Bringing back an old model submarine from the dead.

[bigdave]

Re: Bringing back an old model submarine from the dead.

Thank you for the kind words my friend.
But in my case I have had a long time to learn.
Fortunately I have learned a few right ways to do things along with my many wrong attempts.
There is really no cheap way to get into model subs.
Just less expensive ways. Like most things one does the more you can do yourself the less it will cost you in the end. BD.

[subdude]

Re: Bringing back an old model submarine from the dead.

To answer the hull question, yes the Krick boat hull was bread and butter construction. They supplied a set of 1" thick planks rough cut to shape, and you glued / screwed them together. Then you took out your wood plane and sandpaper and removed anything which didn't look like a submarine. Lots of work which really makes you appreciate a fiberglass hull.

To the "little $$" subject, I'd like to point out that with some careful shopping you can in fact do a reasonable sub with not a huge outlay of cash. I've bought second hand 4 channel radios for as little as $25 complete with 3 servos. A basic speed control is quite inexpensive, or you can go the full on miser route and glue a couple micro switches to the servo for half / full speed control. Battery prices (especially LiPo) have fallen to the point of stupidity. The 3s 5000 mah one in my Neptune cost $34 shipped to the house.

A pressure hull and ballast tank can be built from a couple bucks worth of PVC pipe, with flat lexan for end plates retained by screws into the wall of the PVC and sealed with 50 cents worth of red rubber gasket material.

Yes, model submarines can and do get *very* expensive. But if you want to do it on a budget, it's certainly possible.

Anyway, I look forward to BD resurrecting the beast.

[salmon]

Re: Bringing back an old model submarine from the dead.

Sorry for a slight diversion but, holy cow batman, a 5000 mah battery in your Neptune? Criminy, how long does that run for? (Having serious battery envy)

[bigdave]

Re: Bringing back an old model submarine from the dead.

They last Longtime!
I have a 5000 in mine too. And I think Don and Larry in our group have 6000.
The only issue is the battery is a lot lighter than the stock SLA battery.
And a different shape as well.
All in all a easy to do retrofit.
Also(almost forgot)a trim pot on one of the boards needs to be reset for the slightly lower voltage of the new battery.
If you don't the low voltage safety feature will keep kicking in.
I thought someone had written up a how too. If not maybe I can talk one of the guys into it. BD.

[subdude]

Re: Bringing back an old model submarine from the dead.

Yup. Last long time, have big fun sailor ;-0

And yes, it was me who wrote up the retrofit instructions a couple years ago. Let me know if you need / want them.

Jim

[salmon]

Re: Bringing back an old model submarine from the dead.

PM sent, thank you, and you may return to your regularly scheduled program. Where's the popcorn?

[bigdave]

Re: Bringing back an old model submarine from the dead.

What I am going to do is take each of the things I changed on the kit and explain why.
I will start with the propulsion system.
When I got the hull the only thing left were the two stuffing boxes with no shafts bearings or seals. Just the two tubes.
There were also two vent/greasing tubes one from each shaft that exited inside of the pressure hull.
I assumed that two 380 sized motors were used in the original so as I had two RS380's in my parts bin,that is what I chose.
I made up two simple 90 degree motor mounts from K&S brass strip and staggered them on the floor of the pressure hull to eliminate interference.
I am not sure what the stock kit used to couple the prop shafts to the motors but I went with a simple silicone tubing coupler.
Easy and effective.
I am sure in the stock kit they must have had bearings in the tube ends for the prop shafts to ride on.
Then injected grease into the area between the bearings through the vent tubes making a standard stuffing box type seal.
But I decided to go with a more modern sealing method using Subtech type sealing assemblies.
This would be mounted on the pressure hull side.
It was easy to turn down the end of the seal assembly slightly so it fit inside the tube mounted in the hull.
A dab of RTV was used to seal the assembly to the tube.
On the outside end of the tube at the prop I used a Rulon bearing for the shaft to ride on. I am just using 1/8" brass for the shafts.
In this system I would not have to rely on the grease to keep the water out, just the cup seal inside of the bearing assembly.
For the props I used two I had lying around from an old plastic boat kit.
One left and one right.
I just bonded the props to the shafts with some loctite red.
The last thing I did was connect the two vents together with some silicone tubing to keep any water outside of the hull.
Eazy Peazy!

