Even when I was thick into the r/c aircraft, I was
fascinated by submarines. Starting with a small silver sub, I
built a number of wood models, which I then painted, sealed and
ballasted. Each model was an improvement over the previous model,
which I launched into swimming pools and small tubs. Watching
these models move through the water only increased my interest
in submarines.
Prototype Model Length: 42.50 inches. Beam: 3.75 inches. Height: 6.125 inches.
I have always been fascinated by submarines, building several small models for pool use at first and then graduating toward a larger r/c surface submarine. Looking around at kits available left me somewhat disturbed by the lack of suitable boats, and almost no in-action photos to get me excited. So I set out to develop my own.
Starting with a round hull cross section would be easiest. The Los Angeles Class provided me with the basic outline to follow, from which I made a pattern model and mold for casting a single part fiberglass cloth reinforced epoxy hull.
My first serious larger sub design was based the Los
Angeles Class Attack Subs. Using Computer Aided Design(CAD), this
model was designed with top hatch access to the "Water Tight
Compartment" (WTC) and a one piece hull. CAD design allows
me to check and fit most of the parts during this phase of the
project.
Setting certain limitations on my expectations, I decided
to make the first "Black Submarine" a surface vessel
only. This would allow me to work out the needed hardware for
waterproof control push rods and work out the details of the electronic
equipment. On this model, the entire hull is a "Water Tight
Compartment" (WTC). Also, I decided steer the sub with a
"Flex-Drive" which allowed the push rod and control
horn for steering to be outside the hull. This allowed me access
and simplicity when it came to figuring out how to waterproof
a push rod. The push rod consists of a wire inside a plastic tube,
the area around the tube could be made water tight so what remained
was to secure the tube end where the wire exited. The solution
was end cap made of model airplane silicon fuel tubing half filled
with RTV mold making silicon rubber, through which the wire was
run. With a bit of lube it worked out very well.
After
installing motor, battery, remote control electronics, and ballasting
the black sub, it was time to hit the local lake. The pleasure
seeing the sub in the water was quickly topped when the sub got
under way. The wake generated by the bow plowing through the water
looked just like the pictures and movies of full size subs!
The first test runs revealed an overheating problem with the motor, some provisions had to be made for cooling. Also the model was very heavy, a problem that could be alleviated by converting part of the hull for flooding and reducing the size of the WTC. It was time to build another test model.
The
next test model is the "Yellow Submarine". The hull
was divided into three sections, the center being the WTC and
the rest open to flooding. This significantly reduced the amount
of extra weight needed to properly ballast the sub, making the
actual sub much lighter to carry than the Black Submarine. Water
pickups were installed to cool the motor. Both modifications worked
wonderfully, and the Yellow Submarine proceeded to hunt its quarry
on the lake.
Experimenting with heavier ballast, I was able to "skip and bob" just under the surface with the Yellow Submarine. At this stage the four individual strips of silicon rubber used to seal the hatch could not keep out the water, and the submarine repeatedly sank. Luckily I was able to "power drive" the sub across the lake bed and recover it each time it took on too much water. This however, was not the way I wanted to experience underwater running. Time to make some modifications.
The hatch received a new silicon seal made as a single
uniform part, no water can get in. Then by adding another control
servo, bow planes could now be installed. Once the new modifications
were tested, it was time for the real thing!
Testing
day out at the lake was thrilling. The bow planes worked very
well, as did the new hatch seal. One modification was required,
because when I attempted to dive the stern rose completely out
of the water! I used heavy duty aluminum tape to add trim tabs
to the fixed aft dive planes, which successfully kept the stern
in the water during the dive. However there was a price to pay.
The same forces keeping the stern in the water at the beginning
of the dive also forced the boat back to the surface a short time
later by preventing the boat from staying level while running
underwater. With some practice, I managed the balancing act of
staying under for longer and longer runs. The level of excitement
was high as I set out across the lake, underwater! Over a three
day period, I put several running hours on the model with a majority
of the time spent running under the surface. The model would stay
down as long as forward speed was maintained, using the dynamic
method of submerging. When the battery started to run low, the
model would rise and stay on the surface. At the end of this testing
period I was one happy camper, that is me holding my creation.
