alan

Dave, I have a couple of questions about this. Does this mean you have a ring added to the top of your riser for this purpose or am I misreading something? Also, what is the advantage to this method? Any disadvantages other than the one indicated? I put a small rubberband thru the link (soft or rapide) on the riser, just as I would on the side of the D-bag, to hold the excess brake line. It seems simple and foolproof and it is easy to replace the band when it needs it. alan

"Well, your judgement is obviously very different from mine, but you are the boss. I spent time to express my thoughts in this forum, on topic that I considered relevant and in a polite manner - but if you prefer to throw it away on your whim, OK I will not be here anymore." I'm not sure what post you are referring to, but I did not remove any on a whim. Please send it to me and I'll see about reposting. I'm sorry you would choose to not come here anymore, because as I explained, I removed some threads/posts because I was afraid the clutter would drive people away. I was hoping to encourage people to post to the proper forum and keep the posts relevant to gear and rigging. I am human and I may have erred in judgement. "But in your place - I would have move it to other forum." Good suggestion and I will keep it in mind in the future. I'm not sure you would have known that is what happened to it, but at least I would have perhaps had the opportunity to inform you. Good choice. The fact that you mention it suggests that maybe your post did belong in one of the other forums. I hope you will stay with us. alan

Never had any surge or slack on any of my 300+ VX openings. It is an 89 @ about 2.4. Just to lend a little balance to Chucks' post, review the results from the various swoop meets and pay attention to what canopies are consistently winning, it may give a hint as to why Atair is going to release a crossbraced canopy. alan

"Forum information" "Gear and Rigging " "The Dropzone Gear and Rigging forum where you can discuss any gear related questions and issues." Try to use the appropriate forum when posting and try to keep on topic. We all want to have fun and have open discussions but if we stray too far too often, then this forum loses some of its' usefulness. I don't like to use a heavy hand here, but if you have noticed posts and threads disappearing lately, it is because, in my judgement, they were not appropriate for this forum. I hope you will all understand and be considerate of others when posting. They come here looking for information about gear and rigging. Let's not disappoint them. Thanks for undestanding and helping. alan

The purpose of this forum is to exchange information and ideas about skydiving gear and equipment. Opinions are also welcomed. If you have any facts or real information to share, please do so. It is not proper to spread rumors and innuendo here, so please take that to another forum. There was an accident at the Ranch and it did involve a Crossfire. If it is your opinion that there is a design flaw, then please state that and share with us why you believe it to be true. alan

Pressurization is a function of speed, so a faster moving canopy will have higher pressurization. 9 cells are typically faster at a given wing loading and therefore will have higher pressurization and less need to repressurize in the first place. Sinking it in in turbulence is not a good idea as a general practice during normal skydiving. One may need to during certain demo jumps, accuracy competitions, or in certain emergency landing situations but these are special circumstances. Stability in turbulence? A lot of design factors play a role here, so it may be a bit too simplistic to say seven cells are more stable without detailing the circumstances. Pilot skill and technique can also paly a role in managing the stability of a canopy. Just a little food for thought. alan

You or your rigger should contact the manufacturer before making this mod just as a matter of good practice. When in doubt, contact the manufacturer. A much simpler method I have seen is to leave the top of the loop sewn on parallel over the top of the riser, but sew the bottom end at a 90 degree angle to the riser. See what Sunpath has to say about that. alan

The bungee collapsible pc's that I am familiar with are calibrated to 80 mph or less. The exit speed of most aircraft commonly in use today is 90 mph IAS or more. That would mean that the pc should be pretty effective at exit. They can and do get out of tolerance with repeated use, but with normal, routine care and inspection, it will serve you well for hundreds of jumps. BTW, about shade tree modifications. Adding a bungee and changing the grommet amount to about the same thing. alan

"Well, of course the pin is still there, but the loop should not be if the CYPRES fired.. The CYPRES fire would have severed the closing loop, and the chances of the cut loop staying with the jumper are very slim.." The bottom half of the loop will almost certainly bein the retainer in the reserve pack tray and it can easily be examined to determine if it was cut. It does not take a rigger to deteremine if the CYPRES cutter has activated or not. It is also very possible for the top half of the loop to stay in the reserve pack tray. It is over the reserve pin and may very well stay in the jumpers burble and "fall" into the pack tray. alan

"was he tracking when it happened?" If he was tracking properly he could expect a reasonably soft opening. A good track will result in a slower airspeed than a normal face to earth opening. You will have a faster forward (horizontal) velocity but a slower vertical velocity and the resultant vectored airspeed is actually slower. If you are a poor tracker (dive more than you track, then you may experience a slammer. alan

