New study of how birds fly set to lead to everything from better adhesives to stronger, more efficient aircraft wings
Scientists investigating the structure of bird feathers have revealed some of the secret of of flight and what they have discovered could lead to a new generation of materials for humans.
You may as a child have played with a feather: Running a hand along a feather's barbs and watching how the feather unzips and zips, miraculously seeming to pull itself back together.
That unique zipping mechanism could provide a model for new adhesives and new aerospace materials, according to engineers at the University of California San Diego.
Researcher Tarah Sullivan, is the first in about two decades to take a detailed look at the general structure of bird feathers (without focusing on a specific species).
‘The first time I saw feather barbules under the microscope I was in awe of their design: intricate, beautiful and functional,’ said Sullivan.
She 3D-printed structures that mimic the feathers’ vanes, barbs and barbules to better understand their properties- for example, how the underside of a feather can capture air for lift, while the top of the feather can block air out when gravity needs to take over.
Sullivan found that barbules – the smaller, hook-like structures that connect feather barbs – are spaced within 8 to 16 micrometers of one another in all birds, from the hummingbird to the condor. This suggests that the spacing is an important property for flight.
‘As we studied feathers across many species it was amazing to find that despite the enormous differences in size of birds, barbules spacing was constant.’
Sullivan believes further investigation of the vane-barb-barbule structure could lead to the development of new materials for aerospace applications, and to new interlocking one-directional adhesives. It could also revolutionise aircraft wing design, improving airflow and lift.
Sullivan also studied the bones found in bird wings and like many of her predecessors have highlighted before, she found that the humerus– the long bone in the wing– is bigger than expected. However using mechanics equations, she was able to show why that is.
She found that because bird bone strength is limited, it can’t scale up proportionally with the bird’s weight. Instead it needs to grow faster and be bigger to be strong enough to withstand the forces it is subject to in flight.
This is known as allometry -- the growth of certain parts of body at different rates than the body as a whole. The human brain is allometric: in children, it grows much faster than the rest of the body.