Physics model

The Silent Hunter series did a decent job at simulating the U-boat physics. If you play close attention though, you can somewhat tell they were a bit ‘scripted’.

For the U-boat Simulator, I am working with a very generic physics method aimed at somewhat accurately simulating a few key things:

  1. Air resistance (the conning tower has resistance applied to it when moving or in strong winds)
  2. Viscous water resistance
  3. Slamming forces
  4. And hydro-static forces (buoyancy)

To achieve a generic model, the U-boat and other boats in the game have a hidden optimized mesh model which represents the sub. Each frame, the mesh is recalculated into two pieces, one for above water, and one for under. Each triangle in the mesh then has the 4 values mentioned above computed. This means that the U-boats design plays a crucial role in it’s maneuvering profile.

 

Physics mesh

Above water physics mesh

Underwater Physics Forces

Surfacing physics forces

Power-plant / drivetrain

One of the most important aspects of a deep simulator is the ability to override the automation of certain systems and have full control over all settings. In a U-boat, the power-plant is arguably the most important system; it moves the boat, and charges (or discharges) batteries, blows ballast tanks when surfaced etc.. . Without the power-plant, the U-boat is useless.

In order to simulate an accurate and fun system, I have pulled specs from the VIIC manual. The main powerplant layout includes two banks of motors, engines, 2 clutches, and the propeller itself.

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VIIC Blueprints / Model

When building a simulation, it is critical that the models, both physics/mechanics and visual, represent the real world object as accurately as possible. Even though the WWII U-boats were closely guarded, over time (through historical accounts, released documents, and even a captured U-boat now turned into a museum), information has become more readily available for those who seek it.

After weeks of research I have amassed enough information to incorporate into the game. My focus, from the start, was to simulate the majority of the U-boat fleet, the VIIC . The blueprints I am using as a reference for most of the work are:

VIIC blueprints

Continue reading » VIIC Blueprints / Model