Call the manufacturer of the rig or have your rigger do it, but that is the only answer to your question. They can and will tell you the approved method for removing adhesive residue and/or cleaning. Happy trails. alan

"Also if you are flying a 7 or 9 cell pd 190 made of f-111 fabric you wont get a lot of glide out of it." A PD 190 would be a 9 cell, a PD 193 would be a 7 cell. alan

"To keep up with Cypres maintenance, you have to replace the batteries every 2 years." I'll just add a little detail to this. According to the manual it should be changed after 2 years, 500 jumps, or when the self test stops at 8998 or 8999 (voltage too low), whichever comes first. alan

Have you asked your Jumpmasters/Instructors for advice? Your rigger is also a good resource. Preferably someone who has seen you fly and is familiar with your skills and abilities. Be very leery of any advice you get from anyone who is not familiar with your flying experience and recommends a wing loading much over 1.2 for your first canopy. Higher wing loading means more speed, speed which you may or may not be prepared to handle yet. Light ellipticals may be OK, but they will have a higher rate of turn and I am sure you are already aware of the dangers of a fast turn near the ground, whether it is intentional or just a mistake. For most jumpers at your experience level, a heavy elliptical will mean trouble and one at 1.2 or higher is playing Russion Roullette. alan

I see a lot of good answers here. I'll add Ed Cummings at CRW, Inc. to the list of great dealers with great prices and service. alan

TSO testing standards can be found in Poynter's Parachute Manual. Very informative, even if it is a bit on the dry side for reading. alan

One thing to remember is that the fabric that canopies are made from is "calendered". The fabric is woven from a filament that is nominally round. The woven fabric is then run through a series of high pressure rollers (calender) that flattens the filaments. This helps to seal the spaces between them, making the fabric less poros. ZP fabrics additionally have a silicon based coating applied that efficiently seals the remaining spaces between the filaments that calendering does not seal. It is very durable and can last over 2000 jumps. Over time, and with use, F-111 type fabrics will become more poros as the "flattened" filaments return to their natural shape and the weave looses its tightness. Getting the canopy fabric wet will accellerate the process. After market applications can temporarily improve performance, but will need to be re-applied on a fairly regular basis. A used ZP canopy might be a more practical approach to getting an economical improvement in performance over the long run. You would also probably get the benefit of a newer design with better technology and therefore an additional improvement in performance. alan

While this forum is for ear and rigging questions and technically, this may be stretching it a bit, I am leaving this post up and hope someone can help out on this one. alan

I would not recommend washing a canopy. The fabric is usually stabilized, but the reinforcing tapes generally are not. If you wash the canopy you run the very real risk of putting it seriously out of trim. I have, on occassion, wiped my canopies off with a damp wash cloth, but be careful not to soak it or thoroughly wet it. Then wipe it dry with a soft, absorbant cloth. Do not let a canopy dry in the sun. The UV radiation will damage it in a short period of time, weakening the fabric. If your canopy gets wet swooping the pond, get it out fast and dry it with towels and a fan out of the sun. alan

A recent owners manual for any rig from Rigging Innovations might have what you are looking for. alan