[bigdave]

Re: Bringing back an old model submarine from the dead.

I will be posting some photos.

[bigdave]

Re: Bringing back an old model submarine from the dead.

[bigdave]

Re: Bringing back an old model submarine from the dead.

The next thing I changed was the cover for the pressure hull.
I believe the kit used a wood top that was held down by studs and nuts.
There was a rubber gasket that went around the opening that was compressed by the top to seal off the inside.
Although it works I have never been a fan of this system.
I decided to go with a Lexan cover so I could see what's going on inside.
I did not have a piece large enough to cover the entire opening so I decided to use three sections.
I also decided to use RTV to install the cover sections.
This way I can easily take the covers off if I need to and then reinstall with a thin bead of RTV.
I am also going to add access hatches in the covers for battery, power switch, and ballast.
These would be made from old end caps. Just pop them out to access the inside.
The other reason I used the Lexan will be explained in the control surface installment.

[bigdave]

Re: Bringing back an old model submarine from the dead.

I will talk about how I modified the servo mounting and linkages now.
As stated earlier the output linkages were plastic tubes sealed with thick grease in a carved out cavity on the outside of the hull.
On this hull I acquired only one tube was installed as just the rudder was functional.
The front and rear planes were installed but did nothing.
I think it was built as a surface runner only.
I decided to try a different approach to control surfaces by mounting the servos to the bottom side of the Lexan cover and run a rotary output.
My buddy Crazy Ivan likes to do this.
So I came up with a way to mount the servos and seal the output.
(I will try to make a drawing.)
I also decided to have three servos and run both front and rear planes.
Now since I am going to be running the linkages above the pressure hull cover I would have to change the shafts for the planes and rudder.
This meant removing the bushings from the wood.
Something I would have done anyway as they were all crooked.
The bushings came out easy with a little heat application from a soldering iron.
Heat the brass to soften the glue and push out.
With the bearings out I was able to open cavities in the wood for the bell cranks and shafts.
I used a forestner bit to hog out some nice openings.
Then I installed new brass tube bushings.
I also wanted to change the surfaces from thin brass (pool liner killers) to plastic.
Using the brass as patterns I traced the shapes to 1/8" plastic sheet.
Then sanded to a more streamlined shape.
I also wanted to make the surfaces removable so only one side is bonded to the shafts on the planes. Where the other is pinned with a small brass pin.
Now in case of damage I can replace them.
The linkages themselves are made from brass rod, sheet, and carbon fiber tube for the longer bow linkage.
These too I made easily removable with pins and wheel collars so I can access the end caps in the lid.
I mounted the three servos on the rear lid section.
My reasoning was it would very rarely need to be removed.
There is also a longer center section and a short front section.
The longer center section is the one I figured may need removing from time to time.
Easy to do with a sharp blade.
But even that should not be required unless repair is needed for some reason.
What I did was install 4 end caps into the lid.
One in the front section and three in the center.
The one closest to the rear of the hull is for accessing the battery and ESC switch.
The other three are for adding weight for trimming the sub in the form of pennies.
There are removable pill containers that set inside of each opening.
My idea (as yet unproven) is once the trim is close by adding lead to the pressure hull, is to add the pennies to the three pill containers to fine adjust the trim.
The last (forth) end cap is just large enough to install the drive battery.
A Lipo two cell pack.
The RX and ESC are mounted to the sides of the pressure hull with servo tape.

[bigdave]

Re: Bringing back an old model submarine from the dead.

More photos.

[bigdave]

Re: Bringing back an old model submarine from the dead.

More photos.

[bigdave]

Re: Bringing back an old model submarine from the dead.

More photos.

[redboat219]

Re: Bringing back an old model submarine from the dead.

Happy Holidays Big Dave.

I' ve been following this thread the last few days. Another great project from one of the masters. Can't wait to see the finished boat.

What are you using to seal the servo output shafts? They look like Subtech seals but they don't look like they're made of brass.