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PostPosted: Mon Dec 21, 2015 11:00 am 
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NAUTILUS PART-1

I first became aware of the model work of Andreas Schmehl a few years back while checking out the articles at one of the few forums dedicated to r/c submarine model building. His work-in-progress (WIP) -- a format of article writing that is heavy on in-progress photos with supporting text -- dealt with the construction of a 1/23 scale, U-1. Germany's first combat submarine. It was the most comprehensive and well laid out WIP I had ever read.

That multi-part article had everything: CAD design, CNC'd hull masters; 3D printed detail parts; hard-shell, GRP hull tools; RTV rubber tools for the small stuff; GRP lay-up; resin casting; WTC design and manufacture; trimming; detailing; and painting.

As Andreas put it: "I mainly use CAD to create a virtual model of the hull and the interior technical structure. From that I produce the 3D files for manufacturing 3D-printed parts and for milling preforms for the GRP tooling". What Andreas calls 'preforms' we American's understand these as masters, or patterns.

Once Andreas had worked out the 'plans' in CAD, he sent the files to a second party fabricator who used them to cut machinable plastic medium via CNC milling machine, and to poop out plastic parts via 3D printer. Those parts, back in Andreas' hands, becoming the masters of off which he would produce the actual model parts.

Masters by robot. Tooling and model parts by the good doctor.

SkyNet, call your office!

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His U-1 article showed me, in a very well laid out article, the use of computers and mechanized subtractive and additive item manufacture as part of the model building process.

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Andreas has done the same thing with his current r/c submarine project: a dry-hull 1/87 scale model kit of the famous, USS NAUTILUS.

His first USS NAUTILUS, assembled from his kit -- as is the European practice -- was configured as a dry-hull type r/c model submarine. With the exception of the sail and a portion of the stern (where the stern plane, rudders and propeller shafts make up to their respective running gear and linkages) the entire hull is dry.

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Another European practice -- most suitable for dry-hull types r/c submarines -- is to access the interior through a set of bayonet rings that seal with an o-ring. Set into the forward and after sections of the model, the bayonet rings produce a radial break between the two. To access the interior all that is required is a slight rotation of the hull halves to free the lugs of the bayonet rings and simply pull the two hull halves apart. A positive, quick, easy and pressure-proof closure method. Attaching the equipment-device mounting structure to the stern exposes everything when the forward section of hull is removed.

Unlike wet-hull type models -- which require opening the hull through a horizontal equatorial break, removing the WTC, and only then gaining access to the devices by removing the end-caps of that WTC -- the dry-hull bayonet rings make for excellent access to the internals for repair, de-watering, adjustment and maintenance tasks.

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The advantage of the dry-hull is that there is plenty of available volume in which to stick all the propulsion, control, and ballast sub-systems.

However, as the superstructure and portions of hull above the waterline will displace so much water when they are immersed, it takes a great deal of water weight --- taken into an internal ballast tank -- to create the force needed to counter the buoyant force produced by all that displacing structure. A big ballast tank takes up valuable real-estate within the tight confines of the hull.

The need for such a large internal ballast tank denotes the major disadvantage of the dry-hull type submarine.

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Andreas followed the same manufacturing methodology with his NAUTILUS kit. A second-party produced the masters from which he would make to tooling needed to create the model parts. Here we see some of the CNC milling-machine cut masters.

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Off those CNC cut masters Andreas laid-up these GRP hard-shell tools. A total of eight tools required to render all the hull and sail parts. Those GRP parts rendered as very thin section structures.

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In addition to the resin and GRP parts he produced from this tooling, Andreas also produced the art work from which he had acid-etched a fret of wonderfully detailed deck, radar antenna reflector, other detail parts ... and even a painting mask needed to produce the white '571' on the sides of the sail.

Also provided in the kit is a set of water-slide type decals containing the white draft markings for the hull and upper rudder.

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With this picture I'm jumping ahead a bit -- this is Aundrea's initial assembly of his kit. I include it here to point out the use of the very detailed acid-etched deck pieces. Provision is made in the upper GRP hull to accommodate this. A slight step is provided atop the hull to sit this .015" thick acid-etched item atop the hull so that it sits flush. Though the USS NAUTILUS is distinctive of lines, it is a rather boring subject to look at if the details that are there are not exploited to the maximum -- such is the case with the deck: safety-track, slotted wooden deck, deck hatches, marker buoys, cleats, torpedo loading skid, these and more are items captured by the brass metal deck pieces. Even a bridge deck grating is provided on the acid-etched fret.

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Andreas will be making this kit commercially available. What is pictured above is what I would consider to be a more than adequate kit: right down to pages of exploded-view, orthographic and isometric drawings outlining not only assembly of the kit proper, but recommendations for the fabrication and assembly of the European style internals.

A preliminary kit. What I'm presenting here is likely not the definitive version -- note that there is no bayonet rings to accomplish the water tight radial break between forward and after hull halves; that the hull pieces (five of them) are provided split to suit those wishing to assemble this r/c submarine as either a wet-hull or dry-hull type; and no form of tech-rack (as the dry-hull guys would describe the internals mounting arrangement) or water tight cylinder (WTC) is provided. Also, there may be material changes before the production kits hit the street. So, regard what I've pictured here as a Beta test article, subject to change.

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The resin pieces are of exceptional quality. Right down to the bezels and gyro-repeater that attach to the open bridge!

The items to the right include the bow plane foundation, anchor well, bow planes (detailed right down to the universal cup joints that make up to the retract/deploy struts), deck sonar faring, anchor, and deck hatches. In the middle we see the mast foundation, open bridge well, sail top with all mast and bridge openings, antenna and snorkel induction items, as well as the scopes and antennas attached to their respective fairings. Items to the left are the two rudders and two stern planes.

The dark items are cast from epoxy, the lighter items are cast from polyurethane.

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... And these two little jewels: the NAUTILUS propellers! Brass, no less. However, it is prohibitively expensive to have these propellers cast in brass, so I'm working on Andreas to consider a white-metal alternative -- any heart-burn about that in the future, you can blame me. You do want a kit you can afford, right?....

It's obvious Andreas did his homework on these. The blades appear to be of a scale thickness -- no small feat! And they are of the right shape. These two wheels are simply gorgeous! Matched with the right motors and gear-train, these propellers should scoot the NAUTILUS along at a very good clip.

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The nominal GRP part thickness is about .050"! In the world of model submarines that is as good as it can get! And the uniformity of the lay-up is even throughout the parts. These two observations point to a fabricator who has been grounding in aircraft quality GRP part fabrication. Which Andrea was. He studied at the feet of an FAI quality contest r/c powered glider fabricator and flyer. The quality of his glass work is a testament to this early training. You can't buy that type of training!

Note that the hull kit is presented in five pieces. This break-down offers the customer the option of assembling this kit either for dry-hull or wet-hull operation. Now, that's smart tool-design! And greatly increasing the market this project is aimed at.

A dry-hull would demand gluing the two long center hull pieces together, then bonding the bow to the main hull, and making up a set of bayonet rings to the stern of the main hull and forward end of the tail section. Access would be the radial break between bayonet rings.

If configured for a wet-hull -- as I'm doing with the kit Andreas provided me -- you would bond the forward and after hull pieces only to the bottom main hull piece, leaving the long upper hull half as the removable element, providing plenty of internal access in which to mount and set-up a removable WTC (Caswell-Merriman SubDriver in this example).

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An artifact of Andreas' lay-up process are the radial and longitudinal flanges at the edges of the GRP parts. The flanges are beneficial in that they contribute a great deal of rigidity to the parts, and offer considerable glue area when bonding adjacent sections of hull together.

However, in those cases where you want a much stronger bond between the hull parts, it's best to grind away the flange and to lay in reinforcing strips of glass tape on the inboard side and saturate the tape with epoxy resin. Part-2 of this article will deal with that and other kit assembly issues.

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The two pieces that make up the stern section of the hull. Here you can see, to better advantage, the radial and longitudinal flanges at the edges of the two pieces.

The lower pieces is a hatch incorporated in the dry-hull version of the hull -- needed to access the linkages and running gear in the wet stern section. Not needed on the wet-hull version I'm assembling, I bonded the hatch permanently to the after portion of hull.

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"... well, that takes care of Jorgensen's theory!"


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PostPosted: Mon Dec 21, 2015 2:01 pm 
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PostPosted: Tue Dec 29, 2015 6:25 am 
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NAUTILUS PART-2
Part - 2 to this article has got to be the most boring installment to this WIP! No flashy painting techniques. No exotic model building do-dads on display. No combination of kit parts to make this thing look like the eventual USS NAUTILUS.

BORING!

