English is not my native language. What is this author basically saying?
Quote:
Recently, I attempted to shed more light on the lift versus drag issue using hand lift and drag coefficient data obtained from a testing tank at the Iowa Institute for Hydraulic Research (Sanders, 1997a; Sanders, 1997b). The lift and drag coefficients obtained from the hands tested in the Iowa facility indicated that the greatest forces are obtained when the hand plane is close to 90 degrees to the flow. At this orientation the force is due almost entirely to drag. Lift makes its greatest contribution to resultant force at angles near 45 degrees. However, even at these angles, the contribution due to drag is as great as the contribution due to lift. When these coefficient data were used in conjunction with three-dimensional kinematic data to estimate forces in actual swimming, it was found that drag made a larger contribution than lift throughout the propulsive part of the pull. During the most propulsive phase of the stroke the pitch angle was between 50 and 60 degrees, which means that the hand was pitched to take advantage of drag forces with a smaller contribution due to lift. During the most propulsive phase of the stroke the direction of fluid flow was from the wrist towards the fingers. This is contrary to the situation commonly envisaged and depicted in swimming texts, in which the hand is represented as a foil generating lift forces from lateral movements which produce a flow across the hand.
I don't think it's confusing if you define drag as any force which is directed opposite to the direction of travel.
Good point- my thinking/use of drag has been more commonly (and perhaps not correctly) to describe just the forces of friction. Thanks.
I'm also not sure if the paragraph's conclusions follow from the authors arguments regarding maximum propulsion and angle of attack. Since there is only one paragraph, it's hard to tell. Personally, i've always felt that "drag" was the bigger force at work and lift significanlty smaller, but that's just my opinion.
I don't think it's confusing if you define drag as any force which is directed opposite to the direction of travel.
Good point- my thinking/use of drag has been more commonly (and perhaps not correctly) to describe just the forces of friction. Thanks.
I'm also not sure if the paragraph's conclusions follow from the authors arguments regarding maximum propulsion and angle of attack. Since there is only one paragraph, it's hard to tell. Personally, i've always felt that "drag" was the bigger force at work and lift significanlty smaller, but that's just my opinion.
