Hooknswoop

I totally agree that the steering lines shrink the most because of the reasons you mentioned. I meant (even though I didn't say it very well) that 10 inches of shrinkage was on a large canopy, and that it would very unlikely, if not impossible to find 10 inches of shrinkage on a Stiletto 97's steering lines. The longer the lines, the more they will shrink with use. It's all relative, the larger canopy won't be affected as much by the shrinking lines, even though they shrink more. I wonder if it would be possible to have "Pre-shrunk" Spectra, like jeans? I also agree that Vectran is the way to go. With either Spectra or Vectran, 400 jumps is max, but the Vectran-lined canopy will still be in trim. Hook

From Brush or Longemont to Denver, turn it off. The altitude difference is way over the 50ft Airtec suggests. I turn off my pro-track for the same reason. Hook

I don't think a power racer will work for the size canopies she wants. Hook

Biggest guy I've taken was 6'8, and well over 200 lbs. No problem. I had 2 rules for him, 1) arch or were gonna die and 2) don't jump up and start celebrating until AFTER I get you unhooked The jump went fine. Hook

I don't go out there because they don't call me to work out there anymore. I have got one call from them in the past 3 months, on a Friday, and I had already commited to working at another DZ. Hook

-10 C here Hook

I have seen Spectra shrink over 10 inches on a Sabre 230's steering lines. I think it is a percentage thing. The longer the line, the more it will shrink over time. Hook

I won't be at PIA this year. Do you consider the Cobalt to be a good student canopy? Loaded at 1.2:1? Why does a Cobalt loaded higher than a Sabre of the same size have a slower speed if it is more efficent? Hook

Brake setting and line trim drastically affect front riser performance. A quick and easy test for steering lines to to front riser the canopy without the toggles in your hands, then pick up the toggles and try another front riserr turn. If there is a difference between the two, then the steering lines are too short. Of course, make sure you have plenty of clear airspace and altitude when doing this. Hook

I am a little confused, a square canopy (Sabre) has more foward speed at the same wing loading, but the Cobalt has less drag and is more efficent? Just so I understand, you recommend putting students under Cobalts at a 1.2 wing loading? Has this been done? I have taught students (with 3 tandem jumps) using Sabre mains at a 1:1 wingloading. PD, Icarus, and I'm sure other manufacturers have wing loading charts as you descrivbe, beginner to expert. They don't seem to be very useful, or at least skydivers seem to ignore them. So you agree that planform makes a large difference in a canopy's performance, along with wingloading. So what is so wrong about classifing canopies by their plan-form, then factoring in size and wing loading? If someone is jumping a Sabre and is considering going to a Stiletto of the same size, they will notice different flight characteristics, mainly due to the different plan form. Turn rate, max speed, altitude lost in a turn and recovery arc will all be different without a change in wing loading. Thanks for taking the time, I know you are busy. Hook

Sorry, didn't mean to come off that way. That was my fault. PIA has a set method of measuring the size of canopies. They measure a lot of canopies and publish those numbers. For example to compare the performance of a Sabre 170 (PIA 179 sq. ft.) and a Monarch 175 (PIA 183 sq. ft.) the Monarch is 4, not 5 sq. ft. larger. Not a big difference from the manufacturer's numbers. Tom compare my Safire 189 to a Sabre 170, the manufacturer said that Safire1's are actually printed 7% larger than the way PD measures their canopies, which makes my Safire 189 a Safire 174 for comparing to a PD. Before the 7& rule came out, I let a few people jump the canopy and they all agree that it had more peromance than a Sabre 170. That makes sense, a Semi-elliptical 174 out-performed a square 170. So not knowing that it was a 174 didn't matter for performance comparison. It was faster, regardless of the numbers printed on the label. So, I think it would be nice if every manufacture used the same method to measure canopies, it isn't absolutely necessary for determining canopy performance. Without a series of charts showing turn rate vs. wing loading, glide speed vs. wing loading, max speed vs. wing loading, etc, for each canopy size, all we have is plan form catagory and size. Not excellent standards by any means, but unil something better comes out it is all we have. For someone to say you are doing it all wrong, you should be referencing a non-existant chart to determine performance is silly. I eagerly await Dna's reply to my (and others) questions. Again, my apologies Rigging65, Hook

Dan- A few questions: At what wing loading is a Cobalt "ideal" for beginners, and how many skydives (range) do you define "beginner" as? Your student canopy, do you mean the Cobalt? How do you define performance? Max speed? Max turn rate? Glide ratio? Altitude lost in a 360-degree turn? Do you dis-agree that an elliptical (tapered) [even Atair uses the term elliptical, even though we all know canopies are really tapered, it is a term that is recognized by everyone and understood, like Zerox], canopy will have better performance than a square (rectangular) [another skydiving term, square canopies are really rectangular], all other things being equal? Does Atair have a chart showing performance vs. wing loading for the Cobalt? Hook

