| WTC 1, holding
PCB's, A.L.T., R/C stuff & batteries: |
This is my home-made WTC1, holding all R/C related stuff, and engine incl. gearing etc, and
the 20 batteries at the very end of the WTC. (Placed close to the middle of
the sub when mounted.) It tested tight up to about 2.5 bar, at which
pressure I dared not go further. (Was afraid the bellows might collapse.)
| WTC 1,
Control surfaces output: |
How do we make a water tight mechanical connection from servos to the
rudders? There are several ways to do this, and I’ll give you a few choices again:
A) One way is to make a system of magnetic force transfer. If the
"wet" rods are mounted so that they can slide very easily, and fitted with a magnet in the end, then another magnet can slide back and forth on the other side of a plastic
box, controlled by the servos. (This sliding action must take place on the sides of a plastic box, NOT at the end.)
Use super magnets, or the strong (!) magnets from within old hard-disks, as you
don't want to loose rudder control. This ensures a strong but flexible power
transfer, and a complete sealed WTC. Another advantage is that if the
rudders gets stuck in something, then the servo's will not be forced to a complete and potentially damaging stop, but will be allowed to
move even then.
B) The rods can exit your WTC through a small pipe fitted with
rubber bellows. The old "grease box" (as know from surface
ships) does not work with subs, as the ambient pressure will exceed the
WTC-pressure and thus force the grease into the WTC, make a mess,
and flood the WTC. The bellows goes on to a short pipe, mounted in a
cable gland like my stuffing box. (See image in the next paragraph
about propeller further down.)
The most reliable method is most likely option B, as this has a direct mechanic
connection (Periodical check and maintenance required) |
The bellows from
Robbe, stock number 1-1400 |
(A third mechanical seal is a
rotary type, which is even more reliable than the bellows. The rods need
to be shaped like an S to use this type. Please browse the web for
further details.)
| WTC 1,
Propeller shaft output: |
The power transfer from the engine compartment can be designed in different ways. Again I’ll give you a couple of options:
A) The shafts,
held in place by bearings, can end in a
strong magnet mounted
in a 90 degree angle,
or in a disk with several magnets as shown, with the shaft mounted in the very middle.
This magnet arrangement will be positioned right next to the plastic
end of the box holding the engine. The
motor shaft (within the WTC) will have a similar magnet arrangement mounted on
it.
When the engine revolves, the one magnet arrangement pulls the other magnet
arrangement around with it. This ensures a strong but flexible power
transfer, and a complete sealed WTC.
Another advantage is that if the propeller gets stuck in something, then the engine will not be forced to a complete and potentially damaging stop, but will be allowed to revolve even then.
Disadvantage: Where does the rods for rudders / dive
planes go? hmm...
I'm a bit worried about vibrations, but tests will show
this later on. The idea will be pursued later on, and my sub
might be upgraded later on with this idea. |
|
 |
B) The shaft can exit your WTC through a thing called a
"Stuffing box". It's a ready-made product made for this, and
is about the only working alternative to the old "grease box"
as know from surface ships. The old "grease box" does not work
with subs, as the ambient pressure will exceed the WTC-pressure and thus
force the grease into the WTC, make a mess, and flood the WTC.
The most reliable method is most likely option B, as this has a direct mechanic
connection (Periodical check and maintenance required) This
image shows how my stuffing box exits the WTC through a cable
gland rated "Waterproof" (IP 68) to a pressure of up to 5 bar,
the pressure at 145 ft. (44m.)
To read more about
IP Ratings, click here! |
Click for
enlargement
|
|
|
Ready-made propellers like this is widely
available on the Internet, and
sure would look great on the model. Isn't it a beauty??
(Even at $50?) Getting a result like this when building one on
your own, is
impossible, though I have seen a few very nice home made props.
Danger: Regardless if you buy or
build, do observe the max. RPM rating! It is not without danger to
exceed these ratings, and it has been known to happen that a blade broke
off and flew at a very high velocity in some random direction!
Also, at all times when the sub is turned on: Ensure that no one
(Including your self) sticks any fingers close to the prop. Even if you
do not touch your remote control, there's a danger. Other transmitters,
or interference, might start it. Should it spin while a finger is in
it's path, you can be sure of some kind of injury.
|
- and now to the images of how
mine turned out. Please
click the images to enlarge.
Important:
When sealing the WTC, remember to apply
O-ring grease! (Available in most hardware stores.)
Click images to enlarge.
|
Mechanical Data: |
| Length: |
Weight: |
Displacement: |
Buoyancy: |
| 35 cm / 18.8" |
3,192 Kg / 7.04 lb |
2,226 Kg / 4.90 lb |
-966 g / -2.13 lb |
| WTC 1, compartment connections: |
| Read more about the
compartment function and schematics by returning to the main menu,
and read all electronic chapters, and chapters on R/C related
equipment, as well as the battery configuration chapter. |
|
