For taking down those pesky Space Marine Landing Craft…
This is my Ork Anti-Dropship Flakwagon.
The concept is that upon sighting an Imperial Dropship (or similar) it would fire all three rockets and attempt to take it down.
It is also used on the battlefield as a heavy artillery piece as well.
It is an Ork Flakwagon with the side panels cut off. A Hydra central unit (from the main weapon) is stuck onto the back and then three Pulsa Rokkits are stuck on that.
It could also be used as a Ork Soopagun.