Yes wind sound is needed.
At the WB Con, one of the 44th SOS played a CD that was recorded from inside an Me 109 during an airshow performance. You can hear the wind noise really pick up as the plane speeds up. For a good example of how to implement this, I suggest Grand Prix Legends.
Also I have ridden in planes of all sizes, and there is a definite increase in wind roar as speed increases.
[This message has been edited by funked (edited 10-04-1999).]