skydiverek

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Posts posted by skydiverek

  1. The slower opening, the better for me :)

    Quote

    Because slowing the trying with a different size/profile slider is completely out of the question, right ?


    Wrong. I start with the slowest possible opening canopy, and slow it further with larger sliders, if necessary. I prefer to have the "correct" canopy right away, as opposed to modyfing it later. I will be probably buying brand new.

    Quote

    Please let us know which instrument you use to measure the "7 seconds" and what you consider your starting and end point.


    My own, and also outside video. Starting point: snatch force, body set to vertial position. End point: slider 75% down (at this point canopy is basically inflated).

  4. Do Pilots made after 2009 open somehow worse/faster that Pilots made before 2009? The difference is that before 2009 Pilots had F-111 ribs, and after 2009 they have ZP/ZPX ribs.

    I browsed thru some posts about Pilot canopies here on Dropozne.com. There are a few posts by Bushman (from Aerodyne), back from 2007 when he was their empployee, saying that they were trying going from F-111 ribs to ZP/ZPX ribs, and the openings got worse on those 'experimental R&D' canopies, back then.

    I do know that now the ribs are always ZP/ZPX, no F-111 anymore, hence my original question: do Pilots made after 2009 open worse/faster that Pilots made before 2009? Or, did they manage to fix this 'issue' with ZP/ZPX ribs? I am most interested in Pilot 168, normal ZP fabric.

    Bushman's posts:

    http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2675516;search_string=ribs;#2675516

    http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2676249;search_string=ribs;#2676249

    http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1324058;search_string=ribs;#1324058

  5. skez

    So from what I could figure out some reverse riser designs are alot better then others...I dont use reverse risers but I have a set of atom risers (parachutes de france) I use for ground launching...does anyone know if these type are anygood? There must be alot of them out there as the atoms etc..use them



    From 3-ring inventor Bill Booth:

    "Reversed risers are 3 ring risers where the riser rings face the jumpers body, instead of facing away as they do on normal risers.

    In a misguided attempt to make type 17 (mini) 3 ring risers stronger, the French eliminated the grommet that passes through the riser, thinking this was a weak point. They then put the "0" grommet for the closing loop to go through on a floppy 1" tab. Then, so that the 3-ring housings wouldn't have to come around to the front, flipped the riser over so that the riser rings faced the jumper's shoulders

    There are three problems with this approach. 1. Risers don't break at the grommet. They break where they go around the harness ring. 2. The closing loop on reversed risers does not make the 180 degree direction change it does on properly built risers, so the release force is doubled, and the "suck through" or "jamming" force is cut in half. 3. For a 3 rings to release, they must flip through each other. Since a bag lock might not stand you up enough to pull the risers away from your body, reversed risers might not release in that situation, because your body blocks the flip through motion.

    -------------------------------------------

    I don't know about you, but I want my 3-rings to work EVERY time, in ANY malfunction situation. "Most of the time" just doesn't cut it. Reversed risers, soft housings, and all other "improvements" to the 3-ring lower reliability. Emergency systems are simply no place to cut corners. I cry every time I see a poorly made 3-ring, but there is nothing I can do about it, but tell you again, "There is one best way to make a 3-ring release system, and it doesn't cost a dime more to do it right. The plans are available from the Relative Workshop." How much is your life worth?

    -------------------------------------------

    On reversed (Integrity) risers...The scariest stories I've heard about them happen in two canopy out situations. Often, the main risers are held back across the shoulders, preventing the unfortunate jumper from cutting the main away in a "personal downplane" situation.

    Reversed risers offer no advantages, have lower mechanical advantage, have no published construction or inspection specifications (so you can't tell if they are going to work in a high "G" situation), and can kill you in the above situation (and others). They should be replaced, and you should get very mad at anyone who sold them to you. The same is true for most "soft housing" 3-ring release systems.

  13. Also, can it "change its mind" in the process? That is: initiate a deployment by TRAP, but still be able to release, if the reserve PC 'wins the race'.

    Or, once TRAP is initiated and tight around the bridle, there is no way to revert it (?).

    Also, is it really crucial for it to be able to "change its mind" when needed (when?), or not?

    Probably no Collins Lanyard either on Mirage TRAP, meaning that if the RSL riser (only) releases, than the freebag will be pulled wight INTO the mess. Same scenario of course exists in 99% of RSL equiped rigs, but there only the reserve PC would be pulled INTO the mess, not the freebag right away.

