it is not currently possible for humans to grow functional bat or bird wings naturally. Humans lack the necessary biological structures, such as the lightweight bones, specialized muscles, and unique wing shape, that enable birds and bats to fly.
However, if we were to imagine a fictional scenario where humans could somehow genetically modify themselves or acquire wings through advanced technology or magic, the size of the wings needed to lift off the ground and hover indefinitely would depend on several factors:
Weight of the Human: The larger the human's body mass, the larger the wings would need to be to generate enough lift to counteract gravity.
Wing Design and Physiology: The wings would have to be carefully designed to generate sufficient lift and thrust to overcome gravity and maintain flight. They would need to mimic the aerodynamics of bird or bat wings to be effective.
Muscle Strength and Endurance: The human would need strong and specialized flight muscles to flap the wings with enough force and maintain flight for extended periods without fatigue.
Environmental Factors: The density of the air, altitude, and other environmental factors would also influence the size and shape of the wings required.
It's important to note that achieving human flight through natural wings would be an incredibly complex and challenging endeavor. While flight is possible in the animal kingdom, it has evolved over millions of years with specific adaptations for each species. As of now, human flight without additional technology remains purely speculative and belongs to the realm of science fiction and fantasy.