• Ellia Plissken@lemm.ee
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    2 months ago

    again, as someone who doesn’t know much about this, aren’t they only using the VTOL configuration during takeoff and landing? and, doesn’t auto rotation require a certain amount of altitude? if both of those are true, then they would be in danger at the same time

    • Ilovethebomb@lemm.ee
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      2 months ago

      They’re flying with the engines facing at least partially upwards during takeoff and landing, even when taking off like an aircraft, meaning they’re in trouble if they lose power, not just in a hover. The Japanese crash happened on final approach as they were slowing down, but still a few hundred feet in the air.

      https://en.m.wikipedia.org/wiki/Helicopter_height–velocity_diagram

      This is the combination of airspeed and height you cannot perform an autorotation from, the graph shown is worse than many other helicopters. Robinson aircraft can auto from zero airspeed at around 400 feet. It’s all about having enough forward speed to flare off your rate of descent and land with only forward airspeed, you could successfully flare at head height and enough airspeed over good ground.

      Other tiltrotors are capable of autorotation.

      • ArbitraryValue@sh.itjust.works
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        2 months ago

        I like that the chart there has a little red sliver to indicate that it is, in fact, a bad idea to fly very fast at ground level.

    • atocci@lemmy.world
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      2 months ago

      Anecdotal, but I almost exclusively see them flying in VTOL configuration

      • Ilovethebomb@lemm.ee
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        2 months ago

        That’s at least partly because that’s the easiest time to photograph an aircraft.

        • atocci@lemmy.world
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          2 months ago

          I don’t mean in photos, they just fly around town in VTOL configuration all the time. Hardly ever see them at full tilt.