STUDY FOR TAKE-OFF AND FLIGHT TECHNIQUE IN SKI JUMP

采用录像分析和测力的方法，将世界级运动员的起跳动作分为三类。在初始飞行阶段，采用包含三角项和指数项的数学模型对气动力进行了分析。采用三角模型分析了飞行过程中的气动力。（1）起跳技术的分类本研究通过对跳台滑雪运动员起跳过程中的角速度和关节发力规律的分析，明确了跳台滑雪运动员起跳技术的三种重要类型。A型：上身先上举; B型：大腿先上举; C型：膝、髋两关节几乎同时发力。髋、膝关节在每一跳技术中起着重要的发力作用。动力产生的方式对提高每个跳高运动员的技术水平很重要。特色 关于我们 每种技术如下：1）在A型技术中，每个关节中的功率产生以规则的顺序发生; 2）B型的特征在于腿的向前旋转以及髋关节和膝关节中功率产生的相位谐振; 3）C型的特征在于膝关节和髋关节中功率产生的模式，其中没有相位谐振。（二）、气动力与数学模型在飞行的初始阶段，物体受到两个力学因素的影响，即起飞运动时产生的物体动量和气动力。在空中飞行时，物体动量减小。由于空气对跳高运动员的影响，动量的衰减应收敛到一定的空气动力值。跳高运动员的运动速度与空气动力之间存在指数关系。同时，运动的物体在气流中产生涡流，在物体后面产生涡流。涡流使物体在空气中作周期性运动。在空中，气动力的周期性形式一直持续到着陆，但其幅值逐渐减小。最大阻力产生在着陆区P点之前。在P点后，起跳者受升力的影响大于阻力。空气动力与雪板长度和身体高度有很大关系。少

The take-off motion in World class umpers were were clasified three categories by using video analyses and force mesurement.. Aerodynamic forces were analyzed by mathmatical model which was consistec with trigonometric term and exponential term at initial flight phase. Aerodynbamic forces in middle of the flight phase were analyzed by a trigonometric model. These research results are as follows :(1) Classification of the take-off techniquesThis study clarifies three important ski jumping techniques based on an analysis of the patterns of angular velocity and joint power production. Three techniques were named shuch as 1) Type-A : upper body rose up initially, 2) Type-B : thigh segment rose up initially, and 3) Type-C : Take-off motion bigin almost same time in both joints of knee and hip.The hip and knee joints play an important role for generating power and force in each jump technique. The manner of power generation is important for improving skills in each jumper. Characteristics in … More each technique are as follows :1) The power production in each joint takes place in a regular order in Type-A technique.2) Type-B is characterized by forward rotation of the leg and phase resonance of the power generation in the hip and knee joints.3) Type-C is characterized by patterns of power generation in the knee and hip joint in which there have no phase resonance.(2). Aerodynamic force and Mothematical modelIn the initial flight phase, body is infulunced by two mechanical factors which are body momentum producing during take-off motion and aerodynamic forces. Body momentum decreases during locomotiuon in the aer. Because the aer influence to jumper as a dumper, decriment of the momentum shoud be converged to certain value of aero dynamic force. There was an exponential relation between jumper's locomotion and aerodynamic forces. Also, moving body in the air flow products eddies behind the body. Eddy makes the body to move with periodicity in air. In the air, the periodic fashion of aerodynamic forces continue till landing, however its amplitude decrese. Maximum drag force is produced before P point of landing area. After the P point, jumper is more influenced by lift force than drag force. Aerodynamic force greatly relates to ski length and body hieght. Less