billbooth

Polarbear just asked if you needed to be a rigger to assemble your own main parachute. At the moment the answer is "no". However, it is possible that the answer, in the future, might be "yes". I am on the committee which is re-writing the current TSO, which applies only to the reserve harness and container, reserve ripcord, reserve risers, and the reserve canopy, bag, and pilot chute. This means that these items are the only certificated parts of a parachute system, and therefore the only parts that have to be assembled and looked after by a rigger. However, some members on that committee want to include a new series of tests that the main canopy release device (and drogue release device on tandem rigs) must pass to get a TSO for the rig. In other words, they want to, for the first time, "certify" the main risers. There is good reason for this view in light of all the manufacturers who have made 3-ring releases improperly in the past. However, there is a "Catch 22" involved. If we include the 3-ring system in the standard, it would then become part of the "certificated system" and, some at the FAA might argue, therefore must be assembled and maintained by a certificate holder, ie. rigger. This would mean that a jumper could no longer connect his main risers, to his OWN rig, unless he was also a rigger. If the drogue release is included, it means that a tandem master could no longer close his own main container. Some on the committee (including me) feel that the general jumping population (including you) might not "take kindly" to such a regulation. My question to all of you is this. Would you be willing to trade your current right to assemble your own main parachute, in exchange for the FAA requiring manufacturers to make main canopy releases correctly, in order to get a TSO? Now mind you, just because we include main risers in the standard, doesn't necessarily mean that the FAA will require riggers to hook up main risers. I just opens the door for them to do it, and I'm afraid, for a bureaucrat, it is a "logical" step. Bill Booth

rdutch; From what I have read about RSL's in the short time I've been on DZ.com, I think the subject has been not only well covered, but beaten to death. Bill Booth

Remster; Like all truly responsible fathers, I banned my daughters from the drop zone at age 12 to protect them from guys like you and me. Bill

Crazymel; Pilot chutes are not rocket science. As long as your pilot chute passes the tests I gave you, it should be OK. It is normal for a "fully cocked" pilot chute to slightly "uncock" during the rig closing process. The blue mark on the kill line it there so that you can quickly "pin check" your rig without having to unpack the pilot chute. It seems that your blue mark is just slightly in the wrong place or simply not long enough. The easiest thing for you to do is take out a blue marker, and make it a little longer. Or, you could pay a rigger $40 an hour to do it for you. (Just kidding) Bill

Igor; As long as your 24" pilot chute is correctly made, and your main isn't over 200 square feet, your deployments, while not perfect, will probably be OK. But if the apex is below any part part of your pilot chute's skirt, expect problems. Bill

Jon; Each "no-stretch" line, Kevlar, Spectra, and Vectran has advantages and disadvantages. Because the melting point of Spectra is 100 degrees lower than Nylon, it seems to sacrifice itself, without doing any damage to the Nylon bridle we use. And is much easier to replace the kill line than the whole bridle. And, (I hate to admit this) Spectra costs less. We put a little slack in a new kill line, so that when it shrinks, it doesn't matter that much. Bill

Nope. You seem to know what you're doing. Now remember, the first thing you do with that first great big paycheck, after you get that high paying job you spent all those years in college for, is to buy a bright shiney new Vector. Promise? I've got two daughters I have to put through colleg soon, and I'd appreciate any help you can give me. Bill

Tack your exposed housing to your upper harness ring (if it hasn't already been done) and you can get rid of most of this problem. It is now done standard on Javelins.

Kelly; You're absolutely right. Construction details are much more important on small pilot chutes, just like they are on mini 3-ring risers. You can probably make a 36" pilot chute any way you want, but a 24" must be made exactly right. Relative Workshop offers a 34", F-111, non-collapsible, and a 28" ZP collapsible. Because we can't really control where our pilot chutes go, we don't sell anything smaller to the general market. We do offer a 24" ZP for people with canopies below 97 square feet, but you have to "beg" for it and promise you won't sell it to some unsuspecting newbee with a 280 square foot canopy. I wouldn't go any smaller than that 24". Remember, some day you may have to do a hop-n-pop. Bill

Aggiedave; Nope, it's real. I forgot that one. We add a piece of elastic webbing under the top main flap to insert the tuck tab in. It really does help keep the main protector flap closed. But you're still missing is total bridle protection down to the pouch, which is only about an inch anyway. Of course you still don't have a reserve pin protector flap tuck under, secondary riser covers, pocketed main container corners, or a main pin protector flap that never comes open. Details...

