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Jpn J Biomechanics Sports Exercise 12 (3): 164-182, 2008

A simulation study of approach velocities in ski jumping –the effect of initial velocity–

Kaoru YAMANOBE1), Isao WATANABE2), Akifumi MATSUO1), Junji TAKAMATSU1), Yuichi HIRANO1)

1)Japan Institute of Sports Sciences, Department of Sports Sciences,
2)Research Center for Advanced Science and Technology, the University of Tokyo

Abstract

The purpose of this study was to identify the effects of the aerodynamic forces, mass of the jumper-ski system (m), head wind (Uw) and initial approach velocity (V0) on the approach velocity (Ua) in ski jumping. We measured drag area (SD) and lift area (SL) of approach position from the wind tunnel experiment with 44 athletes of Japanese national team (Nordic combined and Ski jumping). To estimate the maximal initial approach velocity, we measured initial approach velocity using a laser distance measurement module in the actual jumping trials at the Hakuba normal hill. Then we calculated approach velocities by solving equations of motion with changing these parameters (SD, SL, m, Uw and V0) between different approach lengths in Okurayama large hill and Hakuba normal hill. It was found that increases of SD or Uw would reduce the Ua. Furthermore, relatively small m could reinforce these effects of SD and Uw on the reductions of Ua. On the other hand, a given increase of V0 made a constant increase of Ua regardless of the variations of parameters of m, SD and approach length. These results indicate that the importance of the improvement of start technique as much as approach position for maximizing approach velocity.

Key Words: ski jump, aerodynamic drag, simulation, initial velocity, start technique

Submitted for Publication: Apr. 16, 2008,

Accepted for Publication: Aug. 6, 2008

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