Assembling a 1/87 USS NAUTILUS kit

[He Who Shall Not Be Named]

David, you have the index pin for positioning the SD, but how about the endcaps of the SD, how do you make sure they are always in the same position when you close them?

Grtz,
Bart

As the forward and after bulkheads (end caps in Eurobabble) are registered by their flanges against the ends of the cylinder, that takes care of longitudinal (axial) registration. So, that leaves radial (twisting of the bulkhead in relation to the cylinder. I just eye-ball them, but have on occasion simply put an alignment bar across both the cylinder and outboard edge of the bulkhead flange. Align the two portion of bar, and the bulkhead is perfectly radially aligned with the cylinder.

M

[greenman407]

Dave, I see that you have a backup ballast system in there as well as a Sombra Lepton reciever. Good Show.

[He Who Shall Not Be Named]

PART-7

I've elected to represent this USS NAUTILUS model in the 'as built' configuration. The display to look as this historic submarine did as it slid down the ways at Electric boat sixty-some years ago. My God, has it been that long?

Yet incredibly we (along with our UK partners -- who were the first to get the ball rolling) managed to harness the atom for 'useful' work such a short time ago!

There are subtle differences between how the boat looked then as to how it looks today as a museum ship. Originally the top of the sail was flat (not humped); there were two levels of free-flooding observation compartments with deadlights set into the leading edge of the sail; there were no sonar fairings on the deck; there was an array of large, square limber holes on the sides of the superstructure; it had five-blade propellers of traditional shape; and the stern was much more blunt of contour than it is today. Through the decades, the USS NAUTILUS has seen changes in mission as well as looks.

Andreas' kit is a bit of a hybrid: The sail has the hump, yet the stern is as originally built, the old style screws are provided, there are no deadlights in the leading edge of the sail, and the sides of the superstructure are neat. However, should you elect tor represent your model as the early version, this kit contains detailed instructions and illustrations that direct you on where the limber holes go as well as how they were shaped and sized.

I elected to enhance the 'step' between hull and superstructure -- a prominent feature seen on the actual boat, but lightly represented on the kit hull parts. Once I had built up this high relief longitudinal 'break' that ran around the superstructure I marked off and punched out the many superstructure limber holes.

The trough at the top of the hull (there to reduce the total displacement if the kit was to be assembled as a dry-hull type r/c submarine) presents a problem in that the two void areas, that run the entire length of the trough, form voids that if not vented would entrap air-bubbles once the boat made the transition from surfaced to submerged condition. These voids had to be opened up so that escaping air from within the hull could easily make it to the underside of the deck and out open holes placed there to insure a complete flooding of the hull as the model submarine assumes submerged trim.



I opened up most of the void areas either side of the trough. Only the removable upper hull piece had this trough. Note that the removed portions go all the way up to the underside of the deck -- bubbles will pass from the voids to the underside of the deck, then out vent holes to atmosphere. This work done for two reasons:

1. eliminating unneeded structure above the submarines waterline reduces the submerged boats displacement -- ballast tank volume is directly proportional to the volume of water displaced by the above waterline portions of the submarine.

2. since this is a free-flooding hull (only the SubDriver within is watertight) it is vital that all air within the superstructure be vented off as the submarine transitions from surfaced to submerged trim -- opening up the top of the hull like this insures that no bubbles of air get trapped in the 'high' portions of the trough, the voids either side of it.



I built up four layers of masking tap below where I wanted to represent the superstructure-hull slot -- represented on the kit hull as a simple angular transition between superstructure and hull.

Against the top edge of this masking tape dam I built up Bondo over both sides of the superstructure. The base of this build-up, once the tape dam was removed, would overhang the hull by about .030". This greatly increased the 'look' of the scale model.



Bondo, a two-part, exothermic curing filler -- often associated with automotive body work -- Is an excellent material where conformal, tightly bonding, yet easily filed and sanded material is demanded for surface re-contouring or gouge repair. Here you see it being used to build up the sides of the superstructure to produce the pronounced 'step'; simulating the slight stand-off of the upper superstructure plating over the rounded hull underneath.

