Whiteflies, bugs just 0.3 of an inch long that typically feed on the undersides of plant leaves, may hold the secret to stabilizing the takeoff of small robotic man-made flyers, like miniature drones, researchers at Tel Aviv University say.
When whiteflies take off, they don’t just spread their wings and fly. These tiny insects use a variety of sophisticated techniques that provide them with exceptional stability in the air. These same techniques could be used for drones, the researchers said.
The research, presented at a recent Israel Academy of Sciences and Humanities conference, explores how whiteflies, which belong to the order of insects called Hemiptera, successfully take off without flapping their wings, which are 28 percent longer than their bodies. They raise their wingtips to provide air resistance and stabilize.
The presentation was based on new research following an earlier study published by the Journal of Experimental Biology.
“Whiteflies take a powerful ‘jump’ before they start using their wings in flight,” said Dr. Gal Ribak of TAU’s Department of Zoology, who led the research. “Then, when the insects are moving through the air, they have to stop the rotation of their bodies to reorient themselves for flapping flight. They are able to do that by extending the tips of their folded wings, causing high air resistance behind the body. This aerodynamic force stabilizes the takeoff and only then do the insects spread their wings and start flying.”
Small, but with fast responses
The response time is what is of note here, Ribak said, as all this happens in less than 12 milliseconds without feedback from the nervous system. “Nature is providing us with guidance on how to stabilize the takeoff of small robotic man-made flyers,” he said.
According to the study, conducted in collaboration with the late Prof. Dan Gerling, TAU emeritus professor of Entomology, size is a key component of the insects’ successful ascent. Their tiny size allows them to execute swift stabilizing responses using the air resistance of various body parts.
“The whiteflies leave the ground rotating forward,” said Ribak. “That rotation should result in the insects somersaulting upon leaving the ground. But the tips of the folded wings provide adequate air resistance, similar to the horizontal surfaces on an airplane tail.”
As part of the study, the team filmed the ascent of the insects with high-speed cameras, which allowed them to observe the takeoffs in slow motion and extract 3D data. They then used the data to model the aerodynamics and rotation of the insects during takeoff. The model revealed the tips of the folded wings to be the most important element of the stability mechanism.
“To test this prediction, we clipped the wingtips of some whiteflies and observed their takeoff again,” said Ribak. “As we predicted, the whiteflies with clipped wings were incapable of stabilizing before spreading and flapping their wings.”
The researchers are currently studying other small insects with shorter wings that also leap during takeoff but use alternative mechanisms for stabilizing the jump.