The term refers to both a stall turn and a hammer or hammerhead stall. Both maneuvers begin by pulling the aircraft into a vertical climb. In the first case, a rudder is applied to yaw the aircraft to one side and let it fall down and recover in the reverse direction. If the speed is allowed to decay too much before the application of the rudder, the aircraft may tail slide and hammer stall and will recover in the same direction as the original.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved