Alan Levin for Bloomberg:  Hank sat impassively on a Virginia Tech athletic field, ready to take it on the chin for the future of drone commerce.

About 30 yards away, an eight-rotor unmanned copter hovered, buzzing like a swarm of bees. The 21-pound drone tilted forward, accelerated sharply and slammed into Hank’s head, smacking the crash-test dummy’s neck backward and embedding shards of shattered propeller in his plastic face.

There is little disagreement that the small- and medium-sized drones flooding the U.S. market can seriously injure or even kill someone. Understanding and minimizing the risk will be key to convincing regulators to expand their permitted uses, clearing the way for plans by Amazon.com Inc. and Alphabet Inc. to have them deliver packages or news outlets such as Time Warner Inc.’s CNN to use them for aerial video.  Cont'd...