The shape of cars and airplanes directly affect their fuel consumption and performance. For proof of the connection between shape and fuel efficiency, we can look to nature. Biomimetics, which develops technology by imitating living creatures, is acknowledged as a separate branch of science. Yet as has happened in so many other fields, biomimetics is now actively used to design more efficient aircrafts and wind turbines.
With global climate change a serious threat to human existence, saving energy is of crucial importance. Air resistance – or “drag” – is the main force that causes fuel waste. The most important factor in drag is the “drag coefficient,” which is mostly dependent upon the shape of a given object. Objects whose shapes do not sharply contrast the air’s flow lines, and which render the changes in flow lines regular, have lower drag coefficients. In all creatures that move quickly through the air and water, their bodies are perfectly designed to keep their drag coefficients low. Unfortunately, research into these designs is just beginning. Scientists are just starting to study the geometries of certain creatures, in an effort to utilize their shapes to design more efficient vehicles.
The white, or Beluga, whale, has a perfect shape to facilitate its movements in water. Its beaky mouth and characteristic blunt head decrease drag, in spite of its bulky body.
In 1994, Airbus designed a cargo plane to carry very large cargos. As a cargo plane requires an ample interior, it also needs the right design to lower air resistance. In its design, Airbus imitated Beluga whales, which are both very large – and very aerodynamic. As such, the plane became known as the Airbus Beluga (figures 1, 2). In a major departure from normal plane design, a wider fuselage section, which resembles a bubble or hump, was added to the top of the Beluga. This extra space allows the plane to carry very large loads, such as helicopters, satellites, and plane wings (figure 3). The plane, which weighs 86 tons when empty, has the capacity to carry loads up to 47 tons.
The Columbus Satellite, being sent from Germany to Nasa, in Florida.
The plane has been so successful that in order to meet increased demand, the company is planning to build a similar but larger plane, the Beluga XL.
The protuberances on the head and flips of a humpback whale.
In addition to the hump of the Beluga whale, designers have discovered that the rounded fins and heads of humpback whales provide a 10% decrease in drag, and a 5% increase in buoyancy (figure 4). They’ve incorporated these features into the design of next-generation helicopter blades. When a helicopter flies, the blade that spins forward is faster than the blade spinning backward. This situation causes the blade moving backward to temporarily lose lift. Together with turbulence, an extra load is brought to the rotor and the controlling rod, and this decreases the speed and maneuvering ability of the helicopter. In order to solve the problem, the back blade needs to be improved. Humpback whales inspired the solution. German aviation researchers placed 186 rubber protuberances, 6mm in width, on each blade. After good results from wind tunnel experiments, they made test flights and obtained recognizable enhancements in performance.
Thanks to the protuberances, the working angle of the propellers increased from 11 degrees to 17 degrees, and the performance increased 40% (figure 5).
Researchers witnessed a similar increase in performance when using the same principles for hydraulic wind turbines.
New design of wind turbine, inspired by humpback whales.
These are just a few examples of what seem like simple, overlooked qualities in nature that can actually inspire engineers, leading to major technological breakthroughs. We would all benefit from more scientists conducting research on this topic. The wondrous perfection of living creatures allows aircrafts – and our spirits – to soar to new heights.
When designing the next generation of planes, engineers would be wise to look to the sea, where whales offer up a perfect blueprint for decreasing drag and increasing performance.
F. E. Fish, P. W. Weber, M. M. Murray, L. E. Howle, The Tubercles on Humpback Whales' Flippers: Application of Bio-Inspired Technology, Integrative and Comparative Biology 51 (1), 203-213, 2011.
T. Gruber, M. M. Murray, D. W. Fredriksson, Effect of Humpback Whale Inspired Tubercles on Marine Tidal Turbine Blades, ASME Paper No. IMECE2011-65436, 851-857, 2011, doi:10.1115/IMECE2011-65436