JohnSherman

Sure; The best way is to refer you to previous writings. These are sequential as they track the development of line stows to where we are today. The first one tells of the new balanced line stows and how they work. However, it doesn't speak to un-balanced stows. Unbalanced stows are where the distance between the stow bands is greater than twice the length of the bight. http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=NEWSTOW&SortBy=DATE_D http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=Speedbag&SortBy=DATE_D http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=Reserve_Speedbag&SortBy=DATE_D As to how this all affect deployment. When the bag is jerked out of the pack tray only the bag is loaded to the bridle. The canopy wants to stay in the container and the lines also want to stay. The lines are locking the bag giving the caniopy no choice but to go for the ride. The only thing keeping the lines to the bag are the rubber bands and they (the lines)are trying to stay in the pack tray. If the mass of the lines between the rubber bands is greater than the twice the mass of the bights (there are 2 bights) then the lines will pull out of the rubber bands and stay in the pack tray allowing the bag to open and release the canopy before you reach line streatch. This is what that looks like: [inline line_dump.jpg]

MEL, Would you please provide (to this forum) the Data Graph for Altitude and acceleration from the data logger used for these "real life test data". Additionally, I would be interested in the canopy and D-bag type/configuration used in these tests. Also how many test were made and what are the distributed results. JS

Let me see if I understand your ( MEL & Jan) positions correctly. You are saying that the friction or gripping of the lines to the rubber band is the most important aspect of preventing line dump. I am saying that by having balanced mass within the line stows, the friction becomes academic as the downward forces are equal and it would require some sort of lateral force to pull the stows out of the bights which doesn’t exist until the lead line begins the deployment sequence. At his point I would agree that as each stow releases , accelerating the mass, that the more that release can drag the more it can accelerate. But this sequence is long past the line dump phase.

That is correct! Double stowing is a waist of time on bags with balanced line stows. To demonstrate how this is used in everyday jumping we use standard rubber band on our tandems. Sure if you have bights about an inch long you had better double stow them. However if the bag has balanced stows it is unnecessary. JS

"Grip on the line stows"? There is no "gripping line stows" at 120 MPH. Any coefficient of friction was long lost with the speed. Lines strip or dump because of mass imbalance between the span of lines between the bights and the bights themselves. See:http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=NEWSTOW&SortBy=DATE_D for the full definition of the phenomeon. The SPEED Bag, designed for thoes who prefer safety over work load, was a later development.

According to the serial # (20509) it was made the 20th week of 1975 and was the 9th rig that week. It is an original SST (not a Racer). It has a metal Martin Baker ripcord and R3 riser releases system. It appears to have a throw out belly band which must be an after market mod. The patch on the cap is an add-on, not factory, as has been pointed out. Our records don't go back that far so I can't tell for whom it was made. JS

Lee, I think it is important to explaine that your line dump did not occur on a personal deployment. I would love to see the video if there is one and there must be as you identified it as "Line Dump" To the poster who said "if I don't like the whinning cover your ears". I say the whinning doesn't bother me because I understand the ignorance. But it sure bothers the customers when they will not buy it because their packer doesn't like it.

Absolutely, this has been done. The SPEED bag would have prevented it. There has never been a line strip or dump from a SPEED bag. Riggers are too lazy to pack it and the packers bitch every time they see one. What a sport, our equipment is dictated by packers who condemn safety improvements because it’s too much work. The SPEED Bag was used by the USAFA for 3 years I know of and it reduced their malfunctions to 1 in 3 years from 54 in 3 years. It has been available for 10 years now as a main and for the last 5 or so years on reserves.