One more sub was constructed with the same setup as
the Yellow Submarine, this time in traditional black over red.
At the same time I made another 2ch surface runner for a client.
Thats me with both subs. I'm holding the surface runner, the dynamic
diver is on the ground in front of me.
Of course, I could not stop now! Underwater travel
was beckoning, and I was willing to refine my designs to engineer
for deeper and longer dives. With interior details reconfigured
with knowledge gained from prior experience, the next is submarine
hull molds will be created with a greater emphasis on outer scale
detail. The Lafayette Class Ballistic Missile Submarine is the
next chapter in my submarine story. However, I could also make
improvements with my good 'ol work horse LA Class sub, which turned
out to be a whole new adventure.
You see, I wanted to add movable stern dive planes
and a standard steerable rudder, thus solving my dive trim problems
plus doing away with the rather obtrusive looking flex-drive steering.
The new parts for the Lafayette class were rather small, but they
would do. I put them onto a new black and red boat, for which
I had also made other small design adjustments.
When I hit the water with this new hybrid sub, I was
in for some surprises. The good part was, it was definitely faster,
and the dive was more manageable with both forward and aft dive
planes fully movable. The real shock was how sluggish she was
in the turns. The turning radius of this sub was dismal when compared
what it now seems are its very agile predecessors. Even with the
disappointing turns, the sub was lots of fun as it performed easy
dives over longer runs. Later dives did not seem as crisp, and
I learned the control horn had snapped off the aft dive planes.
The aft dive planes had not enough travel movement, the servo
pulled the horn out of its mount. Back to the workshop!
Back at the workshop, I took off the horizontal stabilizers in front of the aft dive planes, then reglued them forward some from their original position, to allow the dive planes enough travel to match the servo output. I've also made some travel adjustments to reduce throws on all movable surfaces, because I noticed that even small movements of steering fins produced drag and I want a finer sense of control. I'll test them the next time I can get to the lake.
Lucky
for me, I got three days in a row to go run the subs. The modifications
to the travel throws worked really well. After some initial balance
adjustments, The Los Angeles Class was doing consistent dives,
moving very swiftly through the water, and responding wonderfully
to control inputs. Now I was really getting a chance to learn
how she handles under the surface, the only serious challenge
was torque roll from power inputs and maintaining enough speed
to stay submerged when I wanted to slow down. The sub disappeared
from sight many times on dives, and always reappeared a short
time after I went to all-stop on the controls. The surprise for
the day was that fish liked following the sub!
Second
day was much like the first, with more fish sightings and a great
deal more sub running time. The third day out I tried out a new
prototype drive screw on the LA Class sub. It was fashioned to
look like the USS Dallas prop in the "Hunt for Red October"
movie. with five cast epoxy blades cemented into a machined acrylic
hub at 2.3 inch diameter. The power was AWESOME!
To close out the last chapter in my history
book of submarine development, I have some pictures of the final
Los Angeles Class Simple-Sub taken on the day she was handed over
to her new captain. With what I have learned from this submarine's
development, new subs will be designed with enhanced capabilities.
This sub has reached the limits of what she is capable of, and
what a great job she has done. Coasting slowly beneath our
platform,
details
are easily visible. With a small amount of forward speed a wake
is generated, the curved scimitar
drive screw
is still visible though slightly distorted. The need for speed
is easily met with more power, the LA Class plows a fast wake
while riding just below the surface. As speed builds
up the bow burrows itself deep, which brings the stern and drive
screw close to the surface or even out of the water. When spinning
fast, a high speed prop will cavitate
when it catches air, which
makes
the sub look like a rocket! However, once
the drive screw can bite firmly into the water
the sub will take off like a dolphin. The high speed
prop allows this dynamic diver to be driven quite well and deep
as well. Speeding ahead of its
own wake while underwater,
the LA Class breaks surface
in a spectacular leap from below. This maneuver was performed
many times during this patrol, often with half the sub emerging
above the surface before a big splash! What a great day!!!
Can't wait to design a new Los Angeles Class, a BETTER ONE!
