Autonomous flight of a single Unmanned Aerial Vehicle has become routine for many research teams. Our interests include multi-vehicle operation as well as developing guidance and control algorithms for each vehicle. These algorithms also need to be implemented in flight hardware and successfully flight tested. A flexible simulation environment is one of the key ingredients towards this goal, more so if heterogeneous vehicles and flight hardware are involved. This paper introduces an integrated simulation and development environment including a code generator, a standard vehicle interface library and unified hardware that enables using the same flight infrastructure for avionics ranging from over 10 lbs to just above 1 lb. The lower payload vehicles have severe restrictions on communications, and processing resources and are most often custom avionics. Reconfigurability for software-in-the-loop (SITL), hardware-in-the-loop (HITL), flight and extension to multi-vehicle operations is emphasized, all using a common code base.