BEND, Ore. (AP) — A team led by an engineering professor at Oregon State University-Cascades has developed a prototype hybrid engine for small, unmanned aerial vehicles, in what could be a significant development in drone technology.

Unmanned aerial vehicles, known as drones, and particularly small drones, are often limited by the amount of battery power. A hybrid engine, using a gasoline-powered engine to re-charge an onboard battery, allows the vehicle to stay aloft longer.

Chris Hagen, OSU-Cascades assistant professor of energy systems engineering, and his team managed to scale down the con...