Final answer:
The minimum control speed airborne (Vmca) may increase when flaps are selected at less than 15% during certain phases of flight such as take-off, due to increased drag affecting controllability. However, the exact amount of increase must be referenced from the specific aircraft's operating handbook, as it varies per aircraft model.
Step-by-step explanation:
The student's question pertains to the concept of Minimum Control Speed Airborne (Vmca), which is relevant in the field of aeronautical engineering and concerns aircraft performance. Vmca is the minimum speed at which an aircraft can be controlled with a critical engine inoperative, that is, when one engine fails on a multi-engine aircraft. Flap selection can have an impact on Vmca because flaps modify the wing's lift and drag characteristics.
Typically, extending flaps increases lift but also increases drag. Using flaps at a setting less than 15% often indicates a take-off or initial climb configuration, where lift needs to be maximized. When you select flaps to less than this amount, in most aircraft, you increase the effective wing area, thus generating more lift at lower speeds, which allows for lower take-off and landing speeds.
However, it also leads to increased drag, which can affect controllability. For Vmca, this might mean an increase because more engine power would be required to overcome the added drag without influencing controllability. Since the exact value of how much Vmca increases would depend on specific aircraft characteristics and could vary, manufacturers provide those numbers in the flight manual.
For practical purposes, pilots should refer to their aircraft's operating handbook to determine the specific amount by which Vmca increases when selecting flaps under 15%. Always consult the actual aircraft documentation for precise and safe operation.