You are very hands on—and I applaud that. I don’t even deserve to be called a kit-assembler less a model maker…but with some of the tech coming out…I wonder if you could make a sub…parts and all…absolutely clear.
Maybe metamaterial strips wrapping the metal bits?
You are very hands on—and I applaud that. I don’t even deserve to be called a kit-assembler less a model maker…but with some of the tech coming out…I wonder if you could make a sub…parts and all…absolutely clear.
Maybe metamaterial strips wrapping the metal bits?
I think you'll find some clear, or semi-opaque resins suitable for 3D printing. Can't speak as the physical properties of that stuff as that's a game I refuse to play.
At least 20 years ago there was this effects guy out of California, Rick Galinson, a mechanical and electronics wiz, who produced a 3-foot long Acrylic r/c submarine. A true work of engineering and materials usage. A detailed demonstration of that model right here:
A single machine screw at the stern is the only thing holding the upper and lower hull halves together. This simple and quick means of attaching the hull halves is possible through utilization of the 'Z-cut'. Named because if you look at an assembled hull from the side you will note that the three breaks between the halves form a 'Z' pattern; the forward radial break, at the bow, runs from the keel up to the central longitudinal break that that runs aft nearly the entire length of the hull and transitions as a radial break traveling up from centerline to the top of the tail-cone. When assembling the two hull halves a recessed radial flange in the lower hulls forward end tucks up tight within the bow portion of the upper hull.
All it takes to assemble the hull is to engage the forward radial flange of the lower hull into the bow piece of the upper hull, then lower the after end of the upper hull down onto the stern cone radial flange and make up a single machine screw to hold that down tight. That's all there is to it.
A quick, fool-proof, and effective means of gaining access to the internals of the wet-hull type r/c model submarine. And who do we have to thank for this scheme that has been in vogue now for several decades? Dan Kachur and Greg Sharpe. To the best of my knowledge these are the guys who developed and popularized this method of internals access.
I modified the flange-forward bearing foundation piece by opening it up a bit. This done to facilitate a GRP reinforcement of the tail cone-to-hull union after tacking it in place on the lower hull with CA. Though this weakens the bearing foundation a bit axially, I determined that the backing loads presented to it in operation will be no where strong enough to distort or break the bearing foundation under extreme backing maneuvers. (best laid plans of mice and men...).
Cast polyurethane resin is easily milled away using a common drill bit spun at high speed. Only took minutes to perform this surgery.
It's vital that every kit part, be the substrate polystyrene, polyurethane resin, epoxy-glass, metal or wood be prepared for adhesive operations by removing all oils, greases, fuzz, pitch and water from the model parts surface. In the case of polyurethane and GRP structures I'm dealing with here, a good scrubbing with lacquer thinner is the best way to go. The soaking is short-term (too long in the bath and the resin parts will go wonky on you) and accompanied by vigorous scrubbing with a stiff brush, steel-wool, a green-pad or other such conformal tool that will get into every crevasse and crease.
With the radial flange-forward bearing foundation permanently adhered to the tail-cone I installed the forward Oilite bearing and centered it with a short length of handy 3/16-inch diameter brass tube. I then applied thin formula CA to secure the bearing in place.
The after end of the lower hull -- where the flange of the tail-cone would seat -- was ground to a wall thickness equal to the radial flange recess depth of the stern-cone. Repeated test fittings (a tight friction fit assured by the leading edges of the horizontal stabilizers nesting up tight against the outside of the lower hull) and grinding away at the internal wall thickness of the stern finally got things to the point where the surface of the tail-cone matted flush with the lower hull.
Initial bonding of the tail-cone to the lower was with CA adhesive. But only to fix the assembly in place. The real strength element holding the assembles together would be fiberglass tape saturated with epoxy laminating resin.
Before tacking the tail-cone in place I ran a 3/16-inch rod through the bearings, carefully adjusting the tail cone position till the rod ran down the hulls longitudinal centerline. This insured that the propeller shaft thrust-line would be perfectly aligned with the centerline of the hull.
The CA was applied inside and out, wherever the resin tail-cone met the GRP lower hull. Using thin formula CA insured that capillary action would drive the adhesive into gaps I could not get at otherwise.
It was in this condition that the CA was applied and left to sit for a night as the adhesive found its way and cured rock hard.
The trouble with most CA adhesives is that the cured bond fractures easily when subjected to a shear shock-load. And since most of us r/c submarine jockeys play hard and drive stupid-fast, collisions with pool sides, bottom, and each other are a fact of life. So, without a more resilient bonding medium, CA is not enough to hold the tail-cone in place.
Here I'm overlaying fiberglass cloth, saturated with West System epoxy laminating resin over the union between GRP lower hull and resin tail-cone assembly.
I laid three plys of fiberglass cloth to each side of the tail-cones lower rudder operating shaft hole. Each layer of glass long enough to extend about a half-inch forward and aft of the radial flange-forward bearing foundation piece.
NOW! This is one tail-cone assembly that won't be knocked off without a fight the other guy will long remember!
The single 4-40 flat-head machine screw that holds the upper hull down tight upon the lower hull. It's the recessed radial flange at the front end of the lower hull, engaging within the bottom bow piece of the upper hull, that holds the front-end in place.
The tapped hole in the resin flange of the tail-cone is not strong enough for field use. I'll install a metal insert drilled and tapped and glued within the radial flange eventually -- this will make the fastening strong enough not to strip out with usage.
The tail-cone and lower hull now one, it came time to assemble the model and Bondo fill the inevitable longitudinal and radial gaps and miss-matches. But, before all that, I scrubbed the entire model with an abrasive green-pad soaked with Prep-Sol, a mild hydrocarbon solvent used by auto refinishing guys to prepare a surface for adhesion to fillers, putties, and primer. Same with model building -- clean that sucker right or your stuff won't stick with any permanence.
Here are the consumables and tools used to build up automotive filler to the low spots as well as those spots that out and out require a re-contouring --specifically the point where the stern of the upper hull half sits atop the tail-cone radial flange.
The Bondo is a two-part, heavily filled polyester paste that is trolled on with putty-knife, finger, or purpose shaped screeding blade. The wax is applied to areas I don't want to stick to the Bondo. The tools are used to knock down the cured Bondo till the low spots are brought to proper contour with the high spots. The file-card and stiff brittle brush are used to clean the teeth of the files as the Bondo quickly clogs the tools which markedly reduces their effectiveness.
The biggest non-conformance between the hull halves was at the stern where the end of the upper hull sits down on the tail-cone radial flange of the lower hull.
There is a sharp 'spine' atop the end of the upper hull which I've picked out here with a pencil lead. I not only had to apply filler atop the stern-cone, I had to continue the spine a bit. The hash-marked area is my estimate of how far the Bondo build-up will travel atop the tail-cone.
I've CA'ed a piece of plastic sheet to continue the spine atop the tail-cone. this will help me guide the putty-knife as I trowel on the Bondo.
After hash-marking where Bondo would be built up I dis-assembled the hull halves and applied wax to the areas I did not want the goo to stick.
The assembled hull was then given the Bondo treatment with the aid of a spatula type putty-knife used at the bow and stern, and a custom shaped screeding blade to address the longitudinal seam areas.
Once catalyzed the Bondo cures quickly, so once a batch was mixed up on the palette I had to get it transferred to the model and troweled out lickity-split.
Once cured hard the Bondo was carefully ground down with a big coarse file, followed by a second-cut file, then a sanding block faced with #200 grit sandpaper. It takes several applications of the Bondo till all the low spots are identified and filled. But, the work goes quickly. All the operations you see in this installment were done in a ten-hour period.
Almost there.
After block sanding the Bondo I brushed on a thick coat of air-dry touch-up putty (good old, Nitro-Stan) to fill file and sanding marks. Tomorrow I'll wet sand everything, then hit the model with a check-coat of gray primer.
I should note that after each application of Bondo and putty, the radial and longitudinal seams were chased open with an X-Acto blade. Gotta do this to keep from sticking the hull halves together once the Bondo or putty had hardened. Forget to do that and you are sooo screeewwweeeeddd!
The hardened touch-up putty was wet sanded initially with #240 sandpaper, followed by #400. Along the length of the constant diameter portions of the hull, where the surface is a simple curve, I used a block to back-up the abrasive. However, when I got to the bow and stern tappers, where the surfaces of the hull transition to compound curves, I switched to a soft block. The soft block having the 'give' required to permit the abrasive to conform to those convex surfaces.
A look at just some of the abrasive tools I've gathered over the decades. Nice to have choices! For the tight, right-angle areas I use double-backed sanding squares and sanding sticks. Rolled up abrasive paper is used for chamfering and round and oval hole refinement.
When all the putty sanding was done, I wiped the work down with a well rung out damp paper towel and waited for everything to dry thoroughly. I then sprayed on automotive grade air-dry acrylic lacquer primer to check the work. Initially, with the two hull halves apart, I primed the edges, both radial and longitudinal.
Once those area had dried (this primer flashes hard enough to handle in no time), I assembled the hull and primed all areas that had been worked with filler and primer.
Time to turn my attention back to the WTC:
The motor-bulkhead was outfitted with a stern plane servo, a bow plane servo, and a rudder servo. The big deal was bending the servo pushrods so that they would experience the minimum amount of drag as they traveled through their respective watertight seals.
In hand is a vital piece of test-equipment, a servo-setter. This device produces the same pulse amplitude and width (variable from 1ms to 2ms) produced by the transmitter for a specific servo. Most helpful while working out the bends in the pushrods. Use of the servo-setter side-steps the need of hooking up the servos to the receiver and fiddling with the transmitter to wag the servos.
A little mill work to get the servos to fit their respective positions on the servo foundation.
Note the extensive milling done to the center of the cast resin servo foundation. This done to drop the receiver well below the servo control horns -- to avoid any contact between the moving parts of the servo and attached pushrod and the receiver.
It took some effort, but I was able to get the receiver to nest tightly between the three servos.
Each servo was set in place with two drops of thick-formula CA adhesive. As there is so little room within the tight confines of the cylinder, I had snipped off the mounting flanges that projected from the ends of the servo case. That move necessitated the need to make them fast with glue.
Representative of the type water tight cylinder (WTC) I produce is this shot of a completed unit. Below are the basic parts of a WTC.
So, back to the WTC I've built for Casey's 1/96 BLUEBACK model. Before populating his WTC with the devices, I sat each one on the table and went through the set-up protocols outlined in the instructions that accompanied each device. Better to do this off WTC than in it... because things NEVER go right the first time you go through a set-up routine! No matter how well written the instructions are. And KLM instructions are the best I've seen written in the English language.
The first devices to be set-up and certified operational were those that required connection to the power bus.
Certified in good working order, these devices were attached to the motor-bulkhead mounted aluminum device tray and bulkhead with the aid of double-backed servo tape. Those items included the low pressure blower (LPB), battery eliminator circuit (BEC), battery & link monitor (BLM), and electronic speed controller (ESC). The input power wires of these devices were all ganged together in parallel and soldered to a male Deans plug. Later, power cables from the forward dry space battery would run aft, terminating in a female Deans plug.
The devices, all mounted to the motor-bulkhead, require only three plugs to interface with the rest of the WTC: The big power bus Deans connector just described, a small Deans connector between the LPB motor and ballast servo limit-switch, and the J-plug of the ballast servo itself. Use of these three connectors make installation/removal of the motor-bulkhead assembly from the cylinder a quick, and easy procedure.
Here I'm soldering the wires to a small Deans plug that makes up to the ballast servo limit-switch. The other half of the little Deans connector has already been made up to the LPB and power bus.
Casey wanted the KLM Depth Commander (DC) device installed. Here I'm verifying the sensitivity of this hydro-statically sensitive device with a column of water in that little hose I'm holding.
I found that the device will deflect the bow plane servo in the required direction with only an 1/8-inch variance in water height. Wow!
This device will automatically hold the submerged model submarine to a specific ordered depth. I've been using these depth-controllers for a couple of years now and found that they greatly reduce operator work-load when driving the model around submerged -- all you gotta do with this thing on line is steer and manage the throttle... if only it could cook!
In the very tight confines of the after dry space of the WTC one must make every effort to reduce the wire runs. Such is the case with the device three-wire leads (servos, DC, ESC, BLM, and angle-keeper). There was way too much slack in these wires, so I cut them short and crimped on new female pins designed to slip into standardized J type Futaba connectors.
Here you see discarded leads. Note the tight packaging of devices and short runs of their leads once everything had been tightened up. Good house-keeping is a virtue in this game.
The power bus is switched on-and-off by a magnetically actuated switch. Yet another KLM device. Here I'm making up the input and output wires to this little device. This switch is situated in series between the Lithium-polymer battery and power bus.
Just wave a magnet over the switch and power is delivered down the power bus to the motor-bulkhead devices. Wave the magnet again, and power is secured. Slick!
With the WTC up and running (but not yet leak checked and suffering a yet to be determined servo chatter during a loss-of-signal event) I returned to the 1/96 BLUEBACK hull chores for a last round before integrating WTC and hull.
