You may have seen on the news that a Dutch chap claims to have flown under his own power from a standing start.
Watch the video...
- those wings beat too quickly to generate enough lift (compare to the beat-rate of much smaller swans, eagles and condors)
- the wing membranes don't show enough sign of being under load - they're too loose and flappy.
- the wings look the same on the down- and up-strokes
- the upstroke should push him down, because the membrane doesn't close up like a bat's wing, or let air through like a bird's wing.