Almost buried under the Bondo is the four ply masking tape used to produce this step. Once the Bondo has been knocked down with sanding blocks, to the level of the mask dams surface, and feathered up to the top of the superstructure side, the masking is removed -- it's edge producing a sharply defined step that denotes the break (artificial though it is) between hull and superstructure.



Once the Bondo had cured reasonably hard (it takes at least a day to cure to 90% of its solid state) I attacked it with descending grits of sandpaper till a reasonably smooth surface had been achieved. most of this work done with sanding blocks to insure that the sides of the superstructure assumed a flat surface.

To the right you see partially sanded work with the step producing masking tape dam still in place. As a section is finished the tape is pulled away revealing the simulated superstructure-hull step. There! … looks just like the real thing!



Wherever possible you want to to use a sanding block on long, simple curved surfaces, such as the Bondo build-up over the existing GRP. To refine the 'slot' I used CA adhesive stiffened pieces of sandpaper. Note that while I was working the slot I also faired in the slight miss-match between bonded bow hull pieces.

Some consider the automotive type fillers as unsuitable for r/c submarine use. That has not been my experience at all. Once well protected under coats of primer and paint this otherwise water absorbent material will stand the tests of time and use -- I have twenty-year-old r/c submarines, coated with Bondo like material, that today evidence no failure of the filler. Bondo is our friend!



The square limber holes on the sides of the superstructure run all the way up to either side of the bow. Only at the bow do these flooding holes differ in shape and size -- becoming a bit smaller and spaced very close together. All the dope about the shape, specific size and location of all limber holes is presented on two of the 'instruction' pages that accompany this very complete r/c submarine model kit. The illustrations are presented in orthographic, isometric and 'exploded' form.

The task of lofting the dimensional information (stated and drawing specific) onto the surface of the model was accomplished with metric scale (this is, after all, a European based kit), proportional dividers, two-point dividers, marking templates, pencil and scratch-awl.



I took a piece of .010" plastic card, trued it up to a perfect rectangle, then scribed a perpendicular line in the middle, and bent it to the angle described by the deck and superstructure side. I fixed that bend with some CA on the inboard side of this marking-scribing template blank and used to to mark verticals (the deck being the datum plane here) on the side of the hull. Each vertical line falling along the point where the leading edge of a square shaped limber hole would go -- those points indicated, in mille-meters, on one of the instruction sheets. You see those vertical pencil markings in this photograph, along with the scribed in outlines of each limber hole.

You might ask why not mark the holes with a pen or pencil. Sure, would have been simpler and less work, but a scribed line is much narrower than an external marking (ask any sheet-metal guy!). The difference between a pencil or scribed line is the difference between a sloppy hole and a tight hole.

(Sorry -- a left-over from Torpedoman A-school).



And here we have the four steps (evolutionary progression) of how I get from marking to completed hole:

1. at the extreme left we have the initial start of a square limber hole, two 1/16" holes punched within the previously scribed limber hole outline, that engraving done with the aid of a special scribing stencil

2. the the limber hole has been refined significantly using the same drill bit as a mill with the flutes doing the cutting, pushing the bit up-down-left-right, keeping the cut within the hole boarder defined by the engraving

3. second from the right is the further refined square hole, done with the smaller bit worked as a mill -- it's smaller diameter produces a tighter radius at the hole corners, the small bit is harder to hand-steer than the larger bit, so it's only used after the hole has been roughed out with the big bit

4. And the file refined square hole to the right using square and three-faced diamond files



Diamond dust coated files are the best tools for GRP detail cutting. They will never dull, and the industry has produced an incredible variety of these files in all sizes and cross sections. I found the most useful files for this job to be straight, Jeweler's sized square and triangle sectioned diamond shape. Those two files to the extreme right.

Also seen to advantage here are the open portions of upper hull -- done to reduce submerged displacement and to properly vent the free flooding hull when the model is commanded to dive beneath the surface.



Though the surface of the hull has been beat up with knife, file, rotary bit, and scribing over-strikes, the depth and severity of those boo-boo's are quickly fixed with air-dry touch-up putty and #400 grit sanding sticks used wet.