Lee, You should read:http://en.wikipedia.org/wiki/Polar_curve_(aviation) Here is the source data logger graphs for you to pick apart: See Attached. [inline Polar_Curve_Source_Data_For_FB396_Solo_2013.jpg] All gilde data is aquired within the air mass of residence. ROD and Forward spped is relative to the air mass. Therminals don't matter, neither does the wind. Data is taken is straignt lines with stready brakes held for the length of the run. The runs are identified and seperated by video record. Bring on the math nag! I don't know whoses theorie you are quoting but you can quote me. Glide slope does vary with wing loading. After all these are just parachutes. If glide slope didn't change with wing loading then we would have 300 pounders swooping JVX84's. I would not dissagree that different sized canopies might perform differently with the same wing loading. Initial data from 3 compariable jumps indicate this might be true. For now it is just theorie, sound thought it may be. Emperically there doesn't seem to make much of a difference, none that we can notice over the 17 sizes of Firebolts over the last 10 years. John BTW: Your cutaway video is comming. Thing have been busy here in Deland. JS

I appoligize for making back to back posts but, one more thing: I had to make a choice several years ago. Should I spend my available cash on a new web site or should I buy the expensive/extensive test equipment I needed to continue to grow my knowledge of parachutes. I bought the test equipment and and therefore am able to convey to the sport test results they other wise would not have as no one else has done it. Sorry 'bout the web site. BTW: I have "Polar Curves" for the FB110, FB119 & FB200 which I previously posted. Additionally, I have tested the Katana120 and the JVX84. Anyone who wants to see them may E-mail me as they are too big and unnecessary to post here.

Here is one for the FB396. [inline Polar_Curve_FB396_Solo_2013.jpg] Error Correction: I just noticed the chart is labled for a "FB386". We don't make a 386 it is a typo which was mine and I appoligize. It should read FB396

Chris, Maybe this will help clairfy my answer: https://www.youtube.com/watch?v=0faDY9a2nEQ John

Larry was a good friend and he will be missed. He stopped by some years ago, after his travels in the Pacific, to say he was setteling down. I am posting the photo of the "10 High Bunch" after a Turkey meet. That's Larry in the lower right: [inline Ten_High_Bunch_small.jpg ]

Parachute ripcords ball ends are crimped with multiple blows from a 10 ton press. They are tested with 300 pound force applied for 3 seconds, No movement is allowed. This process produces a joint which is rated at 80% of the cable strength of 920 pounds. We routinely get 100% of cable strength. Might I suggest a Ball and Shank termination? Most aircraft repair shops have hand tooling which will do the job. They might even have some Ball Shank fittings in stock. JS

You are correct. There was 1 incident in the early 90 somewhere in the mid-west. I will quote Sandy Reid on this one. "The guy died because he failed to read his owners manual". 1 in thirty years - not bad. There have been other instances of this occuring but none fatal. I don't believe they ever issued a bullitin. USPA procedure is to not cutaway from a 2 out. They say that if a cutaway is descided upon, from a 2 out, you should release the shackle on any RSL, one sidded or 2 sidded.

Lee, Your observations were astute. The system failed and your description was enough to send me scurrying. The reserve should not have fired and wouldn't have fired if properly equipped. We are preparing a video, which we will post, with that very rig. The video will show how the system works and why. The problem was chased down to be a typical one of trade shows. It is as simple as someone put the wrong ripcord in the rig. The rig was a Tandem with a medium harness. While preparing for the show someone grabs a sport medium ripcord which is 30 inches long. All tandems are 32 inches. This institutional failure to know the correct component is prompting us to issue a Safety Notice requiring inspection for the correct length on all tandem rigs. The RSL cross connector is there to maintain drag integrity of the main during a malfunction and subsequent cutaway. It does this with the cross connector by preventing riser separation of more than 4 feet. It also prevents reserve activation when only one riser releases. It does this by having enough slack in the reserve ripcord cable as you noted. John

I would really like to know more about this. Can you point me to a source. I'm a liberal and a manufacturer who can't afford puppets, so I guess it is my fault. BTW: Don't try to tell an Administrative Law Judge thet the AC is advisory not regulatory, which I agree it is, they treat it as gosple.

Check the marking for acid with litmus or Hydrozine (Ph) paper. No acid no harm. Have conversation with previous rigger.

