This document is a technical attachment to [1], a paper which provides a study and a methodology for landing and takeoff using a passive tether attached to the aerial platform. This document includes a proof of the flatness of the output y_fL (in Section II) and extended results of the experiments not included in [1] because of page limits (in Section III). The reader interested in the analysis and control of tethered aerial vehicles is also referred to [2], [3], where flatness, controllability and observability is studied, to [4] where the case of a moving base is thoroughly analyzed, and to [5], [6] where the case of multiple tethered vehicles is investigated.