The IMC harmonica

Discussion in 'Cleared for the Approach' started by benyflyguy, Dec 2, 2018.

  1. benyflyguy

    benyflyguy Cleared for Takeoff

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    Anybody notice a cool harmonic when they are literally in the clouds?? I’ve noticed it since I started taking IFR lessons. Mostly in the rainy type stratus clouds that are thicker. It’s a neat sensation as it gives you the effect that you are speeding up or decending. It adds to some of the disorientation to flying IMC. As the first time I was in Thicker IMC early on I found my self pulling up without referencing gauges - a wise early lesson!! . I’ve come to expect it so it doesn’t bother me or add to any disorientation. In fact I look forward to it because it sounds cool.
    Anybody know why that happens? I thought perhaps air is denser intermittently causing sound waves to react differently. I fly a 182H so I’m not screaming through the clouds, in my friends MU2 I don’t really notice it but that beast is a whole different noise!
     
  2. tawood

    tawood Pattern Altitude

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    No, can't say that I have noticed any different sound, but next time I'll listen...I also don't look outside much during flight while actually in the clouds.
     
  3. GRG55

    GRG55 Final Approach

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    The air is not denser in the clouds. Other way around. ;)
     
    Last edited: Dec 2, 2018
  4. SCCutler

    SCCutler Administrator Management Council Member PoA Supporter

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    I have heard references to an altered sound in IMC, typically in Cessna aircraft, but I never noticed it when I was training in IMC, nor flying in IMC.

    Maybe a different harmonic as certain muscles get puckered-up? :)
     
  5. Tantalum

    Tantalum En-Route

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    I couldn't figure out if it was just in my head or not, buy I feel like when I am IMC in the 172 it does sound slight bit different
     
  6. tawood

    tawood Pattern Altitude

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    Maybe its Cessna thing, as I fly a Piper ifr...one thing I've noticed from all planes: on turbulent or gusty/wind shear days, the prop will make a funny sound as it gets blown around...kind of like when I was a kid, and I'd yell or blow into a fan. I know I often hear this noise going into clouds, from the up/down drafts.
     
  7. Clip4

    Clip4 En-Route

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    Struts are the issue in a Cessna. In 182s it is very noticeable.
     
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  8. flyingron

    flyingron Touchdown! Greaser!

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    There are some sounds that I've noticed, though I'm not sure I have the one beny has noticed. There's definitely a hissing noise that accompanies certain ice accumulation, for instance. My wife couldn't figure out why I asked for quickly lower at one point in a flight.
     
  9. benyflyguy

    benyflyguy Cleared for Takeoff

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    Must be. I don’t remember it when I flew pipers before I took a break. It’s a cool sound. I should try to record it. Kinda like a tunnel effect, like winds are howling but they really aren’t.
     
  10. Landing Fees

    Landing Fees Pre-takeoff checklist

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    Definitely get a howling sound in actual. Of course it could be my sphincter grabbing the seat.
     
  11. sarangan

    sarangan Pre-takeoff checklist

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    While it is true that moist air is less dense than dry air, here we are talking about saturated air vs unsaturated air. Moisture content may still be the same in both.
     
  12. Kenny Phillips

    Kenny Phillips Pattern Altitude

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    Probably just the stall warning. Push the nose down a little, it will stop.
     
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  13. GRG55

    GRG55 Final Approach

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    The air in the clouds, saturated or not, has to be lighter than the air mass below it...

    ...otherwise the cloud cannot stay aloft.
     
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  14. Tantalum

    Tantalum En-Route

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    You also get that Cessna harmonic when you go full flaps
     
  15. sarangan

    sarangan Pre-takeoff checklist

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    Clouds don't float. They just become visible where the temperature meets the dewpoint. Otherwise we will never see fog at ground level.
     
  16. VictorBravo

    VictorBravo Filing Flight Plan

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    I fly a Cessna 182T and have noticed the same humming/harmonic sound when flying in IMC. Not so much when in turbulence, but in a smooth layer of stratus clouds you hear a low in tone humming/harmonic sound, like a faint wood wind instrument. Have not noticed it with full flaps, but something to look out for as well.
     
  17. VictorBravo

    VictorBravo Filing Flight Plan

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  18. GRG55

    GRG55 Final Approach

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    Correct. And when there is cloud at ground level (fog) that air mass is less dense than when there is no fog.

    My original post was to try to correct the apparent belief of the OP that "the air is denser" when he is hearing the apparent "IMC harmonic".
     
  19. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    Aha! I knew it! As soon as I read the preview of your post, I thought "I bet that guy's flying a 182."

    Our club's old 182 used to "sing" in IMC as well. Then, we had the entire windscreen resealed due to a slight leak if it was parked outside in the rain, and it never "sang" again. But, it's pretty common to 182s.

    And, BTW, you probably should think about getting your windscreen resealed. ;)

    Nope... Not the struts.
     
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  20. flyingron

    flyingron Touchdown! Greaser!

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    They also need something to nucleate on. Not usually a problem in urban areas. Somtimes you can have a zero DP/Temp spread and still not get clouds.
     
  21. Clip4

    Clip4 En-Route

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    It doesn’t leak and if it ain’t broke.....
     
  22. flyingron

    flyingron Touchdown! Greaser!

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    I'd go with small droplets hitting the airframe somewhere rather than air density issues.
     
  23. Sundancer

    Sundancer En-Route

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    I flew a CAP 182 that sort of "russled" in clouds. Our 172 has no musical talent at all.
     
  24. Blatham489

    Blatham489 Pre-takeoff checklist

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    I definitely notice a very slight change in noise when in clouds in the Archer, very little cloud time in the Bo but seem to recall a slight change in it as well.
     
  25. labbadabba

    labbadabba Pattern Altitude

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    The C182 has a distinct whistle in the clouds.
     
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  26. benyflyguy

    benyflyguy Cleared for Takeoff

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    Did a checkride prep flight for about 2 hours today, flew the planned approaches with my CFI in an ice mix of MVFR and IMC. I could tell when I was in IMC by the hum. Lol.checkride one week away. Approaches went good. Hope I don’t f up something stupid!