Development of scheme to evaluate the performance of parachute canopy fabrics under tensile impact

Abstract

The present research is an extension of the earlier work wherein a wider scheme of small-scale tensile impact testing is proposed, to characterise the whole parachute canopy instead of full-scale wind tunnel testing. The drop height for equivalent tensile impact on the rectangular stitched specimens is chosen as 300 mm, and accordingly, the dimension (Length × Width) has been decided (300 mm × 100 mm). To evaluate the performance of stitched specimen (at 45° bias angle), ungripped width of 20 mm on both sides of the specimen has been worked out. In the work, the actual payload responsible for parachute inflation has been addressed for the calculation of the exact opening shock force. Subsequently, to apply impact load on the specimen, dead weights are predicted based on the different levels of opening shock forces of the C-9 parachute canopy under different aerodynamic conditions. Considering a specific case, the behaviour of the ripstop and plain-woven fabric sample in terms of load versus extension curve and work done at the time of impact have been analysed under different loads using a high-speed digital camera. This study revealed that the plain-woven fabric is to be preferred for human dropping because it has a higher extension and higher impact duration than ripstop fabric. As a result, the plain-woven fabric will produce a lower impact or shock force in the parachute canopy which is to be transferred to the skydiver. On the other hand, ripstop fabric possesses higher strength, therefore can be preferred for materials dropping.