Sit-skis are adaptive equipment that allow people with bilateral lower limb disabilities to participate in alpine and Nordic skiing activities. The Downhill and Super-Giant Slalom (Super-G) alpine disciplines are the highest speed competitive sit-ski events where aerodynamics plays a significant role. This project investigated the aerodynamics of New Zealand Paralympic athlete Corey Peters in the Downhill and Super-G alpine disciplines. Wind tunnel testing was conducted and the data was used to design an aerodynamic adaptation to the sit-ski equipment that reduced the drag force on Peters. The design was validated using computational fluid dynamics simulations. High Performance Sports New Zealand funded the project in partnership with Snow Sports New Zealand and the University of Canterbury. The results of this study filled a knowledge gap of aerodynamics in the academic field of sit-sking.

The first round of wind tunnel testing was done on a third scale model in a closed circuit wind tunnel with a maximum flow velocity of 200 km/hr. The model was mounted to a force balance and the data from the force balance was collected and analysed. Various modifications were made to the third scale model using plasticine. The modifications made to the leg cover had a minimal or non-existent effect on the drag force. The modifications made to the rear of the seat significantly decreased the drag force acting on the model. The most effective modification was a truncated ’Kamm tail’ that protruded off the back of the sit-ski bucket and decreased the drag force by 7.1% at 60 km/hr. Two full scale prototypes of design options were constructed after the testing on the third scale model. Peters trialed skiing with them and reported that they did not noticeably impact his skiing and did not prevent him from using the chairlift. A half scale model was constructed to enable the model to be tested at flow velocities equivalent to Peters’s race speeds. The second round of wind tunnel testing was done on the half scale model. The most effective modification in the testing done on the third scale model was scanned and turned into a CAD model. The design was then 3D printed and tested on the half scale model. further modifications using plasticine were made to the model. The final design had a drag force reduction of 6.9±0.4 % at 100 km/hr and a drag force coefficient of 0.58. The final design was validated by running computational fluid dynamics simulations on CAD Models of the original sit-ski equipment and the improved design. The improved design decreased the drag by 4.9±0.4 % across the speed range of 60, 80, and 100 km/hr.

A more aerodynamic sit-ski improved Peters’s chances of medalling for New Zealand at the 2022 Paralympic Games. Peters won a gold medal in the Downhill event and a silver medal in the Super-G event.