For one thing the basic Ke formula is sort of flawed in that it does not take into account the amount of momentum something has, which is why a heavier object retains more energy down range, it has more momentum. And velocity is not the more prominent factor in the formula. A heavier object moving at the same speed will always have a higher value. Velocity does not become a real asset until you get into high velocities like 2 or 3 thousand fps

And vanes actually start to overtake feathers at around 50 yards, and it is even farther the faster your bow is. But the lighter weight usually makes up for it and you don't notice any way. I can shoot out to 60 yards with vanes and feathers and the feathers only hit slightly low, they also have more FOC, so that may be the reason also. 4 inch feather with a slight offset by the way. Larger feathers with a radical helical would slow down much faster I am sure.

Those are my observations any way.

Paul