Indiana Jen has posted an interesting update on the preservation and restoration of the Confederate submarine CSS Hunley. Interestingly, Hunley is still going to be kept under (fresh) water. The use of water as a preservative against corrosion may seem strange to some, but oxygen is necessary to the corrosive process, so it makes sense.
One interesting aspect of its design is its counter-balanced dive planes, so designed as to make them easier to rotate. They were placed fore and aft. This design might have been a factor in its sinking which many consider to have been due to a loss of depth control. Placing one set of planes forward instead of amidships meant that the angle of the boat was more difficult to control than if one set were placed amidships and dedicated to depth changing. Consider too that the two sets of planes had to be operated manually by different men and somehow coordinated and you begin to understand how formidable that task must have been because the angle of a submerged vessel is inherently unstable.
Modern sub designers struggled with this concept as well. WW II subs and prior had the planes both fore and aft like the Hunley’s, but requirements changed with the advent of the bulbous hydrodynamic shape of the true submersibles made possible by nuclear power. Placing the planes forward on that shape of hull was awkward and made them more vulnerable to damage while maneuvering alongside a pier, but more importantly it interfered with the increasing size and sensitivity of sonar arrays. Designers continued to flirt with forward-placed planes but eventually settled on the midships location, i.e., on the “sail”.
Thus, the sail planes, being near the center of gravity of the boat, can be operated solely to make small adjustments for depth maneuvering while the stern planes are used to adjust the angle of the boat for large depth changes. The penalty for this was a loss of effectiveness by the sail planes at shallow depths (periscope depth) and slower speeds because they were closer to the surface of the water. However, the change proved acceptable because advances in sonar tracking and torpedo-homing technology made operations at periscope depth less necessary.
The Hunley was as much a milestone for engineering itself as it is for war and, I submit, it demonstrates how war itself, abhorrent as it is, promotes technology and economic development. We have come a long way since then. Submarine design is especially apt as a model for technology because as a system it combines all the aspects of engineering, science and physics that I can think of, including:
sonar (active and passive)
radio, including satellite communications
inertial guidance (both weapons and ship)
atmosphere control (oxygen, CO2)
nuclear fusion warheads
sound isolation of equipment
sanitation management in a pressure environment
psychology (isolation, stress, women)
One final thought about this: keeping technology secret is pretty much futile in the long run, although we have to try. One visit to Wikipedia is instructive in showing the breadth, depth, and ubiquity of information in the digital age. It diffuses like salt in the ocean.