Strange noises

[dont overfil]

Why does our C182 make a strange moaning noise in cloud?
D.O.

[robin]

....sure it's not the passengers?

[BackPacker]

Might be moisture on some parts, subtly altering the aerodynamics.

I've got the same with the roof rack bars on my car. Can't hear them normally, but when driving in the rain they start to whistle.

[Pilot DAR]

Could it be that the moisture present in the air, in the form of water droplets, reflects the noise of the aircraft back to the aircraft in a different way?

[Unusual Attitude]

Might be moisture on some parts, subtly altering the aerodynamics.

Thats where my money would be, same reason Gliders dont like flying in rain, airflow no longer laminer over the wing. Droplets and water runs will create lumps and bumps = more skin friction / parasitic drag.....might only be subtle changes but its the same reason we clear ice off our wings...(though ice is obviously more serious)

Poses some interesting points to think about, a wet airframe will be heavier than a dry one with the wings now less efficient and creating more drag for the same speed and AOA as when dry so in theory there should be a performance loss flying in rain....anyone actually noticed a difference in a spam can ? Obviously glider drviers will have but cant say I've ever really noticed in a Cessna and given I live in Scotland I've spent a lot of time flying in rain....!

[dont overfil]

It's definately not the passengers as they moan all the time.

The sound is similar to the noise that occurs in the flare just before the stall warner goes off, but comes from the wing roots.

As Bp & Ua suggest it must be a subtle change in the aerodynamics.. Thanks for the replies. Other C182 users see if yours does it. Ours is a C182T

Ua. Yes, heavy rain knocks at least 5 knots off cruise.
D.O.

[UV]

The sound is similar to the noise that occurs in the flare just before the stall warner goes off

Air density is less too, so you may be changing the angle of attack slightly.

[24Carrot]

Air density is less too, so you may be changing the angle of attack slightly.

Interesting point. The water vapour will indeed be less dense than the air, but the water droplets are a lot denser, and as the wing moves the air around, the water must more or less follow.

One for Genghis?

[fernytickles]

Don't we all moan when its cloudy & wet? Aeroplanes are no different....

[mad_jock]

I reckon its water causing a wet farting noise through the fairings at the strut connections. When they are dry it goes through with out making a noise

[Daysleeper]

Dash 8 Q400 does it as well, I'd never noticed it on any other aircraft.

[mad_jock]

must be the connection then daysleeper only ugly aircraft do it.

[dont overfil]

You know mad jock that's the most understandable explanation yet. I'm sure there's sponge rubber in the air vents that could do it.
I'll check it out in the bath tonight.
D.O.

[Mike Cross]

Two or three years ago I was bimbling along in the Luscombe minding my own business when a sudden vibration manifested itself. At the same time my pripheral vision picked up movement. The port lift strut had started to vibrate, somewhat alarming as it had never done so before. Something was clearly making it resonate. Judicius tweaking of throttle settings got rid of it and it did not subsequently return. Back on terra firma I phoned one of hte other group members to ask if it had ever happended to him.

"Was it raining?" he asked. Well, yes it was.

"Never had it happen to me, but I've read about it on one of the US Luscombe sites, it only happens when it is raining."

Weird