Image Caption: Anthony of Open Plans holding one of two tethers to the first ever Public Laboratory balloon rig flown from a skyscraper rooftop. Photo Credit: Javier do la Torre.
To be successful, urban flights frequently require a greater degree of control than a single tether can provide. The New York City crew has been testing methods for controlling balloons in dense urban settings where there is limited vertical and horizontal space.
The narrow "canyons" of abrasive building facades in Lower Manhattan's Financial District pose a threat to a basic balloon. The limited horizontal space in crowded urban plazas or rooftops mean than simply running after a balloon being blown far off to one side by turbulent urban winds is not an option.
One effective solution has been to put multiple tethers attached to one balloon, or when required, multiple balloons. Varieties of two or three tethers have been successful and have the additional benefit of being able to more easily focus the balloon's Point of View over the intended ground target. Often a secondary tether will be made of Spectra or some ultralight line.
This method requires additional communication between people flying the rig. It also provides a kind of insurance that if one of the flyers is disabled (for instance during a crowded event), the balloon is still held by a partner.
Community researchers: Oscar Brett, Zach Postone, Leif Percifield, Liz Barry