Wind and fairness in ski jumping: A computer modelling analysis |
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| Institution: | 1. Aachen University of Applied Sciences, Institute of Bioengineering, Heinrich-Mußmann-Str. 1, 52428 Jülich, Germany;2. Medical University of Graz, Institute of Biophysics, Neue Stiftingtalstr. 6 (MC1.D.)/IV A, 8010 Graz, Austria;1. Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, TX, USA;2. Department of Biomedical Engineering, University of Texas at Austin, TX, USA;3. Meijer Heart and Vascular Institute at Spectrum Health, Michigan, MI, USA;4. Department of Cardiac Surgery, Medical University of Silesia, Katowice, Poland;5. Institute for Computational Engineering and Sciences, University of Texas at Austin, TX, USA;1. College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China;2. Hydraulic Structure Design Division, Hydrochina Huadong Engineering Corporation, Hangzhou 310014, China;1. Institute for Computational Civil Engineering, Cracow University of Technology, Cracow, Poland;2. Institute of Fundamental Technological Research, Polish Academy of Science, Warsaw, Poland;1. Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, P.O. Box 12, 23000 Annaba, Algeria;2. Department of Physics, Chemistry and Mathematics, Alabama A&M University, Normal, AL 35762, USA;3. Department of Mathematics and Statistics, College of Science, Al-Imam Mohammad Ibn Saud Islamic University, Riyadh 13318, Saudi Arabia;4. Department of Mathematics and Statistics, Tshwane University of Technology, Pretoria 0008, South Africa;5. School of Electronics and Information Engineering, Wuhan Donghu University, Wuhan 430212, People''s Republic of China;6. Department of Engineering Sciences, Faculty of Technology and Engineering, East of Guilan, University of Guilan, P.C. 44891-63157, Rudsar-Vajargah, Iran;7. Department of Mathematics, Howard University, Washington, DC 20059, USA;8. Science Program, Texas A&M University at Qatar, PO Box 23874, Doha, Qatar |
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| Abstract: | Wind is closely associated with the discussion of fairness in ski jumping. To counter-act its influence on the jump length, the International Ski Federation (FIS) has introduced a wind compensation approach. We applied three differently accurate computer models of the flight phase with wind (M1, M2, and M3) to study the jump length effects of various wind scenarios. The previously used model M1 is accurate for wind blowing in direction of the flight path, but inaccuracies are to be expected for wind directions deviating from the tangent to the flight path. M2 considers the change of airflow direction, but it does not consider the associated change in the angle of attack of the skis which additionally modifies drag and lift area time functions. M3 predicts the length effect for all wind directions within the plane of the flight trajectory without any mathematical simplification. Prediction errors of M3 are determined only by the quality of the input data: wind velocity, drag and lift area functions, take-off velocity, and weight. For comparing the three models, drag and lift area functions of an optimized reference jump were used. Results obtained with M2, which is much easier to handle than M3, did not deviate noticeably when compared to predictions of the reference model M3. Therefore, we suggest to use M2 in future applications. A comparison of M2 predictions with the FIS wind compensation system showed substantial discrepancies, for instance: in the first flight phase, tailwind can increase jump length, and headwind can decrease it; this is opposite of what had been anticipated before and is not considered in the current wind compensation system in ski jumping. |
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| Keywords: | Ski flying Computer simulation Optimal control Sport aerodynamics Wind compensation |
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