twisted risers We read in a recent APF News-Sheet of yet another hard cutaway experienced by an Australian skydiver. It prompted me to dig out a still very relevant article from the archives. Several years ago, there occurred a rash of hard/impossible pulls on cutaway systems, prompting John Sherman to conduct a series of experiments in May 2003 to accurately define the problem. John has written several definitive papers on riser construction and 3-Ring technology. In one of

In simplest terms, there are two forces involved. The drag force capability of the pilot chute and the force required to extract the bag. Certainly, the ability of the pilot chute must be greater than the retention of the container. This demands that we know the capability of the pilot chute. To know this requires testing with instrumentation. However, we can calculate the size requirement of the pilot chute and measure the bag extraction force without doing sophisticated tes

The purpose of this article is to illuminate on the facts necessary for jumpers to make an informed decision