OK, time for me to jump back in here. I am not comparing apples to oranges. When I refer to a 7 cell or a 9 cell, I intend that to be the only difference. I am assuming the same wing loading/same size canopy. Both are either square or elliptical. No difference. I'm not saying that the square stops faster, but has a wider performance envelope. Let's look at just one parameter to see what I mean. 9 cell stall speed (at a given wing loading, lets say it is 5 mhp. The comparable stall on the 7 cell might be 3 mph. Now compare forwrd speed in full flight. The 9 cell might be 25 mph. The 7 cells would be more like 20 mph. The envelope for the nice cell would be 25 to 5 with a range of 20. The envelope for the 7 cell would be 20 to 3 with a range of 17. I think the same is true of wing loading. Both the 7 and 9 cell canopies can be flown at very similar wing loading at the lower end of .7 or so, but the 9 cell because of the increased lift provided by the higher aspect ratio, can be safely flown and landed at a higher wing loading. These of course are hypothetical numbers, but I think they reflect what I was trying to say. That same 9 cell won't come down as steep as the 7 cell, but it will outglide it and again have more range in this aspect of performance because the its advantage at the longer glide is more than what it gives up on the steep approach. We may be able to cite examples of personal experience that seem to contradict this, but remeber pilot skill plays a role there as much as canopy performance. I have gotten back from bad spots on my 89 VX at 2.4 when others on the load flying Spectres and Tri's at wing loadings in the range of 1.2 to 1.4 didn't. I've even flown in formation next to a Manta loaded at about 1. Now that's apples to oranges! :-) Ramon is correct in his assesment of the stability and pressurization issue. A 9 cell at a given wing loading will be more stable than its 7 cell counter part. This is not to imply that a 9 cell is a better choice for a first canopy. As I stated previously, there is a trade off with speed. The 9 cell will have more forward speed and that will always magnify the injury at impact. I'm just saying that sometimes the wider performance envelope can help avoid the potential for injury. I'm pretty sure here in the U.S. that the 9 cell Manta is the standard for student canopies. That doesn't mean that the 7 cell counterparts are unsafe by any means. Just that the 9 cell Manta offers some advantages. Here are a few quotes from a paper that you may find informative. I have used this docuement as a reference for my comments. If you would like to read the whole thing, e-mail me and I will forward it as an attachment. It used to be found here in Dropzone.com, but I think it was lost when Sangiro went to the new format. The Aerodynamics and Piloting of High Performance Ram-Air Parachutes Draft 0.2 Jerry Sobieski May 19, 1994 The author would like to thank the follow individuals and organizations for their cooperation and assistance in preparing this document. David Parsons, University of Adelaide, Adelaide, Austrailia. Henry R. Diaz, Aerospace Engineering, University of Maryland. Eric Johnson, University of Florida. Rags. Clint Vincent, Executive Director (Acting), United State Parachute As- sociation. University of Maryland Institute for Advanced Computer Studies. A special thanks to John LeBlanc at Performance Designs. "Due to various complex principles beyond the scope of this document, the lift generated by the wing is directly related to the Aspect Ratio. In other words, given two wings of equal surface area with similar airfoil crossections, the wing with the higher AR will, in general, produce the most lift. This is why gliders and small aircraft with relatively low airspeeds will normally have very high aspect ratio wings." Now we must define some terms relating to motion of the airfoil (be it a ram-air parachute or airplane wing) as it moves through the air. While airplanes and parachutes move through an essentially stationary air mass, it is generally easier to study airfoil ight dynamics as if the airfoil was stationary and the air was moving past it. This is the situation found in wind tunnels. Also, since the direction and speed of the air flow changes as it passes around the airfoil, we would like to define the air flow velocity to be the direction and speed of the air far away from the wing i.e. where the presence of the wing has had no affect on it. We could say: the wind velocity at a distance infinitely far away. This value is refered to as the freestream velocity and is denoted as V 1 . Jumpers will recognize V 1 as the speed and direction of the \relative wind"." "In the skydiving world, stalls are normally associated with poor landing procedures where, in an attempt to maintain lift the jumper ares deeper. This results in momentary lift, but slows the canopy due to the increased drag | which decreases the lift and a vicious cycle results." "To summarize, this means that as long as the external airstream continues to ow over the canopy surface, the interior cell pressure will remain larger than the exterior surface pressure, and the cells will remain inflated. Since the internal cell pressure is a function of the dynamic pressure due to V 1 , the faster a canopy moves through the air, the greater the internal cell pressure and the more rigid it becomes. Rigidity is our friend. A rigid wing is far less susceptible to turbulence or spurious collapse. Do not lose sight of the fact that for cell pressurization to occur properly, the forward stagnation point must remain directly over the cell mouth. If the angle of attack changes, and the stagnation point migrates to either the upper or lower surface, the airstream will ow across the cell mouth, reducing the pressure there, effectively sucking air out of the cell. Result: cell collapse. (This is sometimes refered to as the \Venturi effect.") Most (all) modern sport ram-air canopies have crossports cut into the ribs in order to reduce the risk of cell collapse and to improve reinflation characteristics. Crossports simply allow the pressurized air from more central cells to bleed over into adjacent cells. Another interesting implication here is that cell pressurization is not dependent upon the size of the cell mouth. During inflation, a large mouth will allow the cells to inflate faster. But once inflated, a smaller mouth will [at least theoretically] provide all the pressure necessary for the canopy to retain it's shape - without a reduction in cell presurization." "Another important implication of the dynamic pressure is that it is is a function of V2. This is good. It means a small increase in airspeed will result in a significant increase in cell pressure. This implies that even a small reduction in drag - which results in a higher airspeed - will increase the rigidity of the canopy." I apologize for the lengthy quotes, but they provide accurate and valuable information and that is my intent here. To have open discussion that results in better understanding. Bottom line is there are some myths about the performance of 7 cell canopies. I will repeat though, the advancements in technology have closed the gap in performance with the new 7 cells like the Triathlon. Well, I'll move on now and let you guys debate this. IF anyone is intersted in the paper, e-mail me, or better yet, ask Sangiro to put it up here in Dropzone.com again. alan

"DB> As asked before--"Show me the "MEASURED DIFFERENCE" in forward airspeed with the slider left alone, vrs it being totality collapsed/stowed."" So far on my 89 VX at 2.4+ it has been about 6mph slower with the slider unstowed based on radar gun readings during my landing approach. That is nearly 10% slower. alan

