Hummingbirds vs. helicopters: Stanford engineers compare flight dynamics

A quantitative analysis of hummingbird wings shows that they generate lift more efficiently than the best micro-helicopter blades. The findings could lead to more powerful, bird-inspired robotic vehicles. More than 42 million years of natural selection have turned hummingbirds into some of the world's most energetically efficient flyers, particularly when it comes to hovering in place. Humans, however, are gaining ground quickly. A new study led by David Lentink, an assistant professor of mechanical engineering at Stanford, reveals that the spinning blades of micro-helicopters are about as efficient at hovering as the average hummingbird. The experiment involved spinning hummingbird wings - sourced from a pre-existing museum collection - of 12 different species on an apparatus designed to test the aerodynamics of helicopter blades. The researchers used cameras to visualize airflow around the wings, and sensitive load cells to measure the drag and the lift force they exerted, at different speeds and angles.