The hull parts again front and center I had found that the end of the tail-cone was a slightly smaller diameter than the propeller hub, which would necessitate a build-up of the stern diameter to match the propeller hub. Poor planning! I should have caught this before getting the tail-cone into primer gray. I got rushed. Stupid!
The end diameter was about .050-inch shy of that of the forward face of the propeller hub. Damn! Had to fix that.
And -- as the sail sat within a shallow well built into the deck of the upper hull -- during a test-fit I observed that there were significant gaps between the sides of the sail and the vertical walls of the well. That would have to be fixed as well. Another job for Mr. Bondo. I love that stuff.
Before slogging through all the muck, here's the end-game of this post:
A properly shaped tail-cone-to-propeller hub contour; and a tight, gap free, fit of the sails base within the shallow well of the upper hull. Looks nice, huh? Well... the getting there is the hard part, pal! On to the gory details.
There were many little pin-hole voids in the leading edge of the tail-cone horizontal stabilizers and leading edges of the vertical stabilizers. These were filled with CA adhesive and baking soda sprinkled on to form a quick setting, hard 'grout' that was then worked to contour with careful use of a small flat file. Those areas were then given a light brush-coat of Nitro-Stan touch-up putty. While brushing on the putty I also addressed some areas where tool-marks were still evident in spite of the heavy primer coat previously sprayed on.
At this point in the project I was still blissfully clueless of the too-small diameter at the end of the tail-cone. THAT should have been the first thing I identified before all the fill and putty work. What a dumb-ass... I'm supposed to be good at this shit.
When sanding simple curves on a uniform substrate, I make use of a stiff sanding tool formed from a brass strip outfitted with sandpaper on both faces. #400 grit on one face, #220 on the other. Here I'm wet sanding the putty.
Typically, I'll use a 'soft' sanding block when working a compound curve, like this union between the GRP lower hull and resin tail-cone. But here I'm using the stiff sanding tool. This because there are four different substrates being ground away, each of varying hardness to the other: GRP gel-coat of the lower hull; polyurethane resin of the tail-cone; soft touch-up putty; and hard CA at the hull and tail-cone union.
A soft sanding block would permit the backed-up sandpaper to flex into soft mediums, cutting too much, but ride over the hard mediums, with little cut. The result would be dips where the soft stuff is and bumps where the hard stuff resides. A stiff sanding block won't have any of that! It cuts to a straight plane regardless of substrate hardness.
Hence my use of the hard-backed sanding tools at the tail-cone-to hull interface point. But, later, once I'm just working primer, that's when I fine tune such areas with a soft block.
I use an adjustable radial screeding blade to build-up the diameter of a tail-cone. Not much to it: A pin that fits the bore of the stern tube, and a blade that can be set in diameter and angle to develop the required diameter and taper angle -- that new diameter the same as the forward face of the propeller hub.
Radial screeding is simple. Set up the screeding blade angle and diameter, slather on some Bondo to the ass end of the tail-cone, and rotate the tool by hand. It takes about three cycles to get all areas of the stern re-built like this, but total work time is less than ten-minutes. Bondo is our friend.
After some touch-up work with flat file and sanding block the Bondo areas are coated with a layer of CA adhesive. This fills and strengthens the otherwise porous Bondo. Another wet sanding and the re-contoured tail-cone is ready for primer (again!).
The sail initially sat with a pronounced lean to port when test fitted. That had to be fixed. Here you see the re-worded well corrected to both mount the sail perpendicular to the hull and tightened up to show only the barest of gaps between sail and well.
Within the well that accommodates the bas of the sail you can just make out the hash-marked area I'm going to cut out. Three reasons: first is that you want to take every opportunity to reduce the above waterline structures that would otherwise displace water -- the lower the displacement, the less ballast tank you need to assume submerged trim; second reason is that I need access into the hollow sail in which to pass the pushrod that operates the sail-planes; and third, this opening will quickly vent air and water in and out from within the hull and sail as the boat transitions between submerged and surfaced trim.
Using a standard 1/16-inch drill bit in a high-speed hand-tool I free-handed the bit within the outline -- a poor mans milling bit. The work went quicker and with more precision and speed than would have been the case had I done the work with a cut-off wheel and carbide burrs.
Note that only two machine screws, run up from within the upper hull, are used to secure the sail atop the upper hull. Whenever possible I make as many sub-assemblies removable in order to facilitate later repair, adjustment, or maintenance. The philosophy obviously shared by the kits designer, David Manley.
Initial dry-fitting of the sail atop the hull revealed that it sat canted several degrees from vertical; it was leaning to port. The solution was to lower the starboard side of the wells base to bring the sail into proper alignment. Where to shave? How to identify the 'high' spots? That was solved by coating the base of the sails starboard side with sticky, messy, gets-everywhere-you-don't-want-it oil based crayon.
The crayon black is smeared to the starboard bottom of the sail, the sail pushed down into the well, lifted out, and the high-spots picked out by the black smearing.
I went mid-evil with chisel and files.
The smear-chisel-check cycle repeated till the sail sat perpendicular to the hull.
As I only wanted Bondo to stick to the walls of the well I applied wax to the bottom end of the sail. Giving the wax an hour to harden, the sail was then set in place and secured tight with the two machine screws.
Only two 2-56 machine screws are required to hold the removable sail atop the upper hull.
I must say, David Manley, who is the guy who designed and produced this kit so long ago is still teaching me and guys like me new tricks. Just by working one of his kits the observant model kit-assembler can learn a lot about functional design and appropriate materials selection. I have stolen his ideas shamelessly and incorporate them into my own work whenever the opportunity presents itself.
Every aspect of the model-building Craft has its 'experts'. Off the top of my rather pointy-head let me rattle off a few of these dudes who have contributed so much to the Craft:
Those interested in static/display model aircraft (a more savage collection of anal-retentive, rivet-counters, and know-it-all's cannot be found) have guys like Ben Guenther (an alarmingly calm, gracious, and most helpful man); The static/display model car perfectionists have the unassailable icon of Gerald Wingrove; the model rocket egg-heads have the prolific Scott Lowther and Mat Irvin; the SF vehicle tin-hats have Martin Bower and David Sisson; the model ship guys have William Blackmore and August F. Crabtree; and we lowly r/c model submarine guys have our own David Manley, Matt Thor, Greg Sharp, Dan Kachur, and Robert Dimmack.
The sail secured to the upper hull I mixed up several small batches of catalyzed Bondo. Done in stages as the stuff cures quickly. The time it takes to do this job way exceeds the useful working time of this stuff if attempted in one cycle. The objective is to jam and force the Bondo into the voids between sail and sides of the well. The Bondo will... hopefully... stick to the sides of the well, but not stick to the sail.
Wooden putty-knifes were fashioned from tongue-depressors -- wood because a metal putty-knife would scrap away wax from the sail, leading to sticking of the Bondo to that structure. Something to be avoided.
Once the sail was popped off the well (no problems encountered), the wax was scrubbed off by a lacquer saturated abrasive sponge.
There are many special interest groups (SIG) within the general hobby of radio controlled vehicles. Aircraft, be they fixed wing, helicopters, quad's, and blimps; cars and other wheeled ground vehicles; boats; robots; submarines; and a few other type vehicles -- they all require an operator in the control-loop, guiding the vehicle, sometimes at a great distance, through direct observation.
Hobby vehicle drivers have wanted the ability to shift their perspective from
their physical location to a view presented to them remotely from the vehicle itself; putting them, virtually, in the driver's seat, able to view the world from the vehicle itself rather than observation of the vehicle from a distance -- to see what the vehicle sees and control it from that perspective as though the driver himself was aboard the vehicle.
Today, hobby first person view (FPV) equipment is available, and we have the Juggernaut of the r/c model airplane community to thank for that. The fliers: those guys, tens of thousands of 'em, assured inventors, investors, and manufacturers that a market existed; a market large enough to warrant the effort.
Our very small group of r/c submarine drivers can now dine on the table-scraps of the airplane and drone guys; their win is our win. That gear is now available to us.
FPV equipment became a reality to the general public about the turn of this century with the availability of basic, low quality (by today's standards) camera-transmitters and virtual goggles. The intended market was those people interested in Home Security.
Over time advancements in picture quality, range, size and weight reduction, and standardization within the r/c hobby industry matured the equipment to the point where, today, a system can be bought at a very reasonable price and easily placed aboard the r/c model and put to work with little fuse or technical expertise.
Things started to ramp up for me in the FPV department when Walmart began selling these small, cheap camera-transmitter units, complete with ground-station receiver. This was my entry-level toy to the world of FPV as applied to r/c model submarines. That was about fifteen years ago.
By today's standard the image quality was bad -- these were the days before camcorders, cellphones, and dedicated video cameras went from 'standard' to high-definition (HD) quality imagery. But, for the time, the image was good enough if you really wanted that, I'm aboard the model experience.
The little Swann camera-transmitter unit, other than the power supply, was all inclusive. Only two modifications were required: first was to relocate the transmitting antenna via a shielded coaxial cable up to a position high atop the models sail, where it could project above the water as the model ran at periscope depth. This necessary as the high frequencies (typically in the 2-5gHz range) will not punch through water.
The second requirement was to install a voltage regulator between a 9-volt battery I recommended at the time and the camera-transmitter which typically dinned on 5-volts.
With these two relatively simply modifications the unit would fit within a 1.25-inch diameter acrylic cylinder outfitted with a clear lens forward and a streamlined after access cap at the stern. Atop this watertight enclosure was an antenna interface piece that mounted a streamlined aluminum fairing through which the coaxial cable passed, terminating topside in the 1.25-inch long 2.4gHz transmitter antenna.
Ellie and I produced the 'up periscope' watertight enclosure and made it available for sale during our tenure with the Caswell company. Market acceptance was, to be kind, awful!
Was it something I said?...
This was around 2007 and the associated virtual goggles, through which are projected the camera images into the eyes of the far distant driver, are nothing like what is common today: They was just two low resolution LCD's, one for each eye. Fuzzy. And the power supply had to be jacked into the goggles. Hence the need for this Batman utility belt my kid's wife sewed up for me -- just to hold all the gear needed to make me a walking, silly looking, 'ground-station'. (A tin-foil hat would have completed the look of a well-dressed techno-nerd).
The word, cumbersome, comes to mind about my early effort at FPV. But it worked. Not well by today's standard, but it was a thrill to finally drive a model submarine as though I was right there, in the water. One time, in a chop and trying to maintain periscope depth, I puked all over my pants -- it's that immersive! I've always had poor sea-legs.
All this as preamble to the gear offered today. Things have matured: the goggles now are consolidated with the other ground-station devices. The virtual goggles contain the OLED screen(s), receiver and antenna, audio output, power supply, and ability to scan the accepted bands and frequencies making matching of camera-transmitter and ground-station a simple operation. And somewhere along this road of evolution, picture quality went from 'standard' to 'high-definition'.
Below is 'old school' ground-station devices and utility belt. No more! To the Bat-Cave!
And what kind of r/c submarine is suitable for use of FPV? As the above photos illustrate, any model large enough for you to mount the watertight enclosure atop its hull or sail is a candidate for the system.
But for you purists like me, there are prototype submarines that have features that, without spoiling the look or hydrodynamics of the vehicle, lend themselves to internal camera-transmitters. I submit two fine examples: The 1/12 Williams Models, Japanese KAIRYU suicide submarine, and the 1/35 Bronco, German Type-23 coastal submarine. Both have a substantial 'opening' in the leading edge of their rather large sails from which a camera lens can peek out.
You can see my KAIRYU running submerged while towing a video camera here:
I've built two of these models, this one, for me, was initially set up with a Swann type camera-transmitter set into a short watertight enclosure small enough to fit within the sail, its lens looking out the observers deadlight that was a feature of some of these little submarines developed to ward off amphibious invasions of the Home Islands. Two winks of God's eye negated any need for their use... thank you very much, Mr. Atom.
At this early stage of integration, I was planning on utilizing a long coaxial cable, attached to a float, permitting unrestricted maneuvering in depth. But, quickly abandoned this rather ugly approach to the simpler and more scale like, antenna-within-a-periscope approach.
A floating antenna is too juicy a target for racing hydro's and other fast boats. No thank you.
And here is the eventual arrangement: the antenna residing within the RF transparent hollow resin periscope head. It worked, but I quickly grew tired of squinting at the fuzzy picture presented me by the limitations of standard quality video which was only available during those early years of FPV.
I made a similar packaging of the Swann system for one of my 1/35 Bronco Type-23's, but never got it past the testing stage due to the poor performance of the same type camera-transmitter and ground-station used with the KAIRYU. Note how on this class of boat the camera lens looks out through the temporarily removed line-locker stowage canister door. Perfect!
The video worked, but never used operationally on this model. Arrangement was very much like that aboard the KAIRYU: coaxial cable leading up within the periscope tube, terminating in the antenna within a hollow resin periscope head.
It took over a decade later, but when the high-definition, even smaller camera-transmitter units became available did my interest in FPV operation of submerged r/c submarines flicker on again.
Now we're cooking!
I just received proper VR Goggles, with all the trimmings. And a companion camera-transmitter. They have been tested and worked right out of the box. I opted for the cheap goggles, so video quality is below HD, but much improved over the Swann type cameras I played with in the past.
