Hello, my name is Juan and I am from Spain.
I am new to this forum and I am going to describe a project that I started two years ago and needs some modifications to be done for it to work properly. I would be proud to hear sugestions!
Sorry for any mistakes made using English language.
The main objectives were:
-Low cost : For now it is below 240 € without radio equipment (+- 150 €)
-Simple hull, made out of wood (later discovered that this was not the best material for underwater stuff!)
-Static diving
-At least one hour of battery.
-Operating foward dive planes and twin ruders (only four chanels, so no rear planes).
-Similar to an Type IXB german U Boot.
First stages from the build, as you can see, simple , square-shaped hull:
![1:72 U boot Scratch built P1060616](https://i.servimg.com/u/f58/19/68/71/87/p1060616.jpg)
![1:72 U boot Scratch built P1060617](https://i.servimg.com/u/f58/19/68/71/87/p1060617.jpg)
Water tight compartment.
![1:72 U boot Scratch built P1060619](https://i.servimg.com/u/f58/19/68/71/87/p1060619.jpg)
Policarbonate sheet cut and drilled to form the acess hatch.
![1:72 U boot Scratch built P1060623](https://i.servimg.com/u/f58/19/68/71/87/p1060623.jpg)
Hull construction, simple shapes, cheap and "easy".
![1:72 U boot Scratch built P1060622](https://i.servimg.com/u/f58/19/68/71/87/p1060622.jpg)
Fore.
![1:72 U boot Scratch built P1060620](https://i.servimg.com/u/f58/19/68/71/87/p1060620.jpg)
Aft.
After foward and rear planes had been fitted, rudder assembly done, and frther hull work it looked like this:
![1:72 U boot Scratch built P1060610](https://i.servimg.com/u/f58/19/68/71/87/p1060610.jpg)
![1:72 U boot Scratch built P1060612](https://i.servimg.com/u/f58/19/68/71/87/p1060612.jpg)
![1:72 U boot Scratch built P1060611](https://i.servimg.com/u/f58/19/68/71/87/p1060611.jpg)
![1:72 U boot Scratch built P1060613](https://i.servimg.com/u/f58/19/68/71/87/p1060613.jpg)
Dive planes and rudders were made out of a zinc sheet, bent and soldered. Pushrods are 2mm brass rods, sealed with rubber bellows.
Motors used were taken from an old printer and fixed using a 3d printed piece. Another 3d printed piece is used to hold the propeller shafts. Everithing is glued in place with 30 min epoxy.
Next comes the big mistake of this submarine: The ballast tank: (Quite a strange shape!)
![1:72 U boot Scratch built P1060615](https://i.servimg.com/u/f58/19/68/71/87/p1060615.jpg)
![1:72 U boot Scratch built P1060614](https://i.servimg.com/u/f58/19/68/71/87/p1060614.jpg)
![1:72 U boot Scratch built P1060710](https://i.servimg.com/u/f58/19/68/71/87/p1060710.jpg)
The model you can see on the background of the last photo is a static model I took as a reference.
Made out of 1 mm iron sheet, bent and soldered into shape, and then painted from the outside and from the inside filling it with paint and then removing it to prevent corrosion; It proved too long for the task, its never filled completely and water moves very fast inside it with nothing preventing that, making the submarine incontrollable when submerged. (More on that later, posible solutions, etc) Total volume of the tank is nearly 750 ml.
As a surface boat, performs well, but at the moment controlled diving is nearly imposible.
