Camouflage of Stealth Aircraft Inspired by Nature
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A new research with a wide range of applications has been inspired by ultra-black butterflies. The findings could help engineers design thinner ultra-black coatings that reduce stray light without weighing things down, for applications ranging from military camouflage — for stealth aircraft that can’t be seen at night or detected by radar — to lining space telescopes aimed at faint, distant stars.
The Duke University research team studied the ultra-black wings of the male cattleheart butterfly, that are 10 to 100 times darker than charcoal, fresh asphalt, black velvet and other everyday black objects. As little as 0.06% of the light that hits them is reflected back to the eye. That approaches the blackest black coatings made by humans to help solar panels absorb more energy from the sun, or that line telescopes to reduce stray light.
Yet they achieve this light-trapping effect using wing scales that are only a few microns deep, just a fraction as thick as the blackest synthetic coatings.
According to phys.org, the secret to making blacks this dark and lightweight is an optical illusion created by the 3-D structure of the butterflies’ wing scales. Light goes into their scales, but very little of it bounces back out.
The team used high-resolution scanning electron microscopy and computer simulations to examine the microscopic structures on the wings of 10 species of ultra-black butterflies and four regular black or dark brown butterflies from Central and South America and Asia.
Until recently, the explanation for the incredible light-absorbing properties of some black butterflies was that it was due to a honeycomb-like pattern in the tiny holes on the scales’ surface. But the new study suggests that holes and pillars are deeper and thicker in ultra-black scales compared to “normal” black scales.
Eventually, the study published on the journal Nature Communications could have implications for military camouflage technologies development.