Hi all, Thanks to you regulars and Sangiro who posted reminders that this is a forum for gear discussion and not for advertisements. I am locking the thread and any real information/discussion can be started in a new thread. alan

I would just like to offer some thoughts/comments about these statements. First though, I agree with the conservative approach that is intended. "When I say 7 cells I mean, Tri, Diablo, Spectre, PD, Omega, among others." I think it is a mistake to put the Diablo in the same class as the other canopies mentioned. It turns much faster and has a much higher rate of descent. Simply, it belongs in with high performance canopies. Perhaps at the lower end of the spectrum, but definitely hp. "FOR A BEGINNER, the stability and forgiveness of a 7 cell CANNOT be touched by any 9 cell on the market. PERIOD. It's impossible." Actually, the newer 9 cells are just as good or better. 9 cells generally _maintain_ pressurization better than 7 cells, while 7 cells inflate/re-inflate quicker. 7 cells actually respond quicker to toggle input, but fortunately dive less. The real advantages of the 7 cell for a beginner are the slower speed and steeper glide. The advantage of slower speed is pretty obvious, but the trade-off is less pressurization and stability. The advantage of the steeper glide is it makes it easier to estimate where they will land. A less obvious advantage is it should encourage/force them to stay on the ground in windy/turbulent conditions. A subtle advantage of most 9 cells is that they are more likely to get back after a poor spot and landing off can be more hazardous for a beginner. "Seven cells are safer and have a WIDER performance envelope ESPECIALLY for a low to mid range canopy pilot." Actually, most 9 cells have the _wider_ performance envelope. The 7 cells is just lower at the bottom end. They can fly a little slower and a little steeper. But again, that is a trade-off as noted above. "And ESPECIALLY in bumpy, windy, turbulent conditions." I disagree here. Pressurization is our friend and 9 cells as a rule ( I agree there are exceptions) have a higher internal pressure and maintain it better. You don't see a pilot landing in turbulent, windy conditions slowing down and putting flaps out. Speed is also your fiend here. I'm not talking VX type speed here, but the normal full flight speed that keeps the canopy above a stall. I think this is a myth from the old days of 7 cells. Bringing them in steep and pumping the brakes. They were being landed like a round and not a ram air. Sure with the 7 cell you can keep it inflated/re-inflated and mushing along on the verge of collapse with deep and or pumping brakes, but the 9 cell is more like to fly through the turbulence and not be on the verge of, or stalling at landing. Pumping the brakes on landing approach is a bad habit to learn as it greatly reduces the efficiency of any airfoil. I put my 17 year old daughter under a conservative 9 cell for her training and her first canopy was also a conservative 9 cell ( not a Sabre!). With all of that said, I also think a Triathlon is one of the best canopies for a first canopy and often recommend them. I think the new breed of 7 cells has closed the gap in performance and therefore closed the gap in the relative merrits of the advantages and disadvantages. Keep up the safe, conservative approach to canopies. It is good to see. alan

"Show me the "measured difference" in forward airspeed with the slider left alone, vrs it being totality collapsed/stowed." Depends on the class of canopy you are flying. On a 7 cell loaded at 1.1, the only real effect stowing the slider has, other than reducing wear on the slider itself and suspension lines inside the grommets is aestetic, ie. better view and less noise from it flapping. On a VX loaded at 2.4, stowing the slider improves the speed and performance of the canopy and it is recommended by the manufacturer. Most jumpers fall somewhere in between where performance is not a major factor but every little bit is nice and the quieter ride is appreciated. Parasitic and induced drag are concepts that have little meaning to most recreational pilots. If you want to get an idea of how much drag the slider can cause, find one that is laying around the DZ, tie a 4' piece of rope accross each pair of the outside grommets. Hold the pieces of rope in the middle and stand in back of a truck as it accellerates to canopy flight speed. See how difficult it is to hang onto at 15, 20, 25, 30, 35, and 40 mph. Those are typical sport canopy speeds. IF you want to see the effect it can have on a VX class canopy, try it at 60 or 70 mph. Next, try it with the slider collapsed (draw string(s) or velcro). Be prepared to let it it go during all of these very un-scientific tests. A safety harness would also be a good idea. The change in airspeed on most recreational canopies may only be 2-3 mph or less, depending on if you are in normal flight or executing a high speed diving turn. As you move up the spectrum in canopy performance and speed, the difference is greater. You won't see any blade swoopers leaving the slider unstowed. A collapsible pc will probably do more to improve performance, but combine the pc and the slider, most recreational pilots will benefit from the improvement on all but the biggest and slowest of canopies. alan