Construction of the Ibuki continues but the return of snow, ice and wind chill temperatures far below freezing has prevented the rest of the hull windows being cut out,. That has to be done outside due to the dust. The forecastle deck detailing was finished last night and the forecastle is ready for painting. A friend with an airbrush has volunteered to paint the flight deck with its red and white stripes on the fantail and white lines along the deck. Amidships, the location of the secondary bulge stringers has been marked with 1/8" pinstripe tape. The single available broadside photo (port side view) showed that the hull cross-section plans from 'Japanese Cruisers of WWII' were inaccurate. The secondary bulges ended nearly 30' further forward than shown in the plan and the shape was slightly different. I took the bulge dimensions and shape from the photo instead. I plan to make the secondary bulge stringers (which stick out 1/8" from the hull sides) this weekend using the method previously posted. The stringers will add little extra impenetrable area because they're only 35% of LOA and nearly half of their length is within the 3/8" deck stringer area. The secondary bulges curved up almost to deck level amidships. Very odd but I'm going to add them because they give the Ibuki's hull its unique shape. The original antitorpedo bulges are visible in the photo fore and aft of the secondary bulges so there will be a few inches of main bulge stringer. The same photo shows the 'JCWII' cross section plan was also wrong re the position of the aft end of the hangar. Although the hangar made from the plan is an almost perfect match to the hull at the frame shown, the photo indicates the hangar actually ended at the next frame forward, a difference of over 1" in 1/144 scale. To correct that error I'd have to cut off the rear of the hangar and mold a new rear wall onto it. I'm debating whether to do that or not. At the stern the aft end of the flight deck has been curved downward by heating it in boiling water, then using a piece of hardwood to curve it over a spray can until cool. The downward slope of Ibuki's quarterdeck, which was more pronounced than Mogami's, has been marked for trimming. With that done I can install the quarterdeck and supports for the aft flight deck extension. Speaking of the flight deck the same photo shows the raised double deck elevators clear of the flight deck. The aft elevator is far forward of where it is shown in any of the plans I've found, being almost amidships. Clearly the plans are all wrong but it's too late to change the aft elevator's position. Bob
Ibuki's stern showing curved end of flight deck after heating the polystyrene deck in boiling water and forcing it around a curved surface (described n this morning's post). Note the black 1/8" tape along the stern showing where material has to be cut off to give the downward slope toward the stern. The aft end of the hangar hasn't been sheathed in styrene yet because it may be shortened (plan error discovered as mentioned in this AM's post). Also have to drill the 1/4" holes for the BB cannon barrels before adding the styrene.
View of the large sponson that will support the carrier's island superstructure. This was molded over a hole cut in the side of the hangar as described previously and was done in 2 stages: 1) a wooden mold was used for the 45 degree angled section, and 2) sheet styrene molds were used to form the curved fore and aft sections of the sponson, which are of different shapes. You're looking at the fore end - note the compound curves and the flat vertical section just below deck level where a watertight door will be added. The door opened onto a catwalk along the side of the ship, leading to two levels of AA guns and a lifeboat station. Note also that the side of the hangar has been sheeted with 1.0 mm styrene attached by Lepage's Contact Cement and gaps were filled with Tamiya putty. The putty just aft of the sponson hasn't been completely sanded yet. Top view showing the island sponson sticking out to starboard and the support beams for the forward overhang of the flight deck. Installing the 4 pillars at the correct angles and keeping them alligned in 3 dimensions was challenging!
The forecastle deck showing the framework to support the forward flight deck. Note that the forward pair of pillars has a shaped section of 1/4" square styrene fitted into the gap betwen two pieces of styrene with holes drilled in them (decorative in this case but the holes were present on the real ship in greater numbers and used to lighten the structure). The piece of 1/4" square styrene will be glued to the underside of the flight deck. The horizontal framework is purely decorative and overscale. In reality there were dozens of small steel beams forming a lattice under the flight deck overhang. If shot off it won't be replaced. Side view, this time with the piece of 1/4" square styrene removed from between the tops of the forward pillars. Note the 1/16" sheet aluminum that will be glued into the bow to prevent 'through and through' BB shots. Forward end of the flight deck upside down to show the pieces of 1/4" square styrene shaped to fit tightly between the pairs of support pillars and the pillar side frames. Rectangular areas of the flight deck have been thinned using a Dremel barrel bit on a drill press to reduce top weight. The end of the flight deck that sits on the hangar will be glued to it with contact cement, so it will be removable for forecastle deck repairs. Forward flight deck section in position. It'll be installed after the forecastle deck has been painted.
