Building an 'Improved' Wallace RC 1/16 scale KAIRYU Suicide
Submarine Kit, Part-4

A Report to the Cabal:

Work continued to the end of the week. But, I'll have to jump into other projects, as time to the SubRegatta is getting short and I have turnkeys to get out of here.

Some guys like to run a long length of drive-shaft right up to the WTC motor output ...

... Pussies!

Not me! I insert an 'intermediate drive shaft,' each end equipped with a Dumas dog-bone universal connector. I favor a very short propeller shaft, one that terminates within the hull well aft of the after most control surface yoke (in the case of the KAIRYU, that's the rudder yoke).

The trick with my style of running gear is to establish the outside diameter of the two Oilite bearings that will fit into the stern of the hull and absorb the ahead, aster, and transfers loads presented by the propeller shaft -- this unloads the WTC's output from anything but the torsional load of the running gear -- and to build up a solid resin foundation at the stern to mount those bearings.

I fabricate the foundation by first identifying a rod or tube having the bearings outside diameter, coat it with wax, insert it into a hole drilled into the stern, then prop up the forward end of the rod/tube so that it runs parallel with the hulls longitudinal center line. Clay is how I positioned and held the rod/tube in this model -- the rod/tube becomes the mandrel around which a solid plug of slow-cure epoxy is poured. This plug becoming the foundation for a press-fit set of Oilite bearings.

Gravity is our friend!

Here I'm pouring in a mixed batch of West System laminating epoxy resin to form the propeller shaft bearing foundation. The exact height/depth of the epoxy foundation is set by a hole drilled in the side of the hull; a 'weep hole' that will insure that the forward end of the epoxy foundation falls exactly where I want it. That's why the wax-paper on the bench, to provide a no-stick surface for the epoxy overflow. I had also coated the after end of the hull with wax to prevent the dribble from the weep hole sticking to the work.

Close-up of the ass-end of the KAIRYU after pouring in the epoxy. Note that the
hull had been marked with quadrants, where the four stabilizers would eventually
be mounted. I've also marked on the hull the location and geometry of the after
most control surface yoke.

You can see the weep hole and dribbling epoxy to good advantage here. Within
four hours the epoxy had cured hard enough where I could tear off the wax-paper,
peel the epoxy off the surface of the hull, yank out the rod/tube mandrel,
scrub the wax off the hull with steel wool saturated with lacquer thinner, and press-
fit two eighth-inch i.d. Oilite bearings within.

Damn, I'm good!

All the masters and plugs built to produce the tools that made the resin, metal, and polystyrene plastic parts needed to super-detail the Wallace RC 1/16 KAIRYU kit. Whew! What started as an effort simply to dress up the six stabilizers and control surfaces in no time escalated to THIS! I just can't leave things alone!

A set of the major cast resin items just pulled from the pressure pot and the tools halves separated to show off the work. I used the PolyTech RTV silicon rubber for this set of tools. It cures quicker, is a bit softer than the BJB, TC-5050, and is easier to mix, and de-airs in no time at all.

Instructive here is the design of the sprue and vent network I employed: It's my practice to introduce the liquid resin into the bottom of the tool cavities through a long, centrally located sprue, and to provide a smaller gauge vent channeling network at the top of each cavity to allow the displaced air within the cavities to get out resin is introduced into the tool.

Metal casting was done within a BJB, TC-5050 RTV rubber disc tool. White metal, commercially available as 'leadless solder,' is the stuff I use. This alloy is typically a ninety-five percent Tin to five-percent Antimony mix. The metal is a bit less malleable than standard lead based solder and has the advantage of actually expanding a bit as it changes state from liquid to solid -- a characteristic that insures that the metal captures every detail in the mold cavities.

You see a shot between the two disc halves. Examination of the sprue network of the shot clearly demonstrates how the arrangement of the cavities around the central sprue takes advantage of centrifugal force to drive the molten metal into the cavities before it can freeze to a solid. The pour is done as the tool is rotating atop a modified blood separation centrifuge. Speed of rotation is determined through experiment. Note that I incorporate rubber core pieces within the tool to render bores in cast pieces that need to be hollow. The cores are pulled out of the shot pieces and reinstalled into the tool, as I ready it for the next shot.

