What happens to the UA when there is a reduction in thrust?

When there is a reduction in thrust, the Unmanned Aircraft (UA) will begin to descend. This is because thrust is the force that propels the UA upward against the forces of gravity and drag. When the engine or propulsion system reduces its thrust output, the lift generated by the UA will also decrease. If the lift becomes less than the weight of the UA, then the vehicle will no longer be able to maintain altitude, leading to a descent.

In most flying scenarios, maintaining altitude requires a specific balance between lift and weight, with thrust playing a crucial role in achieving that lift. Therefore, any reduction in thrust disrupts this balance, resulting in the UA descending toward the ground. This fundamental principle of flight dynamics applies to all aircraft, including unmanned aerial systems.