FYFD

Category: Phenomena

  • Reapproaching Supersonic Air Travel

    Reapproaching Supersonic Air Travel

    Before the Concorde even began regular flights, protests over its sound levels caused the U.S. and many other countries to ban overland commercial supersonic flight. Those restrictions have stood for fifty years. But NASA and Lockheed Martin Aeronautics are hoping to make supersonic air travel a possibility again with their experimental X-59 aircraft, designed to have a much quieter sonic boom.

    In supersonic flight, every curve, bolt, and bump generates a shock wave, and these waves tend to coalesce at the front and back of the aircraft, creating strong leading and trailing shocks. It’s these shock waves that are responsible for the double sonic boom that rattles windows and startles those of us on the ground. The X-59 reduces its noise by spreading out those shock waves, a feat designers managed with heavy reliance on computational fluid dynamics. They used wind tunnel studies mainly for validation, since iterating designs in the wind tunnel was far slower than working computationally. With the initial aircraft built, the team will now do test flights and, starting in 2026, will fly over the public and solicit feedback on whether the aircraft is acceptably quiet. (Image credit: NASA; via Physics Today)

    The sound of the X-59's sonic boom compared to other familiar sound levels.
    The sound of the X-59’s sonic boom compared to other familiar sound levels.
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    Visualizing Wingtip Vortices

    At the ends of an airplane‘s wings, the pressure difference between air on top of the wing and air below it creates a swirling vortex that extends behind the aircraft. In this video, researchers recreate this wingtip vortex in a wind tunnel, visualized with laser-illuminated smoke. The team shows the progression from no vortex to a strong, coherent vortex as the flow in the tunnel speeds up. Along the way, there are interesting asides, like the speed where the honeycomb used to smooth the upstream flow is suddenly visibly imprinted on the smoke! (Video and image credit: M. Couliou et al.)

  • “Mason Bee at Work”

    “Mason Bee at Work”

    Mason bees like this one build landmarks to help them navigate as they construct a shelter for their eggs. Even hauling materials, these bees can easily stay aloft. This is in contrast to an old misconception that physics can’t explain how a bee flies. It’s true that bees don’t fly using the same mechanisms as a typical airplane — no fixed wings here! But they, like every other flyer aerodynamicists study, still produce lift and drag and thrust. The flapping of a bee’s wings generates much unsteadier quantities of these things, but at its small size, that is no hindrance to its ability to control its flight and even carry cargo. (Image credit: S. Zankl; via Wildlife POTY)

  • Simeis 147

    Simeis 147

    Sometimes known as the Spaghetti Nebula, Simeis 147 is the remnant of a supernova that occurred 40,000 years ago. The glowing filaments of this composite image show hydrogen and oxygen in red and blue, respectively. These are the outlines of the shock waves that blew off the outer layers of the one-time star within. What remains of that star’s core is now a pulsar, a fast-spinning neutron star with a solar wind that continues to push on the dust and gas we see here. (Image credit: S. Vetter; via APOD)

  • Light Pillars

    Light Pillars

    These lovely pillars of light over the Mongolian grasslands are the result of tiny, suspended ice crystals. With the right weather conditions, ice crystals can align so that their largest faces are roughly parallel to the ground. In this orientation, the crystals collect and reflect artificial lights from the ground into these towering light pillars. It’s worth noting that the pillars aren’t located directly above the light source; instead, the column of crystals will lie roughly halfway between the light source and the observer. Next time you’re out on a cold winter night, see if you can find one! (Image credit: N. D. Liao; via APOD)

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    Sharpshooters

    The sharpshooter‘s superpower is pee flinging. These insects consume nutrient-poor plant sap, so to get the calories they need, they have to drink 300 times their body weight each day. All that extra liquid has to go somewhere, so the sharpshooter evolved to be an expert excretor. Each drop gathers on their anal stylus, then gets launched with an energy-efficient flick. During that move, the sharpshooter compresses the droplet, adding a little extra energy that helps speed up the drop’s flight once launched. (Video and image credit: Deep Look)

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    That Drain Life

    No matter your cleaning habits, it’s possible to get some unexpected roommates. This variety is the drain fly, a species well-adapted to the moist environment of our pipes. As larvae, they slither and squirm in the biofilms that form from the hair, saliva, and food that make their way down our drains. Being fully immersed is no problem for them, since they carry their own air bubble like a mini scuba tank. In adulthood, these tiny flies are incredibly hairy, all the better to escape from water. All those little hairs trap air near the fly, making it hydrophobic so that water just slides off. It takes a serious dowsing to immerse them enough to drown. (Image and video credit: Deep Look)

  • Farewell, Saffire!

    Farewell, Saffire!

    After eight years and six flight tests, NASA said a fiery farewell to the Spacecraft Fire Safety Experiment, or Saffire, mission. Each Saffire test took place on an uncrewed Cygnus supply vehicle after undocking from the space station. Cygnus craft burn up during atmospheric re-entry, so using them as a platform guaranteed safety for the station’s crew.

    A Plexiglass sample burns as part of Saffire-V’s experiments. In this experiment, researchers found that flames grew and spread faster on thin ribs of Plexiglass (left) than on thicker samples (right).

    Saffire itself used a small wind tunnel to push air past its burning materials. The tests included materials like plexiglass, cotton, Nomex, and other fabrics that might be found on a spacecraft or its occupants. The goal, of course, is to understand how fires grow and spread in a spacecraft in order to protect the crew. To that end, Saffire experiments recorded not only what went on inside their test unit, but also what the conditions were in the spacecraft as Saffire burned. (Image and video credit: NASA; via Gizmodo and NASA Glenn)

  • Langebaan Lagoon

    Langebaan Lagoon

    Strands of green and brown mix in Langebaan Lagoon on the South African coast in this astronaut photograph. The shallow tidal estuary has a sandy floor and, since no river flows into it, the deeper green sections seen here are channels carved solely by the back-and-forth flow of the tides. To the north of the lagoon, Saldanha Bay is a busy hub for fishing and industry. The long reddish line extending into the water is a railroad pier responsible for loading 96 percent of South Africa’s iron ore gets loaded onto ships. (Image credit: NASA; via NASA Earth Observatory)

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    Convection in Action

    We’re surrounded daily by convection — a buoyancy-driven flow — but most of the time it’s invisible to us. In this video, Steve Mould shows off what convection really looks like with some of his excellent tabletop demos. The first half of the video gives profile views of turbulent convection, with chaotic and unsteady patterns. When he switches to oil instead of water, the higher viscosity (and lower Reynolds number) offer a more structured, laminar look. And finally, he shows a little non-temperature-dependent convection with a mixture of Tia Maria and cream, which convects due to evaporation changing the density. (Image and video credit: S. Mould; submitted by Eric W.)