alan

I agree, you are changing tha AOA (temporarily), but at the same time you are also changing the camber of the airfoil. I may be wrong, but a higher aspect ratio (9 cell vs. 7 cel for example) and a cambered airfoil are more efficient at lower airspeeds. Hence, at higher speeds we change the AOI and then as speed bleeds off we change the AOA and camber. Sailplanes come to mind here. alan

Yes, I seem to recall that information from the article as well. Riser trim is nothing new, it has been around for years. It is not exactly cheating or cause for an asterisk in a record book. It is normal to change the trim and then release it at any swoop comp. It is just more reliable and efficient to do it manually though, as opposed to using trim tabs. My point was that the newspaper report posted in this thread was not accurate when it stated that Cani was the first to achieve freefall speed under canopy. He hasn't done anything that Pesa didn't do. alan

Possibly, but it is difficult to believe anything you post because you have chosen to also include the profile information below. It creates a problem with credibility with many readers. Your choice. Real Name: Kaloom . Nick Name: flipper Location: Europe/United Kingdom City: planet earth Email: No email entered. Jump Profile Home DZ: No home dropzone entered. License Org: toytown Number of Jumps: 12 Disciplines of Choice: Style and Accuracy, CReW Photographer: Yes Gear Container: Telesis 2 Main Canopy: Fandango 600 ft² (1.50 lbs/ft²) Reserve Canopy: Stellar Reserve 650 ft² (1.38 lbs/ft²) AAD: FXC Model 12000 Ratings Tandem: Instructor Pro Rating: Yes Yes and that is fine. So is all of the other stuff you listed. None of it believeable. My choice, and I'm sure that of others, is to regard you as a troll because of it. At any rate, the post is crossposted in another forum and the Forum Rules do ask that that not be done. A moderator should remedy that. That BTW is not your choice, it is theirs. alan

As an example of how subjective this can be, I have an 85 and 95 I've put a few jumps on and my initial impression has been I think they both out dive my 89 X-VX with much lighter riser pressure. I know that is counter-intuitive but then again more than just the line lengths may come into play and interact to achieve this result. I need to do more jumps. I'm not sure of the sizes though and even that is subjective with respect to the manufacturer. Dan has told me that the line trims/lengths on the Onyx are the exact same as those on the same sized Cobalt. They are about 10 inches shorter on the 95 Onyx than my 89 X-VX. The airfoil and planform are different than the VX as well as the trim angle. The quality of construction looks to me to be as good or better as any I've seen but the mis-labelling thing looks bad. Atair did well in my book in how they handled that, but it does raise a flag. The 95 is labelled as an 85 and Atair informed me via a phone call that it was mislabelled and they didn't discover that until after is was sent to me. Dan very kindly shipped me the 85 which has a label with 75 on it that was lined out and remarked as an 85. I have layed out my 89 X-VX and out the 95 Onyx on top of it. It is smaller with a little less span and more tapered trailing edge. The 85 Onyx is also smaller when layed on top of the others. No suprises with that as most of us are are of the variances in measuring/sizing methods in the industry. I don't have enough jumps on them yet for any meaningful review, but so far they glide very well, seem a bit slower in airspeed, have the "2 stage openings" the company describes, great surf, low toggle and riser pressure (relative to the VX) great flare and a very fast rate of turn. alan

Yes, that information was included in the article I mentioned. I don't see how that changes the fact of the speeds that were reached and recorded under a parachute that was successfully landed. I agree. They do log it as "wingsuit time" I would guess for obvious reasons. I wonder, how does USPA or even the FAI regard it for logging purposes and records and awards and such? A good example of technology getting a little ahead of our "rules" or the definitions in them maybe? alan

Yes, based on the profile the post is a troll. Isn't someone supposed to get rid of those, especially when they are cossposted in another forum (gear and Rigging). alan

