Any airline pilot knows that birds occasionally disrupt aircraft during flight. The most famous incident occurred in 2009, when Chesley "Sully" Sullenberger landed crippled Flight 1549 in the Hudson River after the engines were disabled by a flock of Canadian geese.
According to the U.S. Army, the birds are at it again. This time, hawks and falcons are after the Army's Robo-Raven surveillance craft.
"Generally we don’t see them coming," said mechanical engineer John Gerdes, who works with the Vehicle Technology Directorate at the U.S. Army’s Aberdeen Proving Ground in Maryland. "They will dive and attack by hitting the bird from above with their talons, then they typically fly away."
These predators are attacking Robo-Raven because it looks so much like a bird. The wings flap completely independently of one another, and they can be programmed to perform a variety of motions that allow the craft to roll and dive.
The wings are operated by two independent motors that can be electronically synced together to coordinate wing motion. A handheld radio controls the robot's flight. The motors are much quieter than airplane engines or propellers, which means that the robotic bird can swoop much closer to a target before being noticed.
Robo-Raven is composed of 3D-printed thermal-resistant plastic, foam and carbon fiber. Its wings and tail are covered in Mylar foil. Even though the craft is over 2 feet (60 centimeters) long, it is lighter than an empty soda can. Like real birds, Robo-Raven has a hollow skeletal structure.
Currently, the robotic bird can fly with a small video camera in winds of up to 10 mph. However, researchers hope to increase its payload using improved flight dynamics.
The Army has also noticed that seagulls, songbirds and even crows sometimes fly in formation with Robo-Raven when it's conducting test flights.