When I get this set operational and tested in some clear pool water I'll decide if it's worth it to purchase a top-of-the-line VR goggles, like the $500.00 Fat Shark ground-station that is so the rage among the r/c fliers these days.
We'll see.
This basic, cheap, ground-station is fine for a guy just getting out of the stone-age, like me. Only cost about $70.00, but still is better than the old 'standard' quality video I got from the old Swann systems. And this ground-station is an all-in-one package. No more Batman utility belt required! The camera-transmitter could not be simpler: plug in a coaxial cable between the transmitter and antenna, run power to it from a 5-volt source, and you're good to go!
Nothing to getting both the camera-transmitter unit and power supply into a watertight enclosure and secured within the sail of the KAIRYOU and Type-23.
In the mid-90's I conducted my first practical experiments in receiving, from a submerged model submarine, intelligent RF energy converted to audio by a simple ground-station: an AM radio receiver. WA-La! Passive sonar.
I purchased a low-power AM audio transmitter kit, put it together, crammed it into the forward dry space of our just introduced WTC-3. Turning the thing on, driving the boat out a few feet at Lake Trashmore, then sitting the model submarine down in the muck. I tuned the AM radio head-set (my ground-station) to the transmitted signal and presto! I could hear what the submerged hydrophone was picking up. Boy... was it noisy down there, the Elite fleet had several boats in the water at the time and I could hear everyone except the sailboats (unless a sail-winch was in use).
Amazing! I could hear the over-head model boats running over or near my boats position. In time I could, just by sound, classify each type of model boat. Passive sonar, but without the ability to point at a source to get a bearing. Useless, but fun.
The entire 'sonar package', including its power supply, neatly fit into the cavity of the removable WTC forward bulkhead. The microphone was protected by a silicon oil filled condom and placed in the upper annual space between hull and the WTC's cylinder. Instant hydrophone.
Problem was, once my boat was off the bottom and underway and motoring about, the propulsion, servo, and other noises drowned out all outside sources. Yup! SKIPJACK's are loud boats. I have proof! My ears range for minutes.
I bring all this up because the new FPV equipment supports stereo sound as well as video. Now, with a little phase converter and a steerable hydrophone, I'll be able to get bearing info on a source.
To get a 'modern' FPV video camera-transmitter into a model submarine and in the water in time for the 2022 submarine regatta season necessitated some quick work. So, I set about completing a long-delayed assembly of my 1/35 Bronco, German Type-23 coastal submarine. Over ten years ago I assembled one and got it operational for our former employer, Mr. Caswell. So, I was well prepared to get this one in operational condition with few hiccups.
As I mentioned in the previous post, this particular model submarine is a good candidate for housing the camera system, as its large sail will fit the camera-transmitters watertight enclosure without spoiling the scale fidelity of the model.
First job was to split the upper portion of hull away from the lower, permitting installation of a watertight cylinder (WTC) and all the goodies required to wag control surfaces and make the spinning thing at the stern to go around-and-around.
Here are the tools used to mark and cut the hull sections away from one another: A hand razor-saw for the radial cuts. A waterline marking tool. And a Dremel circular saw to make the longitudinal cuts.
To enhance sales of the kit (Ellie and I were then working for the Caswell Company) we were encouraged to produce a product that would aid the average kit-assembler as he worked to convert the Bronco kit from a simple display piece into a practical well running r/c submarine. So, we produced a 'fittings kit'.
I think the hope was that the fittings kit itself would serve as a loss-leader; enticing customers to buy the real cash-cow of the conversion package, a WTC specifically configured for the 1/35 Type-23 kit.
Unfortunately, the labor-intensive fittings kit -- featuring machined cast resin and metal parts -- sold for more than people wanted to pay. Many observing that our product was more expensive than the plastic model kit itself (they were right). And with that failure all our hopes of brisk hull kit, fittings kit, and WTC sales went down the drain.
Availability of the fitting kits were received with as much enthusiasm as if we were trying to sell a shoe-box full of steaming dog shit with tufts of cat hair in it.
Lesson learned.
Anyway. I had a few fittings kits kicking around taking up space. One of these will speed assembly along as I work to turn this kit into a practical r/c submarine outfitted with a FPV camera-transmitter system.
Securing the hull down tight on a flat working board with taught waxed sail-twine.
That strong, slightly elastic, easy to tie twine was liberated from the TRUTTA during my navy days. Back then Torpedomen were the submarine forces answer to the Boatswain's Mate rate, and most of us became the boat practitioners of marlin-spike seamanship and line-handling. Decorative knot-tying a specialty.
Those skills shamelessly exploited by several commands as I caught 'extra duty' and found myself restricted to the ship till I overcame my evil ways. (Never caught brig-time, but boy did I come close sometimes). Those off-hour punishment hours spent producing bunting, bell clapper dog-dicks, macrame adorned door-grabs, monkey-fists, and rope splicing -- that's how I served most of my penance. Not to worry, I stopped being an all-out asshole once Ellie got hold of me. So, the story has a happy ending.
With the aid of a pen loaded waterline marking tool (analogous to the Machinist's surface gauge) I inked the longitudinal cut lines, port and starboard.
Sliding along the surface of a vertical reference plane, perpendicular to the boat's longitudinal axis, I again used the waterline marking tool, but this time to denote the radial separation lines at the bow and stern. The longitudinal cuts would be accomplished with the Dremel circular saw, the radial cuts done with a hand razor-saw.
Precision layout is EVERYTHING if you want things to be symmetrical and fit properly. Measure twice, cut once!
The circular saw, just like the waterline marking tool, is slide along the smooth surface of the mounting board -- the mounting boards surface is the model's longitudinal reference (datum) plane.
Note the use of a .015-inch-thick piece of strip to check for complete cut-through as I progress the circular saw along the length of the hull. The cutting goes slowly and with light pressure applied. At no time do I permit the plastic to melt. Slow and easy it the word-of-the-day during this operation. I was sure to make this a no-caffeine day!
Polystyrene plastic reacts poorly to high-speed tools as it will melt if the feed-rate is too high and/or depth of cut is too great.
So... duh!... the trick is to minimize tool speed, advance rate, and pressure applied. I found that five slow passes with slight pressure made for clean, wander-free travel of the circular saw along its assigned path. You try to get the cut in one pass and the model is sure to die a horrible death!
Patience!
Once I had made all the longitudinal cuts to the hulls starboard side, it was an easy matter of turning the work around and cutting the port side.
I was pleased to see that the Dremel circular saw produced a very narrow kerf, about .025-inch. I'll build that back up with some plastic strip stock tomorrow.
Carefully following the inked on radial lines, I cut the radial breaks at the bow and stern. Nominal wall thickness of the hull was around .050-inch so there was not much plastic to hack through. The work went quickly.
The remaining connective tabs (those portions of the longitudinal split that were hiding under the waxed sail-twine) were cut through with a razor-saw, completing the split between upper and lower hull halves.
This is as far as I got today. However, I'm ahead of the game as I already had in hand a decade old, assembled WTC for the model I just pulled down off the wall. So, in no time I'll be at a point where I can start integrating the camera-transmitter into the submarines sail.
The interlocking registration tabs -- a set in the upper hull, and a set in the lower hull -- hold the longitudinal edges in alignment and pull the halves together when the tabs of the upper hull engaged the inside of the lower hull; the slight 'pull-down' compression of the upper hull tabs to the over-hanging lower hull interior provides this closure force.
Last thing to install was the forward and after radial flanges. Here I'm CA'ing the forward radial flange, using the same .020-inch thick polystyrene sheet I employed for the kerf-strips that run the length of the longitudinal edges of the lower hull.
One can never have too many clamps!
All model parts were given a ruthless scrubbing with an automotive grade surface prep, rubbed in with a green abrasive pad. Prep-sol is one brand. It's a hydrocarbon solvent that is strong enough to cut away grease, oil, dirt, and the like, but not quite strong enough to melt you or your model. Good stuff, and the last thing you do before body or paint work.
The scratching of the models surface produces some 'tooth' that adds a mechanical element to the adhesive 'stick' of glues, fillers, putties, primer and paint.
There were slight miss-alignments at the radial edges, forward and aft. These low spots would be filled with Bondo automotive filler.
The kit was assembled from four hull sections, The radial union between the forward and after hull sections presented a slight distortion around the girth of the hull -- an unfortunate artifact of kit design. (Oh, well, that's why God gave us Bondo). The dip there had to be Bondo'ed as well. All areas to receive Bondo automotive filler were marked with pencil, the hash-marks you see here.
#200 grit sandpaper provided the additional tooth needed to insure solid adhesion between the polyester Bondo and polystyrene plastic of the model.
(how many of you idiots will fixate on the thumb, but not the presentation?)
To keep Bondo away from places that don't need it, I applied masking.
After troweling on the Bondo I immediately ran a blade along the slight gap between hull halves. Failure to do so would result in the Bondo permanently 'gluing' the two hull halves together. Something to be avoided.
(Stop looking at that thumb!).
Bondo applied, the masking was removed and I got to work with rasp and sandpaper to feather the filled areas to the contour of the surrounding surfaces.
Once the Bondo had cured hard ('green stage' actually, it takes at least 30 days to cure properly) I ground away at the excess material with a rasp file, followed by hard and soft sanding block. The sanding started with #200 grit and worked down to #400. Both the filing and sanding were done wet to prevent clogging of the tools.
Cured Bondo, by itself is porous and weak. To those areas that would be subject to stress, such as the longitudinal and radial edges, I applied thin formula CA over the Bondo'ed areas. The adhesive soaked into the surface of the Bondo and greatly strengthened the substrate. After lightly sanding the CA'ed surfaces, things were ready for some Nitro-Stan air-dry touch-up putty to fill all tool marks and slight pits and dings not addressed by the Bondo.
I find air-dry putty is best applied with a brush. If need be the putty can be cut with a little lacquer thinner to make it more brush-friendly.
Bondo for contouring and major fill jobs. Putty is for shallow scratches and the like. Don't confuse the two.
Deep imperfections get the Bondo. Shallow imperfections get the Nitro-Stan. If applied thin (it should never be applied to depths greater than .030-inch) the putty will dry in about an hour. Regard air-dry putty as that last step before primer. Bondo for the deep ugly stuff; putty for shallow tool-marks and the like.
Well, for some reason, the automotive de-greaser and abrasive pad was not enough to clean the surface of this model good enough to assure tight adhesion of some of the putty I applied. So, after an initial sanding of the putty work I resorted to that tried-and-true method of surface preparation: a slurry of abrasive scouring powder and water, scrubbed ruthlessly on all model surfaces that would receive adhesives, fillers, putties, primer, and paint.
THERE! Now, stick. Dammit!
... and rinsed off with plenty of fresh water, then toweled and left to dry.
The forward, starboard longitudinal edges of the upper and lower hull presented a significant gap. Too high for an air-dry putty. So, I elected to build up the lower hull edge with Bondo. First strip in that process it to place two pieces of masking tape, inside and out, with their upper edges even with the upper hull lower longitudinal edge.
Like so. Now, with the two pieces of masking tape forming a dam that would not only form the Bondo to the wall thickness of the hull but would also define the depth of the Bondo after it was troweled on and screeded off.
After troweling the Bondo into the masking tape dam I laid the blade down flat (with very slight pressure) atop the edges of the tape and screeded away the excess Bondo.
The work was left to cure to a state where I could remove the tape and proceed with fine-tuning of the built-up edge. As the bond between the Bondo and the previous edge of the lower hull is weak, I took exceptional care as I pulled down and aft on the masking tape as it was removed -- the objective was to avoid any force on the Bondo that would pull it away from the model.
Before anything else I strengthened the bond between the just applied Bondo and the previous edge of the lower hull by soaking in some thin formula CA. The process was the same as with the previous Bondo work: slather the CA over the work, then quickly wipe away the excess. Enough CA works into the porous Bondo to strengthen it as well as bonding the Bondo to the previous edge with assurance that it won't break off later.
The edge of the Bondo repair was trued up with file and a stiff length of #220 sandpaper. The hull was then assembled, and the worked areas given a few passes with #00 steel-wool. The model was blown down with low pressure air to dislodge any shards and sanding dust.
Time for primer... at last!
OK. The radial and longitudinal edges between the two hull halves are nice and tight. But all that cutting, grinding, filing and sanding removed some of the nice high-profile 'weld beading'. I want to restore that detail. So that's the next operation: re-building the beading and other high-relief items lost as I worked to separate and make tight the two hull halves.
An idea that might make you some money on internet hits:
Put a simple, ugly sub with a go-pro atop its sail in the path of a waterspout and film it as it passes overhead. Maybe shoot an Estes rocket up into it…with its own camera.
An idea that might make you some money on internet hits:
Put a simple, ugly sub with a go-pro atop its sail in the path of a waterspout and film it as it passes overhead. Maybe shoot an Estes rocket up into it…with its own camera.
Great Idea! I like your style. Hey, here's another idea:
I stick a broom handle up my ass, so that at the end of a work session I automatically sweep the shop on my way to the door. Whadything? Youtube would love that!
In the areas where the hull was split some of the raised detail, the weld beads -- an element of the hull detailing on this fine kit -- were lost as I worked those areas with file and sandpaper. Time had come to re-build the weld beads, using old reliable Nitro-Stan touch-up putty.
