Ohio Class, Ballistic Missile Nuclear Powered Submarine, USS Kentucky SSBN737




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 Iíll 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 Iíll 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.
 

WTC 1, Images:

- and now to the images of how mine turned out. Please click the images to enlarge.

WTC1a.jpg (120818 byte)
This is the 1/6" end plate seen from the inside.


The mechanical output from WTC1,
for dive planes, rudders and prop.
 

A closer look of the rubber bellows, and
the eight bolts securing the end plate.
 

This is the second version.
The plumb bob is out, as are the PCB's.
Module is shortened app. 5.5" / 14 cm
More images soon!!      
       

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.

 





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