Improving the SubTech 1/60 ALBACORE phase-2 Kit, Part-1

A Report to the Cabal:

Over a decade ago, SubTech -- the company originated, owned, and operated by
America's Godfather of r/c submarining, Skip Asay -- Introduced a very
inexpensive, large, and capable r/c submarine kit: the 1/60 scale USS ALBACORE.
For more on that kit click on this page: http://www.rcboats.com/albacore.html

Skip hit on the ideal subject: a very sleek, highly maneuverable research
submarine owned, commissioned, and operated by the US Navy; a purpose built
vehicle to explore radical innovations in the areas of hull form, propulsion and
propulsors, ships control station manning and protocol, control surface placement,
stealth, and the impact such a high-performance submarine had on this nations
ability to employ its ASW assets against such 'modern' high performance
submarines.

During its operational career the ALBACORE underwent four very distinct
appearance changes, each variation assigned a specific 'phase' number. For
example, as launched, the ALBACORE, configured as phase-1 had bow planes, a
dorsal anti-roll rudder at the trailing edge of the sail, and huge stern stabilizers
than hung over the single screw those stabilizers supported the rudders and stern
planes aft, in the wash of the propeller.

Phase-2 saw the control surfaces changed to a cruciform arrangement that is now common on today's American submarines: full flying rudders, and a set of stern planes swinging off of fixed horizontal stabilizers -- all surfaces ahead of the propeller disc. During this phase the ALBACORE had its bow planes removed, never to be employed again.

Phase-3 saw the most radical change in the look of the submarine: the stern control surfaces were arranged in an 'X' fashion -- four identical full flying control surfaces that operated collectively to produce the required pitching and yawing forces. All four of these huge control surfaces would produce yaw and pitching force, as required to maneuver the boat. This arrangement would remain throughout the ALBACORE's existence.

Phase-4. Further modifications of the boat saw the introduction of a counter-rotating propulsor -- two propellers spun by concentrically running shafts, the effort intended to explore the increased efficiency gained by recovering swirl energy. This propulsor also made real the technologies and identified the problems needing resolution, as it was intended to adapt the counter-rotating coaxial propulsor to combat submarines, the intent was to eliminate the noisy main reduction gears then (and regrettably still) employed by our SSN and SSB(G)N's.

This propulsor was intended to speed match the high RPM propulsion turbines to the low RPM propulsor by halving the net turbine speed. This trick performed by making the stator stages free to rotate. The turbine spool matted to the inner propeller shaft, the stator spool matted to the outer propeller shaft. Net torque of the entire propulsion system = zero.

Ideally, the wake from this propulsor would be axial with no appreciable swirl component, the after propeller not only accelerating water, but also recovering the swirl energy imparted to the water mass by the forward propeller. A benefit too was that the wake of this propulsor quickly dissipated in the surrounding water --the US Navy has always feared the wake-homing torpedo. Still does. Reduce the submarines wake signature and it becomes less likely you'll suffer a wake seeking weapon up your butt.

OK, back to the SubTech kit:

Skip designed his forty-inch long sub kit to be cheap to manufacture, and cheap to operate; his intent to make available to the general public an affordable r/c submarine kit that would be fully capable, featuring a proper ballast tank so the model could be dived statically.

Skip elected to construct the major kit structure from vacuformed polystyrene plastic sheet. At the kits inception Skip engaged Model Builder Steve Reichmuth to built the masters of the kits hull, appendages and sail. I was skeptical about the robustness of this material in our environment (slamming car doors, small children and dropped models), but time has venerated Skip: The ALBACORE kits I've built (maybe I hold the record?) are surpassingly resistant to damage as the result of collisions, and grounding ... every see me drive? Not pretty.

Even the internal water tight cylinder (WTC) of the kit is formed from vacuformed styrene pieces, as is the single pump type ballast tank. Pretty innovative stuff. And a departure from normal watertight space design and fabrication. These and other innovative kit features account for the low price of this very capable and good looking product. In the hands of a careful assembler, the ALBACORE WTC (the same unit used on the other SubTech r/c submarine kit, the MARLIN) will remain dry and will give years of faithful service, all the operator has to do is keep the boat above the maximum depth stated in the instructions, perform the suggested maintenance tasks, and he'll enjoy many hours of fun with his ALBACORE r/c submarine.

I've been working as a third-party contractor for SubTech (both Skip and the new company owner, David Keogh) from the beginning. My involvement ranging from research, plan illustration, pattern making, tool making, and supply of fittings kits for the SubTech line of r/c submarine kits. I did the production work on the kits fittings package, components formed from cast resin and cast white metal.

I've been banging on Dave Koegh to enhance the ALBACORE kit for a few years now. I've suggested that we first make the basic phase-2 kit easier to build and improve the scale fidelity of the end product at the same time. For example, substituting the vacuformed tail-cone with its fat horizontal stabilizers with a hollow cast resin stern-cone with built in place horizontal stabilizers of scale thickness.

I've also suggested to SubTech that they offer a D&E Miniatures Lexan type WTC specifically designed to operate both the ALBACORE and MARLIN SubTech kits. Such an alternative to the kit supplied styrene WTC would permit the customer the opportunity to use a ready-made and tested WTC, easing the demands on his kit assembly skills while at the same time increasing the permissible depth at which the model can be operated.

So, here's the first chapter on the effort to enhance the SubTech ALBACORE kit. Here you'll be getting a dose of how I interpret photos and plans; perform layout chores; make masters, tools; and cast resin and metal parts.