Unaware of the problems it will cause, the ballast tank was fixed to the hull with lots of silicone:
![1:72 U boot Scratch built P1060711](https://i.servimg.com/u/f58/19/68/71/87/p1060711.jpg)
The hull was nearly completed and painted with a primer:
![1:72 U boot Scratch built P1060715](https://i.servimg.com/u/f58/19/68/71/87/p1060715.jpg)
![1:72 U boot Scratch built P1060714](https://i.servimg.com/u/f58/19/68/71/87/p1060714.jpg)
![1:72 U boot Scratch built P1060712](https://i.servimg.com/u/f58/19/68/71/87/p1060712.jpg)
![1:72 U boot Scratch built P1060713](https://i.servimg.com/u/f58/19/68/71/87/p1060713.jpg)
Ballast system: Windscreen water pump, servo operated three way valve,
![1:72 U boot Scratch built P1060717](https://i.servimg.com/u/f58/19/68/71/87/p1060717.jpg)
![1:72 U boot Scratch built Http<a href=](http<a href=)
![1:72 U boot Scratch built P1060718](https://i.servimg.com/u/f58/19/68/71/87/p1060718.jpg)
![1:72 U boot Scratch built P1060722](https://i.servimg.com/u/f58/19/68/71/87/p1060722.jpg)
Then the policarbonate sheet was cut to shape, drilled, fitted with screws and glued to the wtc:
![1:72 U boot Scratch built P1060720](https://i.servimg.com/u/f58/19/68/71/87/p1060720.jpg)
![1:72 U boot Scratch built P1060719](https://i.servimg.com/u/f58/19/68/71/87/p1060719.jpg)
The gasket was made out of soft silicone after trying numerous materials.
Then, two wood stripes were glued onto the sides of the sub.
![1:72 U boot Scratch built P1060721](https://i.servimg.com/u/f58/19/68/71/87/p1060721.jpg)
All the wood parts were coated with epoxy paint:
![1:72 U boot Scratch built Captur10](https://i.servimg.com/u/f58/19/68/71/87/captur10.png)
Then, the deck, sail, guns etc. were designed in FreeCAD:
![1:72 U boot Scratch built Freeca12](https://i.servimg.com/u/f58/19/68/71/87/freeca12.png)
![1:72 U boot Scratch built Freeca13](https://i.servimg.com/u/f58/19/68/71/87/freeca13.png)
![1:72 U boot Scratch built Freeca10](https://i.servimg.com/u/f58/19/68/71/87/freeca10.png)
![1:72 U boot Scratch built Freeca11](https://i.servimg.com/u/f58/19/68/71/87/freeca11.png)
And then 3d printed using white abs, glued with acetone and fitted to the hull:
![1:72 U boot Scratch built Captur10](https://i.servimg.com/u/f58/19/68/71/87/captur10.jpg)
![1:72 U boot Scratch built Captur11](https://i.servimg.com/u/f58/19/68/71/87/captur11.png)
![1:72 U boot Scratch built Captur11](https://i.servimg.com/u/f58/19/68/71/87/captur11.jpg)
That black thing on the photo is the fuse cover. The fuse is used to switch on an off the entire submarine.
![1:72 U boot Scratch built Img_5110](https://i.servimg.com/u/f58/19/68/71/87/img_5110.png)
After all comes the painting job :
![1:72 U boot Scratch built P1060812](https://i.servimg.com/u/f58/19/68/71/87/p1060812.jpg)
![1:72 U boot Scratch built P1060910](https://i.servimg.com/u/f58/19/68/71/87/p1060910.jpg)
![1:72 U boot Scratch built P1060911](https://i.servimg.com/u/f58/19/68/71/87/p1060911.jpg)
And the final result:
![1:72 U boot Scratch built Captur13](https://i.servimg.com/u/f58/19/68/71/87/captur13.jpg)
![1:72 U boot Scratch built Captur12](https://i.servimg.com/u/f58/19/68/71/87/captur12.jpg)
First trials in the swiming pool:
![1:72 U boot Scratch built Captur12](https://i.servimg.com/u/f58/19/68/71/87/captur12.png)
And in the local pond:
![1:72 U boot Scratch built P1070010](https://i.servimg.com/u/f58/19/68/71/87/p1070010.jpg)
Result:
> Speed: A bit faster than scale.
> Turning: Fine. Small turning circle. Rudders work great.
> Diving: It dives, but it can't return to surface. After filling the tank, it goes vertical and any try to emerge causes compresed air to release and sinking the sub to the botom.
> Foward dive planes : Useless, even at 45 degrees seem to have no effect.
