Cyclic elongation of strength member in operationFatigue damage of electric conductors due to strain limit < 0.1% at high number of load cycles
Scalability to high power transmissionLow voltage design too heavy. Protection of hight voltage design needed.
Length adaptationSqueezing and deformation leads to damage of electric system on drum. Protection of electric system needed.
Figure-8-pathTwice the area required compared to a circular path
Large load changes and torsion leads to fatigue
Tether: fatigue challengeFor Airborne Wind Energy, an ultralight and fatigue resistant tether is required, windable under workload.
Until now, this is still a missing key element. The tether design of the Makani project e.g. was not windable under workload.
This major drawback has led to a fixed working length, which was a main reason for instable flight conditions and crash.
The swiss inventix tether design fulfils all requirements for Airborne Wind Energy production with crosswind flying drones.