Typ VII C RC Submarine (Work in Progress)

Note:

Anything in this Instructable might be subject to change as im writing it along working on the project.

Discover the practical elegance of the Typ VII C submarine, recognized as one of the successful German U-boats from World War II. Renowned for its efficiency in undersea warfare, this vessel embodies essential traits of stealth and agility. With a streamlined design and innovative features, it became a formidable force beneath the waves, earning its notable place in maritime history.

After watching "Das Boot" (1981), the deal was sealed for me and i set on building the sub in an RC version.

Three projects inspired this make substantially:

The amazingly detailed model of the Typ VII C submarine itself, made by Flaredphoenix:

Can be bought on:

Cults3D

CGTrader

"Bau eines Typ XXI Modell U- Bootes" playlist by MatzeBautWas (German and English Subtitles)

A 10 part series about the construction of a Typ XXI submarine. This series mainly influenced my decisions on the "scaffolding" inside the watertight container, especially the ballast tanks.

"Make a RC Submarine" playlist by tiver21 (Partially subtitled in English)

A mixed playlist around the construction of RC submarines in general. Towards the end, a couple of videos are about working torpedos and the associated launch system, which i will recreate in this project.

The model is printed at a 200% scale on an ELEGOO Neptune 4 Max with ELEGOO PLA+ Filament and an ELEGOO Saturn 3 Ultra with AnyCubic ABS-Like Resin.

Print settings for documentation:

xx

Remember: Calibrating your printer leads onto the road to success! These are my values, yours might differ.

The artist offers multiple versions of the submarine so you can choose to print the hull in circular bits or in the halved variant. This makes it possible to use most of the build platform, which has a size of 218.88mm (L) * 122.88mm (W) * 250mm (H) on the Saturn and 420mm (L) * 420mm (W) * 480mm (H) on the Neptune Max.

After inspecting the model, i settled on using a 150 mm OD/ 140 mm ID acrylic pipe for the main body of the watertight container. The WTC is supposed to protect all the mechanics and electronics from the surrounding water. To transfer mechanical movement from inside this container to the outside, for example to the propellers powering the submarine or the depth rudders controlling its diving angle, a customized cap is needed. For this, i had to become acquainted with Autodesk Fusion 360 and Shapr3D.

Having had no experience with CAD software, i went this way:

1. Watching hours of youtube
2. Designing a part
3. Iterating and refining it with time

The learning curve is a bit steep from my perception, and it propably shows in my models. Nonetheless, i want to share them with you.

This instructable will start with the design and manufacturing of the watertight container, go over the printing of the model, connecting both components and finally the design and creation of a customized handheld controller for the submarine.

3D Printers:

1. ELEGOO Saturn Ultra
2. ELEGOO Neptune 4 Max

Resin:

1. AnyCubic ABS-Like

Filament:

1. ELEGOO PLA+

Tools:

1. Pliers
2. Files
3. Box cutter

Materials:

1. Threaded Rods ISO M6 & M8
2. Bolts ISO M2,5, M6 & M8
3. Nuts ISO M6 & M8
4. Cylinder head bolt M3
5. Self-locking nuts M3
6. Washers ISO M6 & M8
7. Hexagon threaded socket M8
8. Headless screws M1,6
9. Ball Bearings 30mm x 42mm x 7mm
10. Steel Spring 0,5 mm x 4 mm
11. Acrylic pipe 150 mm OD, 140 mm ID
12. Acrylic pipe 90 mm OD, 80 mm ID
13. Gasket ring 78mm x 82 mm x 2mm
14. Hose nozzle with metric external thread M10 x 9mm
15. Silicone tube 12 mm OD, 9 mm ID

Components:

1. MG996R Hi-Torque Servo
2. 12 V Hi-Torque DC Motor
3. L298N Motor Control
4. 12V NiMH battery
5. Limit switch
6. ESP32 V4

This component with all of its subcomponents requires the most thought in this project. The WTC encases all the important mechanics and electronics that control the submarine and ensures that water cannot reach them.

I created the rough schematic inspired by the most WTCs you'll find online that enable boats to dive statically.

The tech frame consists of four M6 threaded stainless steel rods on which the components have their designated place, locked with corresponding nuts on each side.

The following steps will be sub-steps of this one.

We'll start with the design and crafting of the piston tank.

Note:

Static diving in RC submarines involves adjusting buoyancy through ballast tanks, while dynamic diving utilizes propulsion systems like thrusters and diving planes for active depth control.

As i wanted to stay as close to the original with technical functions, i opted for static diving for this project.

The most complex subcomponent is propably the piston tank. At this point i want to thank MatzeBautWas for his detailed documentation on his building process. His Video explains the functionality further, but it breaks down to this:

Inside a cylinder, a piston is driven backwards and forwards by an M8 threaded stainless steel rod. This threaded rod is mounted inside a spindle with a corresponding threading. All of this is mounted inside a ball bearing to ensure a smooth and linear movement. The spindle is connected to the motor gear with a reduction of 2:1. The 12V DC Motor i'm using produces 300 revolutions per minute. With the reduction gears, the spindle turns at 150 RPM.

The limit switches mechanically determine both end positions of the piston. One is being pressed by the piston itself through a spring-loaded screw, the other is released when the end of the threaded rod is reached.

I included the .stl files so you can check out the parts here or print them yourself.

Photos of the prototype will follow soon!