Chapter 4


Main canopies have changed dramatically over the last several years and, consequently, different opening problems have emerged. One of the most common problems encountered is hard openings. The most effective method employed to reduce hard openings is to roll the nose of the canopy to close off the openings in the leading edge during the initial inflation process. This rolling technique varies from a single roll to several rolls. Figure 4-33 shows this technique. If this does not solve the opening problem, riggers should contact the manufacturer for advice. Most manufacturers are very cooperative and have considerable expertise in working with their products.

In the event the manufacturer cannot resolve the problem, it may be necessary for the rigger to modify the slider size, or deployment brake settings. Of these options, the easiest to do is to change the brake setting. Reducing the brake setting results in less pressure on the canopy during opening, thereby reducing the opening force. The negative effect of reducing the brake setting is an increase in opening surge. The new brake setting must find the balance of these results that best fit the user. If changing the brake setting does not work, then the rigger may wish to increase the size of the slider to slow the openings. This usually means replacing the slider with a larger one. This has the effect of increasing the drag on the slider and restricting the canopy inflation.

As canopies age and accumulate substantial jumps on them, many begin to develop slow openings, commonly known as “sniveling.” If the canopy was originally packed with the nose rolled, reducing the number of rolls may speed up the openings. However, many times the slow openings are due to other causes. One of the most common is the canopy getting out of trim due to the stretch of the suspension lines. The rigger should check the trim of the canopy against the manufacturer’s specifications and either re-trim the canopy or re-line it. This has a pronounced effect of improving the openings as well as the flying characteristics, particularly on canopies made from zero porosity (ZP) fabric.

The effect on fabric that originally had a porosity (permeability) of 0-3 cfm or 0-5 cfm, such as PIA-C- 44378, may not be as dramatic. With these canopies, changing the brake setting and increasing it by pulling down the tail will speed up the inflation of the canopy. The rigger must be careful not to set the brakes so deeply as to place the canopy in a stall during opening. If this does not work, then decreasing the size of the slider or the fabric type of the slider may help speed up the openings. Some of these problems, while appearing to be main canopy related, are traceable to other components of the parachute system such as the deployment bag, bridle, or pilot chute.


Hand deploy pilot chutes are generally made from either the PIA-C-44378 (F-111) fabric or more commonly, zero porosity (ZP) fabric. The PIA-C-44378 fabric begins as a very low porosity fabric but as it is used, the permeability increases. As this happens, the drag of the pilot chute decreases. Consequently, the ability of the pilot chute to lift the weight of the canopy decreases and the speed of the opening is affected. Experience has shown that pilot chutes made from this type of fabric exhibit a decrease in performance at around 500 jumps under normal use.

Pilot chutes made from the ZP fabric last considerably longer than those made from F-111. However, there has been some disagreement concerning the use of the two different fabrics in pilot chutes. One canopy manufacturer advocates the use of F-111 type fabric only. They believe the ZP fabric contributes to hard openings. Most parachutists like ZP pilot chutes because they last longer.

The size of the pilot chute has a direct correlation to the type of opening experienced. In the early days of hand deploy chutes, a 36" F-111 pilot chute was standard on most systems. As the canopies became smaller and lighter, pilot chutes became smaller as well. Today, 24-26", 30", and 33" pilot chutes are all common.

Several factors dictate the size of the pilot chute used. The first is the weight of the canopy. Another factor is the main container closing configuration. Some systems are designed to hold the deployment bag so securely that it literally has to be jerked from the container. This type requires a larger pilot chute than the type of container that allows unrestricted extraction of the bag. This same problem can develop when an individual packs an oversized main canopy into the main container. Usually, a larger deployment bag is needed to hold the additional volume. When the bag is forcibly stuffed into the container, the bag can be restricted from being pulled smoothly from the container.

If the pilot chute is too small, a pilot chute in tow can result. If the parachutist puts a larger pilot chute on the system, the bag can be extracted from the container, but the increased size of the pilot chute contributes to increased snatch force during the opening sequence. This results in perceived hard openings. Therefore, the size of the pilot chute and the deployment bag can have considerable effect on the opening characteristics of the main parachute.

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