Re: 98 Passat Wagon - Helicopter mode

[Ralph Poplawsky <rlpplsky@ix.netcom.com>]

Your car interior is a big base fiddle.  The helicopter beat is the
resonant frequency of your interior.  I think that wagons are more prone to
this because the cavity has a higher Q due to the long flat flexible
expanse of the roof.  Cars with big back windows are also prone to resonate
with the sunroof open.  If you crack one of the back windows you will ruin
the cavity and it will stop.

Ralph Poplawsky
'91 200Q  (does not do this of course)


At 04:05 PM 5/20/98 -0400, John wrote:
>Has anyone else discovered the problem with the new Passat
>Wagon's design?  If you have the sunroof open all the way
>with the windows closed, and drive anywhere near 50MPH,
>the air pressure pulses rapidly popping your ears HARD and
>it sounds like a helicopter.
>
>Do any of the Audi's have this problem?
>
>BTW, the Passat sedan does something similar around 70 MPH.
>
>John
>
>