How To Select A Parachute Container System
The harness/container assembly is your safety system. Any canopy, round or square, can be plugged into the main or reserve container/attachment, and be persuaded to open. The container system controls the deployment of those canopies. The harness secures you to those canopies. There have been a lot of dissertations on parachute canopies (how to select, fly, repair, etc…). Little has been published about the harness and container system, because, while seemingly simple, they are infinitely complex. The sheer number of the different emergency scenarios while skydiving is astronomical (i.e., low speed, high speed, total, partial, two canopies out, and so on). Your harness and container system must answer these challenges; it must answer them by prioritizing procedures in the order of the frequency of occurrence. Your job is to understand those options and make an intelligent selection. The purpose of this document is to help you understand the individual features you should consider while making this decision.
The TSO is the minimum safety & testing requirement. TSO standards have changed over the years; so the present day TSO may be measuring one quality adequately but not another. There is a difference between a Performance Standard and a Structural Standard. A test to a “Performance Standard” is fine for a functional test. However, testing structural integrity is another matter. During a “Performance Standard” structural test, it is assumed that the canopy opens normally. In the real world canopies don’t always open normally. As we know there are frequent aberrant openings, usually dubbed “line strip” or “line dump” openings. This type of opening has, in fact, occurred during drop testing by some manufacturers. The results have been catastrophic. Some of the manufacturers who have experienced this have built their products to withstand these aberrant openings. Some have not. Some have modified their products after the original testing with no consideration for the reduction of structural integrity. How can consumers protect themselves? Ask the manufacturer about the strength of their webbing and hardware. Ask them to what load the harness has been proved. Then ask their competitor to confirm this claim. Ask them if the harness is “fail safe”. That is, which location/joint will fail first and what will happen to the wearer if and when it does fail. The wearer should not come out of the harness.
The Ultimate Test
Time in the field = Proof of performance. It takes a minimum five years to “prove out” a new feature of a rig.
There are two choices for container comfort and fit. One is a soft flowing container which flexes and bends and is easy to pack. The down side of this choice, is that this type of container may “catch air”, and create excess drag. The other choice is a hard packed, molded container that is small enough to be completely out of the air flow, and will allow full body movement. This type of container must be shaped by design. Before you put it on look at it -- it should have a shape waiting to clamp onto your back. Modern design contour fit!
There are several fabric types used in the manufacture of sport containers of today. They are generally divided into two categories: Parapac and Cordura. Certainly there is a sub difference of the base types. That sub division is usually defined by denier. military containers used a 420 denier Mil-Spec C-7219 Parapac. This fabric is specifically designed for use in parachute containers. There are deniers less than 420 available and they should be avoided except for decorative purposes. Cordura has proven to be a popular and durable fabric for use in containers in spite of it’s excess weight. Theoretically, Cordura is more ultraviolet resistant because the coarseness of the material casts a larger shadow protecting it from ultra-violet deterioration.
Reserve Container Design
There are two basic reserve container designs in common use today. They are internal pilot chute and external pilot chute. On the internal design multiple side flaps are cantilevered over the pilot chute to a locking loop through a grommet which is secured with a ripcord pin. The external system has the pilot chute sitting on the outside of the flaps with loops passing down through the flaps between the folds of the canopy to the back side of the container where they are retained with the loops through a grommet by a ripcord pin through the loop.
Main Container Design
Which flap closes first and which flap closes last? On some containers this is critical. Buy a container where it either doesn’t matter or where they can’t be assembled incorrectly.
With the availability of over two hundred main canopies alone, container sizing has become an enormous challenge for container manufacturers. Generally, most mains are bigger than the reserve by a small percentage. The sizes of the canopies and the ratio between them should be close(See How To Select The Right Canopy For You). However there are times when you might need to vary from this practice, such as for an accuracy rig. The containers you buy should be sized for the canopy that will go into them. Over-stuffing and under-stuffing can cause problems i.e. cause the container to wear out more quickly by overstressing stitch areas and grommets, in the case of over-stuffing; premature openings, caused by pins falling out of loosely loaded loops, in the case of under-stuffed rigs. Be advised that similarly sized (square) main and reserve canopies seem to fly in unison better if you happen to have both open at the same time. This is a highly debated topic in recent years, with the world-wide move to square reserves and more frequent use of AAD’s.
Main Deployment Choices
In the beginning there were ripcords and spring loaded pilot chutes for deploying our mains from our backs, and reserves from our chests. This system worked by packing a conical spring loaded pilot chute, in compressed form, inside the main container, on top of the canopy and it’s devices. The container was held closed with a cone and grommet/pin system with the release pin on a cable leading to the release or ripcord handle. Pulling on that handle pulled the pin from a hole in the cone allowing the grommet to slip off of the cone, thus releasing the container flaps and allowed the spring to expand and spring out of the pack, hopefully. There were other variations on this theme, such as umbrella type springs, a even a springless pilot chute which was a hat (yes, a real hat!). To deploy, you removed your hat and flung it into the air; which brings us to the next generation in main deployment.
