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How To Select The Right Canopy For You

By adminon - Read 29283 times

In this article we will explore some of the questions you might ask when you go shopping for a parachute. While this advice is intended primarily for the novice jumper--just off instruction to one hundred jumps or so -- instructors may also wish to take note. As instructors we are often asked by our students, for advice on what kind of equipment to purchase. I always try to advise as if I were counseling a family member. “If you were my little brother or my little sister I would recommend the following.” Especially when I am in a student/instructor situation, I feel responsible for this fledgling until he is well on his way.

Picking the right parachute is more complex than you might imagine. With well over 200 main canopies to choose from, this decision can be harder than buying a house. Today, there is a huge spectrum of canopies, from extremely high-performance parachutes to downright sluggish ones. There are some excellent selections for the novice and intermediate jumper in the mid to lower performance range. Let’s begin by defining some key terms for the uninitiated.

High Aspect Ratio: The span (width) of the canopy is more than twice the chord length (straight line measurement from front to back) or greater than 2:1 aspect ratio.

Low Aspect Ratio: The span of the canopy is less than twice the chord length or less than 2:1 aspect ratio.

Elliptical High Aspect: As its name suggests, the elliptical canopy has tapered wing tips that significantly reduce wing tip vortices, thus reducing induced drag. When heavily loaded, this type of parachute goes very fast. The landing and stall characteristics are not as forgiving as a straight wing. It is only for the highly experienced skydiver with appropriate accuracy skills.

Dynamic Flare vs. Steady State Flare

There are two ways to land a parachute. More commonly in the past, the two methods were referred to as the “steady state flare” and the “dynamic flare”. The dynamic flare is one in which the brakes are applied, close to the ground or at the last moment at a toggle application rate of 1 foot per second. This is not a rapid movement -- it is really quite slow if you think about it. This maneuver converts downward and forward speed to vertical lift and diminishing horizontal glide. It should eventually result in a “tippy toe” landing. This maneuver, under a small canopy (meaning more than one pound per square foot of loading), almost anyone can do -- when the winds are up. In zero wind conditions the same maneuver requires years of experience, hundreds, perhaps thousands of jumps and a fabulous understanding of a particular canopy’s flight characteristics.

The steady state flare is what is commonly used by practitioners of precision accuracy. You do not have to be a highly experienced accuracy jumper to use it, as it is a very forgiving technique. You must have a canopy of adequate square footage, however, and it generally works better on the thicker airfoils (accuracy canopies, demo canopies, some student canopies). In a steady-state flare the application of brakes is done more gradually, can be initiated at a higher altitude, and generates a minimum of lift. This is in opposition to the dynamic flare which generates a great deal of lift. The goal is the same with either technique. The last six inches above the ground should look the same: forward speed is virtually eliminated, and the parachute is brought straight down.

The Pros And Cons Of Zero-P

Zero Porosity fabric is impregnated with a silicone-based product that makes the fabric more resistant to wear and aging. This coating is what makes the fabric feel so slippery.

The “Pros”

The “Pros” of Zero-Porosity fabric include a better resale value, because the canopy will retain its original flight characteristics longer. But resale value, I try to stress to all canopy shoppers should be the last parameter. Buy what is right for you now. Choose the colors that you like. Go for the size and model that best suits your present needs. Zero porosity does not improve canopy performance as such. It only improves the longevity of the canopy. That is a big plus. However...

The “Cons”

It is harder to pack. You can sugar coat it a lot of ways but the fact is, the slippery, slimy feeling fabric is more difficult to keep under control, especially for the novice just learning to pack. Zero-P packs “bigger” because you can’t get as much air squeezed out of the pack job as you can with F-111. You will take longer to pack. At this stage of the game you want to keep up with the loads -- make more jumps in a day and not be fatigued. Your energy is better spent learning to skydive, rather than wrestling with your pack job.

Canopies made from F-111 cost less. Considerably less. You can get many happy years of use out of your F-111 canopy, provided there is enough square footage over your head to start. Accuracy parachutes are made of F-111 because it allows the parachute to “bleed air” and sink better. This is something to bear in mind if you plan on doing a lot of demo jumps into tight areas!

Line Drag vs. Pack Volume

When should I choose Dacron? When should I choose Micro or Spectra line? Dacron lines provide greater parasitic drag, helping the canopy to shut down easier. Note that I speak in a positive light about this parasitic drag. In many cases it can be a good thing. Students would likely benefit from Dacron lines, as they often have trouble slowing down enough or at the right moment. Micro line or Spectra line reduces pack volume -- as a container manufacturer I love that aspect. I will grudgingly accept Dacron on my accuracy canopy to help control forward speed, however, and would recommend it to some young jumpers (under 200 jumps), for the same reason.

