Tag: fly

How Can A Drone Cause So Much Chaos In Airports?

In October 2017, a drone collided with a commercial aircraft in Canada, striking one of the plane’s wings. The plane sustained minor damage but was able to land safely.

Research on drone damage to aircraft is still limited but a number of institutions have tested a variety of impact scenarios and each seems to reach a different conclusion.

Other research from the Alliance for System Safety of Unmanned aircraft system through research Excellence (Assure) in conjunction with the US’s Federal Aviation Authority suggested drones could inflict more damage than a bird collision.

The lithium ion batteries that power them may not shatter upon impact, instead becoming lodged in airframes and posing a potential risk of fire.

Ravi Vaidyanathan, a robotics lecturer at Imperial College, London, told the BBC: “The threat posed to larger aircraft by drones is small but not negligible.

“The probability of a collision is small but a drone could be drawn into a turbine. A drone greater than 2kg might break the cockpit windshield as well for certain aircraft.”

Martin Lanni, chief executive of airspace security company Quantum Aviation, said: “A drone looks quite fragile but the battery is hefty and if you compare a drone to a bird, then it could be potentially more dangerous if it goes through the engine or hits the fuselage.

According to the UK Airprox Board, there were 92 instances of aircraft and drones coming close to colliding in 2017.

In the UK, legislation came into force in July, making it illegal to fly a drone within 1km (0.62 miles) of an airport. It is also illegal to fly a drone higher than 400ft (120m).

But experts have pointed out that this could be ineffective, given that a landing aircraft would fly below 400ft. And of course those with malicious intent would have little regard for legislation.

Systems have been tested in some prisons, where drones are often used to smuggle in goods, which aim to block radio signals within a certain area in order to prevent drones from landing.

For airports serious about protecting themselves from drone attacks, there is the option of a more sophisticated, if expensive, system, such as that offered by Quantum Aviation, which employs radar, radio frequency detectors and cameras to detect when drones are nearby and locate where they came from.

In an ideal world, you talk to a person but to do that you need to know where the drones are coming from,” said Mr Lanni.

“What you don’t want is to have them dropping out of the sky.”

The Quantum Aviation system can “jam” a drone – effectively stopping it working – the drone should, in theory, have a default mode that would see it either return to where it came from or land safely.

DJI, the world leader in making civilian drones, introduced geo-fencing systems in its products in 2013.

This technology can prevent drones from flying in some locations and offers warnings to drone operators flying near a restricted zone.

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Pass it on: New Scientist

Bats Have A Vertical “Blind Spot” When Using Echolocation

Bats are well known for their sophisticated use of sound waves and echoes to navigate through areas riddled with obstacles, but now a new study reveals that their use of echolocation can be hindered in the face of smooth vertical surfaces.

The results, published in the September 8 issue of Science, may help explain why injured or dead bats are often found near buildings.

To navigate through the dark, bats rely heavily on echolocation, where they emit high-frequency sounds and use the returning echoes to detect and classify objects in their environment.

However, when Stefan Greif of Eötvös Loránd University was studying how bats use echolocation to recognize water surfaces, he noticed something odd.

I found that bats sometimes collided with our smooth plate when I temporarily positioned it [vertically along] the wall [while] rearranging the setup,” he explained.

That made me wonder why and how those bats would perceive this unusual situation. After my attention was focused on this issue, I started to notice bats sometimes bumping into a metal information plate at the entrance of a cave where we caught bats.

Furthermore, several observations of bats colliding with smooth vertical surfaces (such as glass windows) suggest that bats have problems recognizing them.

Very few smooth vertical surfaces occur naturally in the wild, with objects such as trees and rocks exhibiting rough and uneven surfaces; however, bats do encounter smooth horizontal surfaces in the form of water.

To explore this issue in greater detail, Greif and his colleague Sándor Zsebők monitored greater mouse-eared bats     ( Myotis myotis) as the animals flew through a continuous, rectangular flight tunnel in the dark.

In the corner of the dark tunnel, the researchers placed a metal plate either vertically or horizontally.

Of 21 individual bats, 19 collided with the vertical plate at least once (on average, colliding in 23% of passes) but never with the horizontal plate.

The researchers found that when the bats collided with the vertical plate, they were producing fewer calls, spending less time in front of the plate, approaching the plate at a more acute angle, and had higher flight speeds relative to the bats that avoided collision.

The authors report similar findings in field experiments outside of caves of three different bat species.

It is surprising and intriguing how under certain circumstances even the most sophisticated sensory systems can be tricked into misinterpretation of its environment,” said Greif.

Now that scientists are aware of this sensory loophole for bats during navigation, he noted, they need to gather reliable data about the regular occurrence and extent of these collisions in natural settings.

In ‘high-risk’ areas, like the vicinity of important bat roosts, we should try to avoid setting up unnecessary smooth, vertical surfaces.

In areas where surfaces like extended glass fronts [exist], we should experiment with mitigation tools like acoustic bat deterrents. These emit ultrasonic sounds, inaudible to humans, that are supposed to repel bats.

Even if that fails and curious bats would check on those sounds, they would be very attentive and hopefully realize the obstacles in their way,” said Greif.

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Pass it on: Popular Science

Scientists Discover Diving Flies Using Bubble Submarines To Survive Underwater In California’s Lake Mono

Flies in a Californian lake have abandoned the air for the water.

The “diving flies” of Lake Mono can crawl underwater without even getting wet.

Now scientists have discovered how these insects are able to survive underwater and remain dry.

The flies are incredibly repellent to water; so repellent that a protective bubble of air forms around their bodies when they enter the water.

They also have clawed feet that they can use to anchor themselves to the bottom of the lake.

This strange behaviour was described by the novelist Mark Twain in his travel memoirs, but has never before been understood.

You can hold them under water as long as you please – they do not mind it,” wrote Twain. “They pop up to the surface as dry as a patent office report.

Plunging underwater is “a death sentence” to most insects, said Professor Michael Dickinson, a fly researcher at the California Institute of Technology and one of the study’s co-authors.

Lake Mono in particular doesn’t seem like an attractive place to live. It’s highly alkaline and three times saltier than the ocean.

Despite this, its conditions have proved appealing to these unusual insects.

The hostile conditions mean that there aren’t any predators living in the lake that could eat the flies, but plenty of bacteria for them to feed on.

The chemical composition of the lake should actually make it more difficult for insects to enter it, as negatively charged ions in the water are attracted to positive charges found on insect skin.

What Professor Dickinson and his collaborator Dr Floris van Breugel found was a particularly thick covering of hairs on the diving flies. This hair was coated with water-repellent wax that gave them their aquatic abilities.

The scientists are interested in the applications such a wax might have in materials science, but also in the neurobiology underlying a fly’s decision to live in a lake.

It is such an incredibly weird thing for a fly to deliberately crawl underwater,” said Professor Dickinson.

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Pass it on: Popular Science