Bringing 1/128 Seaview back to the pond!

[salmon]

I have chosen the next sub on my build list. I have a Moebius 1/128 scale 4 window Seaview that I bought from Mike Caswell when he left our industry awhile back. It was built by David Merriman. It was just the hull, no wtc. So, I have accumulated enough parts that I am ready to get this one back to the pond.

I will post more later this week.

[salmon]

Stitched together several photos to give a panoramic view. Looking over the sub, I have to give Kudos to David's skills.


There are some nice problem solving done with the bow planes and the propeller shafts.

The magnet connector is attached to a brass slide. This in turn moves the front planes.

At the moment, I am removing lead ballast and cleaning up rubber from other foam that was used. I may need to remove all the foam as well and re-trim the sub from scratch. The etc I have is not the same that as originally in it. The prior Sub-Driver was smaller in length because I believe this had a video camera installed at on time.

[mar7ck]

WOW!!!

Just how many submarines do you own???
Someone is out of control.

[salmon]

LOL, Mark, I have a few.......

[PaulC]

To paraphrase John D. Rockefeller, "How many model submarines is enough? Just one more."

[salmon]

I carved the existing bulkhead to fit this cylinder and needed to reposition it.

There was not much adjustment here. The front of the WTC buts up to the front dive plane controller. So the rear of the WTC could only go here. That being said, it is slightly closer to the propeller shaft and dog bone, but they do fit the WTC.

With everything in place, I CA'd the bulkhead into position using the rubberized CA.

Removed existing weight since the new Sub-Driver is a different one than was in there, I will need to trim from scratch. The foam is so nicely done, I hate the thought of removing it.


The deck was cleaned up from cured rubber and foam strips on it.

I believe this sub had a transformation to a video sub and the front needed to be open for the camera. Since we are not doing that on here, we will need to see how much weight will be needed to bring the sub to a slightly positive aspect when we trim it out.

[salmon]

Another difference is this sub will have the newer SAS system verses the SNORT system I believe was in here. So, One of the features that needs to be installed is the float This float will raise as the sub dives and seals water from getting in. When the sub needs to dive, the air will be drawn out of the cylinder into the ballast tank pushing out the water. Once the sub breaks the surface, the float will fall and allow air in to replenish the air used to fill the ballast tank.
I needed the foam to clear the deck and not bind or hinder the raising or falling of the float.


A stack of 3 layers of styrene were used. The middle section is cut out more like a "C" than anything else.It is large enough for the nipple and bottom seal to fit in.


The bottom layer was carved out once the stack dried from the glue.


The bottom or largest layer was cut to fit the lip on the deck.


The next thing to do is see if I have the look I was going for.


I think it will work well.

Now it is time to stuff the Sub-Driver.

[salmon]

This is the mechanism that works the bow dive planes.

[salmon]

Using a profile tool and some foam I had, made two blocks to be used as a stand


Marked the end cap to identify the pushrods.


I had ordered two batteries to run in parallel. The batteries are LiPo 7.4V 1500mAh batteries It is already tight in there AND I have not installed a switch or fuse. Maybe one battery???


Another decision is do I put in a magnetic switch (this one is made by Kevin McLeod) or a toggle switch.


Oh the decisions.....
I ran 14 gauge wire in the transverse tube between the battery room and the engine room. I am not sure if this is too thick or not. What do you use? In the meantime I attached the receiver and the leveler to the frame with double sided tape.

[bob_eissler]

14 GA is plenty, can get by with less. I have been switching to the magnetic switches because the toggle switches are very unreliable. They break if you look at them wrong! I'd use 1 battery, a snort system needs air volume in the sub-driver to work well.

[salmon]

Bob,
What gauge do you use? 7.4V or even a 11.1v is not really a lot, so what is the best size. I am ignorant on this.
Peace,
Tom

[KevinMC]

Hi Tom!

Choosing a wire gauge is a bit of an art as there are a lot of things to consider. Peak current vs. avg current, and length of the run between battery and ESC/motor are the dominating factors. Also the "cost" of getting the wire a little too small may not actually be as bad as it seems...

Most batteries come with really fat wires because they're intended for use with high-current draw applications - Submarines don't typically fit that model, so don't use battery wires as a guide for what gauge to use in your sub. Wires need to be sized based on the AMPS that they're going to carry, not the VOLTS or cell count of your battery. The best place to start is to set everything up and measure the current draw of your motors at full speed. (But they need to be connected to props that are immersed in water to be a representative measurement.)

The cost of slightly undersizing your wires are that the wires themselves will get warm (or even hot if you really undersize them) and that will result in a loss of voltage at the input to your ESC. If the wires get so hot that the insulation melts obviously you'll have a big problem. If you lose so much voltage in the lines leading to the ESC/BEC that it causes your Rx to "brown out" that's also a problem. But in most cases the cost of undersizing your wires is that you'll not have quite as much top-end speed out of your motors as what you could. Unless you plan to spend a lot of time a flank speed then you've not lost anything there.

All things considered, you're probably not pulling more than 3 or 4 amps most of the time, so I'd guess that you'd be OK with even 18AWG wires for this WTC. I don't have wire gauge to amp ratings committed to memory so I usually look these things up on the Internet when I need them. Here's a good site with a calculator. You can use the table, but know that the "chassis wiring" column is optimistic for our application where the "power transmission" column is a little conservative. The "calculate voltage drop" calculator at the bottom is a little more telling as it gives a sense of what the "cost" of choosing different gauges really is, but you do have to be able to make some guesses about what your actual current draw will be.

(Of course you can always go the other way on this - just use the biggest wires that will fit in the "tunnel" that connects the battery section to the engineering section.)

[crueby]

Kevin, is there any downside to erring on the size too large side of things, other than bulk?

[KevinMC]

Hey Chris,

You nailed it, there's no such thing as "too big" a gauge as long as you've got space to run it. (But there definitely is a point where if you go any bigger you won't actually notice any difference.)

[salmon]

Thanks Kevin!
That fits to this chart I found.
You guys ROCK!