The white metal propellers had their sprues chopped off at the band saw (and set aside for reuse in the melting pot). >From there each propeller hub receives a tapped hole to take a set-screw, needed to secure the propeller onto the propeller shaft. But, before that, each propeller is secured to a lathe mounted shaft where the work is brought up to speed and the forward and after ends of the hub are faced down to true flats. The cast hubs are about one-thirty-seconds-of-an inch longer than needed, so I have the material to face off.

As there is a very tight taper to the stern of the KAIRYU, meaning that there is not enough room within these propellers for a three-sixteenth inch diameter hole for a standard shaft, I elected to cast these propeller with a bore to accept an eighth inch diameter propeller shaft.

The only fault with the Wallace RC KAIRYU GRP parts is a 'dishing' of the upper hull at the stern contour. This problem was identified with circle stencils as I plotted the quadrants on the stern (needed to denote where the horizontal and vertical stabilizers would fit).

Here you see the Metal Glaze filler and abrasion tools used to build up and re-contour the stern back a near perfect 'round.' The filler was mixed up and 'carded on' with an old credit-card, about three coats built up a good mass. Once the filler had cured to a working state (about five-minutes after mixing), I attacked it with bastard files, then a sanding block initially loaded with #100 sandpaper, then working down to #400. At that point I hit the stern with primer and check the work with the circle stencils again.

A screeding blade was made of two pieces of brass sheet soldered to an eighth-inch diameter shaft. Here you see the screeding blade over the re-contoured stern of the KAIRYU model. I used a combination of the thick Evercoat 'Glazing Putty' and the runny Evercoat 'Metal Glaze' (called 'icing' in shoptalk), mixing them together to get a consistency that was agreeable to the screeding process. These two fillers are of the two-part, heavily filled polyurethane type (great-great grandchildren of that old standby, Bondo).

Test fitting of the parts onto the hull to check for fit and clearance.

I'm a practitioner of the don't-permanently-mount-anything-till-everything-else-isdone school of kit assembly: I work each subassembly through to primer before it's mounted to the hull. Things are easier to work that way and by treating each assembly as a model unto itself, before integration with the whole, you tend to give the assemblies more care and attention than if they are all glued together in one big assembly. And that's what will happen here. For example: the control surfaces and stabilizers will be degreased, sanded, primed and pinhole bubbles filled and flash filed away long before they go onto the hull. Same with the sail and the detail fittings. Nothing gets stuck on the model until each and every subassembly is in primer gray and possesses a pristine finish.

The complete cast resin portion of the enhanced fittings kit. Note the two WTC mounting saddles/foundations, sized to fit the D&E Miniatures WTC-2.5/KAIRYU.

Just to the right of the hatch piece is the end-cap that provides the access point to the wireless video camera-transmitter WTC. This unit will fit within the sail, with the camera lens looking through the porthole cone which, incidentally, shares the same sixty degree of view as the lens of the Astak camera optics -- funny how things work out.

The resin parts come out of the rubber tools with a heavy surface coating of silicon oil. It is vital to degrease these parts before any gluing, priming, filling, and painting work gets underway. I start the degreasing process by soaking a part in Lacquer thinner for about ten minutes (Alumilite resin is tolerant of this, other resins may not be, test on a piece of flash if you are not sure as to the chemical tolerance of the resin parts you are working), then scrubbing the part with '0000' steel wool, but taking care not to soften the detail work with the abrasive. The degreased resin part is then wiped dry and then thoroughly wet-sanded with #400 paper, again taking care not to soften any high relief detailing -- the Flexi-File sanding sticks are excellent tools for this task. Only after all that is the resin piece ready for priming.

And here is a bagged up set of 'enhances' 1/16 KAIRYU metal, resin, and vacuformed parts, all ready to be opened up and used to dress out the fine Wallace RC GRP kit of this interesting looking, well running, and capable r/c submarine.

These are available from D&E Miniatures for a whopping $125.00 plus $5 shipping in the US.

Hey ... you gets whats ya's pay for!