Physics Law Explains Airplane Evolution: Researcher

A physics law can help explain how airplanes evolved. The study also shows why supersonic passenger craft Concorde failed and how companies can improve commercial airplane designs.

According to researchers at the Duke University, airplanes from propeller-driven DC-3s to Boeing 787s have evolved to increase efficiency. The Concorde was too far from the curve of good designs and so ended up as a failed design.

Adrian Bejan, professor of mechanical engineering and materials science at the Duke University, said that a law of physics he proposed over 20 years ago shows that good airplane designs have followed a specific pattern.

Biological evolution takes place over a long timeline. But, airplanes have taken few decades to evolve, letting researchers study them in greater detail.

"The evolution of our use of technology and airplanes to transport people and goods has taken place in little more than a single lifetime, making it visible to those who look. Evolution is a universal phenomenon encompassing technology, river basins and animal design alike, and it is rooted in physics as the constructal law," Bejan said in a news release.

The constructal law states that "for a system to survive, it must evolve to increase its access to flow." For example, the vascular system has evolved over time to let blood flow from large arteries to smaller blood vessels. Bejan said that everything around us, from river systems to tree branches, follow this law, according to a news release.

According to the researchers, good airplane designs can be plotted on a graph and follow specific patterns. The engine mass has remained proportional to the body size of the plane. In addition, an airplane's wing span has also been proportional to the length of its fuselage, Livescience reported.

"The same design features can be seen in any large land animal," said Bejan. "Larger animals have longer lifespans and travel farther distances, just as passenger airplanes have been designed to do. For example, the ratio of the engine to aircraft size is analogous to the ratio of a large animal's total body size to its heart, lungs and muscles."

Bejan collaborated with Jordan Charles, a researcher and development engineer, and Sylvie Lorente, a professor of civil engineering at the University of Toulouse to gather information about airplane designs. The team then plotted thousands of statistics such as year of introduction, size, engine mass, fuel weight, wingspan etc.

The team found that design of the airplanes have followed a specific pattern. And, designs that have moved away from this pattern are the ones that have failed.

The Concorde is retired supersonic passenger airplane. The craft could travel from New York to London, in less than half the time of other commericial airplanes. However, the Concorde was small, had a long fuselage and short wings. The airplane also had huge engines and poor fuel economy, Livescience reported.

Researchers believe that the latest study could help companies design faster, more fuel-efficient airplanes. The study also shows that the evolution isn't limited to biology.

The study is published in the Journal of Applied Physics.

To learn more about Constructal law, visit this page.          

To know more about Bejan and his research, click here and you can read his interview, here.