Time for the Truly Stealth Submarine
By Donald J. Kazimir
Much has been accomplished to quiet submarines over the years—to make them undetectable. Methods used include sound-mounting machinery, insulating the hull to absorb sound, piping compressed air around the outer hull to absorb radiated noise, and coating the hull to absorb active sonar pings.
These all help, and U.S. submarines have been the quietest in the world for many years now. Yet they remain vulnerable to active sonar—from another submarine, dipping sonar from a helicopter, and from surface ships. To make a submarine truly "invisible" under water, we need to design it so it will not reflect a sonar ping. If we can do it with aircraft that deflect radar, we can do it with submarines.
The problem is difficult, but it can be solved with creative engineering. The sides and bow need to be sharp on the edges, the sail angled on all sides, the rudder shaped to deflect, and the propeller hidden (see Figure 1). This is an effective design; engineering creativity becomes a factor when we try to make it practical.