Jimbo 0 #1 August 20, 2003 So, why are they? - Jim"Like" - The modern day comma Good bye, my friends. You are missed. Quote Share this post Link to post Share on other sites
Jessica 0 #2 August 20, 2003 Much easier to pack, and new F111 flies as well as ZP. Most reserves don't see enough wear for ZP to make a difference.Skydiving is for cool people only Quote Share this post Link to post Share on other sites
darkwing 5 #3 August 20, 2003 That would imply that the allure of the hybrid ZP/F-111 reserves is merely a customer illusion (which may be true). I'd like to see some definitive, quantitative comparisons. -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites
rigging65 0 #4 August 20, 2003 Let's not forget that ZP has a tendency to shatter (tear a long, long ways) as opposed to F1-11 which has usable ripstop blocks to stop the tear before it gets to far along. ZPs biggest asset is that it doesn't wear out like F1-11 does...not really an issue with your reserve (at least we hope not ). I'd say the biggest reason is simply that that's the way they've been built for a long time, and there isn't an advantage to changing that. Change for the sake of change isn't usually a good thing... "...and once you had tasted flight, you will walk the earth with your eyes turned skyward. For there you have been, and there you long to return..." Quote Share this post Link to post Share on other sites
Jimbo 0 #5 August 20, 2003 QuoteChange for the sake of change isn't usually a good thing... Neither is doing it that way because that's the way it's always been done. - Jim"Like" - The modern day comma Good bye, my friends. You are missed. Quote Share this post Link to post Share on other sites
hookitt 1 #6 August 20, 2003 QuoteNeither is doing it that way because that's the way it's always been done Is there something Wrong with the way it's being done?My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto Quote Share this post Link to post Share on other sites
mjosparky 4 #7 August 20, 2003 Would you like to pay what it would cost to have a ZP reserve repacked? A new ZP reserve.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
rigging65 0 #8 August 20, 2003 QuoteNeither is doing it that way because that's the way it's always been done. I couldn't agree more...but you've got to show me some reasons to change something that's working fine first... "...and once you had tasted flight, you will walk the earth with your eyes turned skyward. For there you have been, and there you long to return..." Quote Share this post Link to post Share on other sites
Jessica 0 #9 August 20, 2003 QuoteThat would imply that the allure of the hybrid ZP/F-111 reserves is merely a customer illusion (which may be true). I think the assumption is that it's safer to load them heavier. Untrue as far as I know. QuoteNeither is doing it that way because that's the way it's always been done. ZP is really, really hard to pack as neatly as you need a reserve to be. I've never seen as much sweat as I did when I was watching a friend pack a -MZ. I don't see any reason for ZP on reserves.Skydiving is for cool people only Quote Share this post Link to post Share on other sites
Jimbo 0 #10 August 20, 2003 QuoteQuoteNeither is doing it that way because that's the way it's always been done Is there something Wrong with the way it's being done? I don't know if there is or if there is not, I was merely commenting that "because we've always done it that way" is a poor reason to continue doing it that way. QuoteWould you like to pay what it would cost to have a ZP reserve repacked? A new ZP reserve. I think that I wouldn't mind if I thought that a ZP reserve was a better product. Notice that I didn't ask why reserves aren't made of ZP, I did ask why they are made of F111. I think that there's a difference there. - Jim"Like" - The modern day comma Good bye, my friends. You are missed. Quote Share this post Link to post Share on other sites
Jessica 0 #11 August 20, 2003 QuoteNotice that I didn't ask why reserves aren't made of ZP, I did ask why they are made of F111. I think that there's a difference there. You do? Seems to me it's got to be one or the other. What else would you suggest making them out of?Skydiving is for cool people only Quote Share this post Link to post Share on other sites
hookitt 1 #12 August 20, 2003 Packing a ZP Topskin reserve is not difficult. For the reasons stated by Rigging65, i'd consider it a poor choice of fabric. Call Ed Cummings if you'd like an earful about ZP Reserves.My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto Quote Share this post Link to post Share on other sites
BBKid 0 #13 August 21, 2003 Plus, when most people have a functioning reserve over their heads, they aren't too bothered about the comparison in performance and flare lift as compared to their main, they just want to get down safely. Not that I've used one. QuoteZPs biggest asset is that it doesn't wear out like F1-11 does...not really an issue with your reserve (at least we hope not ). Though a certain Langar jumper may disappoint you in this respect... Nick --------------------------- "I've pierced my foot on a spike!!!" Quote Share this post Link to post Share on other sites
sunshine 2 #14 August 21, 2003 Packing ZP is a bit harder than F111. I think it's safer to stick with F111 since it's easier to pack. The last thing i wanna do is struggle with a slippery ZP reserve which might shift the lines around. ___________________________________________ meow I get a Mike hug! I get a Mike hug! Quote Share this post Link to post Share on other sites
MrHixxx 0 #15 August 21, 2003 I asked this question to the folks at PD some time back. This is the reply I received... -Hixxx I have put together a reply based off mine and other feed back from everyone at PD and here are some answers to your questions: Why don't we use ZP fabric in our reserves? First, the tear strengths listed in the specs are very misleading, for two reasons. The tear strength is measured at a specific tearing speed, measured as a certain distance per unit of time. When you tear things relatively slowly, the tear strengths are quite high. However, when you increase the speed of the tearing motion, the actual forces required to keep the tearing motion progressing actually go down. The tear spec is measured at a standard 12 inches per minute, a rate at which the ZP fabric looks superior to the standard fabric. However, this tear speed is not very realistic compared to the way a canopy would really tear. Because of this, we have created our own testing machinery that can measure tear strengths at up to 150" per SECOND. When you measure the tear strength at a high tearing speed more like what would happen in reality, the tear strengths go way down, to the 3 to 7 pound range. The standard fabric actually has a higher tear strength at these speeds than the ZP fabric torn at the same speed. So to cut it short, the tear strength of the ZP fabric is lower than that for the F-111 style fabric when the tear speeds are up where things would be in an actual failure mode. When a ZP canopy fails, it is typically pretty catastrophic, with tears going every which way in unusual patterns. On F-111 type canopies, the damage is typically more localized. Other reasons to not use the fabric? The benefit of ZP fabric is partially the fact that is stays low porosity. If that is an issue on your reserve, you are using it way too much. Another benefit is the presumed aerodynamic advantage. In reality, the aerodynamic performance is due to other aerodynamic issues such as better airfoils, aspect ratios, trim, etc. These items aren't suitable for reserve designs, due to opening issues. When you use good reserve aerodynamics, but throw the ZP fabric in there, you don't really get an improvement in landing performance. An example of this can be seen by comparing the ZP lightning crew canopy to a ZP Spectre. The two canopies are designed to do separate things. The Lightning lands well for a CRW canopy, but is relatively tricky to land compared to the Spectre, even though both canopies have ZP fabric.death,as men call him, ends what they call men -but beauty is more now than dying’s when Quote Share this post Link to post Share on other sites
skygod7777 0 #16 August 21, 2003 QuoteSo, why are they? well, look at reflex reserve pilot chute(s if you have the catipult). they're zp. other than that rig, i haven't ever seen any others that i can think of off the top of my head. and like it has been stated above, F-111 will "stretch" if it gets a hole in it, where as zp will tear utill it hits a seam. it takes more to rip/blow out zp but once it does, it's gone. later Quote Share this post Link to post Share on other sites
mjosparky 4 #17 August 21, 2003 QuotePacking a ZP Topskin reserve is not difficult. For the reasons stated by Rigging65, i'd consider it a poor choice of fabric. Call Ed Cummings if you'd like an earful about ZP Reserves. No thanks, I would just a soon not call Cummings on any subject.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
mr2mk1g 10 #18 August 21, 2003 Quote Though a certain Langar jumper may disappoint you in this respect... Would that be a certain chap called paul??? Quote Share this post Link to post Share on other sites
SCR10480 0 #19 August 21, 2003 Because, that's what parachutes are made of...Denim wears out too fast, and complicates the decision process with wether you want to "button fly" or "zip".... Quote Share this post Link to post Share on other sites