> Watertightness: Not leaked a single drop.
> Batteries: One 1300 mA 11.1 v Lithium battery lasts about 45 mins-1 h
Ballast system explanation & posible solution:
> Here is the schematic of the ballast system: A "water sealed tank" or a "high presure pump" system:
![1:72 U boot Scratch built Ballas10](https://i.servimg.com/u/f58/19/68/71/87/ballas10.png)
To dive, a servo opens the valve and presses a microswitch that activates a windscreeen pump, wich pushes water into the tank, compresing the air inside. Then , the valve is closed.
To emerge, simply open the valve and air presure will force the water out.
There comes the problems I have encountered:
1st: In a long tank, water moves back and foward very quickly, making the sub very inestable.
2nd: In certain situations, air can escape when openning the valve, loosing poresure and beeing unable to surface again.
Case A: Center of gravity (CG) foward, imposible to dive in a controlled manner, but able to surface.
![1:72 U boot Scratch built Ballas13](https://i.servimg.com/u/f58/19/68/71/87/ballas13.png)
Case B: CG back, imposible to dive in a controlled manner, unable to surface, if the valve is opened, compresed air will escape before water. You have to get wet.
![1:72 U boot Scratch built Ballas14](https://i.servimg.com/u/f58/19/68/71/87/ballas14.png)
Posible solution:
As I do not need all the volume of the tank, sides of it can be sacrificed to shorten it, thus making it more stable.
Furthermore, adding a kind of bulkheads inside will unable air to scape in any position (not turning the sub over) and willl certainly make the sub far more stable.
See the images:
![1:72 U boot Scratch built Ballas11](https://i.servimg.com/u/f58/19/68/71/87/ballas11.png)
![1:72 U boot Scratch built Ballas16](https://i.servimg.com/u/f58/19/68/71/87/ballas16.png)
Now, how to put those bulkheads inside a 1 mm wall stell tank? The tank itself is the botom of the sub, s you can see in the photos, so the only way to do it is to cut it open, add the bulkheads, fill sides with silicone and close it again !
I am new to this forum and I am going to describe a project that I started two years ago and needs some modifications to be done for it to work properly. I would be proud to hear sugestions!
Sorry for any mistakes made using English language.
The main objectives were:
-Low cost : For now it is below 240 € without radio equipment (+- 150 €)
-Simple hull, made out of wood (later discovered that this was not the best material for underwater stuff!)
-Static diving
-At least one hour of battery.
-Operating foward dive planes and twin ruders (only four chanels, so no rear planes).
-Similar to an Type IXB german U Boot.
First stages from the build, as you can see, simple , square-shaped hull:
![1:72 U boot Scratch built P1060616](https://i.servimg.com/u/f58/19/68/71/87/p1060616.jpg)
![1:72 U boot Scratch built P1060617](https://i.servimg.com/u/f58/19/68/71/87/p1060617.jpg)
Water tight compartment.
![1:72 U boot Scratch built P1060619](https://i.servimg.com/u/f58/19/68/71/87/p1060619.jpg)
Policarbonate sheet cut and drilled to form the acess hatch.
![1:72 U boot Scratch built P1060623](https://i.servimg.com/u/f58/19/68/71/87/p1060623.jpg)
Hull construction, simple shapes, cheap and "easy".
![1:72 U boot Scratch built P1060622](https://i.servimg.com/u/f58/19/68/71/87/p1060622.jpg)
Fore.
![1:72 U boot Scratch built P1060620](https://i.servimg.com/u/f58/19/68/71/87/p1060620.jpg)
Aft.
After foward and rear planes had been fitted, rudder assembly done, and frther hull work it looked like this:
![1:72 U boot Scratch built P1060610](https://i.servimg.com/u/f58/19/68/71/87/p1060610.jpg)
![1:72 U boot Scratch built P1060612](https://i.servimg.com/u/f58/19/68/71/87/p1060612.jpg)
![1:72 U boot Scratch built P1060611](https://i.servimg.com/u/f58/19/68/71/87/p1060611.jpg)
![1:72 U boot Scratch built P1060613](https://i.servimg.com/u/f58/19/68/71/87/p1060613.jpg)
Dive planes and rudders were made out of a zinc sheet, bent and soldered. Pushrods are 2mm brass rods, sealed with rubber bellows.
