The Flakkatrakk or Flakka Trukks is an Ork mainstay anti-aircraft vehicle like the Imperium's Hydra Flak Tank. Essentially a Wartrakk equipped with varying number of Flakka-Dakka Gunz, the design was pioneered by the Mekboy Grimgutz, who was sick of local Ork aircraft constantly buzzing his workshop. He designed the weapon in the course of an afternoon to shoot down the pests much to the annoyance of the Ork pilots.
Firing the same explosive 'glowy bullitz' used by Flash Gitz, Flakkatrakk's weapons are often fired by Grot assistants and are capable of filling the skies with hundreds of rounds per
minute second, making them a grave threat to any aircraft that ventures into its line of sight. Unfortunately, taking Ork accuracy to reality, the likelihood of a Flakkatrakk actually shooting down a enemy aircraft is quite low, sometimes even accidentally shooting down their own aircraft. What's dat git talkin' 'bout? If yah shoot at it an' miss, it'z wun of yerz. If ya hit it, it'z one of derz. Ded simple, see? I seez it Boss, very simplez Boss!
The design has become popular and copied by many other Mekboyz in light of its success, and wherever the Orks are beset by enemy aircraft a Flakkatrakk is likely to appear.
This was the primary orkish ground based anti-aircraft unit before the arrival of Traktor Kannons and even then it is still not bad. Instead of having two twin-linked Heavy 2 guns like the Hydra, the Flakka-Dakka gun just has a single Heavy 4 weapon. It's very useful against infantry in a pinch, just like its Imperial counterpart, but its lack of twin-linked goodness causes it to suffer somewhat in accuracy (Which is not that much of a surprise given Ork marksmanship).
The reason you don't just go straight to a guntrukk squad with Flakka Gunz is the special rules. Flakka-Dakka Gunz can move flat out and fire their weapons, provided their target is a Flyer. This can let you keep up with a Flyer and move across the board to hit some rear armor next turn. The front and side armor is also higher than a Trukk, and you can get a co-axial bolter to spot for you, giving you that twin-linked goodness you so desperately need (and trust us, with Orkish aiming skills, you need it.)
Its big brother is the Flakk Battlefortress which is like a Flakkatrakk on growth pills.