What happens when a helicopter is close to ground level?

Hikee

Senior Member
Polish/English - bilingual
I've once come across an expression that described the effect of a micro tornado that occurs when a helicopter gets close to ground level. I recall it was a two word compound, written with a hyphen, probably with one of the words being "down". However, I can't put it back together in my mind, so I ask you if you happen to know what is it?
 
  • Hau Ruck

    Senior Member
    English - U.S.
    Settling with power (vortex ring state). Or perhaps...Ground effect??

    Settling with power can lead to a very bad day. Ground effect is simply extra lift provided close to the ground as a result of the air "deflecting" off the ground. Trying to climb out with not enough power while still in ground effect can also lead to a bad day.
     

    Hikee

    Senior Member
    Polish/English - bilingual
    @2: Nah, I've already checked out Ground Effect. It concerns mostly fix-winged aircraft.

    @3: Downwash is what I had in mind. Thanks! Apparently I was wrong about the hyphen ;)
     

    Hikee

    Senior Member
    Polish/English - bilingual
    #6: I'm aware of that. Still, the effect of downwash is the most vivid close to ground whatsoever.
     

    Hau Ruck

    Senior Member
    English - U.S.
    #6: I'm aware of that. Still, the effect of downwash is the most vivid close to ground whatsoever.
    I think you're still confused about "downwash" vs. ground effect/turbulent air caused by the deflection of that downwash near the ground.
    Downwash is no more vivid near the ground than it is in the air. Downwash is simply the air as it streams off the blade/prop.

    I'm not telling you this to be argumentative. I only tell you in case it pertains to what you are doing.

    Downwash, in itself, does not change based on height nor relative proximity to a surface.
     
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    Hikee

    Senior Member
    Polish/English - bilingual
    #9: I know that the air current remains the same in both strength and intensity, regardless of altitude. I only meant to imply the effect's visual aspect (the dust, water, etc. being strewn and flushed all around the place) when the helicopter closes in to the ground level. I do not intend to get in deeper into the physical aspects of it or anything like that at all. This is purely for literate purposes.
     

    Copyright

    Senior Member
    American English
    It's probably downdraught. The writer could have mistakenly hyphenated it.
    I agree ... in American English, downdraft, although I would not be surprised to see down draft and down-draft. It's the most common term I've heard for the last 45 years (if ubiquity has any appeal in this search).
     

    sdgraham

    Senior Member
    USA English
    @2: Nah, I've already checked out Ground Effect. It concerns mostly fix-winged aircraft.
    Absolutely incorrect.

    Or have you never heard of a hovercraft or other ground-effect machines? (Note that ground effect is not a proper noun and not capitalized)

    Moreover, helicopters are rated for hovering "in ground effect" and " out of ground effect."

    And, as others have pointed out, ... downdraft and downwash are not related to the proximity of the ground as specified in the original post. The rotor of a helicopter forces air downwards regardless of whether the aircraft is at altitude or close to the ground.
     
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