When you think of a UAV or consumer drone, generally speaking, you picture a relatively small aircraft. Drone sizing changes drastically when you add a tether or plan on flying in the upper-atmosphere. In both of those cases, you can expect the drones being used to be much larger.
The big business is moving to even larger drones. This is an amazing world of tethered and upper-atmosphere drones, some staying aloft for years on sunshine alone. Some tethered drones create 30 kW to 600 kW of electricity by grabbing the more consistent winds above the height that a ground-based wind turbine can access. The power of those winds is four times more. Such tethered craft range from several meters across up to the size of a jumbo jet (though much more spindly), in that case with eight huge propellers getting the drone to altitude and then becoming wind turbines. These technologies used to be mostly based on cloth kites and then moved to semi-fixed aerofoil wings, but a melding of fixed-wing and multicopter technology makes them a more controllable, efficient aircraft, even able to autonomously take off and rise to position when there is no wind at all at ground level.
Larger designs are commonly used on:
- Solar drones
- Airborne wind energy generating drones
- Tethered perpetual security drones
- Airships and balloons