Hand Deploy / Throw-Out
While the hat trick was a little difficult, a pouch, external to the container, was devised. With the handle for the pilot chute mounted on the top or apex of the canopy, the springless pilot chute was folded into this container and the bridle to the container was Velcro’ed to the rig along its path to the pin on the container. The pin is curved to allow angular loading. Pulling the pilot chute out of the pouch with the handle on the top, and tossing the canopy into the free stream is all that is required to deploy the main. Pouches for this system have been mounted in several places, from the front of the leg strap, to the back of the leg strap, to the bottom of the main container.
The pull-out retains the sequence of the ripcord system and provides the added safety of keeping the springless pilot chute in the same container as the main canopy. It is equipped with a handle, mounted on the back, lower outside corner of the main container. Pulling that handle extracts the straight ripcord pin allowing the container to open, and the internally stored springless pilot chute to be put into the free stream. The handle on this system is mounted on the base of the pilot chute.
AAD On Main?
Generally in this sport, AAD’s are mounted on the reserve container. Some skydivers, and the entire "East Block", have however, elected to put their AAD’s on the main. It was explained to me this way. "I want my AAD on my main because my greatest fear is to be knocked unconscious in freefall. I would prefer to wake up under a malfunctioned main than I would under a malfunctioned reserve."(Al Kruger a.k.a. "Captain Hook"). Of course, having an AAD on the main would require a spring loaded pilot chute.
Reserves must deploy in two different environments. Slow speed, after a cutaway, and high speed, in the event of a totaled main. According to TSO C23c, slow speed deployments are required to complete within 3 seconds after a cutaway. The test allows no more than 2 seconds of free fall after the cutaway before pack opening. If an RSL is used, the benefit of the speed acquired by the 2 second free fall is lost and the reserve must still deploy in 3 seconds. Trying to control the “not more than 2 seconds” rule is difficult, and is allowed only because, without an RSL, there must be some delay. The intent is for immediate deployment. Manufacturers have played games with this specification. Some have interpreted it by saying, “if it opens in five seconds after cutaway it’s OK”. NOT TRUE! The only test that can be trusted is the test where an RSL is used. This is a critical feature, as there are many combinations of canopies and containers in use today which do not meet this requirement. Your only protection is to see a video of the tests. DON’T BUY a system without seeing a video of its reserve deployment abilities. Take a stop watch with you when you view this video and time the deployment. Time it from pack opening to full canopy. Make sure that there is no more than 2 seconds from the cutaway to the time when the pack is opened. If your time on the deployment is more than 3 seconds don’t buy it.
The high speed requirement is not difficult to meet, but some do fail this parameter. It is generally accepted that a reserve should open in 350 feet, at terminal. That equates to about 2 seconds at 174 ft./second. The testing is done by throwing the dummy out at 500 feet, at speed. The test is not timed and is not difficult to meet.
Riser Covers (Main):
There are two choices for main riser covers. Open or trough type covers, and Velcro sealed closed covers. If you skydive on your chest all the time, then you might like the open or trough type. If you skydive in other configurations you will prefer the sealed type, as they don’t open when you are on your back. Recent improvements to the trough type include an "over riser" inside flap.
There are several types of webbing used in the manufacture of personnel delivery harnesses. To understand the choices requires a little history lesson. Originally, harnesses were made of cotton webbing. During this era hardware was designed for use with the cotton webbing. We use the very same hardware today. When nylon was invented, it became apparent that nylon was infinitely better than cotton for use in most applications, especially personnel harnesses. Rather than retool the hardware, the nylon was then configured to be compatible with the hardware. The resultant product was 7000 lb. tensile, Type 13 harness webbing, identified by a black edge trace. At the same time Type 8 (Black Center Line, 4000 lb. tensile), and Type 6 (Red Center Line, 2500lb Tensile) were designed to be used with the Type 13 in a supplemental roll, where involvement with hardware and exposure to environmental hazards were not a concern. Additionally, Type 7 (Yellow edge trace, 6000 lb. tensile) was introduced at that time for use in cargo delivery, where no interaction with personnel hardware would occur. Some sport manufacturers have adapted this weaker webbing (Type 7) for use in sport harnesses. While strength has been a minor issue with this application, it does slip in the hardware and won’t hold proper adjustment.
