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.
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.