Beautiful work on your carrier. Its making me start thinking of what I would like to build in the future for a convoy ship of my own. Keep up the great work. Kim
Thanks guys, We have warmer weather this weekend - above freezing - so I can cut out the rest of the hull windows, mold on the thick secondary bulge stringers and modify the ribs to match the new hull contours where the secondary bulges are located. That should be finished by Monday. I hope to sheet the hull before next weekend's NABS/NATCF display at the Shearwater Model Show. At the show I'll finish the sheeting if necessary, build the island superstructure and maybe the funnel. I haven't decided how to tackle the funnel yet. Bob
I'm curious about the aluminum internal armor in the bow. Internal armor is usually a pretty flexible material to absorb a BB's energy. Is there any concern a BB could ricochet off this metal panel and go back through the balsa creating a large exit hole?
It's possible for a BB to bounce off rigid armor and come back out through the balsa, but it'll lose energy in the initial impact. I've used rigid armor in narrow bows before (Courageous and Hood) but saw no exit holes from BBs bouncing off it. Holes from rebounds may be relatively rare except in close range firing where the BB hasn't lost much velocity.The aluminum sheet in Ibuki's bow will be mounted in silicone so it will have some give side to side when hit. It's 0830 and I'm about to fill the balsa molds for the secondary bulge 1/8" stringers with gelcoat. (They're too narrow for a mix of chopped glass and resin, which would be stronger.) Around 1300 I'll remove the balsa from the new stringers, which will form a shelf sticking out 1/8" from the hull sides. The 1/4" ribs are already drawn on the hull. I'll glue 1/4" strips of balsa over them from the new stringers to the lower hull and fill the gaps between the balsa and underlying original ribs with resin and chopped matt. If that's finished today the hull can be sheeted this week. More photos will be posted tomorrow. Bob
The stringers for the secondary bulges turned out fine and the balsa used to mold them has been removed from the sides of the hull. The stringers extend 1/8" out from the hull side and taper into it at each end. Total stringer thickness including the hull is about 1/4". The hull windows were cut out yesterday and strips of 1/4" by 1/16" balsa were glued over the ribs from the new stringers to the lower hull. The gaps between the balsa strips and the ribs are up to 3/16" wide. One side of each gap has been blocked so the hull can be stood on end and each pocket so formed can be filled with gelcoat. That'll be done tonight so by tomorrow evening Ibuki will have it's secondary bulges. The brass armour mounting bolts will be installed Wednesday and the hull will be ready to sheet. Bob
The secondary bulges turned out fine, with their long curving stringers forming a narrow shelf at the top and their bottom edge blending into the lower hull. Eight ribs per side were thickened to match the bulge contours. While admiring the results this morning I realized I'd made an incredibly stupid mistake. By concentrating so much on the secondary bulge stringers I forgot to tape the main bulge stringers and cut them off with the hull windows. Dohh!!! The main bulges were visible on the hull sides for only 3 windows ahead and 2 aft of the secondary bulges, but the Mogami hull's main bulges were made too short. According to the plan from 'Japanese Cruisers of WWII' they should be visible for 5 windows ahead and 3-4 aft . My original plan was to tape the entire length of the main bulges as shown on the plans and cut the windows out, leaving the main bulge stringers. I was also going to leave the main bulge stringers in the two windows where the secondary bulge stringers are entirely within the 3/8" deck stringer. Thanks to my stupidity I have to rebuild the main bulge stringers in 10 of the 22 windows on each side of the hull. That'll take 2-3 days so the Ibuki won't be sheeted in time for this weekend's model show. Unfortunately the replacement stringers will not have as strong a connection to the ribs. I think I'll cut shallow wedges into the sides of each rib so the new stringers can't be forced inward by BB hits. If I just resined the stringers between flat rib edges they'd easily be sheared off by BBs. Fortunately I'd reinforced the hull with more fiberglass after buying it so the ribs are 3/16" thick. For a really quick repair the stringers can be made of 1/8" by 3/16" basswood, reinforced on the inside by a strip of fiberglass that'll cross the stringers and ribs. Alternatively, I can make balsa molds for the stringers and mold them directly to the hull, which will take a day or two longer but give a stronger result. I'll start replacing the stringers tonight and hopefully finish by the weekend. Bob
