Keep Your Drone on a Leash

Tethered drones aren’t as well known as their free-flying counterparts, but can be more useful.


The New York City Fire Department, the largest in the country, recently used a drone for the very first time to help fight a blaze. On March 6, a fire broke out in a building in the Bronx that quickly grew to a four-alarm blaze, posing significant dangers to firefighters who needed to get to the roof of the building. Normally they would scout out the situation from a taller building nearby. Instead the department used a drone—a Hoverfly Technologies LiveSky—to take high-resolution color and thermal infrared footage that gave them a clear understanding of the fire for safe access.

What made this particular UAV ideally suited for the job was the use of a hardwire tether from the ground, which provided continuous power and an uninterrupted video feed. Only a handful of tethered drones are on the market, but as the Bronx fire shows, emergency responders are finding them useful.

Because they get their power from the ground, tethered drones can stay aloft indefinitely, or at least until a critical component like a motor or propeller fails. In emergency situations, that can mean the difference between life and death. They also can use more power than a battery-reliant drone, which translates to larger motors and heavier payloads. Power and persistence comes at a cost, though: The tethered drones are less maneuverable, and can only fly as high as the tether allows. 

Hoverfly Technologies started off building components for do-it-yourself drone builders, but the company’s current focus is on “persistent aerial video solutions” like the eight-pound LiveSky. HoverFly isn’t alone in this small niche of the unmanned aerial vehicle market: Competitors include CyPhy and PowerLine

We’re likely to see many more tethered drones in the future for “can’t-fail” tasks that don’t require much mobility. AT&T recently tested a cellular telephony repeater mounted to a tethered drone, perfect for setting up temporary cellphone networks after major storms or at remote music festivals. Those same qualities interest the military, which may one day use tethered drones as a rapidly deployable version of the Ground Based Operational Surveillance System, or GBOSS, frequently used to protect small forward operating bases. One military source, who used to be in charge of a high security government installation, pointed to another advantage of tethered UAVs: Because flight control and data transmission are hard-wired and not radio-wave based, their navigation systems can’t be spoofed or overtaken, and their video feeds can’t be hacked. 

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