The Flying Machine is the first flying unit to be unlocked in the game. They are very useful units, but only useful for two ages and have a high upkeep cost.
The air-raid tactic, where only air units are sent, is useful to attack resource tiles. It decreases the amount of time taken to reach tiles, as the Flying Machines have a much greater base speed than any other unit unlocked at that point (with Research, Parade Grond boosts and Wonders, infantry can move faster, i.e. Pollaxers speed 148). Air-raids work the same as sending in Scouts to check out a tiles military protection, but this can also do a great deal of damage to the tile, as opposed to a scouts semi-suicidal one-way trip.
They become obsolete in the Industrial Age, replaced by the Fighting Biplanes.
The Flying Machine is unlocked by researching the wonder: Leonardo's Workshop at the end of the Feudal Age. There has been a recent controversy that Flying Machines have been 'nerfed', and not being as powerful as they were before on the older servers. Therefore players decide to build other useful wonders, such as The Royal Observatory.
Flying machines are very useful units, but only useful for two ages with a high upkeep cost.
They previously had the same image as Firebrands, but they now have a unique image.