Here you can see the nearly completed weld bead work (those red areas) on the hulls starboard side.
Note at the junctures along the longitudinal seam between hull halves, where the radial weld beads just fade away. The result of the evening-up work done to get the edges to match in gap and contour.
First step was to lay down masking tape dams. Incidentally, each strip of masking was actually four pieces of masking tape thick.
Putty was forced into the gap between the two pieces of masking.
And the excess putty screeded off with a putty-knife.
The first application of putty was given twelve-hours to harden, and in so doing shrank a bit as the volatile solvents were given up through evaporation during the drying process. A second coat of putty was applied and left to harden for twenty-four hours.
The masking tape dams were removed. Where I got sloppy with the putty a knife was used to scrap away the smears.
Where putty squirted under the masks a chisel-blade was used to cut and scrape away the putty, tightening up the work.
Feathering in the putty to the original weld beads height and width with bits of sandpaper.
A few strokes of steel-wool to soften the edges of the putty weld beads to better blend in with the original weld beads.
And, finally, a heavy coating of primer to even out the repair work.
As this 1/35 Type-23 r/c submarine will be little more than a mule to move the FPV (first person view) wireless video camera around underwater, I though it wise to give a little effort to the design and construction of the 1.25-inch diameter watertight enclosure needed to house the camera-transmitter, 1S Lithium-polymer battery, and magnetically actuated power switch.
As with most gizmo's that originate here, the object began to take form while I was on the toilet. Thinking. In my head. In the head. Ah, sweet symmetry!
From there, usually at my computer workstation (when not issuing blistering rants on the few forums I've yet to be banned from), I pause occasionally from keyboard pounding to scribble on whatever scraps of paper are at hand the raw idea; then refine the work onto post-it-note or graph-paper, at which point the drawing is to scale with critical dimensions called out.
Simple structures like this enclosure warrant only a single orthographic side-view. More complicated structures get the three-view and isometric treatment.
Such was the evolution of the FPV camera enclosure. Working drawing in hand and a quick trip to the shed garnered a proper length of Lexan tube and a removable bulkhead for the enclosures after end. Now all I have to do is work up the forward removable bulkhead that will house the camera and its lens. That will start life as a RenShape turned master, from which a rubber tool will be struck, and cast resin part(s) produced.
But, first, I got to get this damned r/c model submarine done.
Near the stern of the submarine, each side, are two rows of what I'll call (in the absence of any authoritative explanation) 'zincs'. Near the sawing, grinding, filing and sanding I did to separate the upper and lower hull halves some of these zincs were obliterated. Time had come to scratch-build and install the missing zincs.
Here you see the endgame: I'm finishing off the installation of the after set of zincs on the upper row, port side (the model is upside down).
Each of the replacement zincs were a length of stretched-sprue CA'ed in place after laying out their position and spacing with a pencil.
The kit provided the sprue, which I heated and stretched while semi-molten. An acquired art. The amount of heat, over such and such an area, with just so much tension applied, and that tension throttled till the desired diameter is achieved and halted till the plastic once again assumes a solid state. Much good fun. If you don't burn yourself... you're simply not trying hard enough!
CA was applied with tools, not directly from the tube. Here I'm using a spatula type application tool to drive the adhesive along the length of a zinc, bonding it securely to the hull.
A fault with the kit design was Bronco's attempt to capture the oval shaped upper limber holes (the function of limber holes is to vent and flood the spaces between inner and outer hull) at a high draft-angle of the injection forming tools hull cavity. To prevent entrapment, they made the wall thickness so thin at the extreme draft-angle point (near the top of the hull) that a complete fill during the injection of the molten polystyrene was not achieved and the resulting openings were miss-formed. That had to be fixed!
I skinned over these holes with a CA-baking soda grout, then ground out properly shaped limber holes. This started with blanking off the hole from the inside with some masking tape.
CA was squirted over the masking tape and run up to wet the edges of the hole. Then baking soda was sprinkled on. The high pH of the baking soda catalyzed the CA almost immediately. This build-up continued till the hard grout was well over the contour of the bow.
Before going to town with rasp and second-cut file I outlined around the grout with a pencil. The pencil hashing would tell me to stop with the file work. To the right is a contoured grout filled hole that has already been marked, with the aid of a stencil, to indicate the desired shape of the 'new' limber hole.
To the right is how I make the rough-cut to the limber hole -- using a 1/16-inch drill bit as a hand-held mill. To the left you see a finished limber hole, given final form with careful use of flat and round diamond files. Nothing to it!
Invariably there will be pits and scratches around the work, so I rub in some touch-up putty. I permit the putty to get onto the inside edges of the limber holes. That still pliable putty is then pushed into the edges with a rod of a diameter slightly smaller than the width of the limber hole. The rod is swished around a bit and pulled out. Once the putty dries, the surface is wet-sanded and primed.
We go back in time to the initial 1.25-inch diameter Swann standard quality video camera-transmitter watertight enclosures. The upper one, with the long foil-shaped antenna fairing is the type strapped to the hull of a model submarine. A shot of how that is used posted in an earlier segment.
The lower enclosure is the type designed to be housed within the sail of a model submarine. The tools used to cast the polyurethane parts seen here are still available to me and present options applicable to the current work, such as the 1.25-inch diameter watertight enclosures housing the 'modern', High-Definition (HD) quality equipment now in development.
This new enclosure varies only in that the forward removable bulkhead -- which mounts the camera and lens -- had to be contoured sharply to get the lens to fall along the plane of the 1/35 Type-23's deck-gear access door, which projects slightly ahead of the sails leading edge.
I've nearly completed the masters of the Type-23 enclosure forward bulkhead as well as a new, more robust, antenna fairlead.
That fairlead, mounted atop the enclosures cylinder, routs the transmitters coaxial cable through a watertight gland and up into the hollow periscope cylinder where it terminates at the top as an antenna within a hollow, plastic (and RF transparent) periscope head. The 5.8gHz signal will not punch through water, hence the need to mount the antenna where it sticks up into the air as the model travels about at, 'periscope depth'.
With the FPV system installed aboard the Type-23 the only variance from scale will be the missing deck gear access door and the lens of the systems enclosure peeking out from where the deck-gear access door used to be.
The old enclosure was too blunt at the front to get the lens far enough forward in the sail. However, the new forward bulkhead -- seen here as an in-the-ruff master with its much sharper tapper -- will.
The forward bulkhead was manufactured by turning a dense piece of RenShape on the lathe. Here I'm cutting the blank out from a scrape piece of RenShape board. RenShape is the ideal medium for almost all the masters I produce these days. Expensive, but worth every penny!
First cut was to establish the outside maximum diameter of the bulkhead, equal to the 1.25-inch diameter of the enclosures Lexan cylinder.
Here I've already cut the inside and outside tappers, as well as the recessed radial flange that slips within the forward end of the cylinder. I have yet to cut the O-ring groove that will make the watertight seal between the eventual cast resin forward bulkhead part and cylinder.
I found that the two pancaked printed circuit boards (PCB) that attached to the lens and sensor, being of square profile, became a big-time interference fit only half-way into the forward bulkhead.
So, I moved the work over to the milling machine which had my rotary table bolted to its bed, centered the work on the rotary table and proceeded to cut four equally spaced grooves within the bulkhead. These grooves permitting complete, uninterrupted passage of the camera-transmitter all the way forward. The objective was to get the cameras lens even with the forward end of the bulkhead master.
The front end of the bulkhead needed a little putty and sanding work (damned thing kicked out of the chuck during an earlier turning set-up and got a few scares as a result). I've temporarily installed the camera-transmitter to affirm that the camera lens sits even with the forward end of the bulkhead.
After fixing the damage the master was coated with CA, sanded, puttied where required, spot-sanded, primed and readied for use as a master to give form to a RTV rubber production tool.
Looking into the seated camera-transmitter within the forward bulkhead. Note the milled out longitudinal channels that gave clearance to the PCB's corners.
The completed forward bulkhead and antenna fairlead masters and some of the layout tools used to transfer two-dimensional graphics to the three-dimensional work. Layout is everything! Measure twice and you'll only have to cut once. The ideal I all too often fail to attain.
They used to teach this stuff in shop-class.
What? What's that you say!... they don't teach shop in school anymore?!!! No wonder so many under-forty types today can't even figure out how to stick two pieces of wood together!
To be fair, the government education system of today has taught our kids all about 'fairness'; how many sexes there are (we're up to 15 as of his writing); that all white people are stinkers; and what used to be shop-class is now, how to write code.
I'm side-stepping away from the Type-23 model submarine kit assembly to address the work taken to produce and outfit the FPV on-board camera enclosure.
Here's the completed unit. To the right is the camera lens even with the forward end of the forward bulkhead that contains the entire camera-transmitter unit. Atop the cylinder is the coaxial cable fairlead that also serves as the watertight gland between the coax and the enclosures interior. To the extreme left is the after-access bulkhead with an equalization valve set into its center (used to dump the slight over-pressure that occurs whenever one of the bulkheads is pushed into the cylinder.
The fairlead and forward and after bulkheads are cast from polyurethane resin using rubber tools to give these items their shape.
Tool making starts by securing the masters within containments that hold the liquid rubber till it changes state to a solid. For the forward bulkhead that containment is nothing more than a short length of 2-inch diameter Lexan. This is a one-pour tool, which will be sliced into a two-part tool later, after the rubber hardens and is slid out of its cylindrical containment.
The coax fairlead is a two-pour tool which requires masking half of that master in clay, then pouring the first half of the tool. Its containment will be a wrap of masking tape around the moldboard itself. Note the dimpling of the clay to produces keys that will ensure proper registrations when the eventual two halves of this tool are assembled for use.
Once the tool making rubber had been catalyzed -- a process which also folds into the mix a lot of air-bubbles that if left in the mix would spoil the tool. So, before pouring the rubber, it is subjected to a hard vacuum which enlarges the entrapped air-bubbles, which become super-buoyant, rise to the surface, burst and are sucked out through the pump. Effectively de-airing the mix.
After a few minutes of vacuum the rubber is taken out of the machine and dumped into the containments.
The antenna fairlead tool incorporates a 1/8-inch diameter brass rod that serves as a core which will render a bore through the eventual cast resin part. Additionally, that core suspends two O-rings that will provide the watertight seal between coaxial cable and fairlead body.
Before assembling a tool, it is first coated with a silicon oil spray and then given a dusting of talc. The oil serves as a part-release agent. The talc helps wick the introduced resin into all portions of the tools cavity, helping to insure a complete fill.
The 3/8-inch diameter brass rod core of the forward bulkhead tool produces the bore that will pass the camera-transmitters lens.
Alumilite RC-3 'tan' polyurethane resin is mixed and poured into the tools sprue holes. This resin, at room temperature, has a pot-life of about 90-seconds. Time enough to mix, pour, and get the work into a pressure pot and under pressure. De-mold time is as short as 15-minutes! Good production stuff. I swear by it.
A common spray-gun pressure pot is used as the vessel to contain and put under pressure the resin filled tools. It's while under pressure that the resin stays till it changes state from liquid to solid. About two-atmospheres is maintained. The pressure forces any bubbles in the mix to crush back into solution, resulting in void-free castings.
Removing cast resin parts from their respective tools. Note the vent and sprue channel extensions atop this forward bulkhead cast resin part -- artifacts of the casting process and are snipped off and the nubs block sanded smooth. Removal of its core leaves the bore for the camera lens.
Removal of the antenna fairlead core leave a bore to pass the coaxial cable. However, removal of the core leaves the two O-rings, mostly encapsulated within the resin piece, to affect the seal between coax and the fairlead body.
The main elements of the 1.25-inch diameter camera-transmitter enclosure. All that is needed to power this bad-boy up is to connect the battery to the camera and you're on the air!
So far, I've got two fully functional watertight FPV systems up and running. I've got finished parts for another three. Here's all it takes: The antenna modified 5.8gHz camera-transmitter unit (about $17 on Amazon!), a little 1S Lithium-polymer batter, and the enclosure itself.
As the camera-transmitter was designed and and sold for use by the r/c plane and drone fliers, the orientation of the antenna is vertical, this to ensure maximum RF transmission to the vertically oriented ground-station receiver antenna. But this arrangement won't fit the watertight enclosure; additionally, there remains the need to move that antenna about a foot or more away from the unit, up through the sail, and up into one of the masts that will place the vertically oriented antenna above the waters surface.
The stock camera-transmitter antenna is removed, and a horizontally oriented length of RG-178 coaxial cable soldered to the appropriate pads on the after face of the transmitters PCB. To the left a stock unit. To the right, a modified unit. A simple solder job.
Now, with a length of coax replacing the stock antenna, that little sucker will fit!
Though this specific demonstration is to a 2.4gHz receiver antenna, it does illustrate how the factory antenna is replaced by a length of coax. The objective is to solder the coaxial cables central conductor to the PCB's 'antenna pad', and to solder the RF shield to the PCB's 'shield pad'.
