Whirring

from WordNet (r) 3.0 (2006)

whirring
    adj 1: like the sound of rapidly vibrating wings
    n 1: sound of something in rapid motion; "whir of a bird's
         wings"; "the whir of the propellers" [syn: {whir}, {whirr},
         {whirring}, {birr}]

from The Collaborative International Dictionary of English v.0.48

Whir \Whir\, v. i. [imp. & p. p. {Whirred}; p. pr. & vb. n.
   {Whirring}.] [Perhaps of imitative origin; cf. D. hvirre to
   whirl, and E. hurr, hurry, whirl. ???.]
   To whirl round, or revolve, with a whizzing noise; to fly or
   more quickly with a buzzing or whizzing sound; to whiz.
   [1913 Webster]

         The partridge bursts away on whirring wings. --Beattie.
   [1913 Webster]