czechbase 0 #1 October 28, 2003 Do ZP, F111 and vented pilot chutes make a difference here? I know that they do and I just would like some explanation in terms of how fast they inflate (resulting in a quicker depoyment). Thanks.www.motavi.com Share this post Link to post Share on other sites
Spiderbaby 0 #2 October 28, 2003 Chechbase' question is tailor mader for Tom Aiello."It takes a big man to cry, it takes an even bigger man to make that big man cry" Share this post Link to post Share on other sites
TomAiello 26 #3 October 28, 2003 In theory, PC's should inflate quicker in the order: ZP, vented ZP, F111. In practice, most vented ZP PC's appear to open at almost the same rate as unvented ZP PC's. Especially with a delay (even as little as one second) the difference in inflation time appears to be negligible. Another thing to consider is that the PC toss technique you are using can effect the usefulness of PC vents (or F111 fabric). Venting (or F111) is primarily designed to dampen orbiting of the pilot chute, and secondarily intended to reduce PC oscillation. With a "throwing up" style toss (pitching the PC straight above yourself) commonly used on ultra low jumps, PC orbiting is virtually eliminated anyway (since orbiting usually results from vigorous sideways toss imparting outward motion, and hence initiating an orbit). So, in theory, for fastest PC inflation, a straight up toss combined with an unvented ZP PC ought to be the best combination. In practice, none of this will matter much on any jump where you are going stowed, though. Edit to add: I split this discussion off the "Stowed" thread.-- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
czechbase 0 #4 October 28, 2003 Is there such thing as a vented F111 pilot chute? Forgive my ignorance! Also, what's your take on vented apex pilot chutes and how they perform?www.motavi.com Share this post Link to post Share on other sites
meekerboy 0 #5 October 28, 2003 Tom, I am interested in knowing if there is any special way you hold the PC. I know about the correct routing of the bridle above the elbow and about concetenering the bridle into the mesh. But do you wrap the mesh around and the the PC fabric also? I did a jump recently and threw the to the right and up. I remember letting go of it and watching as it took a while for the bridle to come out and the PC to take hold of the air. Of course this was in slo-mo, but it would have been nicer to see this happen quicker. It was a 45ZP 1 second by the way. Cheers, Meeker Share this post Link to post Share on other sites
czechbase 0 #6 October 28, 2003 I got confused. Vented is vented. Got mixed up with apex vented and vented but it all means the same thing. Thanks for the help Tom www.motavi.com Share this post Link to post Share on other sites
TomAiello 26 #7 October 28, 2003 QuoteI got confused. Vented is vented. Got mixed up with apex vented and vented but it all means the same thing. Although all vented PC's currently on the market have the vents located on the apex, this is not the only possible configuration. In fact, a thin vent located halfway from the apex to the skirt ought to vent far more efficiently (perhaps too efficiently, but that's another discussion).-- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
TomAiello 26 #8 October 28, 2003 QuoteIs there such thing as a vented F111 pilot chute? No. Unvented ZP PC's spill air around the skirt (the air has to spill somewhere and the ZP does not allow airflow through the PC). Venting is intended to allow a ZP pilot chute to spill air in a more directed manner (so that it stays steady instead of oscillating). F111 PC's already spill air through the PC, evenly. In effect, they are 100% vented, at a very low rate. An F111 PC wouldn't need to have additional vents sewn into it. An interesting side note: It ought to be possible to build a ZP pilot chute that had "vents" made of F111. Using vents with a slower throughput might allow for a different configuration or sizing of the vents (possibly opening up new designs which might be superior to the present apex vent designs).-- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
TomAiello 26 #9 October 28, 2003 I'm not sure I'm following the question, but... There are two generally accepted ways to fold a hand held PC. The first is to fold the bridle into your hand, then keep only the bridle attachment of the PC in your hand. This allows the PC to pre-inflate while you free fall, so that releasing the PC is all that is necessary. With this method, you don't have to throw the PC at all, so orbiting is greatly reduced. The PC just goes straight up to bridle stretch. WARNING: Using this method for any significant delay (2+ seconds) can pull the jumper over from PC drag, yielding unstable deployment. This has caused several accidents, and at least one fatality. The second method is to S fold everything after the bridle just on top of the bridle. In other words, when you reach the PC, just keep folding it into your hand. This yields a nice, tight wad that is easier to throw to bridle extension. I prefer this method at ultra low altitudes, because on those jumps it becomes important to pitch the PC straight up to reach bridle extension as rapidly as possible. There are several variations on each of these methods, and at least one other method that is probably superior to either of these for ultra low exits (which I won't discuss here, since it requires gear modification, and if used incorrectly would present great accident risk). I'm not sure if that answers your question, but post again and let me know. Thanks!-- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
Faber 0 #10 October 28, 2003 QuoteAn interesting side note: It ought to be possible to build a ZP pilot chute that had "vents" made of F111. Using vents with a slower throughput might allow for a different configuration or sizing of the vents (possibly opening up new designs which might be superior to the present apex vent designs). If you look at BR and CR pcs youll notice a different in the mesh.At least my 46´zp av pc from CR and my 42´zp av pc has different mesh(CR use bigger holes) also the BR pc s i have has a different zp than CR(looks like CR use more "new"zp than BR) i dunno if theres has been reserach in this. The pc´s i talk about are the once you helped me whith Tom,so they were brand new both as i discovered this.I had no problems by either of them. Stay safe Stefan Faber Share this post Link to post Share on other sites