Mark; When freeflying became popular, my response to making the Vector II "freefly friendly" was the Vector III. While I would not recommend doing a lot of "hardcore" freeflying on a Vector II, there are things you can do to make it more freefly friendly. 1. Replace all Velcro. 2. Get a bottom of container (BOC) pilot chute pouch installed, if it doesn't have one already. 3. Get new main risers with our "TruLok", Velcroless toggle system on them. These things will help, but nothing (in my humble opinion) beats a Vector III or Micron for "Freefly Friendly" features. (Sorry about the shameless plug. I just couldn't help myself.) Bill Booth

"I've had at least a couple of pc's in tow that lasted 2-3 seconds. Sure that's not a long time, but it sure feels like it when it's happening." Kirshan; A pilot chute in tow for "2 or 3 seconds" is terrible. If your pilot chute is correctly made and matched to your canopy weight, and if you throw it cleanly out of the burble, at terminal velocity, the time from pilot chute release to line stretch should be no longer the 3/4 of a second. NO LONGER. Do not jump a pilot chute that hesitates for even a second a the end of the bridle. Please! Bill Booth

Guys; Use some simple logic here. A collapsible pilot chute is designed to collapse when the kill line pulls the apex below the skirt. Right? Well then, if your centerline or kill line (see the definitions at the beginning of this string) is so short that it pulls the apex below the skirt (or any portion of the skirt), when your pilot is fully cocked, then how the hell can it work correctly? Every time someone has asked me why their pilot chute wasn't working very well anymore, the problem has been an apex pulled too far, with support tapes not sewn on the bias. EVERY TIME! Think of the mesh on your pilot chute as the suspension lines of a round canopy. If the suspension lines are all different lengths, then the parachute is not going to work very well is it? We sew the support tapes on the bias (the direction the mesh stretches the most) to stabilize the mesh so that the whole skirt of the inflated pilot chute, especially that part which is between the support tapes, is roughly the same distance from the base. If the support tape is not sewn on the bias, and the apex is pulled to the junction of the support tapes and the skirt, when the pilot chute inflates, the mesh halfway between the support tapes (on the bias) stretches a lot, allowing that portion of the skirt to get way above that apex, spilling a lot of air, and lowering the pilot chute's drag. How much drag is lost depends on how much the apex was pulled in the first place. Why would a manufacturer not sew the support tape on the bias? Well...1. They either they don't know any better, or 2. it's really hard to sew tape on the bias, 'cause the damn mesh keeps stretching. Whether a pilot chute made this way is "safe" or not depends on how big it is compared to how much your canopy weighs, and how fast you are going when you deploy. And don't forget, pilot chutes made this way tend to loose drag as they get older and the mesh stretches. In other words, a poorly made pilot chute might work OK, for a while, if you always deploy a light canopy at terminal or above. Yet, that same pilot chute might be considered "unsafe" with a heavier canopy, or at lower airspeeds (like an emergency hop-n-pop at low altitude), or after it gets older. The point here is; While there are many ways to make a pilot chute, I want each one I make to be as efficient as possible, and have an exactly predictable amount of drag, at any airspeed, for its entire useful life. Isn't that the definition of quality control? Bill Booth

To everybody who has sent me a private message: I must be doing something wrong, because the stinking system won't let me send replies. Bill Booth

To all those who have written me private messages: I have tried to answer, but I must be doing something wrong because the stinking system won't let me send them. Bill Booth

Frank; When I first started making gear, I actually thought I could make it so good than no one would ever die jumping it. I still remember how devastated I was the first time someone bounced on my gear. Since then I've learned to live with the reality that I can do nothing about most fatalities. That's up to each individual jumper, every time they leave an airplane. However, I have spent the last 30 years trying to make sure that no one ever dies because their gear wasn't up to the task. So it means a lot when someone tells me I'm headed in the right direction. By the way, I love your screen name "Iflyme". I wish I had thought of it. Thanks, Bill Booth

Aggiedave; You know, I am beginning to worry about this younger generation of skydivers. I mean, at last year's convention, I even saw a T-shirt which read, "Eat, SLEEP, Skydive". What a bunch of wusses! Bill

Derek; As you know, the V304 Micron is the smallest rig we make. However, I am glad to announce, for all jumpers with a highly developed death wish, such as you, that we are drawing up the plans for a V303 as I speak. When we started Vector III's in 1994, the smallest we made was a V343. So You see, I left plenty of room to go smaller. I hope this stops soon. I only have three smaller numbers left. If you guys don't cut this out, we may have to go negative. Bill

Two little known facts about Scotty; 1. He had the foresight to buy the first hand deployed rig I ever made. 2. During the first year of tandem jumping here at DeLand, when everyone (including me) was a little scared of it, Scotty was in constant demand as a tandem passenger for those jumpers who were getting their initial tandem rating. Why? Because of all the crazy stuff we'd seen him get away with over the years, there was a widely held belief that he simply couldn't die...no matter what. That gave tandem master newbies a nice warm feeling as they stepped out on their first tandem jump. Scotty was always way "over the top", but no one could have a better friend. He even let me judge the famous wet tee shirt contest (where Jerry Bird got arrested) in Z-hills in the late '70's. I think we all got in trouble because the Mayor's daughter came in second. Anyway, at the trial, I was the "unidentified bearded man" sitting right next to Jerry in all the photos. Thanks Scotty. I'll never forget it. Bill

