No more cup seals, bellows, or o-rings! My Magnetic End Cap

[Jakub]

Hey Thomas!

I'm really interested with the results of your test as this thing has such a great potential! Can you say what size/weight of the testing boat will be? Diam 3.5" is quite a tube.

[salmon]

Jakub, I have two choices, one is the OTW Trafalgar 1/72 scale or I can disassemble my Skipjack and put it in there…..One would take longer than the other.

[salmon]

A little video of the test of the endcap. The issue I did have is my water intakes. I did not seal them well. So, I need to disassemble and make some changes there. Other than that, I am extremely pleased with the workings.

https://youtu.be/wV6aS3EYx7I

[salmon]

I have redesigned the water intakes. The Y joint that was exterior to the piston bulkhead is now internal to the bulkhead. 3D printing allows for some fun out of the box thinking. Now I can run two brass tubes straight to the piston bulkhead for water intake. Making assembly easier and sealing more reliable. I have been lazy on completing this (actually working two jobs - one is my primary and the other is training puppies for service work) so hopefully this week I will be able to test and film.

[wlambing]

Tom,
The OTW Trafalgar-fish is 1:64 scale.

Bill

[salmon]

Huh, their website says 1/72 scale. https://otwdesigns.com/trafalgar/

[scott t]

Tom what magnetism you have! End cap looks very cool.

[salmon]

HAHA Thanks Scott!
Did an initial check of trim after the changes. It is aft light! This was not my first guess of the way it was going to go, but the end cap is lighter and has extensions that reach farther aft. The other issue is the foam in the top is hitting the magnetic connectors for rudder and plane controls.





You can see where the connector is binding with the foam.

[wlambing]

Unless they re-issued it in 1/72, it's 1/64. Tony G. has one on his shelf.

[salmon]

Unless they re-issued it in 1/72, it's 1/64. Tony G. has one on his shelf.

No idea. I guess I could measure it and work it out. Either way my crew will be very tall or small depending on scale LOL

[wlambing]

It'll work!!! Shapeways fittings and stuff runs small, and John Haynes stuff ran big. It's all a crapshoot!!

[salmon]

Start round two.....
Just a short note on foam at top of hull, if you have to do it, give air a place to travel through or around.


So I carved out chunks of foam to give amble room for the push rods to move (and they do). yea! I also put in a path for air to escape.


In the water it went and it did set a little lower and more even, but not enough




I put a piece of weigh on the subs hull beginning between where it is and the sail. Kept moving it back and see how it settled. Repeated until I got to this spot and the sub sank level.


Moved the piston to get a neutral or close to neutral buoyancy. I let it hover there to see how the trim was and it remained level.
On my piston system the dial turns clockwise to dive at just past 3/4s the sub will get close to neutral. This way I have plenty of reserve buoyancy to surface. That is why I went with a weight in the rear rather than some foam in the front - Had I added any foam I may not have had enough weight to go negative buoyancy.





Now when I surface, the aft comes out great too!


Finally I took the rubber band and moved it over the weight to keep it in place. A side note, The weight was put on the deck for demonstration, but if it was going to be lifted out of the water (surface trim), I would have moved it to the bottom of the sub and normally I put the weight at the bottom of the sub anyways. One of the rules for trimming: Weight low, foam high.

[salmon]

So waiting on getting to a body of water (health, puppy raising, and other to-dos) started building a second WTC - This one will be for the Trafalgar.


















Two more parts are finished printing and will be added to this tonight.

[salmon]

What if I did not need gears?

https://www.youtube.com/watch?v=eaMD_9kOlTA

[bob the builder]

I have some commercially manufactured magnetic drive couplers that should fit perfectly in an RC sub, but never got around to trying them out. I really like the idea, particularly in a smaller boat. In bigger ones, we're talking a lot more torque, and I'd be worried about slippage, particularly if there was an "emergency back full" situation.

Bob