In fabric covering, what does the term "tightness" specifically refer to?

In the context of fabric covering, "tightness" specifically refers to the degree of fabric tension applied. Achieving the correct tightness is crucial as it ensures that the fabric is securely adhered to the underlying structure, preventing sagging or movement, which could affect both the aerodynamics and the overall appearance of the aircraft.

Proper tightness helps maintain the fabric's strength and integrity, especially when it is subjected to changes in environmental conditions, such as temperature fluctuations and humidity levels. This tension also plays a vital role in the longevity of the fabric covering, as it minimizes the risks of tearing or wear over time.

The other options, while related to fabric characteristics, do not directly define "tightness." The strength of the fibers pertains to how much load the fabric can bear, the thickness addresses the density of the material, and the color refers to aesthetics rather than structural function. Focusing on the tension applied to the fabric is essential for achieving effective and reliable aircraft covering.