But, what I'm presenting here is a vital phase to the kit assembly task: the gluing together of the separate hull sections; the bonding of the bow to the lower hull main section, and bonding the stern section (itself made up of two separate parts) to the lower hull main section. The desired result will be a removable main hull upper piece that permits access to the models interior -- the huge equatorial spit in the hull making WTC installation and removal an easy and quick task.

About this specific kit: Most manufacturers produce GRP hull pieces that arrive warped out of shape, pieces that demand of you the design and creation of specialized holding fixtures, weird hand contortions, and other means of coaxing the parts into proper alignment as you bond them together.

Not the case with this model! Andreas has produced GRP parts of very, very tight maintenance of original tolerance. Near zero warpage. This model kits GRP hull parts rigidity owed to his incorporation of longitudinal and radial flanges. Those flanges both a blessing and a curse: the flanges kept the GRP parts true of form, yet most of those flanges have to be ground away to permit application of internal layers of reinforcing glass tape and resin as the parts are bonded together.

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The end game her e will be the permanent bonding of the bow and stern sections to the lower hull, leaving the upper hull to be removable in order to access the interior of this wet-hull type r/c submarine.

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To insure correct alignment of the hull sections to one another I first secured them into a coherent hull assembly with the aid of brass straps, those straps bolted to adjoining hull sections -- three straps per adjoining parts sufficient to insure a secure, non-slipping union. By making the holes in the straps a sloppy fit to the machine screws, enough slop is present to permit adjustment to me made as the parts are brought into symmetric alignment with one another.


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First task was to drill and tap holes needed to pass the 2-56 machine screws used to hold the straps tight that pulled together adjacent GRP model parts. Initially I used masking tape and hand pressure to hold a pair of parts together, but only long enough to work out strap placement and where to drill the holes.


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Use of a three-foot straight-edge -- placing it to the sides, top, and bottom of the central 'main body' portion of the hull -- was used to check symmetrical alignment between the bow and stern sections to the main body. Loosening the involved straps, repositioning the fit between the sections, and re-tightening the straps was all that is involved to move things around till they are in proper alignment.

To ensure all elements of the hull lined up correctly I included the (eventually) removable upper hull section to the assembly. Once a proper fit between the parts was achieved the upper hull half piece was unstrapped, and the process of bonding the bow and stern pieces to the lower hull begun.


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For the moment, the radial and longitudinal flanges are left on all the parts, and the hull sections are strapped together. Once the hull is assembled, the individual straps are identified with a number, that corresponds to the same number printed on the hull. The assembled hull was then taken apart so I could go about the nasty work of grinding off the radial and longitudinal flanges, with the exception of the flanges between main hull halves and the bow and stern part radial flanges that would mate with the upper hull section.

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The longitudinal and radial flanges at the edges of all GRP hull parts -- to be joined permanently with epoxy saturated fiberglass strips -- were ground away with moto tools equipped with sanding drum and carbide cut-off wheel. The objective is to present a uniform flat internal surface upon which the reinforcing strips of fiberglass cloth can lay and soak up resin, without the internal 'bump' of a flange getting in the way.

The after hull piece has a 'hatch' which has utility on a radially broken hull, but is useless when you are making a wet-hull with the big upper hull half made removable for access. So, you see the flanges between this after hatch and rest of the stern piece being ground away in preparation of bonding.


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In some cases, like this, it's a good idea to remove the straps before getting into the glass bonding chore. The strap screws projected into the hull a bit and would interfere with the lay-up of the fiberglass tape used to lap over the seams between hull parts.

So, to keep things together, I tack glue the hull parts together with CA adhesive, then remove the straps and screws. The machine screws cleared away it was a very simple matter to mix up some laminating epoxy and lay in the fiberglass reinforcing strips within the hull assembly.

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Four-ounce weight (fiberglass cloth/matt density is expressed by weight per square yard) cloth tape was cut into inch-and-a-half wide strips. Those strips cut to a length that would girdle, from the inside, one-half the diameter of the hull. These strips, when saturated with resin becoming the reinforcement that would permanently bond adjoining hull sections together.

A neat way of working out developed length of the strips is to use a malleable item, like solder wire, as demonstrated here, to determine the required length of strip needed within the model, then to straighten it out and use that to determine the length of the strips required. Fiberglass matt and cloth is best cut out with a disc-blade knife as seen here. A cutting board of wood works very well, as long as the direction of cut is in line with the grain of the woods surface.


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The reinforcing fiberglass tape is laid within the model after first brushing on some catalyzed laminating resin. Note the long handle to the disposable brush here -- it permits easy application of resin to those areas not easily reached by hand.

The many holes used to secure the metal straps were first covered from the outside with pieces of tape. Once resin was laid up within the hull it filled these holes -- the hardened resin restoring the outside of the part ... no more pesky holes to fill and be bothered with later.

_________________
"... well, that takes care of Jorgensen's theory!"


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PostPosted: Fri Jan 08, 2016 8:40 pm 
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Unlike most other wet-hull type r/c submarines, this one -- because of the need to achieve an unbroken linkage to the SubDriver (WTC), located in the lower hull, and the bow plan operating and retract linkages, also located in the lower hull -- features a U-cut type break between the two hull halves. With the U-cut both radial breaks occur from centerline up to the top of the hull.
Unfortunately, the U-cut prevents tilting of the upper hull as it's placed down on the lower hull. Where the more familiar Z-cut, with its high radial cut aft and low radial cut forward permits use of a radial capture flange forward, and a single machine screw aft to secure the entire hull assembly -- an assembly that requires angling in the two hull halves during assembly. Not so with a model. making use of right-angle U-cuts.

Presented here is how I worked out the fasteners used to hold the two hull halves together, as well as how 'indexing bolts' (as the German's would describe them) are employed to index the two hull halves tightly together against transverse loads.

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With this type hull separation scheme some means of registering the two hull halves together has to be devised so that they fit together as a tight, non-shifting unit, secured with the minimum number of mechanical fasteners.

I worked out an array of indexting pin-in-hole bolts along the longitudinal flanges of the upper and lower hull pieces to prevent transverse motion of the assembly. I would love to claim authorship to this feature, but ....

... It's a system I stole from Andreas (who produces this kit). He chronicled the use of the pin-in-hole indexing array in this excellent U-1 WIP thread, http://www.modelboatmayhem.co.uk/forum/ ... 50934dcc7b

Longitudinal regidity and alaignment was assured by the vertical flanges at the radial edges of the upper and lower hull.

Closure was achieved by a fore and aft machine screw holding the upper hull down upon the lower hull -- that required manufacture and installment of two brass foundation pieces to receive those screws.

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The pin-and-hole indexing array, that would register the longitudinal edges of the upper and lower hull halves together, started by working out an even spacing between the pins and holes along the length of the flanges. This done with Sharpie-pen and ruler.

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The pin-and-hole indexing array started with laying out of longitudinal lines. That job best done with a compass: the pen point set high enough to cause the shank of the compass needle to ride along the outer face of the hull as the tool is drawn along, its pen tip inking a line along the length of the flange face.

I elected to install the pins within the flanges of the upper hull half, and the holes to receive the points of those pins drilled into the lower hulls longitudinal flanges.

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The compass was adjusted to put the inked line in the center of the flange. As the tool retained its initial setting during the mark-off of the four longitudinal flanges, I was assured uniformity of line-to -hull-surface spacing. close enough for government work. However, as a check, I would later use an old pattern-makers trick to assure a more precise mark-off to assure proper alignment of pin-to-hole.

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The trick is to work one pin-hole pair at a time. Not till a set of pin and hole had been successful achieved, would I move on to the next set.

The process: First, I drill a 1/16" hole into one of the marked spots along the longitudinal flange of the upper hull. A short length of 1/16" diameter brass rod is chucked up into a moto-tool and spun as I filed one end to a blunt point. The pin was then inserted into the hole, pointy end of the pin projecting over the flange face by 3/32".

The next step is to accurately mark onto the lower hull longitudinal flange where the center of this pin goes.

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I applied a very, very small amount of oil paint (black) to the tip of the friction fit pin, then carefully placed the upper hull down onto the lower hull. I kept pushing till the pin makes contact with the lower hulls longitudinal flange -- and kept pushing till the pin was pushed back with its tip flush with the upper hulls flange face. Removing the upper hull revealed a small dot of paint on the lower hulls longitudinal flange where I would drill a hole to pass the pin. That hole slightly larger than 1/16" (.062") -- this to provide a non-interference fit between pin and hole. That bit was a .064" drill. This produces a very tight, non-interference fit between pin and hole.

After removing the upper hull, the pin is pushed to project it's tip 3/32" past the plane of the flange, and CA applied to the inboard side of the flange to affix the pin in place. The two hull halves were assembled to insure a correct fit, then separated and I moved on to the next pin-hole combination. the cycle repeated till the job done.

