The biggest challenge to the plans of Amazon, Google and others to deliver packages directly to customers using unmanned aircraft may be the recipients themselves, including their unfortunate tendency to reach up to grab packages while they are still attached to the aircraft.
The man who launched and led Google’s Project Wing for its first two years thinks package delivery by unmanned aircraft “absolutely is going to happen,” but has revealed some of the challenges identified by the search giant in its research and development effort.
“The biggest challenge for precision delivery is going to be the user,” says Nick Roy, a professor who took a sabbatical from Massachusetts Institute of Technology (MIT) to start the project, including conducting real-life delivery trials in August on a farm in Australia.
Challenges to be overcome before package delivery by unmanned aerial systems (UAS) can become a reality include issues of air-vehicle safety and reliability, customer privacy, neighborhood noise, wind turbulence and even the possibility of packages being stolen.
Project Wing was established within the Google X “Moonshot” organization to wrestle with “hard problems that could change the world,” Roy said in October at a Washington conference organized by the American Helicopter Society International.
Roy says Google X likens the problems it tackles to “a toothbrush—something we face at least twice a day.” Other projects include developing self-driving cars and airborne platforms to deliver Internet access to the two-thirds of the world that lacks connectivity.
The problem being addressed by Project Wing is that transmission of information has been revolutionized while movement of physical objects is largely unchanged. “Self-flying vehicles can be the next-generation platform for rapid and safe delivery on demand,” he notes.
Specifically, Google wants to “allow anybody to ship anything to anywhere at any time,” Roy says. “Our focus is on speed. That’s the attraction of an air vehicle. It’s not same-minute delivery, but we want to fly as quickly as we can over an urban environment. That is the problem we are tackling.”
Google evaluated a range of fixed- and rotary-wing configurations for its prototype before selecting a hybrid design (see photo) that takes off and lands vertically as a tailsitter and transitions to a flying wing for cruise. Small multicopters could not carry the desired payload or fly fast enough, he says.
One lesson learned is that “physical appearance tends to impact on the public impression” of UAS, because of the association with armed drones, so a non-threatening design is needed, says Roy, who has returned to MIT but continues to consult on Project Wing.
Google decided to winch the payload down from the hovering vehicle after looking at, and rejecting, the idea of dropping it ballistically. “It was surprisingly hard to insulate it from the shock, and the user experience was horrible,” he says.
Landing the vehicle, although looking preferable, also was rejected. “The user experience is terrible. It is hard to stop people reaching for the vehicle,” Roy observes. In tests, users were likely to grab the package before release up to 60% of the time.
Research showed it was feasible to deliver packages in urban environments using information already collected for Google Earth. Analysis of Mountain View, California, looking for a 2-meter (6.5-ft.) gap to land the payload 5 meters from the customer’s doorstep, showed 90% of houses could be covered.
But available databases do not capture obstacles such as power lines strung across streets, or trees that change with time. “Unless we have the capability to update them in real time, UAS will have to have onboard sensors to detect obstacles,” explains Roy.
Wind in urban environments is another challenge, with buildings shedding vortices that result in complicated flowfields below rooftop level. “We can model buildings to know where vortices are and avoid flying or delivering there. We can build windfield models to fold into planning.”
Delivery UAS “will need to handle wind speeds up to 20 kt. if we want to cover 90% of addresses in the U.S., but vehicles consume more power in higher winds, and wear and tear on lithium polymer batteries will be an issue,” Roy says.
Noise will be a concern, particularly for neighbors of customers receiving deliveries. “It is less about decibels and pure sound energy and more about quality. Certain types of noise are objectionable. We don’t have answers yet,” he adds.
This version of this article appears in the November 3/10 issue of Aviation Week & Space Technology.