His background is very strong in maintenance and support, and not at all strong in the direction of design, especially controls, aerodynamics, structures or components.
This explains his curiosity in the field of controls and design issues, and brings to question his expertise to answer those type of questions. It also explains how Lu uses maintenance instructor courses as his background for detailed design discussions, instead of typical aeronautical design texts.
I do find it disappointing that, although your CV reflects a lifetime of learning, you seem to be unable to learn from this forum. Your expertise in certain areas has been established without question, yet your grasp of fundamental aerodynamics continues to be flawed despite the efforts of many experts (I am not an expert) on this forum.
Both comments are spot on.