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The completed pin-in-hole array seen along the longitudinal flanges of the upper and lower hull halves.

The forward screw foundation. Manufactured from 1/2" wide, 3/32" thick brass strip, and bend to a 'Z' shape, is seen here temporarily held within the forward section of lower hull with two 2-56 X 1/4" long machine screws -- these screws eventually removed to clear the way for installation of the eventual forward acid-etched deck piece.

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Two hull closure machine screws, one forward the other aft, eventually secure the upper hull to the lower hull. The two foundations (the forward one seen here) becoming the interface fixtures between the two halves.

(Note the second hole, aft of the other, in the trough of the upper hull. The initial intent was to employ a longer foundation tongue, but that was found to put too much strain on the right-angle bend at the bottom of the foundation piece. With the shorter moment the assembly became a bit more ridged).

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Temporarily attached to the forward portion of lower hull, the forward screw foundation is seen with the upper hull not yet positioned in place. You can see how a securing machine screw would pass through the hole in the trough of the upper hull, pulling it down and onto the foundation, holding the hull halves in place.

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This is the end-game: A solid, ridged foundation upon which the inboard side of the upper hull rests upon. So arranged the upper surfaces of the hull halves match perfectly.

So, with the pin-in-hole array I've forced the longitudinal union between the two hull halves to index tightly against transverse loads; and the two foundations with securing screws pulling the upper hull half down upon the lower hull half.

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The upper hull was removed, the lower hull inverted, and CA applied to the foundation-hull matting surfaces, and when cured hard, the temporary securing screws were removed. Then some laminating resin was catalyzed and reinforcing strips of two-ounce glass cloth laid in to strengthen the foundation bonds.

_________________
"... well, that takes care of Jorgensen's theory!"


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PostPosted: Tue Feb 02, 2016 10:36 pm 
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NAUTILUS PART-4

In this part I'm concentrating on how to handle, cut, and trial position the two acid-etched deck pieces. As I departed from the radial aft break to the hull -- this kit designed as a dry-hull with a single radial break aft employing a watertight bayonet type closure. However, I opted for a wet-hull arrangement which, as the hull kit parts were arranged required two radial backs atop the hull. This change meaning I had to split the forward acid-etched deck piece into two pieces in order to work over the forward radial break.

In addition to outlining the care and feeding of this kits acid-etched deck pieces, I'll also give you some insight into just what the acid-etching process -- more correctly described as, chemical machining -- entails to give you a better idea of the end-products strengths and weaknesses.


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THIS is one complete kit: detailed illustrated orthographic and isometric drawings; two beautiful cast brass propellers; GRP sheet marked off to indicate where to cut; bubble free perfectly symmetrical and tight fitting resin pieces; and a complete set of acid-etched parts for the deck, sail bridge, radar reflector, and even a painting stencil used to spray-brush on the large white '571' that goes on each side of the sail.


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First step is to part the two deck pieces from the tabs that connect them to the fret. This best done with a sharp knife pressing down onto a firm, un-giving surfaces -- such as a sheet of glass or, in this case, a slab of sheet iron. Place the blade edge perpendicular to the work, where the tab meets the part, and press down firmly. 'Snap'! As the part is cut free of the frets tab.


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To insure I made the initial forward brass deck cut exactly over the radial seam at the bow, I laid in the two acid-etched deck pieces -- which indexed perfectly within the shallow trenches of the hull there to fit them flush with the top of the hull -- and only then laid down a straight-edge and made the first light passes with a brand new #11 blade. The forward acid-etched deck piece was removed from the hull, placed on the cutting plate and at least ten light passes of the knife made, using the initial cuts to guide the blade. The piece was flipped and a straight-edge used to guide the blade as that side was scored.


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The acid-etched deck pieces are chemically cut from brass sheet. This is flimsy stuff as it is, but after eating away a substantial portion of the material to achieve the high relief and through detailing, the part become exceptionally prone to handling damage.

For this reason, other than using a very thin diamond saw, you should refrain from using traditional sawing tools to part one acid-etched part from another. Instead, as I've illustrated here, you make knife cuts along both faces of the piece; sandwich each half between hard-wood strongbacks; and slightly flex, back-and-forth, the parts at the knife cut till the metal fractures.

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In this shot, you can make out the slight recess in the bow that permits the face of the deck piece to mount on the same plane as the GRP hulls deck. Incidentally, the seam between acid-etched deck and hull, not by any accident, is the same demarcation line between the real NAUTILUS hull and deck. This is one accurately engineered and detailed model kit!

Seen to good advantage here is the break in the forward acid-etched deck piece made to accommodate the forward radial break between upper and lower hull halves.


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Andreas lavished a great deal of research effort and drawing preparation on his kit. It shows in the highly detailed brass metal deck kit parts. He employed a second-party contractor to produced the acid-etched parts -- that outfit using Andreas' art-work to render the engraved and opened details. The process in professional circles referred to as, two-face 'chemical machining'. Acid-etching to you and me.

The process goes something like this: A piece of brass or stainless steel plate is cleaned and both sides coated with an air-dry photo-sensitive resin. the sensitized metal sheet is sandwiched between two indexed negative/positive film masks. The top mask represented those portions of deck that will be cut all the way through as well as those areas that are to be cut half-way through. The bottom mask represents those portions of the deck that have to be cut all the way through.

Once the photo-sensitive resin is exposed (typically an intense ultra-violet light), the masks are removed, and the sheet agitated within a developer solution that removes/protects the light activated portions of resin. At this point specific portions of the sheet are protected by the resin, the other portions of metal unprotected and now subject to oxidation. The developed sheet is then subjected to either a hot acid or caustic solution soak/impinging spray. Oxidation or corrosion eats away those areas of sheet no longer protected by the resin coating.

Hence the term, 'chemical machining'. And you wind up with the thin metal sheet (the 'fret' in some circles) possessing incredibly defined engraved and open areas. Typically, for economies sake, the fret will contain many different acid-etched model parts and masks -- the items within the fret held in place my tiny tabs, elements of the original art-work.


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This little scratch-build model demonstrates the correct selection of materials and fabrication process to suit specific tasks: acid-etched brass sheet to form cockpit detail, markings painting masks, l.g. doors; cast resin parts for small parts of compound curves; and vacuformed polystyrene sheet for large, hollow, low-weight structures of compound curves.


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Why do I know so frig'n much about the process of acid-etching? Because I do it myself, in-house.

Like all model building techniques this process has its uses. But, only in specific situations. The talent is knowing what fabrication process to employ for specific parts, and when. Acid-etching employed here to achieve incredibly small, well detailed parts and and painting masks.

Andreas' kits is an example of correct material and process selection -- each type material and process suited to a specific type part: laid up GRP where you need thin-walled items of high strength and of compound curve; cast metal where thin walled strength and natural color is required; and acid etched items where thin-section plate of fine surface detail is desired. The right material and fabrication process for the right job.


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The one mystery as to the NAUTILUS detailing not resolved in the kit is the number, placement, and size of the bottom hull ballast tank flood and drain holes, and main seawater suction and discharge holes.

Searching my files I found this excellent Jim Christley drawing showing the as-launched NAUTILUS in profile, both cut-away and external. And it's the upper drawing that revealed a great deal of information on those hull penetrations -- holes I'll have to cut into the lower hull for both scale and functional reasons.

David

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"... well, that takes care of Jorgensen's theory!"


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PostPosted: Sun Feb 14, 2016 10:26 am 
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part-5

Basic hull assembly done, it came time to address the control surface linkages, running gear, and the removable SubDriver (SD, also known as 'water tight cylinder') foundations. I first replaced the kit provided metric sized control surface operating shafts and propeller shafts with slightly smaller units sized to the imperial system.

… Hey, this is America! We don't do no stik'n metric!

I also took the opportunity to test fit the sail atop the hull as well as checking the fit of the four acid-etched deck pieces.

The primary objective here was to get everything that movies on this model to work correctly from the source, the SD.

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The kit provides all the parts and documentation needed to produce a very credible model of the USS NAUTILUS. However, other than the way the hull parts break down, provision of propeller shafts, control surface operating shafts, and perfectly formed and positioned propeller shaft bores (stern tubes), it's the job of the kit assembler to come up with the hardware and devices required to convert the kit .

The control surface linkages, some elements of the running gear, and means of mounting the SD (which contains those control, propulsion, and ballast sub-system elements that must be housed in a dry environment) have to be fabricated or purchased separately by the customer. You see some of that work above in the form of linkages, running gear, and SD mounting hardware.

