The unmanned aerial vehicles (UAV) designed for plateau missions are usually installed with tall span chord ratio wings,which provide more lifting force at a relatively low airspeed. Such UAVs, however, or tend to lose their maneuverability. Hence,they usually need a larger turning radius and are unable to preserve altitude during sharp slope turning, as the lifting force produced by the wings decreases dramatically when the bank angle is large. This may pose a risk to flight safety in plateau mountain regions. Variable thrust direction (VTD) technology is a type of thrust vectoring control (TVC) that allows a UAV to manipulate the directions of thrust to the fuselage of the aircraft.
Source: phys.org