What you are implying here is really unfair. There have been cases of Dacron, Nylon, Kevlar, Spectra, and Vectran lines breaking unexpectedly. I can't think of any line I've seen used that hasn't had incidents of unexpected breakage. Just do a search of these forums or the old rec. skydiving ng, you'll find at least one guy (Peter?) who ended up with a broken femur due to an unecpected failure of a Vectran brakeline during a landing approach. Same old, same old. When it was first introduced to the US market we had to hear over and over of the few isolated failures. Why do they fail? A manufacturing defect. An uneven load during deployment. Improper fingertrapping. Hidden wear. Overlooked or hidden damage (someone steps on the line while it is on the packing floor which also has a small, rough piece of gravel on it or it got pinched in a door or trunk hood). There can be many reasons and they may even overlap. When will a line fail? At any time, even good old reliable Dacron. Why? It just depends on the combination of events that puts it into the failure mode in the first place. So, how can you tell when to replace your lines? No method is fool proof. Any line can break without showing visible signs of wear. Complying with the manufacturers' recommendations and instructions are a good start, which usually include inspecting the lines during packing. Careful packing, as per instructions also can help. A slight packing error that inadvertantly and inconspicuously puts a heavy load on one line can damage it during opening enough that it fails later in the flight. Is either Vectran or Technora better or worse than the other? I don't really know, but I do know that annecdotal evidence of failures like you describe can be found for the lines your prefer. Would I prefer lines that I could just look at and know if they need replacing? Yes, but they just don't exist, at least to the degree of accuracy that some people seem to expect. I've had Vectran lines that "looked" like they needed replacing after less than 200 jumps. I replaced that after more than 500 or so. What does that mean? Not much, other than that set of lines, under the conditions that I used them, lasted more than 500 jumps. Why did the brakeline snap in the case of the person you know personally? I don't know and I suggest that you don't either. Was it because HMA is inferior or due to UV exposure? I don't know. Was it due to a quirk (more twists than the other one or a friction knot) in packing that loaded it more heavily during opening? I don't know. I don't think anyone does. Technora is susceptable to UV degradation. So is Nylon. The question is how much and how fast, especially in comparison to the other components. Is 300 jumps enough for too much UV exposure? I don't know. Did the jumper get it wet and hang it in the sun to dry? More than once? I don't know, but in this case maybe you do. The point is it is annecdotal and that leaves us with a lot of unanwered questions. I apologize for the lenthy reply, but it is raining here and I just don't have anything else to do. alan

Please don't forget to let us know what is new with Joe and why it is taking him so long to get back to Rob. alan

Skydiving Magazine and or Parachutist had an article with photos, I think sometime last year, of a Birdman either docked or nearly docked on a Velocity down in Florida. I think Vladi Pesa was one of the pilots. alan

The 300 to 400 jumps numbers for Vectran replacement were based on information provided by Precision Aerodynamics. I would expect that the numbers may vary depending on the source. George or Chris can provide you with technical data from the manufacturer that refutes this. At the time I wrote the article, I had and had read that data. It was over a year ago though. PA was monitoring canopies being jumped in the west and southwest with HMA (Technora) lines, mostly Nitros, and they were still going strong with 700 to 800 jumps. The lines had been in use in Europe for quite several years and PA was firm in it's re-line recommendations for Technora. My canopy now has another hundred or so jumps on it since the evaluation, the HMA lines still show no wear. I have no technical means for testing/measuring UV degradation, so I'll just have to wait until something fails or 800 jumps, whichever comes first. I don't follow the swoop tour closely but as some one else has said, most of those guys are sponsored so I wouldn'd expect many to jump an Icarus canopy with a PA modification. They do experiment with different line trims. I think the few freelancers on the tour would want to jump a factory canopy with the hopes of picking up that sponsorship when their performance merrits it. alan

