The Biplane is the first Fighter Aircraft and also the first unit to be produced from the Airbase. It is available from the Industrial Age. It has very limited range as the fuel runs out quickly but it is very effective against infantry. It is also not very strong, and will be destroyed quickly by land based AA or other biplanes It is best used to defend a town against invasion.
Like all air units in the Fighter line, Biplanes are much more effective against units than against buildings.