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All three sets of control surfaces (stern planes, rudders, and bow planes) are simple affairs: Each set of control surfaces has a straight run-through operating shaft -- there is no need to provide shaft avoidance yokes, which is the case in most single-shaft designs. The two shafts of the NAUTILUS provide plenty of clearance in the stern for straight-through stern plane and rudder operating shafts -- a desirable situation also made possible by the two sets of operating shafts being well distanced longitudinally.

The cast white metal bell-cranks were at hand: these are parts of my own manufacture, used in our line of plastic model submarine fittings-kits. Each bell-crank secures to a control surface operating shaft with a set-screw. One control surface is permanently glued to one end of its operating shaft while the other is made to be a tight interference fit to the other end of the operating shaft. To install a set of control surfaces the shaft is inserted part way through the hull, and the bell-crank (with pushrod made up through a Z-bend) pushed onto the end of the operating shaft, and the shaft pushed through the opposite hole, and the other control surface pressed into place and twisted into alignment with the other control surface. The bell-crank is then centered onto the shaft and its securing set-screw tightened.

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You'll note the use of a large diameter (1/4") aluminum pushrod -- here, made up to the bow plane operating shaft bell-crank. This light weight, yet stiff, pushrod prevents flexing as the control surfaces are positioned against the load presented by flow forces. Each end of a pushrod terminates in 1/16" brass rod. These rods suitable for make up to the bell-crank through a Z-bend at one end, and a magnetic couplers at the other end of the pushrod. In the above photo you can make out the securing set-screw of the bell-crank which makes it fast to the bow plane operating shaft.

Interfacing the small diameter brass rod and the much larger diameter aluminum tube is an adapter. This adapter made from a sprue of polyurethane resin, bored and turned to integrate the brass and aluminum pieces. The assembly made fast with CA adhesive.

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Working out the running gear on this NAUTILUS model is easy: The two beautifully cast and finished brass propellers, and a molded in place propeller shaft bore (stern tube) that runs straight and true through each horizontal stabilizer are provided. All that is required of the kit assembler is to procure and install an un-flanged Oilite bearing at each end of a stern tube; come up with bearing blocks and an astern bearing; and provide intermediate drive shafts that fit between the propeller shafts and SD motor output shaft through universal couplers.

The after Oilite bearing, against which the propeller pushes, serves to transmit the 'ahead' thrust load to the hull. The forward most bearing addressing the backing thrust load through its bearing block which is bonded within the hulls stern.

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Beautiful, isn't it? Other than just a little file work to knock down some flash at the perimeter of the appendages, I have not done a thing -- this is how tight and clean the stern is once the parts are assembled. This kit is a marvel of precision, good kit design and manufacture on display!

Into the extreme after end of the stern tubes are set and glued ahead Oilite bearings, against which is a thrust washer, pushed against by the face of the propeller hub.

The GRP stern piece comes to the customer assembled with a perfectly true stern tube through which each propeller shaft passes. As mentioned before, I substituted imperial sized shafts for the kit provided metric. As this undersized those items it was an easy matter to sleeve up the control surface operating shaft openings (which make for simple bearings) to pass the shafts that operated the rudders, stern planes, and bow planes.

At the stern, the only tricky task was to lathe turn the little 1/4" outside diameter intermediate and ahead Oilite bearings. This operation required to make them fit the existing propeller shaft stern tube bore. Stock 1/4" outside diameter astern Oilite bearing were placed in custom made 'astern thrust blocks'.

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Looking aft into the hull we see the CA secured astern thrust blocks. Each propeller shafts forward end passes through the astern thrust bearing set within its thrust block. Once installed, the after face of a Dumas type universal coupler presses against a thrust washer which makes contact with the forward face of the astern Oilite bearing. This is where astern loads are presented by the propeller shaft when going astern.

Keep in mind that there are three bearings per shaft:

1. the ahead thrust bearing at the after end of the stern tube, against which the propeller hub (through a thrust washer) pushes

2. an intermediate journal bearing set at the extreme forward end of the stern tube, to damp out side loads (vibration) the shaft might experience at high RPM's

3. the astern thrust bearing housed within a bearing block which in turn is bonded to the hull
If you look real hard you can just make out the control surface operating shafts and the pushrod bell-cranks that make up to them. In this shot you get an appreciation how easy it is to make up stern control surfaces with a boat that makes use of two, rather than one, propellers.

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Center, near the top of the hull are the rudder and stern plane pushrods. At the extreme forward ends are magnetic couplers which make up to their counterparts that run from the after end of the SubDriver, the SD pushrods passing through watertight seals and on into the cylinder were each makes up to a servo.

The magnet of each magnetic coupler makes a press-fit within a resin foundation that, in turn, accepts a threaded rod bonded to its pushrod -- turning the magnet foundation permits fine adjustment of pushrod length.

Between the propeller shafts and the SD motor shafts are intermediate drive shafts. These make up at each end in Dumas type universal couplers. These shafts transmit only torque, no axial loads, so no connectors are needed -- the intermediate drive shafts simply slide into place as the SD is installed within the hull.

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This is how the SD integrates within the hull. The SD indexes with the hull through a single brass pin set within the Velcro strap foundation -- this pin, which engages a hole in the bottom of the central ballast tank -- prevents axial and lateral motion of the SD once in place. You can make out the black Velcro strap that securely holds the SD down on the two saddles . The saddles position the cylindrical SD to that its longitudinal centerline falls shares that of the hull.

The removable SD can be installed/removed in seconds. The interface between the hull and SD propulsion, ballast, and control sub-systems are the two propulsion intermediate drive shafts, three magnetically coupled control surface pushrods, and the flexible hose that runs from atop the SD to the sail located snorkel induction mechanism.

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A closer look at the saddles and Velcro strap that index and hold the SD within the hull. The strap foundation came from one of the submarine plastic kit r/c conversion fittings kits I produce. The two saddles were cut from laminations of PVC sheet, layered to a thickness of 3/8". The strap foundation was secured with two 2-56 machine screws. The saddles were CA'ed in place after establishing where the bottom flood-drain holes went - I didn't want the saddles to straddle open holes, so I waited till that work was done before determining exactly where in the hull the saddles would go.

Plotting and opening up the flood-drain holes will be covered in the next installment of this WIP.

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PostPosted: Sun Feb 28, 2016 7:55 am 
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part-6

The flood and drain holes on the bottom of this NAUTILUS model are both an appealing scale feature and a vitally important element in the operation of this wet-hull type r/c submarine.

Through these openings water passes in and out of the hull as the SubDrivers (SD) ballast tank takes on and discharges water. And what better way than through the scale openings in the bottom of the hull? As the kit is primarily designed to be a dry-hull type, there is little in the instructions and no markings on the hull, indicating these flood-drain holes on the bottom of the hull -- it's left for the customer configuring the kit for wet-hull operation to determine the location, size and number of bottom flood-drain holes.

I identified drawings prepared by the much published (and authoritative) Jim Christley That did a pretty good job of identifying the NAUTILUS flood-drain holes. I scaled his drawing up and used them to make a marking template.

Marking the bottom of the hull the location and shape of the flood-drain holes is only part of the task. The GRP hull, essentially silicon glass fibers bound in a hard resin, requires proper tool selection and use to be cut and ground effectively.

The single removable water tight cylinder (WTC), or SubDriver (SD) as I call it, is aligned to the hull through a single indexing pin, and is held down onto two supporting saddles set at the bottom of the lower hull. I'll demonstrate that interface in this installment of the WIP.

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There was no molded-in place longitudinal cheat line at the bottom of the GRP hull pieces. No big deal, I determined the dead-center bottom with a piece of radially placed masking tape -- flopping it from being wrapped on one side, then the other and adjusting quarter-radius marks on the tape until I had a radius line on the tape of a length that worked each side of the hull. Using the marked tape as a measuring tool I placed two BDC points on the hull then scribed a longitudinal cheat line, connecting those two points, as illustrated in the above picture -- this engraving became the bottom hull longitudinal datum line off which I radially distanced the flood-drain and main sea water hole locations.

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I found a Jim Christley illustration in one of my books that indicated credible locations and approximate lengths of the bottom flood-drain holes -- the ports through which seawater went in and out of the submarines ballast tanks. His drawing also indicated four other very important penetrations in the hull: the two sets of main sea water suctions and discharges.

Though there was no way to garner from this small and slightly smudged illustration the distance the flood-drain holes were from the bottom centerline, I made a best-guess using an old training-aid-book from my submarine days on the WEBSTER. Resolving those documents (and a 1/48 drawing left over from a RTR DeBoer Hulls NAUTILUS job done over a decade ago) to the 1/86 scale of the NAUTILUS model I'm currently assembling, I determined their shape and stand-off distance -- and from that I worked up a flood-drain hole marking stencil from plastic sheet.