For those of you who like acronyms how's this?

Albacore Ships Supplemental Work Improvement Program Expedited.

Project ASSWIPE.

About five years ago I built up one of the vacuformed SubTech 1/60 ALBACORE kits to look like the prototype as it appeared during the phase-4 studies: X-tail full flying control surfaces, coaxial running counter-rotating propellers, and sail with large dorsal rudder.

The event where this shot was taken is the annual model regatta hosted by the Mariner's Museum in Newport News, Virginia. This model is very fast and is the most maneuverable r/c submarine I've ever driven! Very, very touchy to control inputs. This particular model initially used a mechanical mixer to integrate the two servo outputs into unified motions of the four control surfaces, and that worked fine. Later, about the time of this shot, I had ripped out the mechanics of that system and substituted an electronic mixer of Skip Asay design and manufacture --which greatly reduced the maintenance and setup chores that precedes getting the model outfitted for an afternoons fun.

Turning the stock vacuformed kit tail-cone into a master started by sawing off the formed-in-place horizontal stabilizers. These constitute a way out-of-scale feature, being much to thick of section than the horizontal stabilizers seen on the prototype as configured for phase-2 studies.

I've already poured a solid plug of epoxy within the stern of the tail-cone to act as a foundation for the propeller shaft bearings. That plug foundation used here to hold a tube mandrel, used to hold and center the tail-cone as it was turned on the machine lathe to refine its shape.

Also, there is a bit of a Hogner Stem shape (coke-bottle shape) in the vacuformed tail-cone. Should not be there and that's my fault. When I did the plans all those years ago I incorrectly read the photos to suggest this shape at the stern. Not so --there is no concavity to the form of the tail-cone. This error was fixed by a heavy fill to the center outer surface of the vacuformed piece followed by some heavy sanding while spinning it on the lathe.

I started the ALBACORE upgrade project with a stock vacuformed tail-cone from an ALBACORE kit. It was assembled, the horizontal stabilizers sawed off, and an inside screeding blade fabricated from brass tube and sheet to permit me to build up a uniform layer of Evercoat Metal Glaze filler within -- I had to build up the parts (now classified as a master) wall thickness to an amount that would be receptive to later resin casting from the tool that will be pulled off the completed master.

I've already poured a solid epoxy foundation into the stern of the tail-cone. The foundation is intended to later (in the cast resin production pieces) to mount two Oilite bearings that will hold the propeller shaft true with the submarines longitudinal axis. At the foundation (as I design submarines) is the point through which the ahead and astern thrust loads presented by the propeller are transferred to the submarine hull structure.

Before the first layer of filler was laid on, I applied some masking tape to the outside of the cone to cover the big openings left when I sawed off the stabilizer appendages. I skinned the inside of the tail-cone with Evercoat filler. As you can see, the screeding blade spins about the centrally mounted mandrel within the tail-cone.

With the interior of the vacuformed tail-cone built up with filler, I then needed to extend the stern a bit, for two reasons: First, the diameter of the original ALBACORE kits stern is too large in diameter and that in turn drove the design of the original kit propeller hub to match, making the propeller hub out of scale too. Second, the length of the tail-cone had to be a bit longer to get the model to the stated forty-inches in length. A win-win deal: lengthening the tail-cone permitted me to extend the taper of the hull to the point where the end matched the correct diameter of the vessels propeller and increase the length of the model to the correct value. Of course, this means I have to build a new propeller master and tool ...

... ah, shit!

That's what I get for being such an anal retentive detail nut!

Meanwhile I began the lay-up work on the rudder, stern plane, and horizontal stabilizer. I made use of RenShape 40 dense Pattern Maker's foam as the substrate of choice here. Here I've assembled one of the removed horizontal stabilizers to illustrate what that looks like. A bit too thick, to be sure. This and other 'kit enhancements' will be stock enhancements. Other enhancements will be packaged as after-market items, purchased by those who want a more scale like display.

Plastic stencils, lofted off the working drawing, were used to mark off the foil outlines onto the aluminum sheet template material.

To insure correctness of section I cut out aluminum sheet templates which were bolted to the root and tip of each control surface/stabilizer. All I had to do from that point on was to cut, file, and sand the Renshape down to the height of the mounted templates.

The phase-4 ALBACORE tooling around in the Lynnhaven Dive Center diver's training pool. Fast, maneuverable, and very, very sexy looking. Too bad this was a turnkey job. I would have liked very much to have kept this model for my collection. During the remainder of the ALBACOR's career there were at least three investigations launched to find the optimum spacing between the two propellers. What I've modeled here is the first investigation, with the propellers distanced they're maximum amount. Weird looking. I love this thing!

Later, the US Navy would install a similar type propulsor onto a front-line attack boat, the USS JACK. Unfortunately shaft sealing problems precluded adoption of this propulsor arrangement on any future American combat submarines. Too bad. It's so damned neat looking!

Looking up from the bottom of the pool as the SubTech ALBACORE phase-2 model makes a pass while traveling at periscope depth.

The phase-2 ALBACORE model underway in the Lynnhaven pool. A better than average turning boat, and possessing reasonable speed using the D&E Miniatures WTC-3. Note the traditional looking cruciform arranged stabilizers and control surfaces at the stern. At the start of the phase-2 program the ALBACORE still made use of bow planes, but maneuverability about the pitch axis was found to be so good that the bow planes were removed (never again to be reinstalled) during the remainder of the phase-2 investigations.