  15. From Bill Booth, talking about the bridle pockets and Para-Flite testing as well:

    "Let me clear up one myth right now. The free bag system WILL NOT pull your reserve bag out of its container in the event of a horse shoe malfunction. A horse shoed 16 foot long, 2 inch wide, free bag bridle generates only about 2 pounds of force on the bag at terminal velocity. Most reserve canopies weigh over 5 pounds, not counting force required to extract them from the reserve container, especially if the main container is still closed. What the long wide bridle will do, however, is stabilize the bag, (if you reach back and throw it out of the container) so that it won't tumble through its own lines as it deploys.
    So, if you ever experience a horseshoe malfunction of your reserve, don't just lie there and wait to hit the ground, sit up until you feel the reserve bridle hit you in the back of the head, reach back and pull on it until the free bag is out of the container, and then let go. The drag of the bag itself, helped out by the bridle, will then carry it to line stretch. I put out a film about this about 15 years ago, but a lot of people seem to have forgotten."

    and

    "The pull generated by a 2" reserve pilot chute bridle in a horseshoe configuration is about 2 pounds. I published a video recording that fact about 20 years ago. Reserves weigh at least 5 pounds. Plus, all modern reserve containers add a "containment" force to keep the reserve bag in the container during pilot chute hesitations, to prevent out-of-sequence deployments (which, by the way, have killed several jumpers using older containers without this safety feature). So, it usually takes at least 10 pounds of force to remove a reserve bag from its container. Therefore, a horse-shoed reserve bridle does not generate nearly enough force to pull your reserve bag out of its container. This is a good thing, because it prevents out of sequence deployments due to pilot chute hesitations.

    The basic problem with two reserve pilot chute systems like my Vortex (which I developed years before the Catapult, but did not market) or the Catapult itself, is that they cannot tell the difference between a pilot chute hesitation (very common) and a reserve horse shoe malfunction (very rare). So, the second pilot chute on these systems can easily pull the reserve free bag above a hesitating primary (spring loaded) pilot chute, allowing that pilot chute to get into the lines below the free bag, thus totaling your reserve. So, the Catapult system actually encourages out of sequence reserve deployments, which as I said above, is a very bad thing. I tried to solve this problem with the Vortex, but was unable to do so. The Catapult does not solve it either."

    and

    "The freebag system only "Works" if the bag is first "ejected" from the container by some force OTHER than the horse shoed bridle. On the Paraflite dummy drops, this force was supplied by the tumbling dummy. Once the bag is out of the container (at terminal) it will blown upward by its own drag. A horse shoed 2" bridle only supplies about 1 pound of drag. Most reserves weigh at least 5 pounds, and it takes at least 10-15 pounds to pull the bag out of most modern containers. This is a good thing because of the likelihood of reserve pilot chute hesitation. If your bag falls out of the container while your pilot chute is hesitating, and gets above that pilot chute, you could be in a lot of trouble."

    and

    "In my tests, a horse shoed freebag bridle pulls only about one pound at the freebag end. Pockets on the bridle don't pull much more, and certainly not enough to pull a freebag out of a modern container. This is good, because the last thing you want during a pilot chute hesitation (common on internal spring-loaded pilot chute systems) is for your bridle to pull your bag out of the container and above the hesitating pilot chute. Reserve totals are rarely fun."

    and

    "With your main container (and riser covers) closed, it can easily take over 15 lbs. of pull to remove your reserve bag from the container. It takes a pilot chute of about 13" finished diameter to do that. Pockets on the bridle won't generate nearly that much drag. But the most important thing to consider, is that the second pilot chute can't "tell" the difference between a reserve horse shoe (which is very rare) and a reserve pilot chute hesitation (which is very common). Ask yourself this simple question: "Do you really want your reserve bag pulled out of the container by the secondary pilot chute while your main pilot chute is hesitating right above?" Sounds like a recipe for an entanglement between the heavy, spring loaded primary pilot chute, and your reserve lines to me."

    and

    "Question: So why do we have 2" bridles in the first place?
    Answer: Para-flite started it over 20 years ago. When they came out with the first square reserve, the Safety Flyer, they decided to "tinker" with a lot of other things too. The "free-bag" with its bungee "safety stows" and 2" wide "anti-horseshoe" bridle was the result. The Safety-Flyer was marketed with the Swift container system which had no pocketed corners. As a result, when you pulled the ripcord, the bag would simple fall out of the container. When they drop tested this combined system with a built-in "horseshoe" malfunction and a tumbling (unstable) dummy, the bag would simply be ejected from the container because of centifugal force (angular acceleration) and be pulled to line stretch by the force of the relative wind on the bag. The super long bridle allowed the lines to unstow, and the freebag allowed the canopy to open. The 2" width merely provided stabilization so that the bag did not tumble through the lines as they unstowed.

    The anti-horseshoe system worked in those test conditions. However, as stated earlier in this thread, it will not work with a stable jumper using a modern piggyback system. The long, wide bridle has persisted out of inertia. i.e. No one wanted to go against an existing, "proven" system. Even though, I suspect, the wide bridle helps create and lengthen pilot chute hesitations, because of the drag it creates in the burble right above a stable jumpers back on initial pilot chute launch.

    I have made one change recently, however. I had to shorted the bridle a bit to make the Skyhook work correctly. I kept the 2" width because of the stabilizing effect I noted above."