The IMC harmonica

benyflyguy

benyflyguy

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benyflyguy
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!
 
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.
 
benyflyguy said:
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...
... 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!
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The air is not denser in the clouds. Other way around. ;)
 
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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? :)
 
SCCutler said:
I have heard references to an altered sound in IMC, typically in Cessna aircraft
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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
 
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.
 
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.
 
Clip4 said:
Struts are the issue in a Cessna. In 182s it is very noticeable.
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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.
 
Definitely get a howling sound in actual. Of course it could be my sphincter grabbing the seat.
 
GRG55 said:
The air is not denser in the clouds. Other way around. ;)
Click to expand...

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.
 
benyflyguy said:
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!
Click to expand...
Probably just the stall warning. Push the nose down a little, it will stop.
 
sarangan said:
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.
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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.
 
You also get that Cessna harmonic when you go full flaps
 
GRG55 said:
The air in the clouds, saturated or not, has to be lighter than the air mass below it...

...otherwise the cloud cannot stay aloft.
Click to expand...

Clouds don't float. They just become visible where the temperature meets the dewpoint. Otherwise we will never see fog at ground level.
 
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.
 
sarangan said:
Clouds don't float. They just become visible where the temperature meets the dewpoint. Otherwise we will never see fog at ground level.
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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".
 
benyflyguy said:
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!
Click to expand...

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. ;)

Clip4 said:
Struts are the issue in a Cessna. In 182s it is very noticeable.
Click to expand...

Nope... Not the struts.
 
sarangan said:
Clouds don't float. They just become visible where the temperature meets the dewpoint. Otherwise we will never see fog at ground level.
Click to expand...
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.
 
flyingcheesehead said:
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.
Click to expand...

It doesn’t leak and if it ain’t broke.....
 
I'd go with small droplets hitting the airframe somewhere rather than air density issues.
 
I flew a CAP 182 that sort of "russled" in clouds. Our 172 has no musical talent at all.
 
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.
 
benyflyguy said:
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!
Click to expand...

The C182 has a distinct whistle in the clouds.
 
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!
 
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