STUDY FOR TAKE-OFF AND FLIGHT TECHNIQUE IN SKI JUMP
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||HOKUSEIGAKUEN WOMEN'S JUNIOR COLLEGE|
SASAKI Tsutomu HOKUSEI WOMEN'S JR.COLLEGE, GENERAL EDUCATION, PROFESSOR, 一般教育, 教授 (40162375)
|Project Period (FY)
1998 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 2000 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1999 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1998 : ¥1,200,000 (Direct Cost : ¥1,200,000)
|Keywords||SKI JUMPING / POWER / REACTION FORCE / VIDEO ANALYSIS / SEGMENT MODEL / JOINT POWER / DRAG FORCE / LIFT FORCE / MATHEMATICAL MODEL|
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 techniques
This 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
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 model
In 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
Research Output (25results)