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Making the SEAVIEW ready for operation as a practical r/c submarine involved working out a watertight containment system for the
motor and electronics. The same three-inch diameter length of clear Lexan plastic tube, outfitted with internal watertight bulkheads, also served as the submarines single ballast tank. The ballast tank
is of suitable volume to buoy the model high enough to present a reasonable waterline in surface trim.
I design and build 'free-flooding' type r/c submarines. This SEAVIEW is no different in that
regard. The watertight cylinder (WTC) and battery were the only main operational elements aboard the model.
In fact, other than the WTC and battery, the entire interior of the hull is flooded with water. A review on this and other types of r/c submarine schemes later, in the next installment. The battery is of the sealed, no-maintenance, lead-acid type that sits within the free-flooding hull. Incidentally, most r/c submarines are operated only in fresh water, which is a very poor conductor of electricity.
It's all but impossible to arrange a ballast system aboard to get the SEAVIEW to the designed waterline, as seen in the movie and on TV. As most of you know, the few times we see the SEAVIEW in
full surface trim - the approach into New York in the movie, the opening credits in the TV show, for example - the submarine (the seventeen-foot miniature, used to scale better with water as the camera
was over-cranked) is unrealistically high in the water - over half of its structure is 'buoyed' into the air.
For a practical r/c model representation of the SEAVIEW, like this project, the
waterline simply has to fall higher on the hull than the Fox people would have it. With this model I provided nearly thirty-ounces of ballast tank floodable volume, enough to get the models waterline
even with the bottom of the missile deck superstructure break in surface trim. A departure from true scale, but still a pretty high freeboard (distance from deck to waterline) as American SSBN type
submarines go. And the SEAVIEW was, after all (among many other things), an American SSBN submarine.
First wetted in my granddaughter's kiddy-pool, it was there that I worked out the initial
placement of fixed ballast weight (low in the hull) and compensating buoyant foam (high in the hull). The objective to lower the submarines center of gravity and to achieve as high a center of buoyancy
as possible. It is the metacentric height, the distance between these two collective force points, that dictates the vehicles pitch and roll stability; the greater the metacentric height, the greater the
righting forces that make the vehicle statically stable.
And believe me, I found right off the bat during sea-trials that the SEAVIEW needed all the static stability possible - this is a
dynamically unstable boat beneath the surface, a gold-plated, God damn bitch to drive once that sail dips beneath the water.
It turns out that the SEAVIEW is easily upset about the roll axis
because of the dynamic forces produced by the manta-fins as they sideslip into the turn. The tall metacentric height I provided this r/c SEAVIEW (lots of fixed weight, lots of foam) is the only thing
that makes it anywhere near controllable in a tight underwater turn. But just barely.
The only physical change I needed to make to the model, a departure from 'scale', based on sea-trial runs and
careful observation, was to install a set of fixed, upward canted vanes in the propulsion tube nozzles, just aft of each pump-jet. These vanes counter a nasty down-pitch force originating at the bow
(those big bow mounted manta-fins again!). However, the vanes are set well out of sight in the nozzles. Unless you're looking you don't know they're there. And that was the trick: to get this SEAVIEW
model to perform as a practical r/c submarine using only those control surfaces indigenous to the design. The model is controlled through the scale rudders, sail planes, and stern planes.
You'll
note, in the first photo of this series, that not even the four bow windows had been cut out as I worked the model through sea-trials. At that point I had deferred not only the finish, but also many of
the internal and external detail chores until after I completed, successfully, sea-trials. Incidentally, later, after I had installed all the detail items I found that they increased the weight by some
four-ounces in excess of the weight of water these items displaced, making the outfitted SEAVIEW model negatively buoyant - that quickly fixed with the installation of some buoyant blocks of foam high in
the bow, displacing a little over four-ounces of water (weight of foam, which is negligible plus the number of ounces 'heavy' the boat is).
Emergency over-ride, Archimedes.
OK, I made
you suffer enough, here's the pay-off, a quick summation of the handling characteristics of the SEAVIEW above and below the surface:
In surface trim, with the sail and those two big 'Cadillac'
fins at the stern poking above the water, the SEAVIEW has a surprisingly good turning radius. However, I had to be very careful not to use too much throttle otherwise the pump-jets, only a couple of
inches below waterline, would pull down air, air-binding the rotors, killing the propulsors ability to produce thrust. Backing down, surfaced and submerged, was a long-term, frightening experience as the
thrust produced full throttle astern is a small fraction of the thrust full throttle ahead.
The intake side of the pump-jets was not baffled with one-way valves to direct all reversing flow into
the propulsion tube intake openings. As a consequence, much of the backing water went into the hull where it found itself outside through the bottom located flood and drain holes and open diving
bell/mini-sub access hatch - remember, this is a free-flooding type submarine. One advantage, not anticipated, of the reverse flow going down and out the flood holes is that an upward thrusting force is
produced that pushed the entire model, without any significant pitching, straight up - this unexpected circumstance, once realized and capitalized upon, latter permitted me to surface the boat from a
dead stop while completely submerged simply by backing down. Kind of neat and a characteristic I used later at public events to wow the crowd.
Speed submerged and surfaced was surprisingly good:
about three mph surfaced, a bit faster submerged. Precision control at periscope depth was possible using only the sailplanes for depth control.
Normally, an electronic pitch stabilization
device, a must aboard r/c submarines, managed the stern planes to control pitch angle submerged. That device is so designed to permit me to over-ride it to operate the stern planes from the transmitter -
for those situations when I have to augment the sail planes - to either maintain periscope depth in a hard turn or to make radical depth changes (like when that less than observant surface r/c boat
sailor 'accidentally' runs the SEAVIEW over, danced to the tune of, "EMERGENCY DEEP! NOW!!!!").
When things get hairy at the lake you would see me operating, at the transmitter, the
rudders, sail planes, stern planes, and throttle. All at the same time. It's like operating a model aircraft - in slow motion. But, most of the time, with the boat trimmed out well and at periscope
depth, I would be seen lazily holding the transmitter with one hand, simply working the rudder and sail planes (those two functions on one transmitter two-axis stick).
Submerged is where the
SEAVIEW design revealed its nasty inherent flaws: The big Cadillac fins, once immersed, acted to super stabilize the boat in yaw, fighting the three rudders, increasing the boats minimum turning radius -
a big liability to maneuverability. As mentioned, the manta-fins tend to pitch the bow down with speed. They also rolled the boat inboard in a turn.
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