The design principles for a submarine hull and a spaceship hull are quite different due to the contrasting operating environments. While it is true that both submarines and spaceships operate in extreme conditions, the challenges they face are fundamentally distinct.
A submarine hull is designed to withstand the high pressure exerted by the surrounding water, which can increase significantly as the depth increases. The hull must be strong enough to resist this external pressure to keep the crew and equipment safe within the submarine.
On the other hand, a spaceship operates in the vacuum of space, where there is no atmospheric pressure. In space, the primary concern is not external pressure but rather structural integrity, protection against micrometeoroids, radiation, and thermal management. Spaceships need to be built to maintain internal pressure and provide a habitable environment for the crew.
The forces acting on a submarine and a spaceship also differ. Submarines rely on buoyancy to control their depth, utilizing ballast tanks to adjust their weight and positively or negatively buoyant forces to ascend or descend in the water. In space, there is no buoyancy due to the absence of a medium like water or air. Spaceships rely on various propulsion systems, such as rockets or ion thrusters, to maneuver and overcome the lack of resistance.
Additionally, the materials used in the construction of submarine hulls and spaceship hulls differ due to their specific requirements. Submarine hulls are typically made of steel or other strong metals to withstand the pressure, while spaceship hulls often utilize lightweight materials like aluminum alloys or composites to minimize weight.
In conclusion, while there might be some design elements or concepts that could be shared between submarine and spaceship hulls, they are fundamentally distinct due to the different environments and forces they need to withstand. A submarine hull design would not be directly applicable for a spaceship operating in a vacuum.