A quick shot of automotive lacquer primer (DuPont's Nason 421-23 gray primer) shows off the shadow thrown by the slot between superstructure and hull. This slot runs all the way aft, around the turtle-back and to the other side. Amazing what you can achieve with a little Bondo!

Roughly speaking, on the actual boat, this slot is the demarcation line between external hull and superstructure. It is through this slot that most of the flooding/draining water passes in/out of the free-flooding superstructure as the submarine transitions between surfaced and submerged trim. The USS NAUTILUS, as built -- in a time where marine Architects where still in the 'submerge as quickly as you can' mind set -- the square flood-drain limber holes were there to augmented the flooding/draining rate of the superstructure. However, as the navy came to realize that the mission of the submarine would forever abandon the need to cruise on the surface, the noise producing limber holes were (for the most part) plated over. This streamlining measure improving both the hydrodynamic and acoustic performance of the hull.

As I wanted to represent the early version of the NAUTILUS I was compelled to incorporate these iconic limber holes during assembly of this kit. Extra work? Sure. But well worth the effort.

[MFR1964]

Adding those holes is a big improvement, brings your model more to live, that is, if done properly, it can be easely messed up.
You can make those holes into a functional dryhull and place some copper boxes inside the hull, use epoxy to seal them off to make them watertight, did the same trick at my type VII, some holes in that sub where on places where this trick helped.

Manfred.

[greenman407]

Yep, thats exactly how I want to do mine. Thanks for the tips. I will of course steal....er...I mean borrow your technique.

[trout]

The information you share is truly a treasure find. I save these postings to review or read over when I travel or may not have internet. Good stuff sir, thank you.

[SSN SonarTech]

Looks fantastic!

[He Who Shall Not Be Named]

Looks fantastic!

Thanks, guys. Steve: should have this thing ready for the first Nauticus run of the year.

I'm loving this kit assembly job. What a wonderful kit. And the subject is a much unaddressed one in our circles -- why has not anyone, but Dennis DeBoer, done a proper kit of this historically important combatant before???

I don't have a horse in this race -- I'm not economically involved at all. That said: why don't you guys give serious consideration of making this kit your next purchase. Get them while their hot!

David

[DrSchmidt]

Hi folks,

may I introduce myself: I'm Andreas and I actually made this little kit for David. With respect to additional kits: I'm currently producing a small series of Nautilus kits, some with dry hull lay out (like I built my prototype) and a few with the wet hull setup David is putting together. When I have all this together I'll put up a little website where I'll offer the kits. Should be around summer.....depending on the demand I'll see if I make some more. The moulds should be good at least 100 parts. But as I do this in my spare time, I'm not sure if I'll pull that many out of them...

Cheers Andreas

[greenman407]

Thanks Andreas! It looks very Good. I am looking forward to Daves continuing on this build and to see your website. Nice Jewel you have put together there.

[He Who Shall Not Be Named]

Part-8
A notable departure from the kit instructions was my inclusion of additional sub-structure re-enforcement cross-braces. These to provide a more sound support under the very flimsy photo-etched (PE) deck pieces.

Though the kit supplied GRP transverse deck pieces served this function to a degree, I determined that there were not enough of them to do the job adequately. My fear is that I or some other idiot, while handling the model would accidently damage the very fragile PE deck, ruining it.

So, better now to strengthen the deck sub-structure than to repair a painted and weathered model after the inevitable deck damage occurred.

Concurrent with that I began the task of representing the clear deadlights at the leading edge of the sail. I could have painted these on with a gray or silver color later – that would have been the simple solution. However, nothing looks like clear windows like … well … clear windows!

These windows which provided visibility from within the sail to the forward deck were used by watch standers while the submarine cruised around on the surface in rough weather. There were three levels of these deadlights – the lower two levels represented by blocks of clear acrylic sheet, and the top level, forward of the bridge, would differ in that its deadlights would be represented by a build-up of clear, 12-hour cure epoxy glue – employing a very neat process advocated by David Manley. More on that later.



