A special scenario from GW to celebrate the release of the Grot Bommer (WHC Article)
If for some reason you don't have the Ryns World book the scenario includes the rules for using both types of Ork Bommer that were not included in the starter set. The scenario also allows you to take Grot Bombs as stand alone aircraft instead of air launches (!).
'After an especially raucous evening in the mekyard, involving too much squig-nog, Rudok Redz bet all the other Grots he could “bomm more ‘umies than any of ‘em” (completely oblivious to the fact that a successful Grot Bommer kills themself in the process). In an uncharacteristic display of spontaneous enthusiasm, the Grots scrambled to their aircraft to prove Rudok wrong... much to the confusion of the Ork flybosses who turned up the following morning to discover all their Eavy Bommers, Grot Bommers and Grot Bomms missing.'
Download the scenario here.