzuya). For some reason their beam was 2' narrower than the first pair of Mogamis. With the Ibuki hull plan enlarged as close to 1/144 scale as possible (there's about 1% error above or below scale on the many measurements printed on the plan) the beam over the secondary bulges is only 68.5'. Because the hull was made by Ralph Coles to represent Mogami the beam is already 68'. That means all I have to do is represent the 1/8" wide shelf at the top of the bulge, which humps up amidships and tapers to nothing toward bow and stern, then make thicker ribs from the shelf down to the widest part of the hull. To do this I'll glue strips of 1/16" thick by 1/8" tall balsa along the line of the shelf and sand them gradually down to be flush with the hull side fore and aft. Then I'll glue a 3/16" flange along the balsa facing downward and forming a 1/8*' deep pocket. With the hull upside down i'll fill the pockets with resin and chopped matte and let it set. When the balsa is removed there will be a 1/8" high and deep stringer corresponding to the top of the secondary bulges. Next the windows and stringers will be and cut out. The ribs will dish in below the stringer so 1/4" strips of balsa will be glued vertically over the ribs passing from stringer to maximum hull beam below. One side of the gap between 1/4" rib and 1/4" balsa strip outboard of it will be blanked off with more basa. Then with the hull on end the gaps will be filled with more resin and chopped matt, forming thicker ribs in the area of the secondary bulges. Some final trimming and the hull will be ready to sheet. I hope to finish the bulges within the next week and will post photos of the process. The hull must be sheeted and ready for detailing the upperworks by early April. Much of the detailing will be done at two model shows on the first and third weekends. If all goes well the Ibuki should be ready for action in June. Bob
Ibuki's hangar is sheeted with 1 mm styrene and the two large flight deck sections have had their locating tabs attached so they're a tight push fit into the hangar roof openings. Tonight I hope to finish installing the first pair of support columns for the flight deck overhang at the bow, then the second pair tomorrow and permanently attach the forward end of the FD on Wednesday. After re-measuring and averaging 3 small plans I found I'd made the flight deck width 1/4" too wide, so spent a few hours and wore out several exacto type blades cutting 1/8" of width off the port and starboard edges of the 1/8" thick flight deck sections, then sanding them smooth. At least it reduced the top-weight a bit. The next big job is the quarterdeck (a section of which over the rudders has to be removable) and the aft end of the flight deck above it, again with two pairs of supports. I've also started marking where the secondary bulge stringers will have to be added to the hull sides, which will be the final difficult part of the build. More photos tonight I hope. Bob
A fantastic build thread Bob. That it is for a little-known aircraft-carrier makes it all the sweeter. Mikey
Thanks Mikey, The build's going slowly due to getting the angles and allignment right on the forward flight deck support pillars. The last pair went in last night, angled outboard at 60 degrees, and a simple but over-scale representation of the steel beam framework under the flight deck was added. At 1/144 scale the beams would have been too fragile. The pillars are made from 3 telescoping sizes of styrene square section 'tubes' glued together with styrene cement plus a 1/16" brass center rod epoxied into a hole drilled in the fiberglass subdeck. They're 1/4" thick so should be quite BB resistant. The forward section of the flight deck clips into the supporting 'beams' between the two pairs of pillars. The rear 2" of the section will be glued to the top edge of the hangar by contact cement. If there's damage to the forecastle area the bow flight deck section can be removed to allow repairs. The contact cement seems to work well. I had to remove a section of styrene from the hangar side due to misallignment and it pealed off with no great difficulty. The glue remained rubbery so I don't expect it to sheer when hit by BBs. I'm doing my week of on-call duty at work but if I get home before dark I'll shoot and post some photos. Bob
