Power and Optical Tether

Conducting tether is a complicated cable having high ratio of breaking strength to weight, a combination of elastic and rigid properties; a combination of rope and cable; a piece of miniature of strength etc.

The conducting Tether is used for holding and supplying electric power to the airborne payload.

a) Breaking strength: only Kevlar yarn is suitable material to obtain high breaking strength/weight. The quantity of Kevlar is constant at a rated breaking strength.

b) Voltage drop: only copper is the best conductor having mechanical as well as good electrical conductivity properties. For a fixed voltage drop per 100 metes. At a fixed load the conductor size is constant.

c) Outer diameter: outer diameter totally depends on the breaking strength component, conductor and protective sheath. The choices in sheath are very limited.

d) Kevlar has some elastic properties. During load the Tether length increases and comes to its original position when the load is removed whereas this property is not possible in any conducting metallic material. Thus a compensation of differential elongation is also critical.