czechbase 0 #11 October 29, 2003 Yuri shared something interesting with me last night: quicker inflation, faster deployment = unvented zp less oscilliation, better onheading = vented zp I guess it would depend which one was more important. I would say it depends on what kind of object you are jumping and what kind of delay you are going to take. I am still a little confused though...object strike is a big risk...but then again, you'd want fast deployment as well. Which one would you choose if you had a low object with little room to run (say a cliff/building)? Now that I think about it, I was watching some guys from KL Tower and 2 jumpers went off together at the same time. The first jumper deployed and you could see his pilot chute oscilliating to the left where the other jumper was; his canopy opened and bam! The other jumper fell through his open canopy. Luckily there was altitude and the other jumper managed to deploy by about 300 feet. Share this post Link to post Share on other sites
meekerboy 0 #12 October 29, 2003 Thanks for the reply Tom, clears quite a bit up. I will try that first method out as this is a 1 second delay. Meeker Share this post Link to post Share on other sites
TomAiello 26 #13 October 29, 2003 QuoteWhich one would you choose if you had a low object with little room to run (say a cliff/building)? In general, object strike is the primary danger for BASE jumpers. I'd say that you should use a vented PC for any object with strike potential (i.e. any solid object). The only time when I'd rethink that is under 200 feet. But, when you are ready to freefall under 200', you will also be ready to make decisions about the appropriate PC.-- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
BASE813 0 #14 October 29, 2003 In addition, I used to use PC's without load tapes on the top skin of the PC - and these used to oscillate considerably. I then used load taped PC's which kept the oscillation to a minium and this was then practically elliminated by me now using AV PC's (except my 46"). - I still get a little oscillation if I flick the PC out to hard (I normally give a little flick of the wrist and let it go (on delays to 2 seconds) - hardly any movement) - On holding and folding the PC on lower jumps (215ft - 250ft) I fold the bridle and then some of the mesh in my hand leaving a 2 or 3 inch circle of mesh exposed to catch the air - I find this method works nicely with 1 second delay from 215 - 225 range. For 2 second delays I fold all the mesh in my hand and leave the ZP top exposed and for 3 second delays I fold all the PC into my hand (dependant on available altitude for opening). A few of us have experimented with 42" at the lower end of 215 - 225 with 1 second of freefall and seem to have come to the "non-video" conclusion that there is not a great difference between a 1 second 42" and Go and Throw 46" from these heights. There seems to be no notiable difference in inflation and extraction time. (its dark so can not comment on canopy opening height). Maybe someone (TA?) can add more insightful comments to this. Thanks Share this post Link to post Share on other sites
andrewstewart 0 #15 October 29, 2003 QuoteQuoteAn interesting side note: It ought to be possible to build a ZP pilot chute that had "vents" made of F111. Using vents with a slower throughput might allow for a different configuration or sizing of the vents (possibly opening up new designs which might be superior to the present apex vent designs). If you look at BR and CR pcs youll notice a different in the mesh.At least my 46´zp av pc from CR and my 42´zp av pc has different mesh(CR use bigger holes) also the BR pc s i have has a different zp than CR(looks like CR use more "new"zp than BR) i dunno if theres has been reserach in this. The pc´s i talk about are the once you helped me whith Tom,so they were brand new both as i discovered this.I had no problems by either of them. Following on from this, does anyone have a preference for which vented PC they prefer? Tom? Share this post Link to post Share on other sites
TomAiello 26 #16 October 29, 2003 QuoteFollowing on from this, does anyone have a preference for which vented PC they prefer? Tom? I don't own any BR vented PC's, because CR was willing to make custom PC's with the old style attachment point for me. I do prefer the CR A/V style (i.e. the overlapping of the ZP) because I feel that the inflated profile itself (with or without vents) is more stable than the older (i.e. non-overlapping) profile. I'm not sure if the BR PC's use the older symmetric style, or use an overlapping cut.-- Tom Aiello Tom@SnakeRiverBASE.com SnakeRiverBASE.com Share this post Link to post Share on other sites
Faber 0 #17 October 29, 2003 QuoteI do prefer the CR A/V style (i.e. the overlapping of the ZP) because I feel that the inflated profile itself (with or without vents) is more stable than the older (i.e. non-overlapping) profile. I'm not sure if the BR PC's use the older symmetric style, or use an overlapping cut. Im not sure what you mean,but ill post a pic tommorrow of my 42´zpav pc then you might be abel to see it. I had NON problems whith either PC´s. Ill happy jump both CR and BR vented PC´s Stay safe Stefan Faber Share this post Link to post Share on other sites
robibird 3 #18 October 29, 2003 ''quicker inflation, faster deployment = unvented zp'' ''less oscilliation, better onheading = vented zp'' **************************************** Hi, well, if the faster deployment caused by using non vented PC will keep you alive than reconsider to make that jump!!! Difference in inflation between vented and non vented are insignificant. Benefit of having vented PC are significant. The vented PC is in every way superior than non vented regardless of the size of the PC. my 2 c... RobiRobert Pecnik robert@phoenix-fly.com www.phoenix-fly.com Share this post Link to post Share on other sites
czechbase 0 #19 October 30, 2003 Awesome insight. Thanks Robibird. www.motavi.com Share this post Link to post Share on other sites