Motors used were taken from an old printer and fixed using a 3d printed piece. Another 3d printed piece is used to hold the propeller shafts. Everithing is glued in place with 30 min epoxy.
Next comes the big mistake of this submarine: The ballast tank: (Quite a strange shape!)
![1:72 U boot Scratch built P1060615](https://i.servimg.com/u/f58/19/68/71/87/p1060615.jpg)
![1:72 U boot Scratch built P1060614](https://i.servimg.com/u/f58/19/68/71/87/p1060614.jpg)
![1:72 U boot Scratch built P1060710](https://i.servimg.com/u/f58/19/68/71/87/p1060710.jpg)
The model you can see on the background of the last photo is a static model I took as a reference.
Made out of 1 mm iron sheet, bent and soldered into shape, and then painted from the outside and from the inside filling it with paint and then removing it to prevent corrosion; It proved too long for the task, its never filled completely and water moves very fast inside it with nothing preventing that, making the submarine incontrollable when submerged. (More on that later, posible solutions, etc) Total volume of the tank is nearly 750 ml.
As a surface boat, performs well, but at the moment controlled diving is nearly imposible.
Unaware of the problems it will cause, the ballast tank was fixed to the hull with lots of silicone:
![1:72 U boot Scratch built P1060711](https://i.servimg.com/u/f58/19/68/71/87/p1060711.jpg)
The hull was nearly completed and painted with a primer:
![1:72 U boot Scratch built P1060715](https://i.servimg.com/u/f58/19/68/71/87/p1060715.jpg)
![1:72 U boot Scratch built P1060714](https://i.servimg.com/u/f58/19/68/71/87/p1060714.jpg)
![1:72 U boot Scratch built P1060712](https://i.servimg.com/u/f58/19/68/71/87/p1060712.jpg)
![1:72 U boot Scratch built P1060713](https://i.servimg.com/u/f58/19/68/71/87/p1060713.jpg)
Ballast system: Windscreen water pump, servo operated three way valve,
![1:72 U boot Scratch built P1060717](https://i.servimg.com/u/f58/19/68/71/87/p1060717.jpg)
![1:72 U boot Scratch built P1060718](https://i.servimg.com/u/f58/19/68/71/87/p1060718.jpg)
![1:72 U boot Scratch built P1060722](https://i.servimg.com/u/f58/19/68/71/87/p1060722.jpg)
Then the policarbonate sheet was cut to shape, drilled, fitted with screws and glued to the wtc:
![1:72 U boot Scratch built P1060720](https://i.servimg.com/u/f58/19/68/71/87/p1060720.jpg)
![1:72 U boot Scratch built P1060719](https://i.servimg.com/u/f58/19/68/71/87/p1060719.jpg)
The gasket was made out of soft silicone after trying numerous materials.
Then, two wood stripes were glued onto the sides of the sub.
![1:72 U boot Scratch built P1060721](https://i.servimg.com/u/f58/19/68/71/87/p1060721.jpg)
All the wood parts were coated with epoxy paint:
![1:72 U boot Scratch built Captur10](https://i.servimg.com/u/f58/19/68/71/87/captur10.png)
Then, the deck, sail, guns etc. were designed in FreeCAD:
![1:72 U boot Scratch built Freeca12](https://i.servimg.com/u/f58/19/68/71/87/freeca12.png)
![1:72 U boot Scratch built Freeca13](https://i.servimg.com/u/f58/19/68/71/87/freeca13.png)
![1:72 U boot Scratch built Freeca10](https://i.servimg.com/u/f58/19/68/71/87/freeca10.png)
![1:72 U boot Scratch built Freeca11](https://i.servimg.com/u/f58/19/68/71/87/freeca11.png)
And then 3d printed using white abs, glued with acetone and fitted to the hull:
![1:72 U boot Scratch built Captur10](https://i.servimg.com/u/f58/19/68/71/87/captur10.jpg)
![1:72 U boot Scratch built Captur11](https://i.servimg.com/u/f58/19/68/71/87/captur11.png)
![1:72 U boot Scratch built Captur11](https://i.servimg.com/u/f58/19/68/71/87/captur11.jpg)
That black thing on the photo is the fuse cover. The fuse is used to switch on an off the entire submarine.
