ZigZagMarquis 8 #26 December 22, 2005 I can see Sparky's point... which I think basically is that different chest strap configurations... rings / no-rings, properly adjusted / over-tight... can change the loads imparted on the MLW and Chest Strap... certainly the Chest Strap takes some loading during opening... however, I think (again, just my words), I think Mike is trying to point out that depending on how the rig is set-up that may change AND certain configurations may be putting more load on the chest strap then what you think. However, knowing what I know about rig construction and the materials and hardware used... whether it be a traditional harness... a harness with just hip rings... a harness with hip and chest rings... Type-8 vs. Type-17 chest strap... blah blah blah... it would seem obvious that these permutations of the system are so over designed, and this is a good thing, as to be very forgiving... notice I didn't say bullet proof, just very forgiving. As for keeper of the peace... I don't think so... if I had been witnessing this arguement between the two of you in person, I'd have long since offered to give you each a KBAR and lock you in a room to settle it... and knowing Mike, his plan on a knife fight usually involves bringing a gun.. Quote Share this post Link to post Share on other sites
mjosparky 3 #27 December 22, 2005 QuoteI have read it. In my opinion, it supports the notion that the chest strap is loaded during deployment. If you have read it, then you should know that if the chest strap is loaded during deployment there is a real good chance it will fail. You MLW is designed to take the load during deployment that is why it is called MAIN LIFT WEB. Try reading PPM on harness design. Door, I gone. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
pilotdave 0 #28 December 22, 2005 Wouldn't overtightening any chest strap, rings or not, have the same effect? If your MLWs are pulled toward each other by the chest strap, it'll take more load during deployment as the MLWs try to straighten out. And the debate about load bearing vs non load bearing is really silly. Instead, why don't you debate whether it's "I could care less" or "I couldn't care less." The chest strap is load bearing for the loads it was designed to bear (the body rotating forward in the harness), not a component of the loads on the MLWs. But it depends on what your definition of "is" is. Dave Quote Share this post Link to post Share on other sites
mjosparky 3 #29 December 22, 2005 QuoteWouldn't overtightening any chest strap, rings or not, have the same effect? If your MLWs are pulled toward each other by the chest strap, it'll take more load during deployment as the MLWs try to straighten out. You are right, but it seems the rings make it easier for the jumper to allow this to happen. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
JerryBaumchen 1,049 #30 December 22, 2005 Hi Sparky, I seem to be with you on this one. In my opinion (and it is my opinion only), the chest strap does take some loading (how much, I do not know) during normal deployment attitudes. Saying that, I can envision some attitude in which the chest strap takes virtually no load; however, I also feel that it always will take some load during deployment (this is of course considering a modern piggyback sport parachute system, not something utilizing a chest pack or some other configuration). As I look at different photos of ringed harnesses, I have reached the conclusion (no actual proof of this) that a fully ringed harness imposes more load onto the chest strap that would a non-ringed or hip-ringed only harness configuration. This is because I see these rigs on people more often like in the one drawing of Sparky's where the MLW is in a somewhat sideways 'V' configuration. To me, it is a very simple vector analysis; something one would learn about in the first month or so of an engineering Statics class. Now please do not ask me to get those very old textbooks out; heck, I doubt if I could actually find it anymore. Any Structual Engineering students out there who might want to analysis Sparky's two drawings for us? Anyway, just my old $0.02 worth. Quote Share this post Link to post Share on other sites
diablopilot 2 #31 December 23, 2005 Agreed. And I've always thought type 17 chest straps to be foolish.---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
mjosparky 3 #32 December 23, 2005 QuoteI seem to be with you on this one. Thanks Jerry, I respect your opinion. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
mjosparky 3 #33 December 23, 2005 QuoteAgreed. And I've always thought type 17 chest straps to be foolish. Didn't you used to jump at Perris? The name sounds familiar. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