The other end of the coax becomes the systems transmitting antenna simply by removing a portion of the shield; making the central conductor (now the antenna) watertight; and hiding it with a hollow scope-head or other retractable mast situated well atop the sail. The objective is to keep the antenna in the air as the model cruises along at periscope depth.
No way the camera-transmitter standard antenna orientation would fit into the forward bulkhead of the watertight enclosure. Hence, the need to not only change the run from vertical to horizontal, but to also run the coaxial cable up to the top of a raised mast and terminate it into a vertically oriented antenna there.
The clear window through which the camera lens peeps is a 1/16-inch-thick piece of Lexan sheet that had been cut to a rough disc, CA'ed to the forward end of the forward bulkhead, then turned on the lath to make the windows edge conformal with the bulkheads body.
The FPV system enclosure features a removable cast resin forward bulkhead used to gain access for turning the system on and off (by simply plugging in or unplugging the battery to the camera-transmitter), or servicing such as battery swap or transmitter band-frequency re-assignment. An equalization valve within the bulkhead is used to vent off the slight over-pressure whenever the forward or after bulkhead is pushed into the enclosures cylinder. This reduces the possibility of the heated air from within (a result of transmitter waste heat) expanding to the point of blowing one of the bulkheads away from the cylinder with catastrophic consequences.
The equalization valve is simply a modification of a standard Schrader type tire-valve you can purchase at any car-supply store. The valve core is removed, most of the stem is chopped off, what remains of the units shank is turned down to the diameter of the bulkheads hole, I go for a 3/16-inch diameter fit. Gluing the modified Schrader valve into the bulkhead, re-install the core valve and I'm done.
The steps needed to create the antenna element at the end of the coaxial cable is illustrated in this picture from top to bottom. The objective is to create a 5.8gHz antenna by removing a specific length of the coaxial cables shield, and then making the exposed conductor (which become the RF radiating element of the system) watertight.
Note: this photo illustrates the antenna length of a 2.4gHz system. The correct antenna length of the 5.8gHz system is exactly .508-inches.
As this 1/35 Type-23 submarine plastic model kit was engineered by Bronco to be a display piece only, modifications -- in the form of internal structures to stiffen the hull and sail, as well as serving as foundations for the propulsion-control-variable ballast WTC and FPV camera-transmitter enclosure -- had to be performed to convert the model to a practical r/c submarine.
A while back I developed a 'fittings kit' for just this model kit. Most of the parts were cast polyurethane resin, and the rest cast white-metal. Before using any of the resin parts I first had to de-grease them with a dunking in lacquer thinner while scrubbing with an abrasive pad and stiff brush.
The WTC foundations were secured within the hull with both 2-56 machine screws and copious amounts of CA adhesive. First, each foundation segment was marked where a fastener hole would be bored, then I held the segment into a spot in the hull where it would go and marked the inside of the hull. That mark indicating where a hole would be drilled to pass the securing screw.
Note that the central foundation has a Velcro strap and an 'indexing pin'. The strap would hold the WTC in place, and the pin would insure that the cylinder was fixed against axial or rotation once mounted into the hull.
It was too awkward to drive a drill bit from within this hull. So, with the aid of a powerful flashlight, I identified the drill identification mark made on the inside and copied that marks location on the outside. Now I could drill the fastener holes from the outside with reasonable precision.
All hull foundation pieces were screwed tightly into place, and thin formula CA applied to secure the foundation pieces to the hull.
Two resin foundation pieces were secured within the sail. These not only provided an aligned platform for the FPV enclosure, they also greatly strengthened the entire sail assembly. Note how Velcro straps are used to secure the enclosure in place.
The rest of the kit parts were cleaned up and assembled. I modified the original two sets of horizontal control surface guards by equipping each with a strip of GRP sheet to act as an internal spar. The tabs of these items -- projecting from the end that mates with the hull -- would pass through square holes in the hull and affixed within to doubler-blocks on the inside, rendering these very vulnerable appendages with the strength needed to resist most collision and handling accidents without breaking.
Meanwhile I continued the touch-up putty work, brushing it on to areas that still evidenced scratches, shallow gaps, and tool-marks.
I pulled this photo of the first Type-23 kit I assembled to show you one of the bow 'guards' in place on the hull. There is another set of guards projecting from the hull at the stern. The guards primary function is to serve as physical barriers to protect the vulnerable bow and stern plans from damage from tugs deadheads, pier pilings, and collisions with other craft at sea.
It was common German marine Architect practice to use non retractable bow planes on almost all submarine types during the two Great wars. However, it was the Type-23's big brother, the Type-21, that ushered in the use of retractable bow planes in the closing months of the second World War.
And just as I did with the larger guards that fit at the bow, I equipped the smaller guards that attach at the stern with GRP strengthening spars to better brace them against breakage as a result of handling accident or collision.
The two small guards were, unlike their two-piece larger brothers, cast as solid units and had to be milled out to accept the GRP strengthening spars.
The tapered and semi-trapezoidal shape of the stern guards presented a problem: how to hold them securely in the jaws of the mills vice without damaging them? The solution came in the form of two little blocks of lightweight RenShape modeling medium. Hard enough to hold the work, but soft enough to conform to the geometry of the parts when subjected to the compressive force of the jaws. A compliant holding fixture, the perfect solution.
I'm slitting my forty-year old slab of sheet GRP to come up with the spars that will be glued into the small guards -- a Carbide or diamond cut-off wheel is ideal for this kind of nasty work as the glass content would quickly dull even my so-called 'metal cutting' band saw blade. Never cut GRP with a hobby razor-saw, knife, or file as you will quickly blunt the teeth... you, after all, are attempting to cut into solid, silica GLASS!
A 1/16-inch end-mill was used to dig out the square bore needed to accept the spar. Care had to be taken to dial down the tool speed and to feed the work with gentile, stabbing force. Otherwise, the heat generated would melt the polystyrene plastic and bugger up the job... which, on one of the guards, I did ANYWAY. What a Dumb-ass!!
Just like on the real boats, the upper skeg of the Type-23 contained the control horn that swing the big rudder that resides aft of the propeller. And in the exact same spot as the real boat, I cut away and made removable the access cover.
After all the painting and weathering is completed the access cover will be secured in place with a small amount of RTV adhesive, affording me the ability to easily remove it should work ever have to be done on the rudder and/or its linkage.
Removing the access cover from the upper skeg was easy: First, a razor-saw was used to make the radial cuts, followed by a very slow plunging of a diamond wheel to make the longitudinal cuts. All I had to do was follow the engraved lines built into the models surface. Easy-Peasy!
Before addressing the running gear (stern tube foundation, propeller shaft and propeller, couplers, and intermediate drive-shaft) I worked out the linkages between the WTC and three control surfaces: bow planes, stern planes, and rudder.
Note that the connecting interface are magnetic couplers. Easy to make/break -- no tools required -- and absolutely no back-lash.
The stern plane pushrod, connecting to the WTC's starboard coupler, because of its long Z-bend, would have flexed to an unacceptable degree without the soldered truss piece, which worked to render the pushrod more rigid.
The rudder pushrod that mated with the WTC's center coupler was almost a straight run to the rudder horn.
The bow plane pushrod was made rigid by using a long length of aluminum tube (running through channels cut into the two WTC foundation saddles) with a 'L' shaped brass tube at the stern to place its magnetic coupler in alignment with the WTC's port magnetic coupler.
You can just make out the bow plane pushrod aluminum tube where it transitions to a length of 1/16-inch brass rod that makes the connection to the bow plane operating shaft control horn. The two wheel-collars prevent lateral motion of the operating shaft.
I substantially increased the surface area where a guard butted up against the side of the hull by digging in shallow grooves in both hull and root of the guard itself. Even so, relying on this CA bonded attachment point alone is not enough as the bond is still terribly weak against a shearing force. Hence the need of the installed strengthening GRP spar within the guard that projects well into the hull.
A guard was tack CA'ed in place with a few dabs of thick CA -- the slower cure time of this glue provided a few moments in which to align the part. Once the tack had set the joint was saturated with thin formula CA -- capillary action drawing the glue into the voids between the two items being bonded.
To prevent getting glue where you don't want it it's good practice to apply the adhesive, one drop at a time, with the aid of an application tool. Typically, a length of 1/16-inch diameter brass rod with a spatula head.
The guards GRP lengthening spar projects into the hull and is sheathed in a two-piece block of dense RenShape. This firmly anchors the guard against shear loads that would be encountered as a result of rough handling or collisions. Once the block foundation is tacked in place the entire assembly is slathered with thin formula CA.
And that's how these otherwise useless appendages transitioned from fragile elements of a nice-looking display model into practical, tough, guards to ward off impact without damage to themselves or the control surfaces they are intended to protect.
I don't trust polystyrene. It's not the ideal medium from which a model -- subject to the typical rough handling and occasional collision of an r/c submarine encounters -- is made. Most plastic model kits are engineered for looks, not strength.
So, all major seams were backed up with fiberglass cloth saturated with laminating epoxy. All hull longitudinal and radial joints received this treatment.
Heat-lamps were used to speed up the cure of the epoxy.
The running gear is a propeller; propeller shaft; cast resin stern tube foundation containing two flanged Oilite bearings; propeller shaft coupler; intermediate driveshaft; and the motor output coupler at the after end of the WTC. The after bearing takes the ahead load, and the forward bearing takes the astern load. These loads transferred to the hull via the cast resin stern tube foundation.
Years ago, I developed a resin and metal 'fittings kit' to make conversion of the Bronco 1/35 Type-23 kit for use as an r/c model submarine a simple matter. Not currently available these kits are planned to be put back into production soon. Here we see two of those items: the running gear, and the rudder. The stern tube, propeller shaft, coupler, and propeller were provided, 'ready to install'.
A quick look at the tooling and white-metal parts produced for the fittings kit.
Any brass alloy or white-metal part that is to be glued, primed and/or painted has to first be 'pickled' in acid to etch the surface, which greatly increase the ability of an adhesive to bond than would be the case if adhesion was attempted onto the virgin metal, no matter how well you de-greased and cleaned it.
After filing and sanding away any flash the part is dunked in Ferric chloride acid and agitated with an acid-brush till the entire surface is oxidized black (white metal) or a darkened brass color (copper, or alloys of copper). The work is then scrubbed clean in fresh water, that water spiked with some baking soda to kill any acid remaining on the work. The part is then dried off and set aside for priming or adhesion to another item.
The white-metal propeller to the left has been pickled, rinsed, dried and ready for adhesion of another part or coating. It appears to be smooth, but in actuality has zillions of microscopic pits that do wonders to enhance the 'stick' of an adhesive. The propeller to the right has only had the dunce-cap turned to shape -- other than that it is fresh out of the mold that gave it form.
Pickled good. Virgin bad.
I'm getting to the point where I'll be trimming the boat in water soon. Outfitting the models hull for in-water use starts with about three-pounds of fixed lead weight mounted within and at the bottom of the hull. The weight is needed to position the vehicles longitudinal center of gravity to the center of the boat and place that c.g. as low as possible. It's the low c.g. and high center of buoyancy that makes the submarine statically stable about the roll axis (and to a very small extent, statically stable about the pitch axis). The greater the vertical distance between c.g. and c.b. the greater the vehicles static stability will be.
Short coupling between c.g. and c.b. bad. Long coupling between c.g. and c.b. good.
I cast my own weights. Nothing to it: some dedicated cookware, select a day when the little lady is out shopping, start cooking metal, and break out the molds. And, most important of all: don't forget to clean up and hide all the evidence back into the shop before she gets back.
Though the Bronco kit represents the actual ballast tank flood-drain opening, they were just not enough in number or sized to conveniently flood-drain the practical model as it was put into and pulled out of the water. So, I marked off and opened up a series of ovoid holes at the bow and stern of the keel. Not scale, but necessary. Sometimes you have to be pragmatic and depart from scale when the situation demands it.
I've fielded enough questions asking how I've arranged my shop to warrant a slight departure from the current Type-23 model discussion and provide a little insight on one method used to make my hand-tools accessible.
And that is to simply hang most of the files, screwdrivers, knifes, hemostats, and small pliers off of magnets. This picture shows one of the four workstations in my former one-car garage, aka the sprawling industrial complex of D&E Miniatures, hidden deep within the earth and protected by fields of intensified Gama radiation and Krell steel.
Note the many tools hanging off the wall with the aid of magnets. Each easy to identify with a quick glance, and within easy reach.
The magnets themselves are cylindrical and are pushed into holes drilled into a wooden carriage screwed into the wall or edge of a worktable. The holes slightly smaller than the diameter of the cylindrical magnet (which, in the day, I bought by the hundreds). A piece of clear acrylic rod was turned into a magnet insertion tool by drilling a bore at one end twice the depth of a magnet.
A set screw permitted me to lock one of these magnets in place so that when a magnet, to be press-fit into the wooden carriage, is inserted (and held in place within the tool by the setscrew retained internal magnet) it projects a distance from the end of the tool that equates to the depth it will penetrate the carriage hole.
OK, back to the Type-23 Bronco kit...
The previously marked out ovoid flood-drain holes in the keel were opened up with drill and worked with round and flat jeweler's files.
The kit supplied plastic ladder rungs that permitted access to the bridge from deck level are fine for a well-protected static display, but wholly unsuited for the rough handling an r/c model submarine will be subjected to. So, I substituted .020-inch diameter brass rod.