The missing main bulge stringers on Ibuki's port side were replaced last night. Using a square file I cut 1/4" wide notches in the sides of each rib at the stringer location. The notches were wedge shaped, 1/16" deep on the outside faces of the ribs and tapering to nothing by the inside faces. (The ribs were 1/4" wide x 3/16" thick.) Next, strips of 3/16" x 1/16" balsa were CA glued to the outside of the hull over the stringer positions. Resin and 6 strips of fiberglass were applied on the inside of the balsa between the ribs, making the stringers the same thickness as the ribs. The fiberglass matt was cut in 1/4" wide strips and each was worked into the notches in the ribs. A final strip of fiberglass matt ran along the stringers and intervening ribs on the inside of the hull. The process took an hour, plus 30 minutes this morning to cut and sand off the balsa and trim the stringers to 1/8" width. They seem strong and can't be driven into the hull because of the wedge-shaped notches. Tonight the process will be repeated on the starboard side. Checking the 'JCoWWII' side plans against the cross-sections showed discrepancies in main bulge length so I went with the cross-section plan, which was a better match to the model hull's shape and had the stringers crossing one less window at the bow and 2 less at the stern. A total of six windows per side will have main bulge stringers restored. The Ibuki hull will be ready to sheet this weekend. Bob
The replacement main bulge stringers turned out fine and are solidly glassed to the ribs. The secondary bulges are finished too. Tonight I'll install 18 x #4 1" brass bolts to hold the internal armour. Usually I put them through ribs (which are at least 3/16" thick at the bolt locations to retain strength). Because this is a carrier the bolts can go through the 3/8" deck stringer. On a regular ship model the deck stringer can't be used because there isn't enough space for the bolts and their nuts with the deck installed. Hull sheeting will start this week. I plan to have the hull sheeted and painted by the Martime Museum Model Show in 2 weeks. The upperworks will still be under construction but should be finished by the end of April. Bob
The original plan was for dual stern mounts mounted beside each other. I realized last week that the aft pair of pillars supporting the flight deck are too close together at deck level for more than one cannon to shoot between them. The options are to put the 1.5 unit gun in the stern and the 1.0 unit gun in the bow or put both in the stern, angled out to either side to clear the two sets of flight deck support pillars. To clear the pillars they'll have to be at least 10 degrees out from the centerline. The third option would be to curve the upfeed tubes of both cannons inward allowing one barrel to fire over the other, both shooting straight aft. Bob
Interesting. I hadn't thought about stacking the guns aft. In the Belleau Wood, I presently have a 50 rounder forward and a 50 aft (didn't have any 75 round magazines on hand...will refit after I decide which gun I prefer to use). The aft gun is very close to the stern and I can put a little bit of down angle on it, so it should be good for some solid "on"s and maybe even some "belows". It's the bow gun that I am really interested in at the moment though. Since I have more flexibility on the carrier then I would on a standard warship for weapons placement, I have the gun mounted on the side of the hull and very low. The barrel is parallel to the deck and if it were mounted centerline, would not clear the raised part of the bow. This will make for a very flat shooting bow gun, which I have high hopes for as a sniper type weapon. If the gun works out for me as well as I am hoping, this might be the one to get the extra 25 rounds.
Here's the Ibuki hull after completion ot the secondary bulge stringers and restoration of the main bulge stringers I'd mistakenly cut off. Four sections of the latter can be seen here, along with the aluminum bow armour. Note the two brass bolts screwed into the deck stringer and the third one to the left with its head cut off. These are the mounting bolts for the internal armour and will also carry clips to secure the wiring harness and CO2 lines. These are #4 bolts screwed into 7/64" holes with CA glue on the last section of thread to go into the hull. After the glue has set I use the tool shown to cut off the bolt heads; any remnants of the bolt shafts are filed flush with the hull. Here's the aft end with the curving secondary bulge stringer and two windows with the aft end of the main bulge stringer. The shiny circles in the deck stringer are the filed ends of several armour mounting bolts. This shows the entire starboard secondary bulge stringer, curving up almost to deck level. Its vertical ends extend halfway onto 1/4" ribs and are about 1/16" higher than the rib surface, so the ends of the secondary bulges will be visible when the hull is sheeted. Those bulges were a prominent feature on the real Ibuki. Bow view showing aluminum amour plate set in self-leveling concrete sealer, which takes a few days to completely solidify. Note the furthest forward of the 9 armour mounting bolts on each side of the hull. Inside the front end of the hangar: the forward 2 pairs of armour mounting bolts are shown, along with the rear end of the aluminum armour in the bow and the curing concrete sealer that'll be trimmed to the end of the aluminum sheet.. The Ibuki's hull is ready for sheeting. Hopefully that'll be done by Sunday. Bob
