Building a 3.5" WTC

[salmon]

Just to get caught up, the WTC is completed.
Trimmed the Skipjack
When I was testing the WTC, I put weight on it until it sank

That gave me an idea what I would need, but because of the weight of the hull and all above the WTC, I began with a "chunk" of lead. I know so scientific, huh?
With that chunk in, I tested it with tanks filled - does it sink if not add more weight. Move weigh around and see if you can get a nice trim. If not foam will be needed.
At first it was tail heavy.

Using sail as my guide

Added foam

This raised the sub

- since this is a ballast sub, I filled the tank a little more to get to where the sail is at the waters edge.

Now we are a bit tail light. Now the foam I added was pre shaped curve on it for hull and a groove to allow air to pass. It was not cut or trimmed down for these adjustments, just moved forward.


Better, but could still be adjusted, a slight movement

[salmon]

Can't add any more photos.....Hmmm
Anyways a small movement towards the bow makes the tail drop, moving it aft would cause the tail to rise. Why? Think of a teeter-totter or see-saw or whatever it is called, it is about leverage. The further away from the rocking point or center of gravity the bigger the impact. If you have a slight adjustment to make to a trim there are two ways (for this reference only) you can go. Bigger block closer to center or small foam block closer to the rudder. Both will cause the sub to adjust your trim, but one will have a large impact on the metacentric height and the other (smaller block) will not.
I will continue this when it allows me to add more photos.
Peace,
Tom

[mar7ck]

Great Job Tom!!!

When can i expect delivery???

[salmon]

2021 started with a great run of the Skipjack, but a disaster for the Gato (broken aft dive plane).

[scott t]

Nice looking fish in that river.

[salmon]

Thank you Scott!

[DrScoles]

Tom, Does the printer you're using offer UV cured resin? Formlabs has resin that is as strong as ABS. What CAD software did you use?

[salmon]

My printing has moved to Elegoo Mars pro and the Saturn. Began with the abs-like resin, but changed recently.

I am now using Siraya Fast Grey. A bit better than Elegoo ABS like Grey. My next test will be to mix a custom blend, but first I want to do some castable resin. My Mars Pro will be tasked with that.
I use Fusion 360 for my CAD work.

Now with all the success I have had with this wtc, this past weekend, I had a failure. The engine room flooded. I have not tested to see where yet, still drying out the innards. I do not believe any got on electronics, but stayed in the engine room. I will update!

[QuarterMaster]

Tom,

What's your opinion on the curing of the grey, or opaque resins in general?

NOT that I have data yet to back it up, but I prefer the more translucent resin to insure UV penetration throughout.

It would be interesting to discover if clear resins have that curing advantage, especially with thick parts/shells.

When I designed the MK148 Gas propelled Torpedo parts I used TinkerCad online (100% free), very easy Shape based 3D modeling (5 yo's or Boomers can use it). For more control I use the Parametric FreeCAD Software (also 100% free).

[salmon]

Ed,
I have some very thick solid pieces and it comes out great. The exposure times for opaque resins is a little longer than translucent and the pieces seem to be cured throughout. Still, it would be fun to do a test.

Maybe when you get settled into your new digs, we can collaborate on this?
Peace,
Tom

[QuarterMaster]

Ed,
I have some very thick solid pieces and it comes out great. The exposure times for opaque resins is a little longer than translucent and the pieces seem to be cured throughout. Still, it would be fun to do a test.

Maybe when you get settled into your new digs, we can collaborate on this?
Peace,
Tom

RGR WILCO!

Not only that. let's see if we, and others here, can collaborate on a "best" practices write up. There's ton's of data out there in terms of YouTube or what not, but one becomes a "prisoner of choices" because of that.
Someplace here the Shipmate can go HERE and be rest assured he's getting tried and true tips.

We'll touch base once I'm back online and the Forum is update.

I may even do a TinkerCad tutorial for those afraid/not desiring a full fledged 3D Parametric modeling tool.