An undersea vehicle having both low emitted noise and low reflectivity is
provided. The undersea vehicle has a hollow cylindrical hull with all
components, sensors, electronics, motors, and other internal components
with the exception of the propellers, located within the shell of the
cylindrical hull. The hollow center of the hull provides a duct and
propeller configuration with the shaping of the inlet tube designed to
reduce forward noise transmissions, such as reflected active sonar
signals and emitted noise. The internal duct gradually constricts to a
throat section and thereafter diverges to an output section where dual
counter-rotating propellers are located. The result is that most of the
internal turbulent flow and the propeller noise is located behind the
throat and is thereby reflected in the aft direction. Steering of the
vehicle is accomplished by canting the leading edge intake section and
the duct exhaust section.