Tag: flight

Using Turbulence in Flight
When small, heavy particles are in a turbulent flow, they settle faster than in a quiescent one. Their interactions with turbulent eddies sweep them along, extracting energy that lengthens their overall path but reduces the time necessary for them to fall. Using the same principles, researchers are finding ways for rotorcraft and other vehicles to extract energy from turbulence for more efficient flight.
The technique forces a vehicle to behave like a heavy particle by sensing turbulent gusts from its own accelerations and adding forcing to those accelerations when they are in the desired direction of flight. In essence, the vehicle uses the turbulence of its surroundings to find helpful tailwinds. (Image credit: A. Soggetti; research and submission credit: S. Bollt and G. Bewley)
May 12, 2022
Hovering Hawk
Birds have a level of control in flight that would make any engineer jealous. This 2021 Audubon Photography Award winning video by Bill Bryant shows off the skills of a red-tailed hawk. On this occasion, the hawk is using strong winds coming off the Rocky Mountains to hover in place. Notice how active his wings and tail are in adjusting to the changes in the wind while his head is perfectly still. With his head still, the hawk can scan the ground for mice and other prey. It’s absolutely incredible to see how effortlessly the hawk is accounting for unsteadiness in the wind here! (Video and image credit: B. Bryant; via Audubon)
September 3, 2021
Flying Spiders Use Electric Fields
Many species of spider fly with a technique calling ballooning. We’ve touched on spider flight before, but more recent research adds a new dimension to the phenomenon. Researchers showed that spiders can actually use electrical fields in their flight. When isolated from flow or outside electrical fields, researchers found that spiders would still begin ballooning behaviors when subjected to electrical fields similar to those found in nature. The spiders were even able to take off in the artificial environment, using the electrostatic force between the surrounding fields and their negatively charged silk strands. While electrical fields alone were enough to get spiders aloft, the team thinks spiders in nature likely still use a combination of electrostatic force and aerodynamic drag in order to travel the vast distances spiders have been known to cover. (Video and image credit: BBC; research credit: E. Morley and D. Robert)
May 17, 2021
Planes Lift
Need a little refresher on how airplanes fly? The middle school students of The Nueva School have you covered with their latest science rap parody. They take a look at the four main forces on a flying airplane and even dig a little bit into the principles behind lift generation. Check it out! (Video and image credit: Science With Tom/Science Rap Academy)
April 19, 2021
Audubon Photography Awards
Several of this year’s Audubon-Photography-Award-winning photos feature birds interacting with fluids. The Grand Prize Winner, by Joanna Lentini, features a diving double-crested cormorant. Like many other species, these cormorants launch themselves into shallow waters from above and endure some incredible forces to do so. They’re no slackers underwater, either; when I encountered a flightless cormorant while snorkeling in the Galapagos, it outswam me in an instant.
The other prize winners above are a little more splashy. The American dipper’s splash curtain comes from sticking its head underwater in search of prey. The Anna’s hummingbird seen in the last image is playing in the spray of a fountain and showing off its aerial agility while doing so! (Image credits: cormorant – J. Lentini, dipper – M. Fuller-Morris, hummingbird – B. Ghosh; via DPReview; submitted by Kam-Yung Soh)
July 24, 2020
How Did Pterosaurs Fly?
One of my favorite aspects of fluid dynamics is how well it pairs with so many other fields, from mathematics and space exploration to biology, medicine, and even paleontology. That last field is key to today’s question, namely: how did a prehistoric reptile the size of an F-16 manage to fly?
As Joe’s video describes, many factors went into Quetzalcoatlus’ flight. The pterosaur had strong but hollow bones to save on weight while anchoring flight muscles. Its wing shape mimicked an airfoil’s. And, finally, it overcame the challenge of taking off by using both its front and hind limbs to leap off the ground, much like modern bats do.
There’s no doubt that it would be stunning (and probably terrifying!) to see these creatures in action. But you may wonder how scientists piece together these animals from incomplete fossils. Don’t worry! There’s a video for that question, too. (Video and image credit: It’s Okay to Be Smart; see also the video’s references)
June 12, 2020
Choosing Swimming Over Flight
When studying modern birds it quickly becomes apparent that they can either be good at swimming or at flying, but not at both. The characteristics that make wings good for flying are diametrically opposed to those that make for a good swimmer. So most species have chosen to invest in one strategy or the other. Penguin ancestors chose the swimming route tens of millions of years ago, in the aftermath of the extinction event that emptied our oceans of the large reptilian predators that had ruled them during the age of the dinosaurs. This video explores what we know about the fossil record of these birds, and it’s pretty incredible. Did you know there used to be 2-meter-tall penguins? (Image and video credit: PBS Eons)
April 22, 2020
Using Flow Separation to Fly
Fixed-wing flight typically favors the efficiency of long skinny wings, which is why so many aircraft have them. But for smaller flyers, like micro air vehicles (MAVs), short and stubby wings are necessary to stand up the disruption of sudden wind gusts. But a new MAV design eschews that conventional wisdom in favor of a biological tactic: intentionally disrupting the flow.
Usually designers aim to have a smooth, rounded leading edge to wings in order to guide air around the airfoil. But here researchers instead chose a sharp, thick leading edge that immediately disrupts the flow, causing a turbulent separation region over the front section of the wing. A rounded flap added over the trailing edge of the wing guides flow back into contact, giving the wing its lift generation.
Odd as that design choice seems at first blush, it actually makes the aircraft extremely resilient, especially to the turbulence that so often thwarts small flyers. When your flow is already disrupted, a little extra turbulence doesn’t make a difference.
The thicker wing also allows them to use a longer wingspan — thereby gaining that skinny wing efficiency — and move most of the components that would normally be in a fuselage into the wings themselves. By essentially turning most of the MAV into a wing, the designers avoid the loss of lift associated with the fuselage section of the wings.
(Image, video, and research credit: M. Di Luca et al.; via IEEE Spectrum; submitted by Kam-Yung Soh)
February 12, 2020
Why Do Backwards Wings Exist?
Over the years, there have been many odd airplane designs, but one you probably haven’t seen much is the forward-swept wing. While most early aircraft featured straight wings, rear-swept wings are fairly common today, especially among commercial airliners. A rear-swept wing has its forward-most point at the root of the ring, where it attaches to the fuselage. The sweep breaks up the incoming flow into a chordwise component that flows from the leading edge to the trailing edge of the wing and a spanwise component that flows along the wing. Compared to straight wings, a swept wing provides better stability and control when flying at transonic speeds where shock waves can form on the wing (even though the plane itself is not supersonic).
The trouble with rear-swept wings is that when they stall, they do so from the wingtips inward. Since the ailerons that control the plane’s orientation are out near the wingtips, that’s a problem. Forward-swept wings were supposed to solve this issue because they would stall from the root outward. But they came with a whole new set of problems, which included the need for robust onboard computers controlling them constantly to keep them in stable flight. In the end, the disadvantages outweighed any gains and so, for the most part, the forward-swept wing design has seen little flight time. (Image and video credit: Real Engineering)
September 17, 2019
Martian Bees, Canopies, and Dandelion Seeds
The latest FYFD/JFM video is out! May brings us a look at the incredible flight of dandelion seeds, numerical simulations that reveal the flow above forest canopies, and a look at bee-inspired flapping wing robots being developed for exploring Mars! Learn about all this in the video below, and, if you’ve missed other videos in the series, you can catch up here. (Image and video credit: N. Sharp and T. Crawford)
May 30, 2018