A Draftsman's circle stencil was used to mark off the propulsion main sea water suctions and discharges -- one set on each side as the NAUTILUS' hull.

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I worked out the ratio between the Christley drawings and the hull, applied that to a set of proportional dividers and lofted the flood-drain hole sizes and distances between centers to a .025" thick piece of polystyrene plastic sheet. The marked off holes then punched out with drill and files to produce a generic flood-hole marking tool. Here you see it put to work marking out some of the ballast tank flood-drain holes in the forward group.

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The flood-drain holes were started with the carbide bit -- this tough, very hard coated tool makes quick work of hard substances such as glass. Glass is the 'G' in GRP.

I segregated all my cutting tools into three categories: those for plastic and brass alloys; those for iron and stainless-steel; and those tools condemned to cut GRP. How does a cutting tool get awarded the prestigious honor of chewing on glass? With use and age that tool has become a bit dull, its got one foot in the grave. So, its final use will be heroically grinding away GRP parts. That's how tough GRP is on tool-steel -- once that tool has tasted GRP, it's a gonner.

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Over the decades I have assembled quit a collection of files of various shapes, cut, and sizes. here I've selected a square sectioned file to finish off opening the square holes -- holes initially punched out with a moto-tool carbide rasp. See those files? They'll be in a land-fill by this time next year.

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The hand-reamer to the left was used to pen up the big circular main sea water openings near the stern. The moto-tool, equipped with a carbide rasp was used to make the initial opening for both circular and square holes; The two square sectioned files were used to give shape to the square holes.

From stencil manufacture, mark-out, to final hole trimming took me the better part of an afternoon. Knowing what tools to assign to the job and how to use them is the key to quick, clean work.

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Holding the SD over the lower hull, illustrating the SD securing hardware in the lower hull that secures and indexes it once installed. The white items are the two CA'ed in place PVC plastic saddles. The foundation piece, that both retains the single securing strap, and supports the SD-to-hull indexing pin is in the center. The indexing pin engages a hole in the bottom of the SD's ballast tank, retaining it and keeping the SD from rolling or sliding once the Velcro strap is made up tight.

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Demonstrating how the Velcro strap is employed to hold the SD down tightly onto the two mounting saddles. The bottom of the strap runs under and around the strap foundation pieces which in turn is secured to the bottom of the hull with machine screws. The double-sided Velcro (hooks on one side, hoops on the other) is slightly elastic permitting a very tight pull-down of the SD onto the saddles. The strap and the indexing pin makes the SD one with the hull, insuring no pushrod backlash or binding of the running gear.

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The thin, very delicate acid-etched deck pieces might become an operational problem. My biggest fear is that some idiot, either launching or retrieving this model, will accidentally push his fat thumb through the very delicate, minimally supported, center acid-etched deck pieces.

To be fair, there are underlying supports for the central acid-etched deck pieces; Andreas has provided transverse GRP cross-bracing upon which portions of the acid-etched deck will sit. The issue is, I don't think there are enough of them -- a lot of flimsy deck remains unsupported.

It's my intention to double the number of below deck braces to give this thing a chance of getting through at least one season of operation without a damaged acid-etched deck!
Contributing to the center deck weakness problem is the incorporation of a trough in the top of the hull.

Why?

Keep in mind that this kit was originally designed as a dry-hull type r/c submarine. The trough was built in to reduce the boats total submerged displacement. Had the kits hull been capped at its deck level (which would have solidly supported the center portions of acid-etched deck) doing so would have resulted in a hull displacing much more water than had the trough been incorporated. More above waterline displacement means a larger ballast tank, and a larger ballast tank takes up more valuable volume within the hull, making installation, adjustment, and replacement of internal devices a Plumber's nightmare.

As it is now the acid-etched deck is divided into four pieces: The forward most piece sits flush at the bow with the entirety of the piece supported by the hull; same with the after most acid-etched piece. The center section, with the trough, has only a few narrow GRP transverse (cross-braces) to support the very flimsy and easily pushed in acid-etched deck. However, the acid-etched deck has narrow transverse solid areas where the actual submarine had these deck re-enforcing cross-braces -- I'll place additional GRP cross braces in the trough, under those solid areas, to add support to the deck pieces over the trough area.

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PostPosted: Sat Mar 05, 2016 4:47 pm 
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PostPosted: Sat Mar 05, 2016 5:23 pm 
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Fortunately, I'm not.

I'll be posting the next installment later today or early tomorrow. This is a wonderful kit -- I'm having a ball with this thing. Andreas is a kit-producing marvel.

David

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PostPosted: Tue Apr 26, 2016 8:23 pm 
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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.

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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.

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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.

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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!

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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.

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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.

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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.

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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 be added.

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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.

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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.

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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.

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PostPosted: Sat Apr 30, 2016 8:29 pm 
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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.

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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.

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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.

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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.

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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!

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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.

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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.

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“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.

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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.

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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.

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PostPosted: Sat May 07, 2016 6:28 pm 
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The first open-water run of the 1/87 USS NAUTILUS r/c submarine kit I acquired from Germany. Produced by Andreas Schmehl this is an easy to assemble and drive r/c submarine.

This outing presented in the following video was to establish surfaced and submerged turning radius. I find this to be a well running model submarine both on and under the surface. The initial run of this boat was in the rather confining boundaries of a local swimming pool which did not give me the opportunity to maneuver the model with any real freedom. However, that all changed when I went to some open water, as you can see in the video.

The model employs a Caswell-Merriman SubDriver -- the system that controls, propels, and manages ballast water. The system is removable and easy access to its devices through the two end bulkheads is quick, easy, and assured.

This SD, customized specifically for this r/c model submarine kit, will be available soon through the Caswell catalog.

I have posted the video to Youtube. https://youtu.be/zRdQ-h9sORE

David

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PostPosted: Mon May 09, 2016 9:00 am 
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Part-10

This model kit WIP installment is exclusively dedicated to the NAUTILUS’ sail. And for good reason: Much as a scale model airplanes cockpit, the sail of a submarine model is the focal point of the viewer’s attention – the ‘front office’ of the vehicle; it’s where the machines intelligence and purpose are housed. The sail is where the people are. The sail also is one of the few places where you get a sense of the dynamic of the vehicle it represents: the optical and electronic sensors rising and descending upon their masts and faring; and It’s the last thing seen as the boat dives, and the first thing seen when it surfaces.

As a display, the sail is the most interesting aspect of the model. One must do it justice if the display is to be attractive and interesting. The model submarines sail is the focal point of the display, have no doubts about that.

The sail, with all those windows (deadlights); masts and fairings; antennas; periscopes; and open bridge with its deck, compass repeater, alarm boxes, platforms and such: all items that demand special care by the model kit assembler.


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Since the earliest days of submarining the conning towers -- and fairings over those conning towers if used -- featured clear windows through which watch-standers could conn the boat, surfaced or submerged.

These windows, properly called deadlights, were quickly abandoned as pressure hull penetrations with the advent of the periscope. Deadlights of any significant size present a flooding hazard should the fragile glass lens fail as a consequence of collision or close aboard explosion. In any event, even with good underwater visibility, only on rare occasions could one see past the bow of the submarine – of little utility to the helmsman maneuvering the boat while submerged.

From the 30’s onward submarine deadlights were relegated to the free-flooding portions of the conning tower fairing where watch standers would seek refuge against the waves while navigating the boat on the surface.

Today, the use of sail mounted deadlights has been all but abandoned (The Russian Rubin design bureau being the last significant advocate). With the advent of nuclear power and AIP the imperative that a submarine ride out a storm on the surface was eliminated – no need for weather beaten watch standers to duck down to a protected platform and peer out through its deadlights. Today, if it’s rough, the boat submerges and everyone enjoys the ride beneath the waves – no longer must the watch standers take green water in the face while powers puking over the side as cold water streams down their backsides (I speak from grim experience!). God bless nuclear power!

DBF … my ass!

As built, the USS NAUTILUS featured no less than three levels within the leading edge of the sail outfitted with deadlights for outside observation. The bottom platform had three deadlights; the middle platform had five deadlights; and the bridge level platform had another five deadlights. That’s a lot of Plexiglas! The US Navy finally abandoning sail mounted platforms equipped with deadlights with the introduction of the THRESHER class submarine.


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The kit provided sail-top represents the ‘armour’ bulged top aft of the bridge opening. This bulg afforded a few inches of protection over the tops of the retractable antennas, induction, and optical heads – an alteration of the origional flat sail top, prompted by the famous under-ice exploits of this world famous submarine.

However, my kit is being assembled to represent the ‘as launched’ boat, with the flat sail- top. I had to make a new sail-top.