Canopy pilots flying the Icarus EXTreme FX and VX now have an option to get an X-Mod done by Precision Aerodynamics. Usually made when the canopy is due for a re-line, which is recommended at about 300 to 400 jumps on a Vectran line set, the modification is an alternative which will offer several advantages and an upgrade in performance. The modification consists of replacing the stock Vectran with non-cascaded HMA lines, re-trimming the canopy, replacing the stabilizers with Precision’s “stabilrib”, and installing a new slider with lighter brass grommets instead of the stock stainless steel. The “stabilrib” integrates the stabilizer with the end rib and improves the efficiency of the end cells by loading the stabilizers and it eliminates the short section of suspension lines from the linestop to the rib inside the stabilizer. Advantages of the continuous HMA lines are reduced chord wise distortion of the airfoil and they will last more than twice as long as Vectran. About 9 years ago Paul “Jyro” Martyn of New Zealand Aerosports introduced a revolutionary new class of canopy based on the Excalibur, an early cross-braced design by Performance Designs. They were known as the Icarus EXTreme and developed into the 21-cell EXTreme FX and 27-cell VX version. In 1997, New Zealand Aerosports entered into a partnership with Precision Aerodynamics of Dunlap, Tennessee to produce and market the Icarus line of canopies. In 2000, CIMSA Ingeneria de Sistemas S.A. of Spain was brought into the partnership to expand marketing into Europe. The advanced design of these canopies necessitated very small tolerances in line trim. Because of the need for a fiber that would be less susceptible to heat shrinkage generated by the slider than Spectra, suspension lines made of Vectran were developed for use on the canopies manufactured by PA and later adopted for use by NZ Aerosports as well. But the ability to stay in trim over several hundred jumps came at a price. Vectran, while more dimensionally stable than Spectra, is much less resistant to abrasion. Vectran line sets began showing considerable wear in as few as 200 to 300 jumps, sometimes even less. Two years ago, Precision Aerodynamics decided to leave that partnership and once again produce its’ own line of canopies, introducing the Xaos models. The Xaos-21 and 27 have a suspension line that has been used in Europe on the Nitro canopies by Profile Research of Germany for over 9 years. The HMA or High Modulus Aramid lines have the dimensional stability of Vectran with the durability of Spectra, with re-lining recommended at 600 to 700 jumps. They have a smaller profile than similar strength Spectra lines, reducing drag. This reduction is at least partially offset by the need for continuous lines, as the small diameter does not allow for cascading. HMA is chemically the same as Kevlar, which is a low modulus aramid, but because of the weave and density, is superior to Kevlar for this application. A reported drawback to HMA line, one that is strongly refuted by PA, is that it is weakened by UV radiation. This review is based on a subjective comparison of an 89 sq. ft VX with approximately 500 jumps in the original factory condition and 100 jumps with Precision’s X-Mod. The canopy was manufactured in October of 1999 and was among the first dozen produced. All jumps were done at an average wing loading of 2.45 lbs/sq. ft from field elevations ranging from 700 ft MSL to 1000 ft MSL over a broad range of temperatures and wind conditions, including turbulence. Some standard VX’s have been know to have firm to hard openings and/or surge on opening. Tail flutter was also a problem on some of the very early VX’s. The subject canopy was a “good one” and never exhibited any of these characteristics. Before the X-Mod, the canopy averaged 3 seconds from container opening until the slider was down. With careful weight control in the harness, the opening would be within 15 or 20 degrees of heading after a little “searching”. Openings since the X-Mod have been consistently about 4 seconds, not as soft or long as a Spectre, but similar to a Stiletto. They have been very comfortable with a video helmet and camera. The canopy also seems easier to keep on heading during the opening sequence as the tendency to seek a heading is less pronounced. One note, Precision recommends using the small rubber bands for line stows and double wrapping them because of the small line diameters of the HMA lines. The canopy was jumped with small, single wrapped mil spec rubber bands with good results. Rear riser turns with the brakes set are quicker and steeper with a more noticeable oversteer. With the brakes released, the rear risers have less pressure and the turns are very quick but controllable and predictable. The glide can be flattened out with very little outward pressure on the rear risers and pulling down more than 3 inches puts the canopy on the edge of a stall. The stall with rear risers is very abrupt and violent. Overall, after the X-Mod, the canopy is more sensitive to rear riser input but has noticeably better glide. Front riser turns have less initial pressure and it does not build as fast or as much as before the X-Mod. Toggle pressure is similar to before the mod, perhaps a bit lighter and the turn rate is not noticeably different. The unmodified VX had a long recovery arc. But now, after an aggressive dive, it requires some toggle input to plane out. Before the mod, an aggressive toggle turn and a transition to front risers during the momentum loss at the apex was needed to achieve a critical dive angle, where the dive could be sustained for several thousand feet with moderate pressure on double front risers. After the X-Mod, the front riser pressures are light enough to achieve a critical, sustainable dive with a front riser snap turn to double fronts. With the X-Mod, there no such things as starting the landing maneuver too high and planing out early…just let it dive and use the front risers to steer it to whatever heading is desired during the dive. The flare is stronger, with longer surfs and better shut down. The X-Mod allows the canopy to maintain its’ lift at a noticeably slower airspeed. One characteristic the canopy exhibited before and after the X-Mod is very high toggle pressure at the bottom of the recovery arc after a high-speed dive. In the dive, speeds in the mid 80s were recorded on a police radar gun with the plane out in the lower 70 mph range. Rear riser landings should only be attempted by very experienced canopy pilots and then only after considerable experimentation at safe altitudes. Careful, smooth inputs by the pilot will result in consistent crosswind surfs of over 200 feet. Erratic inputs will result in a very ungraceful landing, or worse. Since the X-mod, the canopy has been stable and seems to maintain good pressurization during the flare but turbulence is more noticeable. In summary, the X-Mod by Precision Aerodynamics results in an improvement in the overall performance of the EXTreme VX, with better opening characteristics, better glide, longer surfs and a stronger flare. The cost of the X-Mod is $458.00 as opposed to the $268.00 for a standard Vectran re-line and includes replacement of the stock stabilizers with Precision’s “stabilrib” and a new slider. After the initial modification, HMA re-lines cost the same as the standard Vectran re-line. When one considers this and the life expectancy of the HMA lines is more than two times that of Vectran, the seemingly high initial cost turns out to be a good value. The added performance is a bonus. Precision will return the original slider with the canopy after the X-Mod and upon request, will also return the stabilizer logo panels. The HMA lines don’t have the clean, white look of Spectra and packing them is like trying to pack cooked spaghetti. If you are not satisfied with the X-Mod return the canopy to Precision within 30 days. They will return it to the original configuration with a standard Vectran re-line and the final cost will be that of a stock Vectran re-line. Contact Precision Aerodynamics at 423-949-4688 for more information about the X-Mod on your EXTreme FX or VX canopy. alan

