A UA may descend by reducing which of the following factors?

A Unmanned Aircraft (UA) can descend by reducing thrust. Thrust is the force that propels the UA upward and forward. When the thrust is decreased, the lift generated by the UA is not sufficient to counteract the weight of the aircraft. This results in a net downward force, causing the UA to descend.

Understanding this concept is essential as it relates to the balance of forces acting on the UA. Lift must be equal to or greater than weight for the UA to maintain altitude; when thrust is reduced, lift diminishes due to decreased energy input, leading to a descent.

The other factors, such as drag and weight, impact how the UA flies but do not directly cause descent in the same manner as thrust reduction. Drag is an opposing force that can slow the UA down, while weight is a constant downward force due to gravity. Lift needs to be actively managed through thrust manipulation to control altitude effectively.