This paper discusses the preliminary design and implementation of a simultaneous navigation, and mapping method for operation of multi-copter unmanned aircraft systems (UAS) in forest environments under the canopy. A data collection platform has been developed using a 3DR hexacopter platform equipped with laser scanners, cameras, GNSS and inertial sensors to observe the environment and used as an input to the SNAM methods. Details on this flight prototype are addressed. Furthermore, the paper will include preliminary flight test results of our hexacopter UAS operating in a forest environment. In addition to these discussions, the paper will address some application-specific issues, specifically with respect to biological, civil engineering and archeological applications.