PIA has a standard for canopy performance? Hook

Right, but aircraft are equipped with altimeters, VSI's, airspeed indicators,etc. Canopys aren't. Plus the test flight can last 3 hourse, generally. Canopy flights are not anywhere near that long. Didn't like that short field landing, power up and try again, no packing, manifesting, ride to altitude, etc. If was easy and cheap, and proved that a particular canopy's performance, manufacturers would publish these charts. Think about how much it would cost to fully test one canopy, roll rate, descent rate, glide ratio, airspeed, etc, over a wide range of wing loadings. Then compensate for non-standard temperature and pressure. If it was cheap, why hasn;t it been done? I have read a lot of ads proclaiming a canopy to have the "highest perfomance" of any canopy. Jumpers are interested in facts, manufacturers give us marketing. Hook

A few questions: At what wing loading is a Cobalt "ideal" for beginners, and how many skydives (range) do you define "beginner" as? Your student canopy, do you mean the Cobalt? How do you define performance? Max speed? Max turn rate? Glide ratio? Altitude lost in a 360-degree turn? Do you dis-agree that an elliptical (tapered) [even Atair uses the term elliptical, even though we all know canopies are really tapered, it is a term that is recognized by everyone and understood, like Zerox], canopy will have better performance than a square (rectangular) [another skydiving term, square canopies are really rectangular], all other things being equal? Does Atair have a chart showing performance vs. wing loading for the Cobalt? It seems to me a un-bias company would have to do the tests for each and every canopy, using expensive test equipment and a hundred jumps or so per canopy for each size, to get such a chart. Even then, without really nice test equipment, some of it might still be subjective. Sounds very expensive and time consuming. I don't see Performance vs. Wing loading charts in our future. So I guess we are stuck with dividing canopies into three categories, square, semi, and fully elliptical, then comparing them within those categories.

I believe it. I'm sure he means after a speed dive, into a full track, pitch up as much as possible, converting all that speed into lift. Like a cyclic climb in a helicopter. Of course, you can't sustain that fall rate, and speed back up after the "pitch up" manuever. I think it would be very, very difficult to get that fall rate just tracking, w/o a dive first. Hook

Plan-form shape is one consideration of a canopies performance. The terms square, semi-elliptical (really tapered on the trailing edge), and elliptical (really tapered on the leading and trailing edges) allow skydivers to break canopies down into three categories of performance. True, there are beginner-class canopies w/ more taper than some high performance canopies, but there aren't any elliptical beginner-class canopies, nor are there any beginner-class canopies that out-perform the high performance elliptical canopies. Generally as the canopy plan-form goes from square to semi-elliptical, to fully elliptical (marketing terms, but widely recognized) the turn rate and performance characteristics of the canopies increase. There are exceptions to every rule, but I can’t think of a single square canopy that will out-perform an elliptical canopy, all other things being equal (wing loading, size, pilot, material, etc). Breaking down canopies into different classes by square, semi-elliptical, elliptical, and cross-braced doesn't seem like that bad of an idea, given the lack of an alternate idea and serves as a pretty good guide to a canopy's characteristics. Hook

The type of grommets shouldn't affect Dave's lower steering lines, as they never come in contact with the lower steering lines (at least not in any meaningful way). He pulls the slider down before releasing the brakes. Dave, correct me if I am wrong. Hook

From PD's web site: "Since its release, the Stiletto has become the most sought after high performance "elliptical" nine cell canopy in the world... " It is "tapered" on the leading and trailing edges, outer 3 cells. Hook

25 jumps/40 re-packs, close Hook

Have a rigger carefully inspect your harness to make sure it is symmetrical. If one main lift web or leg strap is shorter than the other, it can cause the built in turn you describe. Also check you risers. They also should be exactly the same length. Since you describe the problem as occurring on several different canopies, it isn't likely that they were all out of trim, causing a left turn or all had too many twists in the left steering line. Since you are harness shifting, and aware of your weight in each leg strap, it isn't likely that you are leaning crooked in the harness. Since it happens on different canopies, it has to be the harness, risers, or you. Hook

PIA measured the Sabre 150 as: 413 cu. in., and 159 sq. ft. (Para-Gear, Pg 228) PIA measured the Crossfire 126 as: 363 cu in., and 126 sq. ft. (Para-Gear, Pg 228) Icarus lists the Crossfire 129 as: 295 cu. in. and 129 sq. ft. (Icarus Canopies Owners Manual, Pg 31) These measurements should be taken with a grain of salt. If you are worried about what canopy will fit in your container, try to find someone that has, or has attempted to put the same canopy in the same size container, and ask them how it worked out for them. Ask your rigger. And best of all, ask the manufacturers. Hook