Though the kit provides transverse GRP deck supports, I believe that the very flimsy PE deck pieces will be subject to handling damage (pushed in by fat fingers!) if additional sub-structure bracing were not provided. That’s what you’re seeing here: .015” thick styrene sheet transverse deck braces being installed atop the superstructure. The position of these additional cross-braces fell under (and was hid by) a corresponding all-metal transverse section of the PE deck. Under normal lighting conditions these sub-structure braces will not be apparent through the open slots between simulated wood planks of the PE deck pieces.



You can see how I’ve arranged the additional sub-structure cross-braces, each sitting under the transverse all-metal portion of the slotted PE deck pieces. Later, after most of the painting is done, the PE deck pieces will be secured atop the superstructure with RTV adhesive.

Note how the top of each cross-brass has been outfitted with slots. These to permit the quick longitudinal movement of entrapped air bubbles so they can move about and find a vent hole in the deck so they can escape. Entrapped air within a wet-hull type r/c submarine is a major problem and one has to be ever mindful to provide for complete venting of the hull as it makes the transition from surfaced to submerged trim.



Making me the liar, this flash photography does show the additional transverse sub-structure elements added to strengthen the fragile PE deck. However, in the real-world, you won’t see much past the slots of the deck. This trick of lighting does show how I’ve placed the additional cross-bracing under the transverse ‘solid’ portions of PE decking.

I must comment again at my amazement at how well everything on this CAD designed and CNC and printed tooling of this kit insured all parts fit together almost perfectly-this thing literally falls together out of the box!



A Machinist’s surface-gauge was used to scribe the upper and lower edges of the yet-to-be-established deadlights. A right-angle triangle was used to guide a scribe as I cut in the deadlight vertical edges. Such lay-out precession was needed for the bridge deadlight cut-outs, but was over-kill for the plugs of clear acrylic actually used to represent the clear faces of the lower platform deadlights.

A holding fixture was cut from shelving stock and the sail screwed to it using the same fasteners and foundations that secure the sail atop the NAUTILUS’s hull.



The ballast sub-system employs a float activated snorkel valve within the sail. It was necessary to establish the where the bottom of the mast foundation piece sat within the sail so the snorkel could be made so it would not project above that line. On the outside of the sail I marked where the bottom of the mast foundation piece terminated and designed the snorkel mechanism to occupy the space beneath.



A trick that goes back at least a century is the use of clear plastic plugs, inserted into the portion of model where you want windows, and to then grind the outer surface of the plastic (usually acrylic) to conform to the outer contour of the model. Once the face of the clear part is ground and polished back to an optically clear item, the window frames are made by masking over where you want only clear areas to be, then paint, and remove the masking. That’s what’s going to happen here to the two lower platform deadlights.

Deadlight is navy-speak for windows.

Two ¼” thick pieces of acrylic sheet have been roughed out to approximate shape. Once set into the leading edge of the sail each is CA’ed in place, and ground, filed, sanded, and polished to conform to the curvature at the leading edge of the sail.

The drill was used to rough out the individual open deadlight ports up where the bridge will go. Diamond files were used to refine the square openings. Later these openings will be filled with clear epoxy glue. More on that later.



The solid acrylic pieces filed and polished to conform to the leading edge of the sail. The bridge open deadlight frames will later receive epoxy lenses. But, once it’s all masked out and painted you will be hard pressed to see the difference in materials and fabrication methodology between the three platform deadlights.

I could not use the acrylic trick on the upper deadlights as there is little space between the deadlights and forward section of bridge well – a cast resin piece that will later



The installed pieces of acrylic plastic within the two lower platform deadlight positions has been ground, filed, sanded, and polished to follow the contour of the sails leading edge.

The slabs of acrylic plastic were fine for the two lower levels, but not for the bridge level as those deadlights had to be of a thickness little more than the thin GRP of the sail.



When painting over masked clear parts you always want to go with the final color, from beginning to end. If you don’t, then the different colors (gray and/or red primer for example) will result in a disparity of color at the edges that denote transitions from clear to colored portion of the model.

