Tag Archives: Airplanes

Flying ‘Robotic pigeon’ brings us closer to bird-like drones

Strong and muscular fliers, pigeons are naturally suited to handle the blowy winds between buildings in large cities. That’s why engineers have now turned to them for inspiration, adding pigeon flight feathers to an airborne robot called PigeonBot.

Credit Standford University.

The robotic pigeon integrates true elements of traditional flying machines with elements of biology. David Lentink and colleagues at Stanford University didn’t try to build a machine to act like a bird, which would have been highly challenging. Instead, they closely studied biological mechanisms to learn how birds fly.

“I really wanted to understand how birds change the shape of their wings,” said David Lentink to Popular Science, an assistant professor of mechanical engineering at Stanford and a co-author on a new study which was published in the journal Science Robotics.

Credit: Lentink et al.

Lentink and the team studied common pigeons, looking at their skeletons and feathers. They discovered that the birds control the flight through about 40 feathers, using four “wrist” and “finger” joints to steer their movements. With that knowledge, they recreated the same mechanisms but in a drone driven by propellers.

Image credits: Chang et al (2019) / Science Robotics.

The drone’s body is formed by a foam board frame, with an embedded GPS and a remote-control receiver. The maneuverable wings have actual feathers from pigeons attached. Previous prototypes had carbon and glass fiber but were much heavier, something now solved with the new wing design.

The PigeonBot’s flying capabilities are enabled by a propeller, a fuselage, and a tail. It has motors, a pair per each wing, that can adjust each of the artificial wings and the feathers at two different joints. The researchers can use a remote to move the wing and lead to the robot to turn and bank, mimicking a real pigeon.

“We determined that birds can steer using their fingers,” Letnink said. Both birds’ wings and human arms share basic structural similarities, he and his team argued. For example, wings have humerus, radius and ulna bones and at each wingtip, birds have finger-like anatomy that can move 30 degrees.

Developing the PigeonBot had its challenges and lessons learned for the researchers. One discovery was that the robot works best when all the feathers come from the same bird. Also, incorporating them into the machine required maintenance, specifically smoothing the feathers by hand.

There are parallels between the PigeonBot and actual planes. That’s why Letnik believes that airplanes of the future will make use of morphing wings by incorporating lessons from pigeons and other birds. “You won’t see a feathers airplane but you’ll find mart materials in them,” he argued.

NASA’s morphing wing will make airplanes smoother, more efficient

A new shape-changing wing designed by MIT and NASA engineers could revolutionize the way we design flying vehicles. By twisting and morphing in flight, the “morphing wing” eliminates the need for flaps, ailerons, and winglets, making our planes more efficient and adaptable in the process.

Image credits NASA.

Birds’ wings have long been the envy of the aeronautical industry. While human-built planes may reach higher and fly faster than anything nature produced, they rely on clunky mechanisms and inflexible wings to stay aloft and maneuver. This impacts their energy (and thus, fuel) efficiency, limits the range of motions available, and the speed of maneouver. Birds, on the other hand, can affect subtle or more dramatic changes to their wings in flight, allowing them huge versatility and mobility compared to fixed wings.

So, wing shape has a huge hand to play in determining the flying capabilities of crafts, and rigid designs aren’t always the most efficient. NASA and MIT engineers have teamed together to bring some of the flexibility birds’ wings exhibit to airplanes.

“The ability to morph, or change shape, is desirable for a number of reasons in nature or in engineering, such as responding to varying external conditions, improving interaction with other bodies, or maneuvering in various media such as water or air,” the team explains.

They ditched the conventional system and started from scratch, assembling the wing using “a system of tiny, lightweight subunits” creating a mobile frame. These are covered with overlapping parts resembling feathers, which create the wing’s surface. The whole frame is built using only eight black, slightly squishy, carbon fiber elements — compared to the millions of plastic, composite, and metal parts that make a regular wing — covered with the shiny orange surface. Here’s an experimental, 5-feet (1.5 meter) model NASA put together:

Image credits NASA / MADCAT.

Image credits NASA / MADCAT.

Each of these eight components has a different stiffness, and the specific way they are interconnected makes the wings tunably flexible. Two small engines are all that’s required to twist the wing, changing the way it cuts through the air.

“One of the things that we’ve been able to show is that this building block approach can actually achieve better strength and stiffness, at very low weights, than any other material that we build with,” says NASA’S Kenny Cheung, one of the leaders of the project.

