Even better is the similarity between a bird seen side-on in level gliding flight and the same view of a B2. I tried to get an image link to put here but the in

Even better is the similarity between a bird seen side-on in level gliding flight and the same view of a B2. I tried to get an image link to put here but the internet has become impossible to use, so just Google it I guess. It seems that the biggest difference between bird wings and airplane wings is that the former use a bell-shaped (per Prandtl) span loading that induces proverse yaw on on roll and allows them to turn without separate yaw input. The elliptical span loading used by the vast majority of man-made aircraft causes adverse yaw, which is probably the biggest reason most aircraft need rudders. Even the B2 has split-aileron drag rudders at its wingtips for this reason.