I identified that point along the length of the tapered jaws of a needle-nose pliers whose width was that of a ladder rung. One of the jaws by wrapping with two pieces of masking tape to identify that specific width. Bending the rungs at that point in the tool insured consistency as I made the required number of ladder rings for this model.
Slight indentations on the leading edge of the sail were where the plastic ladder rungs would be glued. I drilled through these with a .023-inch drill bit. Later, after all painting had been done, the metal ladder rungs would be inserted and glued in place from the inside of the sail.
The top of the sail, after gluing it in place, required a bit of filing and sanding to get its edge even with the sides of the sail. Before doing that, I pencil marked both sides of the seam.
As I blasted away with file and sanding block one side of the work would have its pencil smear scrubbed away immediately. As I got the level of the seam almost equal on both sides, the other side of the pencil smear would start to abrade away -- that's when I shifted to the sanding block and became a bit more exacting on how I progressed from that point on.
All filing and sanding over the touch-up putty was done wet. Here are the tools and the work. Special care had to be taken not to obliterate the many raised weld lines. This is a wonderfully detailed kit. Bronco got this one right!
For those hard-to-get-at spots on the model (and there were many!) I used special abrasion tools, such as these little metal-backed sanding tools. Grits ranged from #240-#400. The sandpaper glued to various widths of .014-inch-thick brass strip.
Another useful abrasion tool is double-backed sanding squares. Just fold a piece of sandpaper, slather some CA between the two halves, close and compress, and in no time, you have a very stiff, double-sided sanding tool. Just cut the tool to size and shape with scissors.
All sanding completed I spot primed the model parts.
This is my primary workstation. Note all the hand-tools hanging off magnets.
The kit supplied plastic railing that girdle the sides of the sail are just too fragile to be serviceable on a practical r/c submarine. So, I substituted brass wire railings.
The two brass railing assemblies are formed of .020-inch diameter brass rod. The pins are about .375-inch long, pointed at the inboard end, and ground to a flat at the outboard end.
The RenShape pin-retainer, which temporarily resides within the sail -- and conforms to the curve there -- securely holds the embedded pins in place and also serves as a heat-sink to rapidly dissipate soldering heat away before the easily melted polystyrene plastic of the sail.
After the pin-retainer is installed within the sail (shown outside so you can see how it would be used) the bore clearing-pin setting tool is used to push a pin through one of the .023-inch holes that have been drilled through the side of the sail.
Pulling the bore clearing-pin setting tool away from the work leaves the pin well embedded into the pin-retainer bearing against the inside of the sail. Use of the tool results in an array of railing pins projecting from the side of the sail, all of the same height.
A long length of brass rod becomes the railing proper. Here I'm using thin strips of masking tape to secure the railing over its pins. Note the finished railing assembly laying near the top of the sail. With the aid of the internal pin retainer the sail itself becomes the holding fixture of the parts that, once soldered together, become a railing assembly.
The secret to keeping the heat localized to the joint is a hot soldering iron tip; a tip that is ground small to minimize heat transfer to non-joint structures; and use of the pin-retainer which also acts as a heat-sink.
The tip of the iron is applied to the joint with half-second jabs, just long enough to get good solder flow, as evidenced by these small, tight fillets between rail and pin.
Snipping off the excess railing at the forward-most pin. The raw end here would be worked with file and sanding stick after contouring with very light, carefully applied jabs of the carbide cut-off wheel.
While still in place on the sail the railing assembly has all the solder unions cleaned up by scraping away excessive fillet with a blade; sanding and filing away solder and crystallized flux; and finally abrading away all scratch-marks with a good polishing using #0000 steel-wool.
After all soldering and clean-up work had been done on the railing assembly the RenShape pin-retainer, within the sail, was pried away from the pins and removed.
The pin-retainer is used as a handling fixture if any further work on a railing is required off-sail. Note the three items needed to do the soldering: a 35-Watt soldering iron with custom ground tip; acid paste flux; and 60/40 solder. At the bottom of this shot is the bore clearing-pin setting tool.
With the basic structure of the sail assembled, the brass railing assemblies put away in safe storage, and the FPV camera-transmitter enclosure foundations installed, I test fitted the sail atop the assembled hull and... Dammit!
There was a bow in the sail that resulted in a significant gap between the after end of the sails diesel exhaust muffler fairing and the hull. I'm pointing to it.
Unacceptable!
The quick, easy fix was to slice through most of the fairing where it met the trailing edge of the sail proper, leaving just a bit of plastic at the bottom. I placed the razor-saw on the after-side of the fairings forward most radial weld line, using that as my guide as I sawed through most of the fairing.
With careful pressure I bent the fairing downward to get its ass-end to meet the top of the hull. This over-stressed the little bit of plastic still connecting sail proper from its fairing to maintain the downward slope required so that the after end of the sail-fairing butted down against the upper hull.
Of course this resulted in a radial gap were I had sawed away. But this was easily filled with baking soda saturated with CA which formed a hard filler.
Note the pink looking 'weld line' running horizontally near the top of the sail. This was formed from Bondo using the same technique I described earlier during restoration of lost weld lines at the longitudinal break between upper and lower hull halves.
The inside of the sails fairing also received the baking soda-CA treatment as well.
Before filing away excess grout from the surface of the fairing I pencil smeared both sides of the work. As I filed away and got down to the level of the plastic the smear would tell me when to stop with the big guns and switch to descending grits of sandpaper.
The objective was to preserve the radial weld line and knock the grout down to conform to the original contour of the fairing.
As the sail would contain the removable FPV camera-transmitter enclosure I needed the ability to pop the sail clear of the hull in order to access the system. To achieve that objective I elected to secure the sail to the hull with magnets alone.
Eventually the only interface with the sail and the rest of the model would be a flexible hose between the sail mounted snorkel induction valve and WTC's ballast sub-system. In this photo you can just make out the paired magnets within the sail and atop the upper portion of hull where the sail sits.
Magnets were also employed to insure a tight hold-down between upper and lower hull halves at the longitudinal break.
Basically -- as illustrated by this training-aid I built to show how magnets are employed to hold structures together -- a set of magnets are secured within cast resin foundations which in turn are CA'ed within the model parts. A pair of magnets are so arranged to exert their magnetic force to hold the parts together. The magnets are sized to withstand most operational and handling loads, but not so powerful as to prevent deliberate separation of model parts when required.
Years ago, I developed the tooling required to produce cast resin magnet foundations of geometries that would suit just about anything I would want to use the magnets on. In most cases the magnets -- typically of the disc or cylinder type -- are tight interference fits to the foundation that supports them; and those foundations provide the broad footprint that aids in adhering a unit to the inside of a model part.
Here I'm using a hand-press to set cylindrical magnets into their respective foundations.
Four magnet units are being glued within the base of the sail. As I wanted the bottom end of each magnet to touch the surface of the upper hull, I achieved that objective by pulling a neat trick: As each unit was placed inside the sail, another a raw magnet was placed the outside of the sail to hold the one inside in place. The internal magnet units were lower than they had to be so that when I gently placed the sail upon the upper hull all units would be pushed upward (dragging their outside counterparts upward along with them). This positioned each bottom face of a magnet to just touch the surface of the upper hull.
The sail was carefully removed from the upper hull and CA applied to permanently affix the units within the sail. You can make out the raw retaining magnets still clinging to the outside surfaces of the sail.
The sail was then firmly held to the upper hull with rubber-bands and the entire assembly inverted to give me access to the inside of the upper hull so I could work out the location of the hull mounted magnets that would interface with the sail mounted magnets.
As magnetic force is ruled by the inverse square law, it behooves you to get the joining magnets -- one inside the removable sail, and its counterpart set within the upper hull -- as close as possible when the sub-assemblies are joined if maximum attractive force is to be realized.
As the wall thickness of the hull (about .095-inch) represents a stand-off distance between a pair of magnets, just gluing a magnet within the hull would result in a terribly weak attractive force. So, to get the hull mounted magnets to physically touch their counterparts within the sail, holes had to be drilled into the upper hull to pass the hull mounted magnets.
But, first, the exact location of where to punch those holes had to be ascertained. That done by simply plopping some magnets down into the inverted upper hull, letting each find its own counterpart, in the sail, through the magic property of magnetism. Neat!
I traced the circles where each magnet sat onto the inside of the upper hull and later bored out over-sized holes through which the eventual upper hull magnets would pass so each would actually touch a counterpart up in the sail.
Suitably shaped resin foundations, bored with non-interference fit holes, were slipped over a seated upper hull magnet and foundation-to-hull and foundation to magnet unions made permanent with CA adhesive.
Though the upper-to-lower hull union was a mechanical one -- the upper hull capture-lip engaging the hulls forward radial flange, and the after end of the union secured with a machine screw -- in some areas along the long longitudinal split some spots presented unacceptably large gaps. These were addressed with magnets that worked to pull the two hull halves tightly together when assembled.
A ferrous item -- a flat file in this case -- with two foundation mounted magnets sticking to it was laid down onto the opposed edges of a hull half (in this case the upper hull). The foundations pulled outboard till they made contact with the inside of the hull and were then affixed with CA. This method insured that the face of each magnet fell across the same separation plane that divided the two hull halves.
I found that only four sets of magnets were required to pull the seam down tight when the hull haves were assembled.
There's a lot going on within the massive sail of this Type-23 submarine model: The FPV enclosure, with its lens peeking out from where the removable deck-gear access door fit; the snorkel induction valve, an important element of the WTC's ballast sub-system; and the magnetically latched foundation that permits raising and lowering of the models 'scale' snorkel induction and exhaust tubes.
All these things have to be easily accessed for adjustment and repair should the need arise during the operational lifetime of this model. That's why I made attachment of the sail to the hull a magnetic one -- to permit quick and easy access to the sails internals.
All the gizmos that fit within the sail: To the extreme left is the models non-functional scale snorkel mast, and just below it the foundation/platform that permits smooth travel for the mast from the 'retracted' to the 'raised' position (this foundation also provides a short length of tube that receives the base of the removable DF antenna.
To the left of the sails trailing edge is the practical SemiASspirated (SAS) float actuated snorkel valve, it's foundation mounted to a G10 sheet adapter platform that interfaces with the sails interior.
Atop the sail is a fully operational watertight FPV enclosure.
To the right of the sails leading edge are the internal strong-back and scale deck-gear access door. A magnet on the strong-back and another in the door permit attachment to the models sail when the FPV enclosure is not installed.
As you can see, inclusion of all these things within the sail takes a bit of planning and black magic to accomplish. As is my want in this game, I make as many sub-assemblies removable as possible. All but the scale snorkel foundation are either attached with mechanical fasteners (machine screws), Velcro strap, or through the use of magnets. The scale snorkel foundation is semi-removable as it is secured within the sail through tack-gluing -- bonds that can be easily broken without damage to foundation or interior of the sail.
Before any tool was lifted, or raw material cut to shape, I first did a paper-study of what would go where within sail. This done to work out, on paper, what would go where. This is the poor-man's way of working out system integration before committing to stupid moves that usually lead to paradoxical interference situations between part-A and part-B.
(In the days before CAD modeling big outfits like Gibbs & Cox would actually build big 'proof' models out of clear Plexiglas to assure their naval Architects that any system paradoxes that slipped by the Drafting department were identified and corrected in-house before any metal plate was cut at the shipyard).
The design process starts right here at this table where I'm banging out yet another installment to this never-ending, soul-crushing screed -- to my right will be a fresh, unmolested post-it-note awaiting scribbling as an idea leaks out of my head in the middle of my keyboard pounding, and demands I address a current shop problem in graphic form.
You see such a note, now in the shop, used as reference as I work out the internals arrangement -- in this case, the SAS snorkel assembly. The graphic tool here is a full-scale profile drawing of the Type-23's sail. That's how an idea evolves from mind to hardware.
The major job accomplished at this point is the scale snorkel foundation/platform, which features a magnetic latching scheme that permits me to position the mast to 'retracted', 'raised', or to even remove it.
And here's the scale snorkel riding within its foundation/platform. The magnets set within the exhaust line of the unit hold the mast in either the 'raised' or 'retracted' positions atop the sail. They 'latch' to the platform mounted mother-magnet.
Here, the raised scale snorkel is held in the 'raised' position by the magnet set into the lower end of the parts exhaust pipe, held there by its force and the mother-magnet affixed to the bottom of the scale snorkel foundation/platform piece.
I'll fill over the upper scale snorkel magnet. Once the part is painted no one will know that within it is one of the two latching magnets that positions the mast in either the raised or retracted position.
Nothing so fancy for the DF antenna, I either plug it in, or yank it out and toss the poor thing into the field-box.
The SAS ballast sub-system requires a means of actively shutting off the air induction line once the sail dunks under the water. This is accomplished with a simple float actuated snorkel induction assembly, temporarily plumbed into the sub-system to show how it integrates with this models WTC.
Incidentally, that induction hose is the only physical connection between the mechanisms within the sail and the rest of the model. Which is a good thing: In the very likely situation where the sail is knocked off the hull (road rage unleashed whenever another r/c boat wanders foolishly into my patrol area). It's this hose that will keep the decapitated sail dangling in close proximity to the hull as the model is recovered and the sail unceremoniously plopped back atop the hull (hopefully in time to exact some revenge).
