eli5: Why is it not possible to build bird-like attachable wings that account for body proportions to allow humans to fly or glide around?

Question

eli5: Why is it not possible to build bird-like attachable wings that account for body proportions to allow humans to fly or glide around?

In: 2102

Answer 1

Thus, an average adult male human would need a wingspan of at least 6.7 meters to fly. This calculation does not even take into account that these wings themselves would be too heavy to function.