Canopy Design Accomplished design skills are not necessary for the rigger to  properly service parachutes. The skills involved to become a  designer can take several years of training and practice. It is  necessary, however, that the rigger understands some of the  basic concepts to relate the performance characteristics to the  design theory of the components involved. For the average  rigger, these concepts are accepted as those proven and tested  in the finished product. The following are specific areas that the  rigger should understand to determine the identity, function,  and assembly of parachute components and their interaction.  Understanding the sequence and method of deployment is  necessary when assembling components to assure proper  function. Most ram air parachutes are trimmed nose down,  and as such the canopy tries to fly over its nose during  deployment. This flight angle causes the top skin nose of the  canopy to roll over the bottom skin leading edge closing off  the cell preventing inflation. To counter this, the trailing edge  of the canopy is deflected downward to apply brakes during  inflation; this holds the nose up and open allowing air intake.  These are called “deployment brakes” and are implemented  by providing a “brake eye” in the steering line of the canopy  located so as to apply the proper amount of brakes. The  steering line is pulled down through the steering guide ring  on the risers and locked with the nose of the steering toggle  during the packing process. Loss of one or both brakes during  opening will most likely cause a malfunction. Loss of one  causes the canopy to turn into that side as the cells remain  collapsed and the inflated side over-flies the collapsed side.  In flight corrective action is to grab both toggles and apply  both brakes evenly and quickly. All riggers should become familiar with Parachute Industry  Association (PIA) Technical Standard 100 (TS-100),  Standardized Nomenclature for Ram-Air Inflated Gliding  Parachutes (See Appendix I). This document is the official  language and terminology used for ram-air parachutes. It  specifies the parts of the parachute, the various construction  methods, and the seam configurations used. This is necessary  for the rigger to understand the manuals and repair procedures  provided by the manufacturers for their products.  Figure 2-6 identifies the components of a typical round  emergency parachute. The nomenclature of this design  has remained constant for several decades with a few  exceptions. While some riggers who skydive think that  the square parachute has replaced it, the round parachute  still has many uses, and in certain instances, fulfills some  Nomenclature TS-100 describes the various ram-air construction methods  such as half-cell chord wise, full-cell “I” beam chord  wise, full-cell interlocking “T” chord wise, and span wise  configurations. When learning the various construction  methods, the beginning rigger can become confused as to how  the seams are folded together. Seeing the schematic diagrams  of the various configurations can help in the repair sequence.  Additionally, there are two basic methods of construction for  the main seam used on modern ram airs. One method is to roll  the adjacent bottom skins with the attendant rib together and  double needle 301 stitch to hold the joint. Line attachment  tabs are then appliquéd over the rolled seam for subsequent  line attachment. The other method is the foil method where  the rib has the line attachment tab attached directly to it and  is flat stitched to the bottom skins allowing the bottom edge  of the rib to be exposed. mission requirements better than the square parachute.  Poynter’s Parachute Manual, Volume 1, Chapter 8, provides  an excellent discussion of the design parameters and  characteristics of round parachutes for those needing more  technical background. Construction Concepts and Techniques  Figure 2-6.  Round parachute assembly.  Bridle Canopy Pilot chute Harness Risers Container Lines 2-5