I substituted a .031” thick piece of commercially available fiberglass sheet (G-10) for the kits sail-top. This very strong material is dimensionally stable, and takes to adhesives, primer and paint very well.

Note that the G-10 sail-top piece is temporarily held to the cast resin mast foundation piece with the aid of two machine screws (seen atop the sail-top between the masts and fairings). The ability to refine the shape and position of the many sail-top holes for wells, lookout stations, masts and fairings with the mast foundation piece out of the way makes those jobs a lot easier.

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The kits cast resin mast foundation piece – used to both provide some of the housing wells and supports of the masts and some of the antennas atop them – had its sides milled down and a good portion of its bottom cut away to reduce total weight/displacement. This one piece, as it was, displaced nearly one- ounce. After the cut-down it displaced about a third of that. That’s a lot of weight removed from the tallest point on the model, aiding greatly in keeping the models center-of-gravity reasonably low. This weight reduction would minimize heeling in tight turns on the surface, and would contribute to better static stability about the roll axis.

Using the original resin sail-top piece as a template, I scribed onto the G-10 the sail outline as well as the shapes and locations of the holes for the bridge, lookout stations, antenna and optics retractable masts, and fairings. Those scribed lines highlighted by smearing some artist’s oil paint over the work.

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The G-10 was cut out on the band saw to outline; and the well, mast and fairing holes punched out and shaped with drills, burrs, and diamond-dust jeweler’s files.

The only two retractable masts not represented in the raised position on this model will be the communications UHF-VHF whip-antenna mast-fairings. The top of those ‘retracted’ mast-fairings represented as engraved tear-drop shaped forms scribed upon the sail-top piece.

An aluminum scribing stencil used here – the cutting done with two scratch-awls: a starting scriber with a sharp point, and a widening scriber with a blunt point to widen the engraved line. GRP material is very, very tough to scribe owing to the glass content which quickly dulls the steel tools, which required their sharpening several times during the course of this work.

As a great deal of force is applied to the scribe, both down into the work and against the inside edge of the stencil, it’s a good practice to glue the stencil in place during the entire cutting operation least the stencil shift, resulting in a ruined engraving. It’s easy enough, once the scribing is done, to pop the glued stencil off the work and scrap away any remaining adhesive from the work. On occasion I will even use machine or wood screws to hold a scribing stencil down securely onto the work.

Engraving is hard.

Filling and fairing over screw holes and scraping away glue is not.

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While I was integrating the G-10 sail-top and cast resin foundation pieces I kept the two registered together with two machine screws that temporarily pulled the two pieces together. This permitted me to easily access both pieces, separately, as I cut out the holes for the masts through the G-10 sail-top, and worked to bore or sleeve the mast foundation piece bores to imperial sizes.

Damned metric-system! Can’t these people count to twelve!?....

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As I stated before, big blocks of clear acrylic were employed to represent the transparent elements of the two lower platform deadlights. However, a different means of producing clear deadlights at the bridge level was required owing to the very small space between the inside surfaces of those deadlights and the front of the cast resin bridge piece.

I opened up the deadlight openings; each framed as on the prototype, and then touched the edges of these holes with a clear self-curing resin, such as epoxy glue. Now, if those openings were small enough (they were not), the strong surface-tension of the liquid would hold its form and it would bridge the entire opening as the application tool was slowly removed. The clear resin would be left to changes state from a liquid to a solid.

However, the larger openings, like these deadlights, require additional steps as the deadlight holes are way too big to be bridged in one glue application. Though it did not bridge the opening entirely, that first application of glue did build up a significant radius of clear adhesive at the deadlight corners and did build-up along the edges, reducing the amount of glue (and reducing the risk of introducing air-bubbles in later applications) needed to complete the bridging of the deadlight openings.

(You plastic model plane and ship guys may recall the ‘crystal-clear’ product for representing port holes and the like – a thick, clear-drying liquid that had the surface tension to hold form once applied with a round tool to the edges of a hole. When applied correctly the goo would hold as a film within the opening where it would be permitted to harden into a not-quiet optically clear transparency).

What David Manley taught me, and I replicated here, is to place a masking tape damn around the leading edge of the sail and apply glue from the inside, building it up thick enough to conform to the inner curvature of the sails leading edge – bridging all the deadlight openings. The outside mask insuring that the forward face of the clear glue assumed the curvature at the leading edge of the sail.

After the clear epoxy glue has cured hard the masking tape is pulled away from the sails leading edge, the inside and outside surfaces of the clear deadlights are filed, sanded, and then polished to the contours of the sail, inside and out. Deadlight masks were applied and the black (very, very dark gray) exterior painted.

Nothing to it!

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It’s my practice to keep as many model assemblies separable as long as possible during the course of the job.

The entire sail assembly, only some of which you see here, is a case in point: the removable sail-top (secured to the to the sail during the in-water trimming operation and when there is a need to integrate pieces that need clearance between both sail-top and sail) permits easy access to the inside of the sail for SD snorkel mechanism integration and installation; work on the three platforms of leading edge deadlights; finish and detailing tasks to those inside surfaces of the sail seen through the open bridge and lookout stations; detailing ;installation of the sail-to-hull screw foundations; and the manufacture and fitting of the hand-rails that run both sides of the sail.

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Another departure from the kit-as-provided was to make the forward ‘tub’ -- that forms the open bridge atop the sail -- removable. Accomplished by gluing four RenShape drilled and taped foundations: two to the bottom of the sail-top and two to the back of the bridge tub. Once the sail-top is glued permanently atop the sail I retain the ability to install/remove the bridge tub as required.

The two ‘L’-shaped brass items, each projecting from a side of the sail, are the mounts that interface the UHF-VHF whip antennas (represented by lengths of stretched sprue or cat whisker …. “here, kitty, kitty, kitty!”) with their respective ‘retractable’ fairing. A RenShape block glued to the bottom of the sail-top receives a whip antenna mount. Cut-outs in the sail-top and sides of the sail permitted each mount, with its attached antenna, to project well clear from the side of the sail.


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The completely assembled sail-top being test fitted atop the sail. Note that all the deadlight work is done and that each deadlight has been masked and dark paint applied and the masking removed to reveal the correct number and size of deadlights that, on the real thing, permit crew observation from the three platforms within the sail – but only on the surface as the entire sail (except for the bridge hatch access tunnel) is free-flooding.

At this point the mast foundation piece will be glued to the bottom of the sail-top, the two temporary screws holding the two assemblies together removed, and their holed filled and faired over. The bridge tub will be unscrewed, removed, and set aside. And the sail-top permanently CA’ed atop the sail and the edge between sail-top and sail will be filed and sanded to the proper radius.

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PostPosted: Mon May 09, 2016 2:10 pm 
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Last edited by carr on Thu Jul 26, 2018 12:33 pm, edited 1 time in total.

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PostPosted: Wed Jun 15, 2016 7:29 pm 
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Part-11

I assembled this NAUTILUS kit as a ‘wet-hull’ type r/c model submarine. The hull and sail are free-flooding and the only spaces aboard that are dry are those two compartments at either end of a removable cylinder. This water tight cylinder (WTC) -- also referred in Europe as a ‘module’ … or, ‘Tupperware’ when they’re in a particularly mischievous frame of mind -- contains the three basic sub-systems needed to animate the model submarine, endowing it with the ability to cruise either on the surface or submerged. Propulsion, control, and ballast.

Pushing out ballast water is done either by water pump, air-pump, piston, an onboard gas, or a combination of methods.

The removable cylinder concept has been around since the 60’s and commercial product since the late 80’s.

(For the Record: In the States credit for the design and continued development of the WTC is mine. In Europe I believe the lion’s share of credit for what they call a module goes to Brittan’s Nick Berge – one of the most prolific and out-of-the-box thinkers this hobby has ever had. In the days before the internet Nick and I worked toward development and promotion of similar systems, initially we were not aware of the others similar work).

Typically a WTC is divided into three sections, partitioned by four bulkheads -- one at each end, and two near the center of the cylinder. Between the two internal bulkheads is formed the WTC’s ballast tank. There are variations on this theme. The work of Ron Perrott http://www.rcsubs.co.uk/ and Norbert Bruggen come to mind, but for brevities sake I will focus specifically on the 3” diameter, two-motor-two-shaft SAS type SD worked up for the 1/87 USS NAUTILUS kit – the subject of this rather comprehensive WIP.

Most WTC’s differ as to materials and method of ballast water management. The WTC is an old idea: I have a picture of what otherwise looks to be a current version of a clear cylinder WTC from an old issue of Model Boats dated 1967. However, its cylinder was formed from Acrylic plastic – a material prone to cracking and difficult to machine. Today most clear cylinders are formed from Lexan, the same tough clear plastic used for soft-drink bottles and clear r/c car bodies.


