Gyrocopters have two main purposes: to scout, and to attack air units. If someone is making a lot of air units, use Gyrocopters to attack them. Upgrade the Gyrocopter to enhance it with more damage.
Gyrocopters also act as detectors for invisible units.
The ingenious dwarven engineers, taking a nod from their inventive gnomish cousins, constructed the ultimate airborne scout
vehicle. The gyrocopters are small but versatile flying machines that can cover great distances at speed and evade enemy ground forces. Though the contraptions are somewhat rickety, they are armed with mounted cannons and bombs, and piloted by the daring – if not insane – dwarven pilot corps.