Owl Inspired Noiseless Aircraft In The Pipeline
As I survey the wondrous Manipur with blue mountain ridges and green valley, the dusty country roads beckon me to the land where I was born.
Though politics is not my brand of whisky, I’m like meeerkats of Kalahari Desert that often stand up to look around and make low-pitched barking sounds. I’m a believer in the survival of the fittest or the survival of the best fitted.
With the arrival of a special envoy from Delhi, it seems that the great uprising at Churachandpur is not merely for the three Bills but for a separate political administration of the Khongsais. Why not? The Tangkhuls and Kabuis have been doing it for a long time. What they say in Hindi: “wo apna apna hai”.
While in the valley, the passive wars of bundhs and sit-ins of the Meiteis are causing immense hardships to the plains-people. Khwairamband Keithel, sporadically, continues to don an eerie look of an abandoned cowboy ghost town with dry sedge grass blowing in the wind.
It is said that there have to be wars to have peace. Meanwhile, to rest weary-brains of some of my readers, let me switch on to the ingenuous stealth flying techniques of the wise old owls in their daily nocturnal wars for food for survival.
Owls have fabled mysteries and folklore. Owls have been revered and feared. It is dated back 60 million years and have been found in prehistoric cave paintings.
I can remember seeing an owl as a child in Imphal, brought to our house. Owls are spooky birds for Meiteis because of their creepy, long drawn out shrieks (they do not hoot like other owls). With a seriously ill person in the house and hearing an owl making such an unnatural noise, dead at night from a tree nearby, was regarded as bad omen.
Owls have great cultural significance in Asia. There is a very wide variety of owls in Asia. In Japanese culture some owls are seen as divine messengers, while others, particularly Barn owls, are viewed as demons. In India. A white owl is considered a good omen of prosperity as a form of Lakshmi – the goddess of wealth as well as an icon of wisdom.
Owls have thus been left at arms distance until recently. British scientists, in collaboration with US scientists have now resolved how to make noiseless aircraft. Though they have known for centuries that many owls – primarily large owls like barn owls or great grey owls – can hunt by stealth, swooping down and capturing their prey undetected, they have been unable to understand how and why owls are able to fly in silence.
Those of you who have lived near a busy airport will be familiar with the nuisance value of big aircrafts flying overhead day and light. I have had this experience while staying for a couple of days at a time with a Punjabi friend – Sushma Kapila at Osterly near Heathrow airport in West London.
At London’s Heathrow Airport, 1,400 flights take off and land every day – one every 45 seconds. There are set noise limits for departing aircrafts at 94dB (dB = decibel is a dimensionless unit of noise measurement) during day and 87dB at night. First departure at 6 am and the last at 10.50 pm. All planes follow departure routes until 4,000 ft at which point they are directed off the route towards their final destinations by Air Traffic control.
A research conducted by a few doctors and published in the British Medical Journal (BMJ) on October 8 2013, covering 3.6 million residents living near Heathrow Airport, showed that High levels of aircraft noise were associated with increased risks of stroke, coronary heart disease, and cardiovascular disease for both hospital admissions and mortality.
Recently, Professor Nigel Peake of University of Cambridge’s Department of Applied Mathematics and Theoretical Physics, led a research with collaborators at Virginia Tech, Lehigh and Florida Atlantic universities, using high resolution microscopy to examine owl feathers in fine detail.
They have developed a new coating which mimics the unique wing structure of owls to substantially reduce noise not only in aircraft but in wind turbines and computers . Early wind tunnel tests of the coating have shown a substantial reduction in noise without any noticeable effect on aerodynamics, researchers said.
They observed that the flight feathers on an owl’s wing have a downy covering, which resembles a forest canopy when viewed from above. In addition to this fluffy canopy, owl wings also have a flexible comb of evenly-spaced bristles along their leading edge, and a porous and elastic fringe on the trailing edge. “No other bird has this sort of intricate wing structure,” said Peake.
“Much of the noise caused by a wing – whether it’s attached to a bird, a plane or a fan – originates at the trailing edge where the air passing over the wing surface is turbulent. The structure of an owl’s wing serves to reduce noise by smoothing the passage of air as it passes. over the wing – scattering the sound so their prey can’t hear them coming,” Peake added.
In order to replicate the structure, the researchers looked to design a covering that would ‘scatter’ the sound generated by a turbine blade in the same way. Early experiments included covering a blade with material similar to that used for wedding veils, which despite its open structure, reduced the roughness of the underlying surface, lowering surface noise by as much as 30 decibel.
Research engineers have proposed the possibility of creating retractable fringe to mirror owls’ trailing feather. For the owl, this fringe reduces turbulence and noise. Some researchers think that applying a velvety coating — similar to that of an owl — on landing gear will absorb noise just as it does for the owl.
The barn owl like the Manipuri owl (that I have seen) is pale coloured (beige-white) with a short squarish tail (a distinguishing feature from other owls). It measures about 36 cm in its overall length. It has a heart-shaped pale face like a flat mask with oversized black eyeslits and a ridge of feathers above the bill resembling a nose. Al these make it look like a wise face. it has undulating (rising & falling) flight pattern with feathered dangling legs.
Owl’s eyes are most striking. They are Large and forward facing and that give an Owl its “wise” appearance, also give it a wide range of “binocular” vision (seeing an object with both eyes at the same time). This means the owl can see objects in 3 dimensions (height, width, and depth), and can judge distances in a similar way to humans. The field of view for an owl is about 110 degrees, with about 70 degrees being binocular vision.
The bird has long and wide wings. It hunts by flying slowly, quartering the ground and hovering over spots that may conceal the prey. The ears are placed symmetrically to detect sound position and distance It does not require sight to hunt. Once the target is located it dives to the ground, penetrating its talons through grass, bush or snow to seize the prey with deadly accuracy.
It does not hoot like other typical owls but it produces an eerie long-drawn-out-shriek. When pleased, it will make a ‘kee-yak’ sound. When cornered or captured, it defends itself lying on its back with wings spread out and flailing with sharp-taloned (hooked claw to catch the prey) feet, while emitting rasping sounds.
Barn owls live in hollow tree, old building or fissure in a cliff. They are nocturnal ie they hunt by night and specialises hunting animals on the ground. Nearly all of their food consists if small mammals (breast feeding animals with a spine) especially rodents (rats), which they locate by sound.
They have an effortless wavering flight as they quarter the ground, alert to the sound made by potential preys. They fly silently; tiny serrations on the leading edges of their flight feathers and a hairlike fringe to the trailing edges help to break up the flow of air over the wings, thereby reducing turbulence and noise. Hairlike extensions to the barbules of its feathers, which gives the plumage a soft feel, minimising noise produced during wingbeats.
They are monogamous – a partner for life unless one of the pair gets killed. The females lays egg on alternate days, about 5 eggs and does all the incubation. The male looks after food. As they are prolific breeders,. most barn owls are short-lived, the actual longevity is much higher up to 20 years of age in captivity.
During their courtship, the male emerges at dusk, climbs high into sky and then sweep back to the vicinity of the female at speed. He then sets off to hunt. The female in the meanwhile sits at eminent position and returns to the nest a minute or two before the male arrives with food for her.
For an industry struggling with fuel costs and other problems, the “wise old owl” of English language nursery rhyme may provide some solutions.