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And here we have the WTC ‘system’ – a self-contained, removable, easily accessed water tight cylinder that contains the three sub-systems needed to effectively animate an r/c submarine: propulsion, control, and water ballast.

Atop is an assembled, outfitted, tested, and operational SubDriver (the proprietary name given our extensive line of WTC’s). These two sized and arranged specifically for the 1/87 scale USS NAUTILUS. Pictured are the significant components that go into the manufacture of this SubDriver (SD).

Four cast resin bulkheads divide the Lexan cylinder into three sections. The after dry section contains the propulsion and control elements; the center section forms the ballast tank; and the forward dry space houses the battery and mission switch.

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Examine the above cut-away examples of a typical WTC bulkhead and pushrod watertight seal to get an idea how the conduit, bulkhead, and pushrods are made watertight to the SD.
All four resin bulkheads are made watertight to the cylinder through edge sealing O-rings. The conduit -- a brass tube that running the length of the ballast tank -- is made watertight to the ballast bulkheads via partially encapsulated O-rings during bulkhead manufacture.

The pushrod watertight seals are descrete items that are RTV’ed into holes punched through the motor and after ballast bulkheads. Each pushrod seal features a 1/16” diameter bore with an encasulated O-ring at the seal bodies center which effects the watertight seal between its axial running pushrod and SD proper. The three pushrods that project aft make up to the stern plane, rudder, and bow plane linkages – all of which are external of the SD and make up with magnetic connectors. A single pushrod passes between the dry and wet side of the after ballast bulkhead and is part of the linkage that controls the operation of the ballast tank vent and emergency gas blow valve.


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Three servos are mounted on the motor-bulkhead device tray. The one about to be made up to its 1/16” diameter brass pushrod drives the stern planes. This servo is tended by the ADF2 angle-keeper circuit (with operator input always available); the middle servo is for the rudders; and the port servo operates the bow planes.

Each servo pushrod goes through a watertight seal set into the motor-bulkhead. Those seal bodies made fast with RTV adhesive – this permits easy replacement if called for.


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Like cramming ten-pounds of stuff into a five-pound bag!

That’s always been the situation with r/c model submarines. As illustrated here. All the devices that have to fit, coherently, onto the motor-bulkhead device tray and bulkhead can now be fit into a very tight package. Only with the development of small footprint devices (computer assisted circuit design and surface mount technology) and very selective receivers (signal processing in addition to detection) has this magic-trick been possible. Device size and receiver selectivity has been a boon to this hobby.

Pull the motor-bulkhead away from the cylinder and there are only two electrical connections to break to free the entire unit from the system: one pair of plug connectors interface the motor-bulkhead to the battery power cable, and the lead going to the ballast servo mounted to the dry-side of the after ballast bulkhead.

In order to better describe the function and arrangement of three sub-systems, I’ll discuss each in some detail with supporting pictures:

PROPULSION SUB-SYSTEM

The devices regarded as belonging to the propulsion sub-system include the battery, Electronic Speed Controller (ESC), mission switch, battery cable, battery, cable plugs, motors, motor spark-suppression, gear reduction and propulsion shaft seals.

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• BATTERY This particular SD is sized to fit the 1/87 USS NAUTILUS kit. As I found the size of the ballast tank left little room for both the forward and after dry spaces, this necessitated the use of ‘short’ 11.1-volt Lithium-polymer batteries. Two of these short batteries, wired in parallel, achieved the 3-Ampere hour capacity needed to keep the model running for a few hours between charges. Note the use of a three-plug adapter used to gang the two batteries together in parallel, permitting me to retain the original battery discharge plugs. One of these ganged batteries made up to the foreground motor-bulkhead devices through a test/set-up power cable – this cable making set-up of the installed devices an easy matter, and is a perfect analog to the one that runs through the SD’s conduit tube.

• ESC The electronic speed controller is a common, commercially available item that directs battery current of the desired polarity and intensity to the motor(s) as commanded by the transmitters throttle stick. I’m a big fan of the Mtroniks brand of brushed motor ESC’s. These units are waterproof, robust, and easy to program, and feature a relatively small footprint for the work they do. It’s a good practice to select an ESC with a maximum sustained current draw that approximates 2X the stall current of the motor(s) it’s connected to. For this application, where I’m driving two motors in parallel, I’ve found the fifteen-Ampere Mtroniks ESC to be more than adequate to the task. Though provided, you do not use the ESC’s battery eliminator circuit on the larger SD’s – it simply does not have the current capacity to meet the load presented to the receiver power bus. Either snip off or pull clear of the ESC’s lead the red wire to disable the ESC’s BEC …. NOT THE BLUE WIRE, OR WE ALL DIE IN A HORRIBLE EXPLOSION (for you WW-2 movie fans out there).

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• MISSION SWITCH The entire system is powered through a single battery – which provides power to control, propel manage ballast water. The mission switch is a simple, series connected single-pole, single-throw toggle-switch rated for 10-Amper’s at 110-volts. The on/off function is done at the forward face (wet side) of the SD’s forward bulkhead – simply flipping the toggle to either the ‘on’ or ‘off’ position. The switch itself is made waterproof by a rubber boot that fits over the toggle and makes a watertight union to the face of the bulkhead through an O-ring. The mission switch is wired in series to the battery power cable – the wiring passing through a strain-relief block within the forward bulkhead, its job to prevent breakage of the wires at the switch terminals during handling.

• BATTERY POWER CABLE To be capable of handling up to a sustained 20-Ampere’s at 12-volts it’s two conductors are of 16-gauge; enough copper cross section to preclude any significant voltage drop or heating. This is the main-line between the battery and all the devices requiring electrical power in the after dry space. The power cable runs aft through the brass tube conduit within the central ballast tank. A male Deans-plug at the forward end makes up to the battery (parallel battery harness in this case), and a female Deans plug at the after end of the cable makes up to the devices female Deans plug off to the side of the motor-bulkhead device tray, within the SD’s after dry space. As pictured below.


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• CABLE PLUGS As mentioned, the power cable plugs are of the Deans type. These are polarized to prevent accidental polarity screw-ups when making up the battery and devices to the power cable. Though four devices get battery power direct (BEC, MPC, BLM and ESC), it’s the ESC we’re interested in here. This vital propulsion device gets the lion’s share of current when the propulsion motors are running and accounts for why the power cable and connecting plugs, and mission switch are of such a robust nature.

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• MOTOR AND SPARK SUPRESSION Two 40 turn, three-pole, 12-volt, brushed, 380 sized motors are mounted within the dry side of the motor-bulkhead. Each motor is spark-suppressed with two .01 micro-Farad capacitor – each soldered to the motor case and one brush pole. These capacitors store and discharge at a low RF frequency the ‘electrical noise’ created by the arcing between brushes and commutator pads. Noise that if it got into the very tightly package array of electronic devices would drive them nuts! The two motors are wired to a single ESC in parallel, is such a way that each shaft turns counter to the other.

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• GEAR REDUCTION To better speed-match the high RPM motors to the low RPM propellers I usually employ a 3:1 gear reduction as pictured above. The typical motor bulkhead comprises two pieces: a forward back-plate to hold the motors with their press fit pinion gears; and the motor-bulkhead proper in which are housed the drive-shafts, spur gears, and drive-shaft cup type watertight seals. The motor-bulkhead also mounts the servo pushrod seals, receiver antenna extension, and SAS suction and discharge nipples. Screwed to the forward face of the motor-bulkhead back-plate is the aluminum tray and bulkhead, upon which all the devices are either screwed or double-back taped in place. The motor bulkhead is HEAVILY populated with stuff!

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• SHAFT SEALS Each 3/16” diameter motor drive shaft is made watertight to the motor-bulkhead through a cup-seal. A cup-seal is housed within a plastic shaft seal body and the seal backed up against transverse motion by an internal Oilite bearing. Cup type seals are ideal for rotating shafts as they offer minimal friction and have the feature of increasing their sealing pressure with increasing outside water pressure. Each shaft seal unit is affixed within the motor-bulkhead with RTV adhesive – this flexible material easily absorbs vibration and can be easily defeated if the occasion arises where the shaft seal either needs replacement or repair.

CONTROL SUB-SYSTEM
The control sub-system constitutes the ‘brains’ of the SD system; devices that take the commands that originate in your massive brain, into the transmitter, then on to the receiver where that intelligence (or an autonomously functioning environment sensing device) emerges as modulated pulse-width. Each channel from the receiver feeds a device or devices with a command from the transmitter. Then, each device either converts that intelligence into physical motion (servos), applies a voltage to a motor or solenoid (ESC and MPC), or generates a pre-set pulse-width data stream to drive other devices to a pre-set ‘fail-safe’ position (Lipo-Guard, BLM, or ADF2).

