A recent study by Swiss and American scientists has revealed the aerodynamic characteristics that keep bats aloft. Just like insects, bats make use of air currents they set up with their wings to keep themselves in the air during flight. These air currents comprise up to 40% of the total force keeping bats aloft.
Bats are highly manoeuvrable. They are able to beat their wings between 3 and 17 times a second, and are superb aerial acrobats capable of making sudden U-turns when flying at full speed. They perform perfect slaloms and the most complex manoeuvres in even the most difficult and irregular flying conditions. This sublime manoeuvrability stems from their ability to dynamically alter their wing surfaces during flight. Bat’s fingers extend the length of their wings, which are covered in a thin membrane and contain no feathers. The bat uses these long fingers that extend the entire length of these membranous wings and the muscles attached to those bones to control the shape of their wings during flight and also their timing. They adjust their bodies to the desired shape and delicately and accurately determine the subsequent shape to be taken by their wings according to the direction they wish to take. This produces an effect similar to that created by the flaps or ailerons on aeroplane wings. They use pressure receptors on their wings to detect air movements around their wings and transmit the relevant data to their brains, in a manner that no technological device has ever achieved and that scientists have yet to fully understand. These data are analysed in the bat’s brain and the most appropriate wing shape is determined by the nerve muscle system that controls wing movements, together with calculations regarding the animal’s speed and direction.
Geoff R. Spedding, a Southern California University aeronautics and space researcher and one of the authors of the study in question, compares this ability possessed by bats to a flawless, electronically controlled system. Spedding said this on the subject in the New York Times:
We don’t yet understand how the whole system works,” . . . “but it ends up generating a beautiful, orderly airflow over the wing that is just what we’d dial up if we could dial up flow.”
The Aerodynamic Factor Keeping Bats Aloft: The Wingtip Vortex
Scientists used three bats, trained to feed on a mixture of water and honey, inside a wind tunnel in their experiments. During the experiments they observed the air currents around the wing as the bats fed on the food source in question. Scientists made use of coloured water vapour inside the air tunnel and observed the movements of air particles with a camera using laser beams. They were thus able to establish the interaction between the wing and the air around it, and the sort of supporting currents that arose. These observations revealed that the pointed tip of the bat wing sets up a vortex at the tip. Spedding described his observations thus:
The air flow passing over the LEV of a flapping wing left an amazingly smooth and ordered laminar disturbance at the trailing edge of the wing, and the LEV itself accounted for at least a 40 percent increment in lift. . . while the bat’s ability to actively change its wing shape and wing curvatures may contribute to control and stability in the leading-edge vortex.
The lifting effect produced by the wings was previously known in flies, but this was the first time it had been demonstrated in heavier life forms.
The perfect systems in bats can be used in the development of reconnaissance aircraft
The flight mechanisms that establish a flawless system in bats also constitute a source of inspiration for technologies being developed in the field of aeronautics. Heading the list of these are miniature reconnaissance aircraft.
Anders Hedenstrom from Lund University in Switzerland, the main author of the scientific paper, makes the following comments on the subject:
This shows we still have lots of engineering design inspiration to recover from nature. . . This kind of work paves the way for a new generation of bat like robots, or "micro air vehicles" measuring just a few inches in size to be built.
How did such a perfect system first emerge?
This question inevitably confronts us in this most recent study showing that the bat is a life form equipped with the most perfect systems. As we have already seen, the bat’s highly complex manoeuvring systems are directed by the brain, which acts as a flawlessly function command system. The brain analyses data regarding air currents transmitted to it by the receptors installed on its wings like perfect computers and issues flawless commands to the relevant nerve and muscle systems.
If we reflect on the subject a little further, however, we see that organs such as the bat’s wings, fingers, muscles and brain actually consist of cells, and that the cells are made up of a mass of molecules devoid of any consciousness whatsoever. So how are all these cells able to establish a perfect co-operation and communication between them and carry out all the necessary processes in order for the bat to be able to fly? Why is it there is no random activity or chaos among these billions of cells, and how do the cells know how to cause the tissues to which they belong to perform their own particular tasks? Is it possible for the cells themselves to have first planned these systems that amaze and intrigue even scientists working in the most highly advanced laboratories?
Of course not. It is Almighty God Who creates all this system and its functions by commanding them to “Be!” God, our almighty Lord, reveals in a verse from the Qur’an that it is He Who holds flying creatures aloft:
Do they not see the birds suspended in mid-air up in the sky? Nothing holds them there except Allah. There are certainly Signs in that for people who have iman. (Sura an-Nahl