So, if the final color will be a dark, dark, gray (the case with this model), then that’s the only color you will shoot over the clear part masks. Once the deadlight masks are in place I’ll lay down the first of many layers of final color. Paint does not typically have the heavy fill ability of a thick primer, but multiple coats will eventually get the job done around the deadlights.



The bridge level set of deadlights has yet to receive its clear lenses. The two lower platforms have had their individual deadlights (each set actually a single hunk of clear acrylic plastic) represented by pieces of masking tape followed by a coat of dark-gray paint. Here, with the masking removed, we see what appear to be closely spaced, deadlights along the two lower sail platforms.

[greenman407]

Magnificent!

[bwi 971]

Can they open?

Yeah you must have mist me around here (like a headache).

Grtz,
Bart

[Slats]

just discovered this thread and I'm carrying a semi. I hate you David!

[He Who Shall Not Be Named]

Part-9

A statically diving type submarine submerges by taking on water ballast (variable ballast). The weight of the ballast water equal in weight to the water displaced by those portions of the submarine formerly above the surface.

The more structure above the surfaced submarines waterline, the more ballast water needed to counter the buoyancy of those structures once they are immersed in water. Good design practice would have you make the ballast tank as small as possible for two reasons:

First, is to minimize the volume given over to the ballast tank itself, leaving room for other devices needed to animate the submarine.

And less ballast water to be shoved in and out means less energy expended to move that water. Usually, as in this design, the air in the ballast tank is simply vented to atmosphere, done by a servo – not much energy expended there. However, to empty the ballast tank of water an air-pump has to be run, and that means a drain on the battery and wear and tear on the pump controller, pump, and its motor. Also, as my SD also employ’s an emergency gas back-up ballast blow sub-system, there is the kinetic energy stored within an on-board bottle of liquefied propellant, that energy given up each time an ‘unscheduled’ emergency surfacing occurs. We want to husband the vessels energy reserves. So …

… Small ballast tank-- good; big ballast tank -- bad.

In a wet-hull type r/c submarine superstructure and sail wall thickness is the main driver of total above waterline displacement. Most of the appendages are solid cast items, and they too contribute to the total above waterline displacement.

This kit, designed and manufactured by a model aircraft guy – which makes him a GRP weight conscious fanatic -- has above waterline structures of very thin section. That’s why this r/c submarine kit, even though it represents a boat of high freeboard, requires a relatively small ballast tank.

(GRP and polyurethane resin have specific gravities close to 1, so in this game weight pretty much equals displacement).

Unfortunately, when I sized the ballast tank for this model, I still managed to wildly underestimate the total displacement of the above waterline portions of the surfaced model NAUTILUS. The first trimming trail with that SubDriver (SD for short, or for you old-school types, WTC) revealed that shortcoming immediately. Compelling me to build another SD with an enlarged ballast tank.

The SubDriver is a removable system comprising the propulsion, control, and ballast sub-systems that animate the model. I’ll outline the SD’s design, fabrication and functions in a later installment.




The two machine screws that hold the upper hull down upon the lower hull are accessed through holes drilled through the PE deck – one forward, one aft. Great care was taken to secure the deck pieces onto the drill press bed: any drill chatter would easily tear the thin brass piece to shreds. Also, long before I determined securing screw locations I found spots on the PE deck pieces that were solid, and not impossible to drill slotted portions.

And that’s the case here. Note that the forward upper hull securing screw access hole will run through the PE deck where the solid deck hatch rescue-bell seating foundation is.



With the basic submarine structure completed and the SD and other internals worked out, time came to install the fixed ballast weight and buoyant foam – all arranged to work with the variable ballast water to set the boats displacement for both surfaced and submerged trim.

The trick is to make the center of gravity and center of buoyancy well distanced vertically; and for these two collectives of force to shift longitudinally, in unison, as the boat makes its transitions between surfaced and submerged trim.

Experience tells me that a four-foot long wet-hull type r/c submarine requires at a minimum two pounds of fixed lead ballast weight as low in the hull as possible. Here I’ve broken out some ingots of lead for a trial installation of fixed ballast weight.

A single screwed submarine would need more fixed lead ballast to better counter the torque of the propeller. However, as this submarine has two counter-rotating propellers (net torque is zero), I could get away with two pounds worth.



