Jumper Kinematics on Terrain Park Jumps: Relationship between Takeoff Speed and Distance Traveled

    Volume 7, Issue 10 (November 2010)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 2 November 2010

    Page Count: 10


    Shealy, Jasper
    Guidance Engineering and Applied Research, Seattle, WA

    Department of Industrial and Systems Engineering, Rochester Institute of Technology, Rochester, NY

    Scher, Irving
    Guidance Engineering and Applied Research, Seattle, WA

    Univ. of Southern California, Los Angeles, CA

    Stepan, Lenka
    Guidance Engineering and Applied Research, Seattle, WA

    Harley, Erin
    Exponent Failure Analysis Associates, Bellevue, WA

    (Received 21 January 2010; accepted 11 September 2010)

    Abstract

    The performance of individuals jumping tabletop features in terrain parks has not been widely studied. A field study was conducted to measure the takeoff speed and horizontal distance achieved by jumpers at two tabletop style jump features: A smaller jump at Snow Summit, CA and a larger jump at Mammoth Mountain, CA, USA. Analyses were also conducted to determine the effects of equipment type (skis versus snowboard) on jumper kinematics. Before each data collection session, the physical dimensions of the jump were measured and recorded. For consecutive jumpers, the speed parallel to the ramp was measured at the end of the takeoff by using a laser speed trap accurate to 0.11 m/s. The landing zone was marked at 3.0 m intervals with colored dye, beginning just past the flat deck portion of the jump. A high-definition video camera was used to record the landing of each jumper, and the landing point of the projected center of mass was determined by using photogrammetry, accurate to within 5 cm. The actual landing distances measured in the field were compared to predicted landing distances by using ordinary ballistic equations. A total of 280 jumps was observed on the two features: 105 on skis and 175 on snowboards. The correlation coefficients between the square of the takeoff speed and the landing distance for the smaller and larger jumps were 0.75 (R2=0.56) and 0.41 (R2=0.16), respectively. The measured landing distances differed significantly from those predicted by models using the ballistic equations of motion. The average landing distance beyond the knuckle was 2.4 m on the smaller jump and 2.1 m on the larger jump. For both features, skier and snowboarder jumpers did not differ in average landing distance.


    Paper ID: JAI102885

    DOI: 10.1520/JAI102885

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    Author
    Title Jumper Kinematics on Terrain Park Jumps: Relationship between Takeoff Speed and Distance Traveled
    Symposium 18th Symposium on Skiing Trauma and Safety, 2009-05-02
    Committee F27