SAN FRANCISCO — The tech industry’s enthusiasm for building small delivery drones may be getting ahead of figuring out what to do with them.

On Thursday, with much fanfare, Google revealed Project Wing, an experimental program out of the company’s long-term projects division, called Google X. In a video, Google showed a buzzing aircraft — half plane, half helicopter — using a 200-foot fishing line to drop dog treats to a farmer in Queensland, Australia.

But for all the Tomorrowland wonder of a potential delivery-by-drone service, plenty of issues will be tricky to solve. Drone technology has not been thoroughly tested in populated areas, and commercial use of drones is not allowed in the United States. Even if it were, it is not clear that companies could make a profit using advanced, helicopterlike vehicles to deliver dog food, toothpaste or whatever else a modern family might need.

Still, dozens of companies have experimented with using drones for tasks like crop dusting and monitoring breaks in railroad tracks and oil pipelines. Late last year, Amazon revealed its own experimental delivery service, Prime Air, which it says could one day deliver packages to customers within a half-hour.