Comment on why do reverse thrusters work on an airplane, but a fan on a sailboat doesn't work?

• CarbonIceDragon@pawb.social ⁨1⁩ ⁨hour⁩ ago

  It can be, as long as the sail is set up in such a way that incoming air is deflected backwards to some degree rather than at a right angle to the fan (such as with a curved sail). Consider a still boat in still air (thus with no net acceleration in any direction to start). You push some air forwards towards the sail, then the sail deflects that stream of air outwards and slightly backwards. This means the combined fan-sail system (the ship taken as a whole) is taking in initially still air, and that air ends up with a net momentum backwards, so there must be push forwards. This is very inefficient compared to doing away with the sail and pointing the fan the other way, so theres no reason to do it in practice, but it doesn’t violate conservation of momentum or anything because the ship isn’t a closed system.

  source
• remon@ani.social ⁨5⁩ ⁨hours⁩ ago

  That’s pretty much exactly how a propeller works …

  source

  • gastroglizzy@piefed.social ⁨5⁩ ⁨hours⁩ ago

    Show me one airboat with a sail on it, you dunce.

    source

    • remon@ani.social ⁨5⁩ ⁨hours⁩ ago

      The great thing about air boats is they don’t need sails.

      source

      • gastroglizzy@piefed.social ⁨5⁩ ⁨hours⁩ ago

        BECAUSE BLOWING A SAIL WITH A FAN DOESN’T WORK.

        source

        • -> View More Comments
• bitteroldcoot@piefed.social ⁨5⁩ ⁨hours⁩ ago

  So you have never seen an airboat?

  https://en.wikipedia.org/wiki/Airboat

  source

  • gastroglizzy@piefed.social ⁨5⁩ ⁨hours⁩ ago

    Have you ever seen an airboat with a sail?

    source