Hummingbirds hover more efficiently than helicopters

If you’ve ever watched a hummingbird drink sweet nectar, you’ve noticed its amazing wings that flutter up to 80 times per second, making it act like it’s floating in the air. In fact, hummingbirds are the only birds that can be kept hovering, which is a unique feature that has an expensive energy price.

What determines the efficiency of this behavior and what is it like compared to flying machines made by humans? These are the questions that scientists from Stanford University and Wageningen University wanted to answer.

Using helicopter and airplane design theory, scientists predicted that the characteristics of a hummingbird wing (the relationship between wing length and width) determine aerodynamic efficiency. However, hummingbird flight performance is particularly difficult to measure, as the forces it generates are too small.

To overcome this, the scientists used separate wings of the museum specimens and placed them on an apparatus called a wing rotator, to measure the resistance. The team then combined the data with those taken from wild hummingbirds, which allowed them to determine how much strength the hummingbird’s muscles must have to keep the bird afloat. They then compared the performance to propellers made by humans for a micro-helicopter called the Black Hornet to determine what was more efficient.

Scientists have reported several interesting discoveries. They found that the force required to maintain hovering was highly dependent on wing characteristics. During downward swing, wings with a higher ratio need much less power than those with lower ratios.

While most hummingbirds have similar results as a helicopter, they have discovered a species of Ana’s hummingbird (Calypte anna) that is 27 percent more efficient.

“It shows us that if we design wings with the same properties, we will have drones that will hover as efficiently as hummingbirds, if not more efficiently,” said lead researcher David Lentink.

Gallery

1 / 2 Photo: Shutterstock

If you’ve ever watched a hummingbird drink sweet nectar, you’ve noticed its amazing wings that flutter up to 80 times per second, making it act like it’s floating in the air. In fact, hummingbirds are the only birds that can be kept hovering, which is a unique feature that has an expensive energy price.

What determines the efficiency of this behavior and what is it like compared to flying machines made by humans? These are the questions that scientists from Stanford University and Wageningen University wanted to answer.

Using helicopter and airplane design theory, scientists predicted that the characteristics of a hummingbird wing (the relationship between wing length and width) determine aerodynamic efficiency. However, hummingbird flight performance is particularly difficult to measure, as the forces it generates are too small.

To overcome this, the scientists used separate wings of the museum specimens and placed them on an apparatus called a wing rotator, to measure the resistance. The team then combined the data with those taken from wild hummingbirds, which allowed them to determine how much strength the hummingbird’s muscles must have to keep the bird afloat. They then compared the performance to propellers made by humans for a micro-helicopter called the Black Hornet to determine what was more efficient.

Scientists have reported several interesting discoveries. They found that the force required to maintain hovering was highly dependent on wing characteristics. During downward swing, wings with a higher ratio need much less power than those with lower ratios.

While most hummingbirds have similar results as a helicopter, they have discovered a species of Ana’s hummingbird (Calypte anna) that is 27 percent more efficient.

“It shows us that if we design wings with the same properties, we will have drones that will hover as efficiently as hummingbirds, if not more efficiently,” said lead researcher David Lentink.

Gallery

1 / 2 Photo: Shutterstock