Which type of flap creates the greatest coefficient of lift?

The slotted flap is particularly effective in increasing the coefficient of lift compared to other types of flaps. This is primarily due to the unique design that allows high-energy air from the upper wing surface to re-energize the boundary layer over the flap. By having a slot that provides a passage for this airflow, the slotted flap can delay airflow separation, which significantly enhances lift at lower speeds.

Additionally, slotted flaps typically have a larger surface area compared to the other flap types when extended, leading to a greater increase in lift generation. This characteristic makes slotted flaps ideal for aircraft that require improved lift during takeoff and landing phases, allowing for better control and performance.

Other flap types, such as plain, split, and Fowler flaps, do improve lift but generally do not achieve the same degree of enhancement as slotted flaps due to their design limitations in managing airflow and maintaining lift at higher angles of attack.