When the team placed a mock-up with the new wings in the wind tunnel at NASA’s Langley Research Center, Virginia, the dummy plane showed some spectacular aerodynamics.

“We maxed out the wind tunnel’s capacity,” says Cheung.

Airplane wings rely on ailerons to change directions and flaps for boosting lift at take-off and reduce landing distance. But when extended or manipulated, these surfaces create gaps in the wing — disturbing airflow, reducing performance, and generating noise.

“They require complex hydraulic and other actuators that add weight, complexity, and things that can go wrong,” adds Mark Sensmeier, an aerospace engineer at Embry-Riddle Aeronautical University.

The full paper “Digital Morphing Wing: Active Wing Shaping Concept Using Composite Lattice-Based Cellular Structures” has been published in the journal SoftRobotics.

First peer review paper on chemtrails finds exactly what you’d expect — it’s all pseudoscience

Pack up your tinfoil hats and sit down, conspiracy buffs everywhere, because I have some bad news — chemtrails aren’t a thing. The conspiracy theory, according to which shady organizations or even governments use aircraft to seed all sorts of chemicals into the air we breathe, just doesn’t stand up to scrutiny, finds the first peer-reviewed study on the subject.

Image via wikimedia

Ah, chemtrails. These glorious, elegant, white trails that airplanes leave in their wake have long been, without any form of proof, believed to be the government’s way of…I don’t know really. Controlling the weather? Controlling our minds? Something nefarious, anyway. Still, the conspiracy theory is going strong, unabated by the total lack of evidence. A 2011 international survey showed that nearly 17 percent of respondents believed in secret, large-scale spraying programs. Humans are very good at finding explanations to fit their beliefs, and everything from how long a trail lasts in the sky, differences in color or shape have been cited as proof that The Government is pumping chemicals into the air, man!

The sad thing is that there actually is an explanation for why these trails form. They’re called contrails, short for condensation trails, and it’s been shown that they form as water vapor condenses around aerosols in aircraft exhaust. The scientific community has been reluctant to engage the issue head on, however, as they do with nearly every piece of pseudoscience or conspiracy theory out there.

Why? I don’t know. Maybe researchers feel that there are better issues to spend their time on, or that their reputation will suffer if they discuss one of these subjects. Maybe they just think that no amount of evidence is going to dissuade some people.

Whatever the cause, ignoring these issues isn’t in anyone’s best interest. Luckily, a team stepped up and published the first peer-reviewed journal article regarding chemtrails. They report not finding any evidence of covert large-scale chemical spraying programs going on, and concluded that distinctive ‘chemtrail’ patterns in the sky can all be explained by the regular science of water vapor.

“We wanted to establish a scientific record on the topic of secret atmospheric spraying programs for the benefit of those in the public who haven’t made up their minds,” said lead researcher Steven Davis from the University of California, Irvine.

“The experts we surveyed resoundingly rejected contrail photographs and test results as evidence of a large-scale atmospheric conspiracy.”

The team interviewed 77 scientists, atmospheric chemists who specialize in condensation trails or geochemists working on atmospheric deposition of dust and pollution. Out of this group, 76 said they hadn’t come across evidence of secret, large-scale spraying programs. The 77th said she came across a “high levels of atmospheric barium in a remote area with standard ‘low’ soil barium.”

In other words, a geochemical imbalance that could be caused by chemicals being sprayed into the atmosphere but no evidence of it actually happening.

The researchers were also shown four images that are commonly circulated as chemtrails, and all of them agreed they were all ordinary contrails. They even provided peer-reviewed citations to back up their statement.

“Despite the persistence of erroneous theories about atmospheric chemical spraying programs, until now there were no peer-reviewed academic studies showing that what some people think are ‘chemtrails’ are just ordinary contrails, which are becoming more abundant as air travel expands,” said one of the researchers, Ken Caldeira from the Carnegie Institution for Science.

“Also, it is possible that climate change is causing contrails to persist for longer periods than they used to.”

The researchers also suggested that contrails are more common these days simply because air travel is becoming more regular.

The team says that their research probably won’t convince anyone who already has their mind made up that chemtrails are real, but they hope it will offer people new to the topic some objective information for when they research chemtrails.

“I felt it was important to definitively show what real experts in contrails and aerosols think,” said Caldeira. “We might not convince die-hard believers that their beloved secret spraying program is just a paranoid fantasy, but hopefully their friends will accept the facts.”

The full paper “Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program” has been published in Environmental Research Letters.