alan 1 #34 December 23, 2005 I can see Spary's point too. What he doesn't seem to understand is that when he flatly stated: "The chest strap is not designed to be load bearing during deployment." he contradicted himself since he had already previously stated:"With chest rings it is easy to pull the MLW out of alignment and transfer the opening loads to the chest strap which is not designed to take that kind of load." I added the bold font. The chest strap IS designed to be loaded. IF it is OVELOADED it may fail. An improperly adjusted harnes COULD overload it. During a normal face to earth deployment, the weight of the jumpers upper body is transferred in part to the chest strap. That IS loading it! And if Sparky was as familiar with PPM Vol ll page 335 as he has suggested I should be he would know that Poynter never mentions a chest strap speciffically but does say "The purpose of the parachute harness is to transmit the opening forces to the wearer in such a way as to preclude injury and to support the wearer during descent." He does not exclude the chest strap and I would argue that the chest strap is part of the TSO'd harness container system. Is it not? Poynter goes on to state: 5. The harness must securely retain the body. 10. The harness will not slip off the shoulders. 11. The wearer will not fall out the back of the harness even when the knees are drawn up to the chest. The only specific mention of the chest strap refers only to the fit on women. The most important and relevant point that Poynter makes (ha! ha! I said point that Poytner makes ha!ha!) is: 20. Angle the straps in the direction they will be loaded so the anchoring stitching will be evenly loaded. That is Spark'y point, I believe, based on his diagram. My point is it is loaded. Sparky should have just stuck to his original statement that it is not designed to take "that kind of a load." Sure the purpose is to keep the wearer from falling out.....what do the leg straps do? Ummm, keep the wearer from falling out. You and Sparky and JP and Jerry gonna tell me that the leg straps aren't load bearing either? Sparky has recently stated that the main lift webs are load bearing that is why they are called "main lft webs." All that means is they carry the main load, not all of it. Hell even the back straps are load bearing during deployment! Yes! The back straps. Sparky, if you are reading this, go to page 243 of PPM Vol 11 and read the second paragraph. You chide me about what Poynter has to say about harness design, here is what Poynter says: " In fact, only about 15% of the opening force is taken in by the back straps (my emphasis). Well if the back straps take only 15% of the load I wonder what the chest strap takes when a load is applied directly to it, as in your chest during the deployment sequence. So, what I understand is that Sparky seemed to have it right and then contradicted himelf and decided to get into a pissing match with me rather than admit he misspoke when he said: "The chest strap is not designed to be load bearing during deployment." As far as the KBAR comment goes, you'd feel pretty bad after Sparky was shot with his own gun. And Sparky, while you are reviewing the section in PPM about design, check out the part that distinguishes deployment from inflation. Based your comments in a different thread, you seem to have missed that part. I know you shut the door on this, so I figured I address my comments to you here, you'll read 'em.alan Quote Share this post Link to post Share on other sites
alan 1 #35 December 23, 2005 Jerry, you say this: QuoteHi Sparky, I seem to be with you on this one. knowing that Sparky has said this: ""The chest strap is not designed to be load bearing during deployment." then you say this: Quotethe chest strap does take some loading (how much, I do not know) during normal deployment attitudes. Which is it, load bearing or not? QuoteAs I look at different photos of ringed harnesses, I have reached the conclusion (no actual proof of this) that a fully ringed harness imposes more load onto the chest strap that would a non-ringed or hip-ringed only harness configuration. If a fully ringed harness imposes more load onto the chest strap that (sic) would a non-ringed or hip-ringed only harness configuration, would it not then follow that it would be designed to bear that load, i.e. be designed to be load bearing? I realize that what you agree with is when Sparky said this: "With chest rings it is easy to pull the MLW out of alignment and transfer the opening loads to the chest strap which is not designed to take that kind of load." Which he later contradicted. But who cares, what the hell, it's Saprky. Hell, he confuses deployment with inflation. At least that time he was man enough to admit he could still learn a few things here.alan Quote Share this post Link to post Share on other sites
alan 1 #36 December 23, 2005 QuoteIf you have read it, then you should know that if the chest strap is loaded during deployment there is a real good chance it will fail. If the chest strap is overloaded during deployment, there is a chance it will fail. But then that is true of the entire system. I don't recall the report saying anything about chest rings or improper harness adjustment. Did the webbing fail or was it the harware? Maybe it was the stitching. Maybe the stitching had been worn or broken, maybe the selvage edge of the webbing had been damaged or was defective? Do you have info that isn't on that report? What is a "real good chance"? How many properly routed chest straps have failed? I do know that the chest strap is loaded during deployment, even your buddies Jerry and Zigzg admit that.....whose opions you have stated you respect BTW. QuoteYou MLW is designed to take the load during deployment that is why it is called MAIN LIFT WEB. It is called the MAIN LIFT WEB because it takes the MAIN load, not the entire load. QuoteTry reading PPM on harness design. I have, please see my latest response to Zigzag, you may learn something you missed. QuoteDoor, I gone. Good riddance.alan Quote Share this post Link to post Share on other sites