Friction Adapters are the only hold over from the cotton webbing days. Most harnesses don’t use any other hardware, as additional hardware adds weight and creates a weak spot in the harness. Additionally, hardware can cause bruising of the wearers body. On harnesses where other hardware is used, for articulation for example, the consumer should know the ultimate strength of the hardware and its associated joint. A minimum of 4500 pounds, with a “fail safe” configuration is required for safety along the main lift web.
Sizing and fitting a harness is like sizing and fitting a suit of clothes. There are several benchmarks or “hard points” that must be held as the harness size changes. One is the point of suspension; it occurs at the top of the pectoral muscle in the hollow of your shoulder. Many rigs allow this point to rotate up to the top of the shoulder. This is incorrect and you will know it when you look under the shoulder portion of the harness and while the chest strap is keeping your mouth closed. If your harness suspends you correctly you will feel like you are sitting in a chair. This might require sliding your leg straps down under your thighs after opening. The other benchmark is the top of container. The harness must encircle your body while holding these two points. You should make sure that the harness you buy is custom made for you and that the manufacturer sizes your harness in both the main lift web and over-the-shoulder dimension. The harness must be comfortable in three different environments: in the air (in freefall), under canopy, and lastly on the ground. In the air we are usually on our bellies; under canopy, sitting in a chair; and on the ground, walking. The flex of webbing accomplishes this job just fine if the harness is configured properly.
Harness materials should meet mil-spec., but that is not enough. The material must be used as design intended. The webbing should be “shuttle weave”(the weave of both edges look the same) as opposed to “needle weave”(the weave of both edges look different). A “shuttle weave” is a locking weave, that will not unravel if the edge is nicked or broken. Refer to The Parachute Manual, pg. 80 - , sections 4.060 through 4.062.
There are two kinds of foam used in comfort pads -- closed cell and open cell. Most manufacturers use open cell foam that they buy at the carpet store. Buy a rig that uses closed cell athletic padding that will float and not absorb water.
The riser release system in common use today is the “3-Ring”, it is the de facto standard. There are several variations of this design in use. Due to some recent incidents where cutaways have been from difficult to impossible, I would anticipate additional variations or improvements. The 3-ring is a single point riser release system designed around three rings of decreasing diameter. Each is able to nest inside the larger with clearance for mounting webbing. They are secured and released with a locking loop, through a grommet, into a “push/pull” cable system that releases both sides. The housing pushes, while the cable pulls from the locking loop, which when released, allows the ring/levers to “tumble” open. There are two sizes available. The mini, which is capable of approximately 3600 lb. load and has about a 60 to 1 mechanical advantage, and the large or standard, which has more than a 200 to 1 mechanical advantage. The mini is generally accepted as adequate for normal solo sport jumping. The large is used for tandem, military and situations where high loading is anticipated. (See “The 3 Ring, What It Is And How It Works”)
You should look for a rig manufacturer who can provide you with the options your skydiving requires. Be reasonable, there are some options which might be dangerous. Find a designer with whom you can talk it over.
Pilot chutes have become an included component in Harness and Containers, therefore they should be discussed.
Main pilot chutes were generally discussed in the “Main Deployment” section. They do have some additional features mentionable here. There is large hole mesh and small hole mesh and there are two types of canopy fabric in common use, Zero-P and F-111. The zero-p is a silicone coated F-111, and as such, has a lower permeability, both initially and in the long run. The initial difference is minor, and for all practical purposes doesn’t exist. However, if you consider the following you can make your own decisions about the fabric and the mesh. A colander or sieve is held under a slow running stream of water. The water passes through the sieve as fast as it enters. Increase the water flow and the sieve will fill up and the water will spill over the edges. This is equivalent to what happens with porous fabric being drug through the air.
There are two important aspects of the reserve pilot chute. As it is usually spring loaded, the “jump” or launch of the spring is important. Additionally the drag capability must be considered. While you can judge the jump with your eye (remember to judge it coming out or off of the container) the drag capability is more evasive. You could drag them through the air with a fish scale but your airspeed might vary from jump to jump. The only way to accurately determine the coefficient of drag, is in a wind tunnel test. Poynter reports on tests of several kinds which might be enlightening and help to establish a mental base line. You must ask the manufacturers and judge their answer. If they can’t supply a “Coefficient of Drag” number beware!
Read our What you should Know About RSL’s article.
Will the rig of your choice accept the AAD of your choice? Has the rig maker approved the AAD makers installation? Has the AAD maker approved the rig makers instructions? The important thing to remember whenever you consider an AAD, is that the container, not the AAD, is the primary life saving device. The AAD must not interfere with the proper function of the TSO’d container and its TSO’d reserve.
© The Jump Shack
Reprinted with permission
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