![1:72 U boot Scratch built Img_5110](https://i.servimg.com/u/f58/19/68/71/87/img_5110.png)
After all comes the painting job :
![1:72 U boot Scratch built P1060812](https://i.servimg.com/u/f58/19/68/71/87/p1060812.jpg)
![1:72 U boot Scratch built P1060910](https://i.servimg.com/u/f58/19/68/71/87/p1060910.jpg)
![1:72 U boot Scratch built P1060911](https://i.servimg.com/u/f58/19/68/71/87/p1060911.jpg)
And the final result:
![1:72 U boot Scratch built Captur13](https://i.servimg.com/u/f58/19/68/71/87/captur13.jpg)
![1:72 U boot Scratch built Captur12](https://i.servimg.com/u/f58/19/68/71/87/captur12.jpg)
First trials in the swiming pool:
![1:72 U boot Scratch built Captur12](https://i.servimg.com/u/f58/19/68/71/87/captur12.png)
And in the local pond:
![1:72 U boot Scratch built P1070010](https://i.servimg.com/u/f58/19/68/71/87/p1070010.jpg)
Result:
> Speed: A bit faster than scale.
> Turning: Fine. Small turning circle. Rudders work great.
> Diving: It dives, but it can't return to surface. After filling the tank, it goes vertical and any try to emerge causes compresed air to release and sinking the sub to the botom.
> Foward dive planes : Useless, even at 45 degrees seem to have no effect.
> Watertightness: Not leaked a single drop.
> Batteries: One 1300 mA 11.1 v Lithium battery lasts about 45 mins-1 h
Ballast system explanation & posible solution:
> Here is the schematic of the ballast system: A "water sealed tank" or a "high presure pump" system:
![1:72 U boot Scratch built Ballas10](https://i.servimg.com/u/f58/19/68/71/87/ballas10.png)
To dive, a servo opens the valve and presses a microswitch that activates a windscreeen pump, wich pushes water into the tank, compresing the air inside. Then , the valve is closed.
To emerge, simply open the valve and air presure will force the water out.
There comes the problems I have encountered:
1st: In a long tank, water moves back and foward very quickly, making the sub very inestable.
2nd: In certain situations, air can escape when openning the valve, loosing poresure and beeing unable to surface again.
Case A: Center of gravity (CG) foward, imposible to dive in a controlled manner, but able to surface.
![1:72 U boot Scratch built Ballas13](https://i.servimg.com/u/f58/19/68/71/87/ballas13.png)
Case B: CG back, imposible to dive in a controlled manner, unable to surface, if the valve is opened, compresed air will escape before water. You have to get wet.
![1:72 U boot Scratch built Ballas14](https://i.servimg.com/u/f58/19/68/71/87/ballas14.png)
Posible solution:
As I do not need all the volume of the tank, sides of it can be sacrificed to shorten it, thus making it more stable.
Furthermore, adding a kind of bulkheads inside will unable air to scape in any position (not turning the sub over) and willl certainly make the sub far more stable.
See the images:
![1:72 U boot Scratch built Ballas11](https://i.servimg.com/u/f58/19/68/71/87/ballas11.png)
![1:72 U boot Scratch built Ballas16](https://i.servimg.com/u/f58/19/68/71/87/ballas16.png)
Now, how to put those bulkheads inside a 1 mm wall stell tank? The tank itself is the botom of the sub, s you can see in the photos, so the only way to do it is to cut it open, add the bulkheads, fill sides with silicone and close it again !
Last edited by JuanGg on Sun May 14, 2017 7:30 pm; edited 2 times in total
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