alan 1 #37 December 23, 2005 QuoteAnd the debate about load bearing vs non load bearing is really silly. Yes, and yet you jump in. QuoteThe chest strap is load bearing for the loads it was designed to bear (the body rotating forward in the harness), not a component of the loads on the MLWs. Almost right. It also takes a component of the MLW, same as the back straps do. Please refer to PPM Vol ll page 243. The problem as Jerry has already pointed out is the vectoring of the load. PPM is in agreement as well (page 335, item 20). Hell, Sparky was even in agreement until he started contradicting himself. I think his diagram was correct, it was later when he flat out stated: "The chest strap is not designed to be load bearing during deployment." that he got off track. QuoteBut it depends on what your definition of "is" is. Yes, kinda like when Sparky was stating that deployment doesn't start until the canopy is out of the bag. What he meant was inflation doesn't start until the canopy is out of the bag. Then he was lecturing someone about opening shock theory.alan Quote Share this post Link to post Share on other sites
alan 1 #38 December 23, 2005 QuoteAgreed. With what? This: "The chest strap is not designed to be load bearing during deployment." Sparky said that. QuoteAnd I've always thought type 17 chest straps to be foolish. If you agree they are not designed to be load bearing, then what difference would it make what you use? Well, it has to hold you in the harness, but that would make it load bearing. Your body does place a load directly on the chest strap, plus it has to hold the MLW from separating off your shoulders....that would be a tensile load. I don't think the Ty 17 in itself is foolish. The hardware could be beefed up and the method of attachment to the MLW could be improved, see item 20 on page 335 of PPM Vol ll.alan Quote Share this post Link to post Share on other sites
alan 1 #39 December 23, 2005 QuoteIn Reply To -------------------------------------------------------------------------------- I seem to be with you on this one. -------------------------------------------------------------------------------- Thanks Jerry, I respect your opinion. Sparky I respect his opinion as well. Quote In my opinion (and it is my opinion only), the chest strap does take some loading (how much, I do not know) during normal deployment attitudes. It would seem that he is seeming to be with you on this one to the point of circling the wagons against me and not agreeing with this statement of yours: "The chest strap is not designed to be load bearing during deployment." Don't let that door hit you in the ass on the way out.alan Quote Share this post Link to post Share on other sites
riggermick 6 #40 December 23, 2005 QuoteQuoteIf you have read it, then you should know that if the chest strap is loaded during deployment there is a real good chance it will fail. If the chest strap is overloaded during deployment, there is a chance it will fail. But then that is true of the entire system. I don't recall the report saying anything about chest rings or improper harness adjustment. Did the webbing fail or was it the harware? Maybe it was the stitching. Maybe the stitching had been worn or broken, maybe the selvage edge of the webbing had been damaged or was defective? Do you have info that isn't on that report? What is a "real good chance"? How many properly routed chest straps have failed? I do know that the chest strap is loaded during deployment, even your buddies Jerry and Zigzg admit that.....whose opions you have stated you respect BTW. QuoteYou MLW is designed to take the load during deployment that is why it is called MAIN LIFT WEB. It is called the MAIN LIFT WEB because it takes the MAIN load, not the entire load. QuoteTry reading PPM on harness design. I have, please see my latest response to Zigzag, you may learn something you missed. QuoteDoor, I gone. Good riddance. STOP THIS! gentelmen, What you are argueing is is assinine.Let it go. Chest straps are load bearing albiet in conjunctin within their applicable load recuirements. they are NOT considerd primary load path's but secondary load paths, that is what they they do. Period! End of story! Merry Christmas. Mick. Quote Share this post Link to post Share on other sites
mjosparky 3 #41 December 23, 2005 QuoteRather condescending attitude displayed here. Sound familiar? Have a Happy Holiday.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