Mel, Please share with us what you know. When will AC-105-2d dissappear? AC-105-2e went out for comment over a year ago, and it was the same as 2d was before modification. It will not be adopted with that language (re: The non-existant chart in NAS-804). I know the FAA better than that. If the language changes they will again need a comment period. JS

It may have been but it was just as quietly implimented. It is the law of the land. http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%20105-2D.pdf

No! An arch does not fix everything. As the man above mentioned if you’re kinesthetic are bad you can't tell if you are symmetrical or not when you arch and an unsymmetrical arch can exacerbate the spin. The answer, as I was taught some 50 years ago, is to go into a track. Drop your arms back along you side and straighten your legs. As soon as direction is established go back to F&S. I spent much of my career training students. One of my favorite pastimes was to "Straighten out" Spinning Students. I would get close enough to grab them by the hands as they spun past and shake them out like a bed sheet, into stability. Video always showed an asymmetrical anomaly in the students’ body position. These anomalies were usually caused by a past injury such as a broken bone which had to be immobilized by casting followed by a period of inactivity. Once the anomaly was defined the student could concentrate on correctly controlling that body part or compensating so as to remain on heading. This lesson used to be standard fair in the first jump course. Its probably in a USPA Training syllabus, somewhere but it seems to have stopped being taught some years back. Don’t feel bad Felix missed this lesson also.

How about the sleves in the risers for the ends of the cable. They get tight when twisted so the lube would help there as well. All surfaces contacted can produce friction however the loop is the biggest contributor The cable is what moves and if you lube the entire cable you lube the entire moving surface. No harm at the loop as it will get oil 2nd hand anyway.

Yes, Jerry it is Galvinized. I will use this post to answer the issues about the Teflon coated cable revived from some 10-15 years ago. It is always my preference to answer issues on and individual basis. However, it would be fruitless to revisit each issue individually when all may be answered with a single statement. I am not avoiding answering specifics and will respond to specifics at a later time if so requested. All of the negative comments from the 90’s which have been brought up in this thread have come from competitors and riggers, not users. User comments have been good. New product development is difficult and fraught with pit falls. It is also expensive. It also takes time to perfect the product for this unique application. Ok, so here we are 10-15 years later and time to count the chickens. Fact: There has never been a 3 ring failure to release due to the Teflon Coated Cable. Fact: There have been numerous 3 ring failures to release due to the yellow “Lolon” (Loos, Inc. name for Nylon) and clear coated cable, due to failure to lubricate. I personally had one. I had not lubricated because I was told, in writing via the owners manual, that the Yellow cable was “Teflon impregnated and did not require lubrication”. I later spoken to the chemist at Loos who formulated the Lolon, during my search for a Teflon coating, who told me there was no Teflon in the Lolon coating. They were not interested in supplying the Teflon coating because of the small qualities required but gave me the name of the vendor we began with. This inaccuracy nearly killed me. It’s amazing how we can get motivated. Fact: We did have a cracking problem which occurred in the field after the units left the factory. It was expensive, but we replaced them at no charge. This problem occurred in random batches and we never found a way to identify the potential cause. About 8 years ago we changed vendors. The color of the cable changed from deep red to more of an orange color. We did this for control purposes. Since the vendor change we have had no complaints of any kind. I do want to specifically address the “Suck Through” issue. This is in reference to the force required to cause the cable to bend in half and pull through the grommet. The test quoted was performed with un-lubricated cables of both kinds. Of course the yellow cable was more resistant to pulling through. It was not lubricated. When the test was repeated with lubricated yellow cable they performed the same. Skydivers want things easy and maintenance free. This product gives that yet because of the power of the marketing megaphone it is unknown. So maybe it is a good thing to bring it up again. We have just been sitting quietly here in the corner doing our thing and having no trouble. Come join us.

Now you know why I said "I want to test it". You just can't tell by looking. You gotta test it. Good job TSE

You will find your answer here. http://www.jumpshack.com/default.asp?CategoryID=TECH&PageID=3RING&SortBy=DATE_D