what is dry brush

If you check your other post a gave a brief description of what drybrushing is.
No the airbrush cannot be used for this technique.

dry brushing is having a very small amount of paint onthe tip of a small brush and gently going over an aleady painted area witha different color or shade. on tanks we use a metallic color to show rubbing of areas like handles and hinges and high spots where the paint would have been rubbed off. and like shermanfreak says. airbrush is not the medium of choice for this