open/closed handed freestyle??

Originally posted by knelson Do you mean the cross-sectional area of the hand as viewed from the side or as viewed looking at the palm? In the latter case I think it does change, at least effectively, when the fingers are spread. Sort of like a skydiver. To slow down they go into a spread eagle position. Their arms and legs are still exactly the same size as they were before, but by spreading them they are creating more air resistance. I mean viewed looking at the palm. I know nothing about sky diving but my guess is that the spread eagle position has more to do with balance and control than how fast you fall, unless the sky diving suit acts as webbing. I would expect that a sky diver in a vertical position would fall faster due to the smaller profile but that your velocity would be the same if you were falling horizontally whether your limbs were out just enough to maximize your profile or spread eagled. I think form drag is strictly a function of profile and that this was verified by the aforementioned study. I suspect that the intuition that keeping your fingers together has the same basis as the intuition that cupping your hand will be effective and is based on the conception of the amount of water you are moving rather than the amount of drag is what is important. It might be instructive to think about holding your hand out, palm up, under a stream of falling sand. The sand will form a sort of cone/pyramid on your hand after which the following water will flow down the sides of the cone, water will do pretty much the same thing as you move your hand through it. Cupping your hand will result in a little more sand in your hand but that doesn't do you much good because you don't get your force by accelerating mass backward you get it from drag forces - which are reduced by the smaller profile of the cupped hand. I think :)

Originally posted by knelson Do you mean the cross-sectional area of the hand as viewed from the side or as viewed looking at the palm? In the latter case I think it does change, at least effectively, when the fingers are spread. Sort of like a skydiver. To slow down they go into a spread eagle position. Their arms and legs are still exactly the same size as they were before, but by spreading them they are creating more air resistance. I mean viewed looking at the palm. I know nothing about sky diving but my guess is that the spread eagle position has more to do with balance and control than how fast you fall, unless the sky diving suit acts as webbing. I would expect that a sky diver in a vertical position would fall faster due to the smaller profile but that your velocity would be the same if you were falling horizontally whether your limbs were out just enough to maximize your profile or spread eagled. I think form drag is strictly a function of profile and that this was verified by the aforementioned study. I suspect that the intuition that keeping your fingers together has the same basis as the intuition that cupping your hand will be effective and is based on the conception of the amount of water you are moving rather than the amount of drag is what is important. It might be instructive to think about holding your hand out, palm up, under a stream of falling sand. The sand will form a sort of cone/pyramid on your hand after which the following water will flow down the sides of the cone, water will do pretty much the same thing as you move your hand through it. Cupping your hand will result in a little more sand in your hand but that doesn't do you much good because you don't get your force by accelerating mass backward you get it from drag forces - which are reduced by the smaller profile of the cupped hand. I think :)