The capablility of an aerospace craft to angle the thrust of the engines in directions other than parallel to the longitudinal axis of the craft. Thrust vectoring can help an aerospace craft achieve STOL or VTOL (short/vertical take-off and landing) and also allow the Valkyries to perform maneuvers with less dependence upon control surfaces. All variable fighters possess thrust vectoring engines; most utilize single-axis thrust vectoring by default (in variable fighters where the main engine is also the foot unit) while others employ three-dimensional thrust vectoring.