I will do my best to make me understand..
Warbirds of the client mod is a multiplayer game mode a bit different from the usual. Because in addition to the dogfight, it also makes a territorial battle because the goal is to take the bases to win the battle and keep them until the end of time.. here are all information well explained in detail:
http://www.war-birds.com/what_is_warbirds_mod.php
or tried, at my own risk, playing with IL-2 with the client-mod active (
it is a thing that is not recommended, it's a mod made just to play on the internet
) but goes equally well with the client (ok I've only tried QMB)