The discovery, made by researchers from Tel Aviv University, may help aviation engineers develop in the future tiny aircraft with a unique and efficient take-off mechanism. The research was presented at a conference held at the beginning of the week in Kfar Blum on the subject of the connection between mechanics and physiology in flying animals.
Researchers at Tel Aviv University's Department of Zoology have revealed the take-off mechanism of the tobacco moth aphid - a tiny creature, whose body is about a millimeter in size, and is better known as a pest that damages a variety of agricultural crops. They found that the aphid launches itself into the air at great speed, and then stabilizes with its wings folded, using the air resistance of the wing tip surfaces. The discovery may help aviation engineers develop in the future tiny aircraft with a unique and efficient take-off mechanism.
"In recent years, there has been a growing trend in the world of collaborations between biologists and engineers, with the aim of learning from the wisdom of nature, and developing tools for the service of man that rely on millions of years of evolution in the animal world," explains Dr. Gal Rybak, who led the research on the aphid mirror, with the assistance of the student Il Daphne. "In my lab we focus on the biomechanics of flight in animals. Among other things, we are trying to find out how the size of the animal's body affects its aerodynamics, and how flying creatures can be imitated in order to design better aircraft. In our latest research, we looked at the tobacco moth aphid, and discovered a unique appearance mechanism: the aphid manages to take off and stabilize itself in the air - even before it spreads its wings."
The researchers filmed the aphids with special video cameras that take 3000-2000 images per second, and then viewed the images at a speed 50 times slower than the original process - which lasted less than 12 milliseconds. "We saw that, unlike many of the winged creatures we know, the aphid does not take off by retracting and flapping its wings." says Dr. Ryback. "First, it steps on a sort of 'biological spring', and launches itself upwards with tremendous force and enormous acceleration (34 times the acceleration of gravity). The launch destabilizes the aphid, and its body begins to roll in the air, but it manages to stop the rolling movement almost immediately - while its wings are still folded and close to the body."
To reveal the secret of the aphid's takeoff and stabilization, the researchers built a computer model of the aphid's body and its aerodynamics. The model showed that the aphid uses air resistance to stabilize, and that the organ responsible for stabilization is the tips of the wings. "We discovered that when the wings are folded to the sides of the body, half of their surface protrudes beyond the length of the body, and that the protruding wing surface produces air resistance that stops the rolling movement," says Dr. Rybak. "In fact, the stabilization mechanism is automatic: the aphid does not have to do anything to activate it, as it is built into its wings from the start." To confirm the findings of the model, the researchers examined aphids in the laboratory, and found that indeed, aphids whose wingtips have been clipped do not manage to stabilize in the air, and continue to roll.
"Our findings may have great significance for aeronautical engineers, who aim to develop tiny artificial flying machines for aerial purposes," concludes Dr. Ryback. "We believe that by imitating the tobacco moth aphid we will be able to design much more efficient take-off and stabilization mechanisms than those that exist today."
The research, which was published in the Journal of Experimental Biology, was presented at a special conference held at the beginning of the week in Kfar Blum, which dealt with the connection between mechanics and physiology in flying animals. The conference was organized at the initiative of Dr. Gal Ribak from Tel Aviv University, in collaboration with researchers from Haifa University and Ben-Gurion University, and 18 leading scientists participated (12 biologists and 6 physicists and aeronautical engineers), including four from Tel Aviv University, and seven from leading universities in the world - USA, Germany, Canada and India.