Micro lines do not cause hard openings. Loose, short line bites, oversized rubber bands or Tube Stows, or otherwise improperly stowed lines cause hard openings. Consistently soft openings are commonplace on many micro-lined canopies. Likewise, hard openings are easily achievable with big, fat Dacron lines, if improperly stowed.

Thick Dacron lines do not necessarily mean stronger lines. Jump Shack uses 1500 lb. Spectra on its’ Tandem canopies. There is nothing with greater tensile strength in use, in the parachute industry today.

I almost always recommend Micro or Spectra on reserves. It is stronger. It reduces bulk in an area where space is at a premium. You may want to fit an AAD in the reserve container later on. Because your reserve is most likely a relatively low aspect 7 cell, excessive forward speed is not a problem. The reduced line drag will enhance the performance of your otherwise low-performance canopy.

Winds And Field Elevation Change Everything

Ask yourself this question: “Is it predominantly windy where I jump? Is it rarely windy where I jump?” If you are lucky enough to jump in Hawaii where it is absolutely beautiful, but windy most of the time, you can get away with a smaller canopy. You may in fact need a higher aspect canopy to survive if you are a lightweight. You don’t want to risk blowing off the DZ, after all. If it is only sometimes windy at your Drop Zone, and mostly calm, anticipate having to judge the distance of your glide on those low wind landings.

Also consider Drop Zone elevation, and density altitude in the Summertime. Your parachute is going to display decreased performance capability at airports above 2000 feet, and on high temperature, high humidity days (the air actually gets thinner). You will have more difficulty stopping your canopy. The higher the elevation of your drop zone, the more square footage you should have. Otherwise anticipate a longer distance to bleed off forward speed. Above 2000 feet is where this factor becomes very evident, but I can feel the difference when I go away from DeLand, elevation 80 feet, and jump in New England at about 500 feet.

Surprised is the student who makes his first 8 jumps in a 7 - 10 mph breeze, on a 288 sq. foot canopy, then suddenly finds himself off instruction, with no radio, on a windless day, with a 190 sq. foot demo canopy. Don’t let it happen to you -- unless you have endless desert stretched before you, free of barbed wire fences. This brings us to another important point -- drop zone location. In conservative New England (God love it), where the drop zones are small and the obstacles many, novices are generally guided toward canopies that are adequately large and docile. Whether it is done consciously or not, I have witnessed that the square foot per pound ratio (important! not the pound per square foot ratio) amongst young jumpers in that region is about 1.5, which I think is perfect. If you jump in a congested area, or one with many obstacles on or near the Drop Zone, you are generally better off with a relatively low-performance canopy. Don’t buy the argument about not being able to “get back” to the Drop Zone on a long spot day. Keep in mind that even todays “low performance” canopies could fly circles around the parachutes that we used 15 or 20 years ago, and we used those parachutes for demos, for accuracy, for students...

Take The Conservative Approach

Fifteen to twenty years ago, instructors were jumping parachutes that were not significantly different from those of the student. Giving advice was easy. You could go round or you could go square. If you were a big fella, you jumped a T-10. If you were a lightweight you could have a 28 ft. flat circular. If you had some money to spend you could get a ParaCommander. If you really wanted to go out on a limb you could have a Cloud or Paraplane (the latter not all that low in performance)! The point is, most of the canopies were relatively low in performance, or sufficiently high in square footage (or area).

If I am speaking on the phone to a potential buyer, I always inquire about his age, physical condition, weight, and experience. I also ask where he jumps to get an indication of field elevation and prevailing conditions.

Because many of us have fantasies of being a Sky god or a World Champion of some sort, we have a propensity to project this onto our students, giving advice with this in mind for one and all. We forget how many years it took to achieve our present status. We forget that many are in this sport just for fun! We should remind ourselves and our students, that there is plenty of time to learn, and there should be no rush. The instructional community seems to have no problem with telling the new jumper to sit down on a windy day so that he can jump tomorrow, rather than risk a bad landing that will put him out for three months. Likewise we should be telling them to take the conservative approach to canopy selection. We must assume that the novice jumper is going to make a mistake at some point, so why not let him do it on a big, forgiving canopy?

Before you shop, talk to a few people, including your instructor, and some of the older, more experienced skydivers on your Drop Zone. Be careful not to let a salesperson dictate what you should buy. Because, while most retailers out there are reputable and knowledgeable -- they have a tendency to want to sell you what is in stock.

A Formula To Go By

Most manufacturers of parachutes speak in terms of pounds per square foot. For example, if John weighs 200 pounds and jumps a 97 sq. ft. canopy, he is loading it at 2.06:1 or 2.06 pounds per square foot of canopy.