You're correct, my bad. Meant to say "longer" in the first quote. Sorry, it was late and I was tired. Going back over my post , I now notice a number of errors and typos. At any rate, the Nitro/Nitron is an excellent canopy......with a little longer recovery arc than a Stiletto.........and very worthy of consideration in comparison. alan

Planform refers to the shape of the wing and we sometimes genereically refer to a wing as an airfoil. With respect to parachutes they are generally referred to as having an elliptical planform, square, round, tapered, semi-elliptical, etc. Airfoils are generally described by a series of NACA numbers that are used to describe the shape of the airfoil. They are typically flat bottomed, symmetrical, asymmetrical, or cambered. alan

I've got about a dozen or more jumps on each of the 120 Nitron and the 135, exit weight about 220# or 225#. I believe it is the same canopy as the Nitro. Very nice, consistent openigs. Very good swoopers. Seemed to have a recovery arc a little shorter than a similar Stiletto. Once it planes out, it needs very little adjusting to kep it flying level. When it runs out of speed, just finish with a deep flare and it shuts doen nicely. I watched Safire 149 @ ~1.25#/ft2 and a 120 Nitron @ ~1.6#/ft2 jump side by side yesterday. I got the distinct impression the Safire was faster. In my opinion, anyone looking at a Stiletto should also give some consideration to the Nitro/Nitron, they have higher toggle riser pressures, but a longer recovery arc. Just goofing around doing balloon jumps. John and I made a flop and landed back in the ball park we departed from, while Ken flew. Then I traded places with Ken ans flew so John could go up and make a second jump only with Art this time. I landed the balloon right where Art and John landed. BTW, people can diss the Safire I all they want (not referring to bill). Allowing for a few "lemons" that truly are bad and can be found in any line of parachutes, if you have a good one, you just need to learn how to fly it. It does not respond like a PD canopy. That does not mean better or worse, just different. They are fast and they can swoop. You can shut them down for nice walk offs. They like a deep stroke to plane out, but once it is planed out, you really don't need to keep milking it, it will surf right there until it runs out of speed and starts to sink, then finish the flare to the full stroke. Try it, you'll like it. alan

I'm sure you already have done this, but just in case you overlooked it, when you are up high and getting a feel for planing the canopy out, try to get a feel for when and how it will stall. Actually stallling a HP elliptical can add a certain amount of risk so go easy and work your way up to it. A rear riser stall during landing can be very dangerous so it may be best if you get a feel for what it feels like up high. They usually come very abruptly, with little warning, so be prepared for a subtle change in the flight and feel of your canopy as the stall approaches (very soft feel and no lift ). The stall can be induced by a slow, gentle input (static stall) or a quick, aggressive one ( accelerated or dynamic stall ). The amount of input needed will vary with the rate at which it is applied. Hope this helps, if it is old hat for you, maybe it will help someone else just reading the thread. alan

I have been under the impression that the speed building manuever was to lengthen the distance of the "surf" and that the flare comes at about the same airspeed on a given canopy regardless of the length of the surf or speed at which the canopy enters the landing approach. Wouldn't high lift at low airspeeds and a high critical AOA be the factors that create/allow for a more powerful flare, unless you are flaring at high speed? I'm thinking that a flare at high speed would just cause you to pop up. Just curious. Still love my old Jedei, I think it is like being an old Deadhead. alan

Awww crap. I just posted answers to all of your questions in the other thread. alan

Wrong. The bungy connects the apex to the top of the bridle where it attaches to the base of the PC. Correct, when assembled and maintained properly it collapses the PC. Correct. It will no longer collapse the PC. Yes. Yes, it loses it's elasticity in that it remains in the "stretched" configuration and will not contract back to the length that will collapse the PC. So, while it does lose elasticity, that causes it to leave the PC inflated rather than preventing it from inflating. No, only shrinking or in some way shortening the bungee would cause this, or more likely, an incorrectly assembled bungy. alan

