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Is there such a thing as "ceiling effect" (analogous to ground effect) ? — Parallax Forums

Is there such a thing as "ceiling effect" (analogous to ground effect) ?

TubularTubular Posts: 4,708
edited 2011-12-20 17:51 in Propeller 1
If one flies a quadcopter inside, close to the ceiling, is there a region where flight is more efficient ?

Just wondering

(edit: sorry meant to post in general discussion; feel free to move it)

Comments

  • Bobb FwedBobb Fwed Posts: 1,119
    edited 2011-12-19 14:58
    I would say it's the opposite, it would get less efficient. Because there is less air to gather. The less it is available, the more resistance there will be.
  • TubularTubular Posts: 4,708
    edited 2011-12-19 15:34
    That's one way of looking at it.

    On the other hand the air that is between the blade and the ceiling is "less mobile" than free air (thinking along da Vinci's "air screw" line, it might therefore require fewer rpm to 'screw' into this air than free air and remain static).
  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2011-12-19 15:34
    I never heard this called that but yes.

    Just as it takes less power to hover when near the ground it takes less power to hoer near the ceiling.

    In "Ground Effect" one is supported not only from lift but also from pressure under the structure.

    In "Ceiling Effect" one is supported not only from lift but also from vacuum over the structure.

    Duane
  • Bobb FwedBobb Fwed Posts: 1,119
    edited 2011-12-19 15:54
    He didn't say anything about putting a vacuum over the quadcopter.

    I'm kidding. I didn't think of that. It makes sense, but it seems like the lift lost due to the vacuum would be fairly significant. Would the benefit of the "ceiling effect" have to do a lot with the design of the overall structure? Or would the vacuum above the blades always create more lift than the lift lost due to the vacuum?
  • W9GFOW9GFO Posts: 4,010
    edited 2011-12-19 16:06
    I've found it hard to hover close to the ceiling without bumping into it, this could have something to do with it.

    Close to the ceiling the air must rush in from the sides to supply the rotor. The higher velocity of the incoming air would create an area of lower pressure above the rotor. At some point I think the benefit will reverse when not enough airflow is available.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-12-19 16:28
    W9GFO wrote: »
    I've found it hard to hover close to the ceiling without bumping into it, this could have something to do with it.

    This is very true for indoor helicopters. It behaves as if it is being sucked into the ceiling.
  • Graham StablerGraham Stabler Posts: 2,510
    edited 2011-12-19 16:43
    Sounds like a project. Add a distance sensor and add a ceiling flight mode to your copter.

    But I think the aerodynamics put forward might be a bit off.

    Graham
  • TubularTubular Posts: 4,708
    edited 2011-12-19 16:52
    Graham Stabler wrote: »
    Sounds like a project. Add a distance sensor and add a ceiling flight mode to your copter.
    But I think the aerodynamics put forward might be a bit off.
    Graham

    Exactly. Ping sensors to control elevation, and stud finders to determine how far one has travelled.

    And light sockets for recharging

    :)
  • VIRANDVIRAND Posts: 656
    edited 2011-12-20 17:51
    I think DaVinci was wrong about helicopters because they get lift from blowing downward, not driving upward.
    The vacuum is zero force, not a negative one.
    I am not sure why, if it is true, that the helicopter is attracted to the ceiling. Perhaps because a relative absence of air pressure develops up there.
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