Comment on Praise Helix

captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

• FuglyDuck@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  It’s sort of like those traits that handicap the bearer and so the better that aspect is, the more suitable a mate. Like peacock tail feathers.

  The swallow is spiraled for her pleasure.

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  • captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

    No it’s more that physics is a fickle bitch.

    Those spirals are called tip vortices. They occur because there is relatively high pressure under the wing and relatively low pressure above. At the wing tip, that higher pressure air wants to roll up over the wing tip to get to that low pressure area, which is what sets that spiral in motion. Any airfoil that is creating lift will have a vortex at its tip. Wings, tail surfaces, propeller blades, rotor blades, you name it. The higher the angle of attack, the more significant the tip vortex.

    Have you ever seen a jet airplane that has fuel tanks out at the wing tips? Most of the reason they’re there is to reduce tip vortices and thus reduce drag. The additional fuel capacity is a minor byproduct. You might notice most newer airliners feature winglets; the wing tips are turned up. That’s not for additional yaw stabilty, those are there to reduce tip vortices, decrease drag and decrease fuel consumption.

    Tip vortices are the main factor in wake turbulence, which is an entire class session in flight school. All a tower controller will say to you is “caution wake turbulence.” And they’re right. It’s the pilot’s job to know what to do about it, because trailing behind and below the wing tip of every airplane is an invisible sideways tornado you just have to know is there so you don’t get thrown onto your Cessna’s roof when landing behind a Boeing.

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    • massive_bereavement@fedia.io ⁨2⁩ ⁨weeks⁩ ago

      I have spent a lifetime watching birds, and this is the first time I learned about this.

      Thanks

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      • dellish@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

        Next time you’re watching a bird that likes to glide a lot, such as an eagle, have a look at how long their wing tip feathers are. They tend the curve upwards in flight and act in much the same way as winglets on aircraft.

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      • Alcoholicorn@mander.xyz ⁨2⁩ ⁨weeks⁩ ago

        Now you will spend the rest of your lifetime imagine what type of wingtip would be most suitable for a bird.

        Image

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    • Bytemeister@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      I think there is a other layer to this. The image in question (I think) is showing how a birdoid body in flight avoids adverse yaw when banking for turns. That is done by managing the tip vortices in such a way to create a proverse yaw force. Quite literally, by befriending the spirals.

      en.wikipedia.org/wiki/Adverse_yaw

      en.wikipedia.org/wiki/Prandtl-D

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      • captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

        Hmm, that’s interesting, I’m thinking like a pilot here but tip vortices increase in magnitude as AoA increasess, adding to adverse yaw of ailerons. I figured birds handled yaw control through wing sweep, kind of like how a weight shift trike does.

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    • FuglyDuck@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      That whooshing sound was the joke’s vortexes flying over your head.

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      • captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

        We’re in the science memes sub, I talked about the science. I actually have credentials in this subject.

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