Only three machine screws are used to secure this easily removed/installed device within the sail.
This is how the SAS ballast sub-system works. Ballast blow air is either taken from the surface through the snorkel induction assembly when broached or in proper surface trim. However, enough air is available within the WTC's dry spaces that when compressed by the LPB, to blow enough water out of the ballast tank to broach the sail, no matter the depth at which the blow commences (within reason, of course).
Pretty much how we normally started and completed the main ballast tank blow on the USS TRUTTA back in the day. What's good enough for the US Navy, is good enough for me!
At the top you see the installed snorkel foundation/platform screwed in place aboard the sail. Note the bottoms of the scale snorkel induction and exhaust pipes projecting through a cut-out at the forward end of the snorkel foundation/platform. Obviously, the scale snorkel is in the 'retracted' position in this shot.
You can clearly see the magnet equipped strong-back that works to hold the magnet equipped deck-gear access door in place whenever the FPV enclosure in not installed.
You can just make out the white snorkel float aft of the scale snorkel pipes.
Without the aid of my basic and refined paper-studies, this job could have turned into a Chinese fire-drill/screaming plumber's-nightmare/useless assemblage of sometimes-working-sometimes-not-working junk.
I go to the lake/swimming pool to play. Not fix things! Keep it simple. Make it right before it leaves the shop.
What's the point in assembling a complicated, practical, beautiful looking r/c model submarine only to have it damaged and defaced during transport and later storage as you shift your attention to other matters?
I answered that rhetorical question long ago by making it a practice to provide each of my r/c submarine models with its own, custom built, transportation-stowage box.
Illustrated below are just a few examples, their lids removed to show the contents. Note how soft foam-board frames are used to cradle the model, the hull centered in the box.
Not shown here, but each box lid has attached to its underside a like array of foam frames, each contoured to girdle the models upper works, just as the lower set of frames supports and girdles the models lower works.
No big deal. A transportation-stowage box is, after all, just a six-sided,1/4-inch-thick exterior grade plywood container, reinforced at the edges and corners within by 3/4-inch square wooden molding, and outfitted with 1/2-inch-thick insulation foam frames cut out and arranged to support the model within.
Ellie and I, over the years, have built and worked with small, medium, and stupid-large transportation-stowage boxes. Those boxes serving one major purpose: to protect the contents from damage, no matter how the box is bounced, shoved, inverted, and dropped.
My model boating buddy, Phil Kordich, built this box. It's fine for the most part, but there is no provision to stabilize the model within should some fool load the box upside-down, or the box should tip over for whatever reason.
No. I found the only sure-fire way of protecting the model is to cushion it from force applied in any direction; it is my practice to literally cocoon the model in protective foam framing and structural webbing.
The job, of course, starts with the wooden box. Big holes in the sides permit air to flow freely within. That's an important feature as often the model is put in there still wet from a run at the lake or pool.
As to the box dimensions here's my rule-of-thumb (these are inside measurements):
Length is model length + 2-inches front, and 2-inches at the back.
Width of the box is width of the models maximum appendage projection + 1.5-inches each side.
Height of the box is the height of the model from keel to top of sail (masts stowed retracted or removed) + 2-inches at the bottom +2-inches at the top.
In addition to the foam sheet frames I'll also provide foam sheet structural webbing, top and bottom, to lend further support of the model within the box and to also stabilize the frames.
The lower array of frames and webbing is glued to a 'floor' made of the same insulating foam as the frames and webbing. This floor sits within the bottom of the box and is removable. The upper array of frames and webbing is glued to the bottom side of the boxes removable lid. That lid is secured in place with deck-screws that run into the molding strips atop the box.
First item cut out from the sheet of insulation foam is the floor, which is marked for locations of lower foam frame pieces which will be epoxied to it once they are cut to contour with the bottom of the models hull. Same will be done for the upper half of each frame, but those items will be affixed to the bottom side of the boxes lid.
As the hull section geometry is constant through most of the submarines length, most of the frames will be cut out in an identical fashion. Only at the bow and stern will special frames be required because of the hull tapper at those points. I've already started in on a cardboard template that will be used to mark out the frame cut-outs -- having lofted off the sectional form of the submarine with the aid of calipers, compass and other drafting tools.
Using the paper template to mark out the cut-outs to the frame blanks. Each frame will be divided into an upper and lower half, the split occurring at the centerline of the submarine.
The floor is set into the box and the bottom halves of the first two sets of frames are positioned within and the model carefully lowered into the box. All this to validate that the model is properly centered within the box. That check completed I can, with confidence, finish cutting out the rest of the frame blanks.
The band saw, equipped with a very narrow blade, capable of tight radius ruff cuts, makes quick work of punching out the centers of the foam frames. At this point the frames have not been cut into halves.
An oscillating vertical drum sander refined the cut-outs. Once cleaned up each frame was cut into an upper and lower half.
With the aid of straight pins the lower half of the frames were epoxied to the floor piece.
The model was then plopped down onto the frames, and I began the laborious task of lofting the geometry of the bow and stern stations off the model. That dope needed to start work on producing accurate (Ha!... never happens the first time!) cardboard templates for the bow and stern frames.
Cardboard section templates for the upper and lower forward frame. Note the tight, perfect fit with almost God-like accuracy... achieved after only five previous, unsuccessful attempts! This method is more gosh-and-by-golly than science, I can assure you.
With all bottom half of the frames glued to the floor, the floor was inserted into the box and the upper half of the frames pined atop their counterparts at the bottom. I then applied epoxy glue to the top edge of each upper frame half, sat the lid in placed, and drove all of its deck-screws down tight. This permanently bonded the upper frame halves to the bottom of the boxes lid.
The lid was pulled clear and foam structural webbing installed.
As most of the two-part automotive fillers produce a rather grainy surface finish -- a finish subject to water absorption if not totally filled with primer and paint -- it is of particular importance to those of us who run vehicles totally submerged in water, for extended periods of time (ain't that right... Ken!), to ensure that the surface of the worked filler is sealed before progressing to putty and primer work.
My current project, getting a 1/96 BLUEBACK kit put together and partially ready for a friend, demanded a re-contouring of the upper and lower hull longitudinal edges as they got slightly out of alignment after I installed the WTC saddles, and WTC. This problem presented the perfect opportunity to document how to protect said filler against water entry.
The problem area in question is high-lighted by pencil hash-marking the lower hull near where its longitudinal edge meets that of the upper hulls edge; there was a bit of over-bite to the upper hull. The miss-match is too deep to address with a slow hardening, air-dry putty. No. This was a job for the quick-curing, two-part automotive filler, Bondo (or any other of the Bondo like products out there in car-restoration land).
Four steps are followed to get the two edges back into alignment: First is to fill the sunken half hull with filler and file and sand it to proper contour. Second, is to overcoat the surface of the Bondo with thin formula CA to produce a waterproof barrier over this porous filler, give the CA coating a light sanding to produce some 'tooth'. Third is to over-coat all that work with a thin layer of air-dry, touch-up putty to fill all file and sanding marks, followed by a wet sanding.
Then... FINALLY! the work is given a heavy coating of primer.
Believe it or not, all that work accomplished in under an hour (thank you Black & Decker heat-gun!).
A small about of Bondo was catalyzed on a palette and putty-knifed onto the hash-marked areas of the lower hull. I had previously laid the edge of some low-tack masking tape above the longitudinal break between hull halves to minimize the filing and sanding work which came next. Here I've temporarily pulled away some of the tape to run the point of a #11 blade into the gap. This to break any bridging of Bondo between the two hull half edges.
I then hit the Bondo with a heat-gun to quicken the cure of the stuff. 5-minutes of that and I was ready to rock-and-roll with file and sandpaper.
Initial shaping of the Bondo was done with the biggest, ugliest single-cut file I had in the drawer. The cutting was done with a surgeon's touch; just enough pressure to cut the Bondo but not obliterate adjoining areas of the models surface. A file card was used often to clear Bondo chips from the files teeth. Clean cutting tools are efficient cutting tools.
Putting the big-gun away I switched to a stiff, double-backed #220 grit sanding square, to remove the file marks. I also made use of a #240 grit nailfile for the compound curved areas near the bow. All this cutting was done dry.
Always file and sand in the direction of the curve, and when dealing with a compound curve, sand in a swirling motion, favoring the dominant direction of the curve.
The Bondo'ed areas were then given a heavy coating of CA adhesive. This seals the surface of the Bondo and greatly strengthens the upper edge against chipping or other type damage resulting from forced trauma, typically the joining/separation of the two hull halves.
The CA cures quickly so you have to be quick with the wiping rag!
(One hour later at the local Doc-in-a-box: "hey, can someone remove this submarine looking thing from my fingers?").
The hardened CA skin was then wet sanded with #400 to produce some tooth that will aid greatly to the adhesion of the later putty and primer layers.
To fill the inevitable tool marks and missed dings I brush on a very thin layer of Nitro-Stan air-dry, touch-up putty.
Don't have any? GET SOME! Automotive refinishing supply houses are your friends!
Some more heat-gun action and the putty is dry enough to wet sand in 5-minutes.
The putty is wet sanded with #400 grit sandpaper.
... And primed. All this performed within 60-minutes! Nothing to it fellow air-breathers.
Well, my buddies little 1/96 BLUBACK r/c submarine is almost ready for trimming and sea-trials. All I have to do now is cut out and install some flotation foam in the hull -- an interim measure. Final amounts and location of the foam will be determined through experiment in the test-tank.
Note how the forward running leg of the sail-plane pushrod, situated within the top of the upper hull half, terminates aft in a magnet, which -- when the two hull halves are joined -- links to the center magnetic coupler projecting aft from the lower hull half WTC's motor-bulkhead.
With everything an operational model submarine must have aboard, a trial amount of fixed lead ballast weight in installed low and forward. The objective is to get the submarine to balance at its longitudinal center-point. For the smaller r/c submarines like this 1/96 BLUEBACK, about a pound of fixed ballast weight is a good starting point.
Ideally the center of the ballast tank is also at the c.g. -- that situation desired but not absolutely required.
The fixed lead ballast weights are there to position the vehicles longitudinal c.g. at the center of the hull, and to place the center of mass as low in the hull as possible. The c.g. at the boats center assures reasonable maneuverability; that mass low in the hull also makes the boat statically stable about the roll axis.
Most submarines have no active means of managing stability about the roll axis. Therefor the boat has to be statically stable in roll. The magnitude of the righting force is contingent on the vertical distance between the vehicles c.g. and center of buoyancy; the greater the distance between those two points of force, the more stable the boat becomes about the roll axis.
Should there not be enough fixed ballast weight, and enough buoyant foam to counter that weight, the distance between those two points of force will be too short and will not have the moment arm required to right the boat from a roll in a timely manner.
Experience has taught me that so much weight in the bow demands a great deal of buoyant foam up forward.
I turned this foam piece on the lathe, its shape conforming to the geometry within the bow.
A blank of dense, closed-cell foam was cut out on the bandsaw and mounted to the face-turning plate of my Taig lathe. The eventual shape of this piece insured by use of a cardboard template that represented the inside of the model submarines bow.
In background you see the upper hull half of the 1/96 BLUEBACK model. Note how the bow plane pushrod runs from the sail back to where its magnetic coupler eventually makes up to the bow plane servo linkage when the two hull halves are assembled. Also seen to good advantage here are the many 'capture lips' that work to hold the two hull halves in tight registration with one another when assembled.
Turning the foam bow piece on the lathe. Note that I'm not using the X and Y drives of the cross-slide to cut the foam. Instead, I'm using the long shank of a tool to serve as a tool-rest for some hand-cutting of the work as its brought up to speed. Caveman, yes, but this method made the work go a lot quicker than if I had elected to drive the cross-slide around with the cranks. You can get away with such an expedient if the stuff you're turning is soft, like this foam, and no shop Supervisor screaming that you're 'unsafe' and a bad example to the other drones.
(Thank God OSHA's agents have never goose-stepped across my shop floor. Oh, oh... did I just put myself on their radar?! Fuck 'em).
From the day I integrated all the servos, speed controller (ESC), battery eliminator circuit (BEC), low pressure blower (LPB), r/c receiver, and the specialized devices produced by KME I was plagued by a twitching problem when I turned off the transmitter -- something was getting RF junk to the receiver decoder outputs; all mechanical devices (motor, servos, LPB) would dance around crazily and would only stop and resume normal operation once the transmitted signal was once again sent. I don't have the smarts or equipment to signal-trace, so I embarked on a week's long march to swap out components with ones I knew worked. All that effort in the hope that my Easter-egging would find the culprit of this 'glitching'. And I eventually succeeded. The bad guy was... thank you, Murphy!... the last thing I swapped out: the r/c receiver itself!
A new receiver installed, everything working as it should, I finished setup on the BLM and that got me the fail-safe throw and delay I wanted for this model submarine. Sometimes you guess right. Sometimes you don't. This was one of those 'don't' times.
(If I had access to a Terminator sized hydraulic press that bum receiver would have been reduced to a smoking, wafer thin Frisbee by now!).