I'm sure you get more foward speed. Hook

Time (sec.) Altitude (feet) Speed TAS (mph) Speed SAS (mph) 55.50 2463.16 74.10 69.60 55.75 2446.18 72.48 68.10 56.00 2422.42 72.43 68.07 56.25 2402.06 71.20 66.97 56.50 2378.33 70.76 66.57 56.75 2354.62 70.31 66.17 57.00 2334.31 68.70 64.67 57.25 2314.01 67.88 63.94 57.50 2300.48 65.50 61.72 57.75 2283.58 63.51 59.86 58.00 2263.32 62.30 58.74 58.25 2239.69 61.87 58.37 58.50 2216.08 61.43 57.98 58.75 2195.85 60.22 56.86 59.00 2179.01 58.25 55.01 59.25 2165.54 55.89 52.82 59.50 2148.71 54.70 51.70 59.75 2128.52 53.50 50.58 60.00 2104.99 53.08 50.22 60.25 2078.12 54.19 51.29 60.50 2054.63 54.15 51.26 60.75 2031.15 54.89 51.99 61.00 2007.69 55.62 52.69 61.25 1984.24 56.35 53.39 61.50 1964.16 56.70 53.75 61.75 1944.09 57.05 54.09 62.00 1920.69 57.01 54.09 These numbers and graph are from my pro-track from a 22 way dive. I was last diver out. I was wearing a normal RW suit w/ booties. I regularly see these speeds on longer tracks. I can feel myself accelerate as I come out of the track, so I usually pull very quickly after coming out of my track for the softest openings. [edited for spelling ] Hook

Checking the condition and trim of your canopy’s line set is simple. Run up your lines from the container to the canopy the same as the beginning of a normal “PRO” pack. Inspect the lines as you go, looking for areas of wear indicated by fraying. Check the length of your steering lines with the brakes set. They should be exactly even. If they are not even, check to see if they are twisted. A twisted steering line will be shorter than a line that is not twisted. It is best to remove any twists from your steering lines each time you pack. A high wear area, is near the loop for setting the breaks. As you fly the canopy, this area of lines is being pulled back and forth through the guide ring on the rear riser, causing wear. Stainless steel guide rings on the rear risers will reduce this wear because they are smoother than the zinc plated rings. When your canopy opens in brakes, the steering lines are under tension. Every time you release your brakes, you pull the tab (the stiff part of the toggle for setting the brakes) out of the loop. This “sawing” action results in tremendous wear on the loop, eventually causing it to break. Steering lines seem to wear the fastest. Another high wear area is where the lines attach to the links. If the slider is allowed to flap as you fly your canopy, the grommets beat on the lines, causing wear. A simple solution is a collapsible (kill line) slider. Vectran is more susceptible to these types of wear than Spectra or Dacron. Your rigger can replace a line or two that is fraying. Some riggers will replace entire line sets, but the manufacturer can replace a line set easier and in less than half the time it would take most riggers. Stainless steel slider grommets and soft links will also increase the life span of your lines. A brass slider grommet impacting a stainless steel Rapide link will cause the grommet to dent and burr. Instead of having a smooth grommet sliding down your lines, the grommet will have a rough surface, wearing out your lines at a faster rate. Inspect your slider grommets for nicks and sharp edges. Use emery cloth or fine sandpaper to smooth any rough edges. After inspecting the condition of your lines, check the line trim. Gather up the nose cells as in a normal “PRO” pack, and making sure that your risers are even and your lines are taunt, compare the length of the “A” lines (the lines that attach to the nose of the canopy). Compare the difference in length of your outer “A” lines (the lines that attach to the end cells of the canopy) to your center “A” lines (the lines that attach to the center cell of the canopy). When the line set is new, the “A” lines are all the same length, except for a few canopies, (check your owner’s manual or call the manufacturer for the specifications). As the canopy is jumped the outside lines will shrink faster than the inner lines (except with Vectran or HMA lines) because they are in contact with the slider grommets more than the inner lines. This uneven shrinkage affects the openings and performance of the canopy. If your outer “A” lines are shorter than the inner “A” lines, measure the difference with a ruler. Then check your owner’s manual or call the manufacturer of your canopy to find out how much the line set is allowed to shrink. If the line set is out of tolerances, send the canopy back and have the manufacturer replace the line set. I have had a line set replacement take as little as one week and as much as four weeks. When you inspect the sections of line with another line “finger trapped” inside it, be careful. When the outer line frays, it can look as if the line is not in bad condition because the inner line makes the line thicker. But if the outer line breaks the inner line can slip out and the line will come apart. Replacing the line set of your canopy is a part of the regular maintenance of your rig and will bring new life back into your canopy. A line breaking on opening can result in a cutaway and a line breaking at low altitude could be fatal. Hook