When you go shopping for a canopy, you should think in terms of square feet per pound of your body weight (i.e. you weigh 200 pounds and you have 0 - 20 jumps). Using the following chart, multiply your 200 pounds by the 1.75 sq. ft./pound recommendation for your number of jumps, and find that you should be jumping a 350 sq. ft. canopy.

The following numbers are general guidelines from a conservative point of view. They are based largely on my own personal experience as an instructor, and active competitor, with 20 years of experience, flying canopies in every size range. For tandem jumping, I prefer the 400 square foot range. For accuracy, I jump a 252 to 259 square foot canopy, and for style, RW and everything else, I use a 107 square foot elliptical. So you see also, that different jobs require different canopies! Also remember -- there is an exception to almost every rule. For example, not all 7 cells are low aspect. The new Triathlon is a recent exception to that old rule. Not all reserves are 7 cells. There are 9 cell reserves, even 11 cell reserves. There is such a thing as thick Spectra line, and rather thin Dacron suspension line. There are a lot more exceptions where those came from.

Number Of Jumps Appropriate Square Footage Aspect Ratio : 1
1 - 20 1.75 sq. ft. / lb. <2.0 : 1
21 - 50 1.65 sq. ft. / lb. <2.0 : 1
51 - 200 1.50 - 1.35 sq. ft. / lb. 2.0 to 2.5 : 1
201 - 1000 1.30 - 1.10 sq. ft. / lb. 2.0 to 2.8 : 1
1001 - ? 1.10 - 1.00 sq. ft. / lb. >2.8 : 1

Some interpolation will be required here. Round the figure up or down as much as 15% to find an existing canopy size.

We know that highly experienced jumpers can and do exceed the one pound per square foot maximum as prescribed by most canopy manufacturers. This is one of the benefits as well as one of the hazards of living in a free society. We just have to be sensible about such freedoms.

A jumpers’ age and physical condition must also be weighed into the equation. Ask yourself honestly,

  1. Am I athletic and limber? Can I run off excessive forward speed from a small, high aspect ratio canopy on a high-density altitude, no wind day?
  2. Am I simply in good physical condition? (Perhaps you can’t run as well or as fast as you used to.)
  3. Am I in fair physical condition? (I don’t want to have to run at all.)
  4. Or am I in poor physical condition (Lacking in strength and muscle tone, not very flexible)?

If you are a “1," eventually when you have gained experience, you will be able to jump the sportiest of canopies. If you are a “2,” you may want a high aspect canopy, but with square footage in the 1.35 to 1.15 range. If you are a “3” or a “4,” consider a low aspect canopy, as well as abundant square footage.

The Step-Down Method

Spend your first two years or first 500 jumps on a canopy that is 1.5 square feet per pound in relation to your body weight. You should be completely comfortable in any situation or meteorological condition with that canopy before you graduate to the next size down. Then spend a year-- or 300 jumps-- whichever comes first, on the next size down the canopy, and so on.

Riding The Clutch

Fly with a little bit of brakes. It is OK to fly leaning on the toggles a bit. We do not have to be in full flight all the time until landing -- especially when there is a lot of other canopy traffic in the air. I routinely fly my Stiletto 107 in 1/4 brakes when on a large RW load or when picking my departure point to land in the pea gravel area. In a congested situation, one has to get in the landing queue (ahead of the big floater, behind the hot little 99 square foot canopy). The main reason for flying with a little bit of brake applied is to provide for more forward speed in the event you misjudge and find yourself short of your targeted landing area. You now have a little “extra gas”. Additionally, if you’re “steep” (high and close to your target), it is OK to apply some brake and sink till you reach the desired angle of attack.

Timing the flare is infinitely critical. Learning this skill simply takes a number of jumps to perfect. I think it is probably harder to master than the basic freefall skills. Some jumpers have a natural “feel” for this. Others may take hundreds of jumps to learn it! Most skydiving schools do not spend enough time on canopy control. More emphasis should be placed on canopy control in the post-instructional period. Teaching drop zones might consider a five or ten-jump “stand-up accuracy” course before graduating that student. Abundant square footage will provide for a greater margin of error until you develop the necessary canopy control skills. There are canopies out there for you.

If you have under 200 jumps you should allow yourself ample square footage, seriously consider low aspect, and resign yourself to a medium or large sized container. There is plenty of time to work your way down in size of canopy. No one ever screwed themselves into the ground because they were jumping a canopy that was too large.

Nancy J. LaRiviere
USPA/ I, Tandem Examiner
Pilot, COM, MEL
Senior Rigger
May, 1995

© The Jump Shack
Reprinted with permission



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