After installing the new receiver, I had to once again run through the rather complicated protocol of setting up the Battery Link Monitor perimeters. That single, relatively small device performs the function of battery monitoring; it also will command the ballast sub-system to blow the ballast tank if the r/c signal is lost or a low voltage condition exist on the main bus; and informs you of how many 'loss of signal' events occurred during the last run.
The BLM isn't you grand-daddy's fail-safe... no sirree Bob! It's that and so much more. But, because of its multi-function design, setup is an exacting and most frustrating experience. Yet the instructions are not to blame as they are clear and methodical. But! You have to follow those instructions to the letter, or you won't get the results desired.
The KME Depth Cruiser (DC) device automatically positions the model submarines bow or sail planes to maintain the last depth ordered from the transmitter. It measures the hydrostatic pressure at the keep level of the submarine and works to autonomously drive the planes to keep the submarine at that depth. However, for the device to work its pressure sensing pick-up point (on this model in the form of a brass intake tube glued to the bottom of the hull) has to be well forward of the vessels center of gravity. A length of flexible hose runs aft to the WTC's motor-bulkhead where it terminates in a brass nipple. On the dry side of that nipple, within the WTC, a shorter length of flexible hoses connects sea pressure to the DC's pressure transducer.
You can turn the DC on/off from the transmitter. When off you have direct control of the planes. When 'on' you still drive the planes from the transmitter, but once you put the stick to neutral, the DC remembers the depth there and takes over the planes to keep the boat at that depth.
A water filled length of flexible hose was used to verify the sensitivity of the DC as well as to affirm that the sail planes would travel in the appropriate direction as a consequence of a change in depth. Just 1/4-inch of vertical travel of the water column gave me either full rise, or full dive on the planes.
Impressive!... MOST impressive!
With an angle-keeper working the stern planes, and the DC working the bow/sail planes, a well-trimmed submerged submarine model is hands-off as far as depth management is concerned, all you have to do is steer. A most remarkable gadget. And setup is easy.
With all WTC sub-systems running properly time had come to test the Lexan cylinder, seals, and bulkheads for water tightness. The equalization core valve (a common tire-valve) was removed, and a length of flexible hose made up so I could blow air into the WTC -- the slight over-pressure within the WTC would cause bubbles of air to escape from any leak points. The bulkhead O-rings and pushrod seals are the usual culprits when it comes to leaks, but I'm glad to report that the first tightness test was successful. I then moved onto a function test of the submerged WTC.
The transmitter and WTC were turned on and the WTC submerged in the test tank. The ballast tank was vented, flooding it.
First, the 'normal blow' as commanded from the transmitter. The end-point adjustment had been made to the transmitter so that the ballast sub-system servo traveled only enough to turn the LPB motor on. The OPB pushing compressed surface air into the 'soft' ballast tanking blowing the tank dry.
(It's called a 'soft' ballast tank as it does not see much of a differential pressure between its interior and the outside environment because it is always open to sea through two large flood-drain holes at its bottom).
Next, operation of the 'emergency blow' function was tested by turning off the transmitter -- representing a loss-of-signal to the WTC's receiver -- which caused the BLM (acting in fail-safe mode) to position the ballast sub-system servo to full travel, which not only switched on the LPB (which would be useless as its air induction intake would likely be well underwater in a real-life situation), but also engaged the emergency blow valve, releasing propellant gas into the ballast tank to blow it dry.
All checks and test completed to my satisfaction; the WTC was certified for use aboard the BLUEBACK.
Now to trim the entire assembly for proper surfaced and submerged trim.
Today... FINALLY!... I put Casey's 1/96 SWM BLUEBACK into a sizable hunk of water and worked out the bugs. Almost there. Tomorrow, I go back to the JCC for some u/w shots from a tow-body and a camera strapped to the deck of the model. Stay tuned, sports-fans!
The hull halves matted up; the WTC populated with working devices and certified operational; the entire boat was then taken through the harrowing process of adding fixed ballast weight and buoyant foam to make it stable, maneuverable, and to assume near neutral buoyancy submerged, and to float at the correct waterline when surfaced. Easily said. Not so easy to do!
All that, and more, before its first open-water tests. The open-water test did in fact reveal one last goof that had to be corrected before the model could be sent off to Casey for him to paint and add to his fleet.
Here I'm installing about 1-pound of fixed ballast lead weight low in the hull, well forward, to place the submarines c.g. at its longitudinal center. I have yet to install the buoyant foam in the nose and within the upper hull to counter that weight with an equal amount buoyant force.
As there was only about a 1/2-inch annular space between the hull and WTC I had to install the initial hunks of buoyant form -- each shaped with convex and concave surfaces -- to fit that tight space. A cardboard template used to mark off those curves to these closed-cell foam blanks.
I knew from experience that I would need a lot of flotation near the bow; these preliminary hunks of foam were installed long before any in-water testing. Only after the in-water tests would I fine-tune the amount and location of the buoyant foam elements within the hull.
All foam pieces were secured in place with RTV adhesive. Quick and easy to break if, and when, the need comes to remove and/or replace/relocate buoyant foam pieces during the trimming process.
Initial trimming was done in a big trough of water just outside the shop. First, I worked out how much foam, and where it had to be located to get the model to suspend itself totally submerged with the ballast tank full of water, the boat statically stable with no roll and a zero pitch-angle. I then blew the ballast tank dry and noted how high, or low its waterline was, compared to where it should be. Moving foam either above or below the waterline -- a trial-and-error process that can go quick, or not so quick -- until the model submarine sat with the waters surface right at the designed waterline.
Trim for submerged trim first. Trim for surface trim last.
Here's the layout of buoyant foam after achieving correct submerged and surfaced trim.
The submarine was now ready for open-water tests. Here, everything needed to support that activity has been assembled and ready for its ride to the local Jewish Community Center outdoor pool. Show time!
Here's a quick video clip of the JCC pool tests. Things went very well. But, after arrival back at home I found about a spoon-full of water in the WTC's after watertight space. Shit! A leak. Gotta fix that...
A quick look-see at the dry side of the motor-bulkhead showed some water weeping out from between the motor-bulkhead and its back-plate, which holds the motor in place. Looks like a bad motor shaft seal!
Break out the tools... going to be a late-night fix.
!#@^@&*$)^&(%$^%$^##!
The three servo pushrods were pulled; the aluminum tray and bulkhead with attached devices was unscrewed from the back-plate; the ESC leads to the motor de-soldered; the receiver antenna lead undone from the antenna stud; and the DC and LPB hoses pulled from their nipples. Now I had access to the motor-bulkheads internals.
I removed the back-plate and found water still gathered in the well where the motor pinion and motor drive shaft spur gear resided. Yup! Water was getting by the shaft seal. Nuts!
Turns out I failed to properly polish the shaft and a small burr chopped up the inboard lip of the rubber cup-seal. The shaft was turned and polished, and the cup-seal replaced.
Note that with a cup seal only a very narrow internal and external lip makes contact with the seal body and shaft -- any deformation of the shaft or body, or tear in either of the seals lips will offer a path for water to get by the seal.
Before installing the new cup-seal I thoroughly cleaned out any gunk from the space where the cup-seal resides.
A liberal amount of silicon grease is packed into that space, and the new cup-seal jammed in place, followed by the motor-shaft, and re-assembly of the entire motor-bulkhead.
The entire WTC was once again leak checked and operated successfully before packing things up for delivery to my boating buddy, Casey.
It's the height of foolishness to have gone to all the work and expense of building an r/c model submarine and to then neglect the need to protect it properly as it is stored and transported between home, pool, lake, cross-country, or even internationally.
Here you see five cardboard boxes. Two containing an r/c model submarine hull and associated parts; two more boxes containing the WTC's for those hulls; and the open box in which I am packing a transmitter and other smaller items that will support operation and maintenance of the models.
All this in preparation to my trip next week to Texas to go play with my former boss, Bob Martin of Nautilus Drydocks fame (in the voice Sheldon Cooper: "it's a trap!").
These items will all go into a much larger outer cardboard box which will convey everything from here to there.
I employ two basic types of storage-transportation boxes for my models: A heavy, large, stout wooden box to protect the completely assembled model during long-term storage and local transportation. And a light-weight cardboard box tailored to tightly fit the model and in turn itself transported within an outer protective box suitable for commercial shipping. Both type boxes illustrated here are custom made to house my little 1/96 SWM BLUEBACK r/c submarine model.
The cardboard box can start life as a store-bought product or it can be cut, bent and glued to shape from a suitably sized slab of 200# cardboard (the weight of this stout cardboard is 200 gram's per square foot and is my preferred type material for this kind of work).
In this example I'm 'telescoping' several 200#, 6" X 6" X 6" boxes to produce a 32" X 6" X 6" box. A hot-glue gun is the ideal tool for sticking cardboard-to-cardboard.
The only reason I employ cardboard as the major box construction material is to minimize the weight and physical dimensions of the package -- these being the two metrics that drive the cost of shipment, be the carrier the United States Postal System (USPS), UPS, FedEx or any other commercial transportation outfit.
Design of the cardboard box is driven by the end-use of the box: is the purpose of the box just to protect the model during transport, to be discarded after arrival. Or, will that box itself be employed for further protection of the model during storage and transportation at the destination?
This particular box is of the disposable variety. The model hull is wrapped in a suitable cushioning packaging material (in this case, bubble-wrap) to suspend it within the cardboard box. As it is my practice to make the sail removable on most of my r/c submarines that feature permits me to greatly reduce the boxes height (and to a lessor degree) and length by housing the sail, and propeller within the models hull. Packaging is provided for and aft between the model and ends of the box.
The objective is to suspend the model within the cardboard box through the use of non-abrasive packaging that has the 'give' to cushion the model against rough handling as it is bounced along from point-A to point-B.
When transporting this is one overriding consideration: Inertia is the enemy!! NEVER package your model for carrier delivery with its WTC in place. ALLWAYS ship the WTC in its own purpose built shipping box when dealing with a (insert air-quotes here) professional shipper.
The other type cardboard box -- this one recently made to get my BLUEBACK from here to Texas, and to be used there for local transport -- is not disposable. This type cardboard box will also be used as I send my stuff back to Virginia. It will see a lot of use!
That requirement demands a more involved and easy to use suspension system between model and box interior -- like that used with my more robust wooden storage-transportation box. This type cardboard box employs soft foam frames, top and bottom, to suspend the assembled model within its cardboard box.
The lid is secured with three Velcro belts, and the upper cushioning frames slide out. The lower half of the frames and back-stops are hot-glued within the box. Getting the hull into and out of the box takes only seconds, not minutes.
Preparing the model for shipping includes transferring the sail and running gear to within the model itself. Also included within the hull are the masts that project from atop the sail; spare fasteners and washers; sail planes, and WTC's snorkel assembly.
Before making up the two hull halves paper sheet packing material is held in place over the bagged items to keep them from rattling around during transport so things don't get lost or start kicking around within the hull as it's outer box is brutally knifed with fork-lifts, dropped from extreme heights, crushed in conveyor-belts, tossed into trucks, slammed into cargo bins, and drop-kicked and used in target practice by bored, over-paid, idiot shipping employees.
The lower frames and back-stops were hot-glued into the box. The upper half of the frames are removable. This feature permits me to install and remove the model from this box with ease.
Protecting my type water tight cylinder (WTC) gets a bit involved because of the delicate pushrods projecting from the motor-bulkhead, aft; and the fragile mission-switch watertight boot-seal at the forward bulkhead. Cardboard cylinders were wrapped around those ends of the WTC, insuring that neither cardboard box or packaging material would make contact with the pushrods or boot no matter how roughly the box is handled during shipment.
The delicate ends of the WTC protected in stiff cardboard cylinders, the unit was bubble-wrapped. Note that the box is over-sized in girth and length to make plenty of room for protective bubble-wrap -- needed to absorb shock-loads encountered during transport.
Plan and execute for the worst. Hope for the best.
To keep the WTC from banging around laterally within the box bubble-wrap occupies the annular space between box interior and WTC. Hunks of balled up bubble-wrap at each end of the WTC absorb longitudinal shock loads as the contents are subject to the not-so-gentle hands of the commercial carrier.
NEVER ship the WTC with batteries installed!
Sending model hulls and WTC's through the various shipping services is one thing. Sending 'dangerous' items -- and in our world, that means high-pressure gas cylinders, spray-cans, pyrotechnics, and Lithium-polymer/ion batteries over a specific capacity -- is another matter entirely. There is a strict protocol to follow. And its our responsibility to follow that protocol to the letter! We don't want that stuff anywhere near a commercial aircraft!
Yes, you can ship these things, but they have to be specifically identified so the shipper (USPS, UPS, FedEx, etc.) will give them 'special' handling -- and that means keeping that box off of airplanes!
The batteries for my BLUEBACK and KILO are just such items and here you see them ready for their trip to the local post office for drop-off. Truck(s) got them from Virginia to Texas in only four days! Not bad.
Same here. Never much had a use for submarine models, but seeing what can be done with them - and Certain Current Geopolitical Events - inspired me to purchase a number of submarine model kits from a Ukrainian model kit company.
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