Biplane

 is a generic air unit available in the Industrial Era after researching the Aeronautics technology.
 * Description
 * Although monoplanes offer aerodynamic advantages over the biplane, their structural weaknesses mean that the twin-wings have gained early dominance in the skies.

Class and Specialty

 * Patrol aircraft unit able to provide and counter enemy aircraft.
 * Patrol aircraft unit able to provide and counter enemy aircraft.

Unique Action

 * Air Patrol
 * Toggle patrol mode for the Air Unit. While patrolling the Air Unit provides over their Territory and adjacent Territories, and will also intercept enemy Air Units that attempt to perform air strikes in these Territories.