The USS NAUTILUS, in surface trim, has a very distinctive waterline: A high freeboard (distance from waterline to top of deck); the bow high, and the stern low. Unlike so many of the cold-war era American submarines, this conservatively designed -- first vessel to be nuclear powered -- submarine embodied many of the post-war, old-boat characteristics: hull form optimized for surface cruising; wide flat deck; and a high freeboard owing to its (by today’s standard) a significantly large amount of reserve buoyancy.

Before starting the trimming operation – a process, by trial-and-error of the amounts and location of fixed ballast weight and buoyant foam – I marked out onto the hull, with a wide Sharpie pen, the submarines surface trim waterline. The objective is to have the boat, with dry ballast tank, float at this waterline in surface trim; and, with a flooded ballast tank, to project only the top of the sail above the waters surface in submerged trim. The marking was laid down with the model rubber-banded to a flat work surface, pitched up the correct amount (that angle established by checking with a Machinist’s surface gauge as the bow was shimmed upward), and the waterline marking tool run around the model, laying down the waterline where it should go.



The first attempt to trim the boat revealed that I did not have enough ballast tank volume to get the boat up to the designed waterline once the tank was blown and emptied of water. From submerged trim I needed a weight of ballast water equal to the weight of water displaced by all the above waterline structures. Didn’t have it! Damn thing sat low in the water with the tank dry. The ballast tank was too small. Who was the dumb-ass who designed this system anyway?!.....

Nuts!



Nothing for it but to make a new SD with an enlarged ballast tank.

(Two, actually: one to replace my first attempt at the SD, and a second one for Andreas who’s putting together a wet-hull version of this kit back home in Germany)

The new SD features a ballast tank possessing 150% the volume of the first. Note that I retained the initial SD cylinder length by giving up space in the forward and after dry sections of the cylinder.

The aft dry section had excess space so that was easily given up to the forward section of ballast tank by moving the after ballast bulkhead aft a bit more. The forward dry section, containing the battery and mission switch was shortened by simply going to a shorter battery – cramming two of them in there and wiring them in parallel, giving the same capacity of the single long battery. The forward ballast bulkhead moved forward. Other than the bigger ballast tank and some minor relocation of ballast sub-system components, the length, function, and dry weight of the short and long ballast tank SD’s is identical.



Submerged trim is worked out first. The ballast tank is flooded. Once that’s set, you establish surfaced trim.

Yes, with all that foam hanging off the model it looks like hell.

Just the top of the sail projects above the water as the boat stabilizes at zero pitch and roll angles. Perfect submerged trim for a typical r/c model submarine equipped with a ballast tank. This is the condition of the submerged boat once the correct amount and location of buoyant foam has been established.

Working out foam amount and location to the outside of the hull is a lot easier than stuffing it within the hull and hoping you got it right. This way, the trimming is done in one, quick, sitting, without having to yank it out of the water numerous times.



“Are we done yet??!!!!”

Surface Trim, the ballast tank blown dry.

Some of the buoyant foam has been moved vertically, either above or below the surfaced waterline – the objective to get the boat to float at the designed waterline. There is more ballast tank volume than that needed using the new SD. That’s a good thing! The higher the center of buoyancy is over the center of gravity, the more statically stable becomes the vehicle.

Submerged and surface trim fixed, the model is taken back into the shop and all that foam is glued to the inside surfaces of the hull and superstructure.



The laborious process of shifting all that foam from the outside of the model to its inside has begun. It’s vital that the buoyant foam you select is of the closed-cell type. The blue and pink polystyrene expanded foam is of this type. Unlike open-cell type foam (usually white), the closed-cell type will not water-log over time. There is absolutely no need to ‘seal’ installed closed-cell type buoyant foam.

Here you see the installed fixed lead weights, and foam pieces ready to be installed within the hull. Note that some of the foam has already been shaped and bonded within the upper hull half.



The important thing is to get the longitudinal and vertical position of the foam correct. What was established during the trimming operation, placing the foam on the outside, now has to be replicated as the foam is glued to the inside of the model.