Assuming the rest of the PC is serviceable, it would have been much less expensive to just have a rigger replace the kill-line. alan

Ed, you said the each of the above quotes in two different posts. Can you see a little inconsistency in your comments? I'm not agreeing or disagreeing with either, I just wish you would make up your mind. alan

I'm needing a new RW suit and have narrowed it down to Tony, Bev, or Windline. Mr rig is black with royal blue tye die trim. The canopy is white with royal blue crossbracing. Thye rowal blue use to be called cobalt blue I think. Can anyone post pics of their jumpsuits. I need ideas for mine.Please include a pic of the rig if it is color coordinated. alan

You might want to review what a stall is and the correct terminology. I think what you are trying to refer to is a static stall when you say slow-speed. A stall by definition is when an airfoil exceeds it's critical angle of attack. The boundry layer of air flow separates from the surface of the airfoil and lift is lost. There is a little burble of turbulent air at the trailing edge of the airfoil and as the AOA increases, this burble moves toward the leading edge. When it gets near the thickest part of the airfoil, usually about 30% back from the leading edge along the chord line, The air delaminates and the airfoil loses all lift and stops flying. A stall can happen at any airspeed. A static stall occurs when you gradually increase the AOA and make no other adjustments. The airfoil will settle into a new slower airspeed and static flight at the new AOA. Continued slow, smooth increases in the AOA will eventually get you past the critical angle and the airfoil will stall. It will usually give some warning by getting very mushy. You canopy scenario at 300' will result in a canopy that gets mushy and will momentarily "porpoise" a bit to seek a static state of flight with neutral control inlut. It will not stall, unless there is something else going on. An accellerated stall happens when you keep increasing the AOA while trying to maintain your airspeed. The airfoil will still stall once it has exceeded it's critical angle of attack, which by the way is determined by the angle the relative wind hits the airfoil relative to the chord line. You have a higher airspeed, but the airfoil still stalls. A dynamic stall is a whole new and dangerous beast. This type of stall appears when you effectively increase the wing loading of the airfoil by doing a manuever that adds a "G" force load to the airfoil. This means the airfoil is effectively supporting more weight and that reduces the AOA that it will stall at. So here we have a manuever at a relatively higher speed, inducing "G"s, meaning it is supporting a heavier wing load, with a shallower critical AOA. Now, during that manuever, a rapid jerky control input causes a rather abrupt and dramatic increase in the AOA of the airfoil that is now moving fast but supporting extra weight because of the induce G's. All of these factors combined result in a dynamic stall, what some are mistakenly referring to as a high-speed stall. Bottom line is, the canopy scenario you give at 300' and recovers at 30' will just porpoise a little as it seeks to return to a static state of neutral flight, it will not "slow-speed" stall as you call it. I'm not sure what they taught you in the four canopy classes you claim to have taken, but there seems to be an indication that there was some deficiency either on their part or yours, with respect to basic aerodynamics of canopy flight. alan

I wouldn't be so quick to just accept this. Too many assumptions. Yes, the Velo has a longer recovery arc but it is also a more efficient airfoil, so if flown properly it can be made to recover to level flight very quickly after yanking the toggle to do that emergency 180. That is not to imply that you cannot accomplish the same thing with a Stiletto, they both do the same thing, just at different rates, so pilot reaction time and control are critical factors. I can yank a toggle on my VX, do a 180, stop the turn, climb 25' or more and return to level flight or even do a barrel role with considerably less than 200' of altitude loss and never come close to any kind of stall. alan

Just a typo I expect, but short recovery arc equates to positive, not negative as stated above. alan

Good point. Just a bit of semantics, but I think the proper term is dynamic stall. Your point does address the issue of a canopy with a shorter recovery arc, such as the Stiletto. I think the perceived advantage of the shorter arc in recovering and planing out quicker is offset by the tendency of most people trying to dig out of the corner and thereby inducing the stall you refer to. The Stiletto with the shorter recovery arc will also respond to a given toggle input more and make it a little easier (more likely ?) to induce a dynamic stall. I've seen it quite often, low turn, try to dig it out and a bad situation just got worse. Some situations are not recoverable, but I have seen far too many that were, but instead of remaining calm and using smooth controlled toggle input, the pilot digs in a little and as he/she realizes it is not working, they panic and sharply dig in even more. The result is a dynamic stall and injury. Many of those would have been recoverable with a smooth application of brakes to some point far less deep than the hips. alan