Originally Posted by
Danial9874
What is actually Aircraft Zero Stress ? I think that no stress acting on aircraft is kind of impossible
In what context are you asking? For example, when it comes to G-force on aircraft structures the stress can go from positive in nature, to neutral (zero), and to negative in nature. In general, most aircraft require some minimal positive force/stress to keep all the systems functioning properly unless it is specifically certified to do otherwise.