Ballistically protective air passage

A ballistically protective air passage module for an armored structure, comprising:

• a duct having one end and another end;
• a spiral axis;
• a spiral portion of the duct wound about the spiral axis;
• the duct having a first opening at the one end and a second opening at the other end, the first opening displaced relative to the second opening in at least one direction, the one direction being parallel to the spiral axis;
• a continuous girdler of armor surrounding the duct at the one end;
• an armor bell section extending from the girdler and flaring from the duct;
• means at the other end of the duct for catching projectiles;
• wherein the spiral portion is between the bell sector and the catching means.

A low signature, low restriction, ballistically protective air passage assembly formed by a plurality of modules, wherein each module comprises:

• a duct;
• a spiral axis;
• a spiral portion of the duct wound about the axis;
• the duct having an outer opening at one end and an inner opening at another end, the outer opening remote from the inner opening in a direction parallel to the axis;
• an bell section of armor material at the outer opening, the bell section curvedly flaring away from the duct;
• an armor plate adjacent the bell section and faced on the duct at the one end;
• means for catching projectiles at the other end of the duct;
• wherein the spiral portion of the duct is between the bell section and the catching means;
• wherein the one ends of the ducts are adjacent one another, the bell sections together form an unobstructed bell and the armor plates form a continuous girdler encircling the one ends.