There is a vast difference in the performance (efficiencies) between a “straight” high aspect foil with a small flap on the trailing edge and the same high aspect ratio foils raked backwards with the whole foil “turning” (up and down). Then to complicate matters even more if very small “tip winglets” are added then the efficiencies increase dramatically again. (The adage applies – “There are many more than one way to skin a cat”) Consider that a low aspect ratio foil set “straight” to all intent and purpose becomes a much higher aspect ratio in practice when raked, it’s chord length becomes much smaller in ratio to the surface that it is exposing to the direction of the fluid travelling over it. (If these principles hadn’t been exploited they would still be trying to break the sound barrier in aircraft today)