Aether / TOP


Facts and figures

2Seas 20
  • Diameter: 1.0 m (motor to motor)
  • Configuration: Hex
  • Weight: < 7 kg
  • Power plant: 240 V Diesel generator and redundancy LiPo batteries
  • Endurance: 24+ hrs
  • Payload: Gimballed thermal and optical zoom camera


Aether (also known as TOP - Tethered Observation Platform) is a generator-powered, tethered, hex-config unmanned aerial vehicle which can reach an altitude of 300 m on its tether. However, this is limited to 120 m in UK airspace due to CAA rules. The airframe and tether weigh less than seven kilograms and include a gimballed thermal and optical camera payload that is controlled by the operator at the ground control station.

The UAV and generator system is housed in a small trailer for ease of transport. The outputted 240 V from the generator goes to a 480 V converter and then is stepped down to 24 V DC on-board the UAV. To ensure a fail-safe system, batteries are also present on the airframe to allow it to land safely if there are any generator issues. The tether is fed in and out by a smart reel which controls the catenary of the triple braided reinforced tether. With this system the observation platform can stay airborne for over 24 hours (the fuel tank on the generator is the limiting factor: it can hold enough fuel for 24 hour operations).

The challenges of this design were mostly related to the tether and smart reel system. Maintaining a steady supply of 240 V from the generator, along with the catenary and resistance of the tether, and the PID control of the smart reel all had to be carefully designed.

The application this UAV is designed for is as a long endurance observation platform of large areas. The project was completed in collaboration with Cardinal Security.