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Most of the devices are common to the average r/c model vehicle user. The servos, ESC, BEC, transmitter-receiver, battery, and connectors can be found at any hobby shop or through the Internet. However, r/c model submarining places demands on the system, and employs special devices that are only available from a few dedicated on-line services, Such as the Caswell Company – the outfit I work for. Their catalog can be seen here: http://sub-driver.com/ This outfit also supplies a wide range of SD’s for the r/c submarine modeling community.

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The above photo shows a typical hook-up arrangement of the devices that control, propel, and manage the ballast water aboard a SubDriver type WTC. And this is not all of it, just the devices that mount to the motor tray and bulkhead. If you look carefully you’ll see that four of these devices (ESC, BLM, MPC, and BEC) have their own red-black power wires. These red-black wires will all be ganged together in parallel and made up to a Deans male type plug which will make up to the battery cable.

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• BATTERY ELEMINATOR CIRCUIT Not actually a controlling device, but vital to the whole sub-system, is the BEC, the battery eliminator circuit. This devices takes the high-voltage battery current, reduces it to the 5-volts the other devices require (distributed through the receiver bus via each devices three-wire lead). But, unlike the low capacity ESC BEC’s, this dedicated BEC has the ass to pump out a continuous 8-Ampere’s of current (enough to smoke the receiver bus foils if ever attained … but that’s another issue!). The stand-alone BEC in larger models (such as the case here) is used because of the higher stall current situations larger servos can present. The BEC is the circuit power source for all devices and as such is a vital element of the control sub-system. Smaller systems, using smaller servos, can get away with using the dinky ESC BEC.

• BATTERY LINK MONITOR/LIPO-GUARD If your system employs Lithium batteries you must have on board either the old Lipo-Guard or the recently introduced (and much more capable) battery link monitor (BLM). Both devices monitor battery voltage and work to prevent a low voltage to damage the battery. When activated, the device locks you out of the ballast channel loop, so that the model must be returned to shore for re-set – by that time even the most dense r/c submarine driver will have figured out that his battery needs replacement/re-charging. The difference between the Lipo-Gurad and BLM is the added capability of the BLM. The BLM not only protects the battery but also serves as a loss-of-signal fail-safe; real-time battery voltage meter; and r/c system performance monitor -- actually counts and displays the number of frame drop-outs that have occurred since last switching on the system.


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• ADF2 The ADF2 is two devices in one: An angle-keeper and a fail-safe circuit. The angle-keeper plugs into channel-5 of the receiver. The circuit employs a position sensor (accelerometer) to detect and work out the displacement of the gravity line (established during device set-up/programming) to the model submarines axis. And that is what you see in the above hook-up between the ADF2, stern plane servo, and receiver. The angle-keeper is both an autonomous artificial stabilization device – working the stern planes to keep the boat at a near a zero pitch-angle while underway submerged -- yet able to permit operator input to the stern planes; mixing both driver and angle-keeper inputs into a viable command output to the servo. The fail-safe side of the ADF2, if used, plugs into either the Lipo-Guard or channel-4 receiver port. In this example the ADF2 fail-safe circuit is not used – its lead not used.

• RECEIVER The r/c system receiver is the RF link between your transmitter and the devices that control, manage ballast water, and propel the r/c model submarine. Today’s receivers are so well designed and crafted that they have the signal selectivity to work in the very tight confines of a very RF noisy environment (The closer the receiver is to all those motors and signal-generators the more hideous becomes the inverse-square rule). Bottom line: we can cram the SD with so much stuff today and not have to worry excessively about the receiver being swamped and made stupid by all the electrical noise. At a minimum you want a five-channel receiver on any RF band below 75mHz if you want the ability to sail the model underwater with the antenna completely submerged (and then, only in fresh water). 2.4gHz r/c systems just won’t work with the receiver antenna under water.

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• MOTOR PUMP CONTROLLER The MPC is an electronic switch that solders directly to the back-plate of the small brushed motor that drives the low pressure blower (LPB), which produces the compressed air used to blow the ballast tank dry. The above photo demonstrates the low foot-print of the MPC. The larger unit above is used in my line of larger SD’s. The MPC gets its power from the battery cable through a voltage-dropping resister that permits the LPB motor to operate at its optimum 3-6 volts, not the 11.1-volts that comes directly off the battery. The MPC’s three-wire lead makes up to one leg of the Y-lead that comes out of the ADF2 fail-safe side or output side of the battery link monitor (BLM) – that signal shared with the ballast sub-system servo.

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BALLAST SUB-SYSTEM
Models that don’t employ a variable ballast (ballast tank) can only dive dynamically – they require forward motion to generate the dynamic force on the hull to drive the submarine beneath the surface. Submarines that can dive in place, without the need of hull produced dynamic force, do so by changing their weight; increasing it so that the added displacement caused by the above waterline structures being immersed is countered by the weight of the water taken into the ballast tank.

The ballast sub-system comprises the ballast tank and the means of flooding it with water and pushing all the water out as either commanded from the transmitter or automatically through one of the detected fail-safe conditions: loss of r/c system signal or low battery voltage.

Either the normal SAS type vent/blow cycle or a back-up emergency gas ballast blow will empty the tank. SAS normally. Gas and SAS when commanded by the fail-safe circuit. The ballast sub-system servo and its linkage are common to both the SAS and gas elements of the sub-system. Moderated travel of the linkage produces a SAS type blow. Extreme movement of the linkage results in both a SAS and gas type blow.

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All our static diving type SD’s use the ‘soft’ type ballast tank – the tank is open at its bottom permitting the free flow of water in or out of it. If the vent valve is closed and air is in the tank, then it will compress to the ambient water pressure (usually, on the surface); opening the vent valve permits a pressure drop within the tank and water quickly floods in, displacing the water. The normal means of discharging the water is to compress air from either the dry-spaces of the cylinder or atmosphere and discharge that air into the ballast tank, forcing the water out as the higher air pressure displaces the water. Blowing air is selected in the Semi ASpirated (SAS) elements of the ballast sub-system by the snorkel mechanism.

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• SERVO The ballast sub-system servo drives a pushrod that runs through a watertight seal set within the after ballast bulkhead. The wet side of that bulkhead (within the ballast tank) has the linkage that translates the linear travel of the pushrod to a vertical motion which works to open/shut the vent valve atop the cylinder. Extreme motion of the servo in the ‘blow’ position not only keeps the vent valve shut it also causes the ballast linkage arm to open the emergency gas blow valve – the extreme motion can only be achieved through the fail-safe circuit or engagement of the transmitters channel-4 trim lever to the extreme ‘blow’ position.

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• MPC As mentioned, the motor pump controller is a form-fitting electronic switch that solders directly to the back of the low pressure blower motor. It is one of the four devices that takes battery current directly, and sends it to the motor as directed by the command that comes through the battery link monitor (as commanded by the transmitter or fail-safe circuit built within the BLM). Both the ballast sub-system servo and MPC get their control inputs through a Y-lead from the BLM, so they work in unison. (The above illustration shows both the small and larger type MPC’s we use with our line of SD’s – the USS NAUTILUS SD makes use of the smaller LPB-MPC unit).

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• LPB The low pressure blower is a positive displacement pump with the ability to pass a non-compressible fluid, like water, without damage. It is (the smaller unit) a two-stage diaphragm type – and it’s the flexibility of the diaphragm that permits it to pass water without getting hammered. A non-reversible type pump, it can only pass the air in one direction. And in this application the air is always directed into the ballast tank. That air pushing out the water within -- emptying the ballast tank. The air either comes from within the SD dry spaces or from atmosphere through an induction snorkel mechanism set up high within the sail, usually. Up high, the snorkel will broach the surface as the boat ascends. The above SAS layout illustrates both function and the devices used to draw air from either the cylinder or atmosphere and push it into the ballast tank.

• BLM The battery link monitor is an upgrade from the Lipo-Guard. Unlike the Lipo-Guard -- which only monitored battery voltage and simulated a ‘loss of signal’ condition to activate the ADF’s fail-safe circuit – the BLM produces a ‘blow’ signal when the battery voltage drops below the critical level. Also, the BLM is suitable for a number of different battery chemistries and cell counts; can be set for specific servo travel; as well as time delay between activation and ‘blow’ command. A very useful device regardless of battery type, but a must if you employ a battery of Lithium chemistry.

David

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"... well, that takes care of Jorgensen's theory!"


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PostPosted: Sat Aug 04, 2018 11:08 am 
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Joined: Sun Jun 25, 2006 3:13 pm
Posts: 23
Location: Ohio
What happened to this kit? was it ever developed? if so does anyone have contact info -- thanks Randy


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