• R.H. Sanders
  • J. Selina


The purpose of this study was to develop a method of determining lift and drag forces produced by the 'wing' blade In flatwater kayaking using data digitised from cine film or videotape. The method involves six operations. 1. Recording by two cameras on film or videotape known positions of points on a three dimensional calibration frame, two reference points on the kayak, and three reference points on the shaft of the paddle. 2. Obtaining the three dimensional positions of the digitised markers using the Direct Linear Transformation (DLT) method, 3. Determining the path of the blade and its orientation with respect to the external reference frame. 4. Calculating the 'sweepback' and 'pitch' angles of the Made using the direction of the blade centre path as the reference. 5. Applying known lift and drag coefficients for each calculated sweepback and pitch angle combination to determine the magnitude of the lift and drag force vectors at each sampled instant. 6. Determining the components of the lift and drag force vectors in the desired direction of travel and using these to calculate the efficiency of the lift and drag vectors. Reliability of the method has been estimated for the operations up to operation 4 using data obtained from elite New Zealand flatwater kayak paddlers under simulated competition conditions. Research initiated by the first author at the International Center for Aquatic Research to determine the lift and drag coefficients for any given sweepback and pitch angle combination is continuing. This paper describes the operations outlined above and presents some reliability data for these operations.
Equipment / Instrumentation