Simple double barrel automatic cannon. Due it's size suffers from low ammo capacity but at the same time has really big muzzle velocity.
Controls:
just select cannons while in flight, and shoot them (BY DEFAULT IT'S LEFT ALT)
Adding it on your vehicle:
Simply detatch the cockpit, and drag it to subassemblies (up-left corner), name whatever you want, then load your aircraft>+>Sub Assemblies>type the name of assembly>drag it out and simply place it on pylon or whatever you gonna place it on.