What is the size of the slipstream area considered in relation to rib lace spacing?

Understanding rib lace spacing is crucial when it comes to fabric covering on aircraft, particularly in maintaining structural integrity and aerodynamics. The slipstream area refers specifically to the airflow that is affected by the propeller as it rotates and generates thrust.

The correct answer, which identifies the propeller diameter plus one additional rib, emphasizes that this slipstream area extends beyond just the immediate diameter of the propeller. This is important because the airflow produced by the propeller creates a slipstream that can affect the areas just beyond the propeller's edge. By taking into account the diameter of the propeller and adding one more rib, it ensures that the rib lace spacing accommodates the influence of this airflow on the surface of the wing, which may affect aerodynamic performance and the adherence of the fabric covering.

This consideration is crucial in ensuring that fabric remains taut and secure under the dynamic pressure created during flight, contributing to both performance and safety.