JerryBaumchen 1,049 #42 December 23, 2005 "STOP THIS." You took the words right out of my mouth, Mick. Thanks and have a good one yourself. Quote Share this post Link to post Share on other sites
alan 1 #43 December 24, 2005 Quotegentelmen, What you are argueing is is assinine. I agree, but yet now you feel the need to jump in as well. QuoteChest straps are load bearing albiet in conjunctin within their applicable load recuirements. they are NOT considerd primary load path's but secondary load paths, that is what they they do. Period! End of story! You tell me I'm assinine and then restate what I have said in several posts now in reply to Sparky stating: ""The chest strap is not designed to be load bearing during deployment." Perhaps if you posted a reply to Sparky that went something like this: Sparky, What you are argueing is is assinine.Let it go. Chest straps are load bearing albiet in conjunctin within their applicable load recuirements. they are NOT considerd primary load path's but secondary load paths, that is what they they do. Period! End of story! then I would be more inclined to let it go. Until then, what is really assinine is you and others jumping in to lend your support to Sparky but then subtly restating what I have been trying to get him to acknowledge.alan Quote Share this post Link to post Share on other sites
alan 1 #44 December 24, 2005 QuoteSound familiar? Yes, it does. I posted that to Rob in a different thread. You have copped that same attitude since CReWLL posted a rather correct interpretation of your sketches and then went on to state: "The other one shows a chest strap that is too tight and allows the load to be transferred to the chest strap. The chest strap is not designed to be load bearing during deployment." Ever since I replied to the bold faced statement, your replies have been condescending and you have circumvented what I have been trying to tell you. If my comments in the exchange below seem condescending to you then so be it. I apologize for that. However, condescending or not, it does not change the fact that you were in error when you stated that the chest strap is not load bearing....as evidenced by Jerry and now Mick, among others. If all of this was really about my attitude in my initial post, then perhaps you could have saved everyone some frustration by doing simply as I did in response to Rob. That one was put to rest rather quickly. QuoteRe: [alan] Harness question [In reply to] Quote | Reply -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- In Reply To -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Quote -------------------------------------------------------------------------------- The chest strap is not designed to be load bearing during deployment. -------------------------------------------------------------------------------- Tell that to the family and friends of the young woman that fell out of her harness during deployment after forgetting to fasten her chest strap. There is such a thing as load distribution. There is a reason for having a chest strap and it is load bearing. -------------------------------------------------------------------------------- I think that would be called containment of load. Forgetting to fasten it does not make it load bearing. If it was load bearing why is the rest of the rig not be made of Type 17 webbing and 500 lb. hardware? Sparkyalan Quote Share this post Link to post Share on other sites
mjosparky 3 #45 December 24, 2005 Let it go! You win. Put it in your log "I win". Get a life.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
riggermick 6 #46 December 24, 2005 QuoteQuotegentelmen, What you are argueing is is assinine. You tell me I'm assinine and then I would be more inclined to let it go. Until then, what is really assinine is you and others jumping in to lend your support to Sparky but then subtly restating what I have been trying to get him to acknowledge. Ok now this is just plain childish. I didn't call YOU assinine and I'm not siding with anyone. The whole thread has deteriorated in to a "you called me names and everyone is ganging up on me". I think the point has been made about load paths and the like, now it's time to move on to bigger and better things don't you think? For the record if you feel an apology is necessary from me, here it is: I'm sorry if I offended you in any way that wasn't my intention. If an apopogy is not needed then just ignore this. I for one am done talking about this subject and any related finger pointing. later. Mick. Quote Share this post Link to post Share on other sites
RMURRAY 1 #47 December 24, 2005 QuoteQuoteCan anyone tell me the benefits of paying an extra $250 for hip & chest articulation on a container. Most (but not all) of the jumpers that I have talked to that have put a few thousand jumps on rigs with and without articulation, all else being equal, prefer the standard harness. if I were buying new, I'd pass on hip and chest rings. the harness I'd get would be fine without them. rm Quote Share this post Link to post Share on other sites
riggerrob 558 #48 December 26, 2005 Children! Children! Children! Let's play nice together ... Quote Share this post Link to post Share on other sites
