Extra-large Autonomous Underwater Vehicles (XLUUVs) offer the potential to rapidly launch and recover smaller AUVs within onboard payload bays on the larger mothership. These launch and recovery operations present control, guidance and navigation challenges, as well as hydrodynamic flow structures that need to be safely avoided. To better understand the size, structure and strength of these flow phenomena, and the implications this has for LAR, experimental testing has been undertaken. A range of assessments including computational fluid dynamic analysis, wind tunnel testing and particle image velocitimetry have been used to comprehensively understand the forces, structures and physics involved. These studies indicate that LAR remains possible, but small modifications to the XLUUVs may aid such undertakings.