Rap; I agree. Relative Workshop's website sucks. That's probably because I hate almost everything about computers, which is probably because I know next to nothing about computers. I have, however, recently hired a website designer and told her to build a website the way we build a Vector. I can't wait to see how it turns out. The way I'm forced to spend money on computers, software, and the people to keep it all up and running, I'm beginning to think that soon, all of us will be doing nothing but selling computer services to each other, and no useful work will get done in the world anymore. Bill

Kikidi; If you think the difference in performance between main and reserve canopies is a problem now, just go back a few years when we were all jumping square mains with ROUND reserves. And many jumpers had never jumped a round before. Talk about fear factor. You guys have it easy nowadays. One problem with reserve demos is that the low porosity fabric that is now available is not nearly as "good" as F-111 used to be, and canopies made of it "rag out" after not too many jumps. As a matter of fact, research, especially the Belgian Army study, shows that pack jobs on F-111 type canopies affect the porosity even more than jumps. That's why PD wants your reserve back for a porosity check after 40 pack jobs, whether you have jumped it or not. So a demo reserve with hundreds of jumps on it would probably not make a very good impression, would it. However, I just talked to Bill Coe of Performance Designs, and he said that his company does ship out demo reserves, on main risers, which they retire (turn into car covers) before they get too many jumps on them. Bill

Dave; As you know, I have been doing just that recently, at least in regard to the three ring release and hand deploy pilot chutes. I could write volumes about reserve pilot chutes, toggles (Yes, toggles. You would be surprised how dangerous some toggle set-ups are.), riser covers, bridle protection, reserve cover flap tuck tabs and a dozen other subjects. But quite frankly, I'm beginning to get a lot of grief from some of my staff. Their complaint goes like this: "Bill, you have spent 35 years of nearly endless experimentation and observation to gain what knowledge you have of parachute systems. Now you're simply giving it away to people who aren't even our customers. It's your job to make our equipment the best in the world. It is not your job to give the results of hundreds of thousands of dollars of research to our compeditors for free. If you want jumpers to benefit from what you know, let them buy a Vector." In a way they're right, but at the same time I'm tired of jumpers being hurt or killed because of improperly manufactured or maintained gear. I have two children, a staff of 50 people, and an ex-wife who depend of me for their livings. What should I do?

Jason; The same basic construction rules apply to a "bungee" collapsible pilot chute. They, of course, have the advantage that you don't have to cock them after each jump. However, bungee pilot chutes have pretty much "lost favor" with the jumping community for several reasons. 1. They are hard to "calibrate" in the first place, that is open when you want, and stay closed when you want. 2. They tend to go out of calibration as they age (even temperature affects them). 3. They tend to re-open during the extreme swoops that are so popular today. Because people quit asking for them, we have not made one at the Relative Workshop for almost three years now. However, if yours is working for the kind of jumping you do, I see no reason to change it. Just keep an eye on your bungee cord, and replace it before it gives you any trouble. But please be sure to use exactly the same style, diameter, and length of bungee cord as the original. I, for one, always liked the user friendly simplicity of the design. It just didn't work out in "real life". Bill Booth

Yesterday, I responded to a post from a jumper who had a pilot chute in tow. Someone suggested that I post it here too. Here is the string: Subject PC in tow... for real this time Reply Posted by pilotdave (Enthusiast) (Full Profile) How ironic... My first jump after posting a fake picture of myself with a "PC" in tow, I had myself a real life pilot chute in tow. Always wondered exactly what I could/would do in that situation. Everything happened so fast I barely had time to think about it. I didn't cut away. I reached back, grabbed my bridle, and yanked. The bag came right out, but I flipped over on my back so I watched it come off. Canopy opened with enough linetwists that I could't look up, but that was fine with me. Linetwists cleared themselves and I landed normally. I had originally pulled at 3500. First time I looked at my altimeter I was at 2000 but I had been under canopy for a little while at that point. It's hard to judge but i'd guess the whole PC in tow lasted no more than 3 seconds. I talked to the DZO about it and he suggested that maybe I need a new pilot chute. He checked the tightness of my closing loop and it was fine (after I repacked). I did one more jump, had a kinda delayed opening... But it opened again with linetwists (probably my body position as I turned to see what was happening that time). After that I brought it straight to the most experienced rigger there and he found the problem right away. My kill line had shrunk (I bought it used), so the PC wasnt inflating fully. The center of the PC, where the handle is, gets pulled down too far. Cost to replace the kill line: $15. I think I can afford that. Dave Reply from Bill Booth: What happened to you is getting more and more common. Although I hold the patent on the hand deploy pilot chute, I never charged anyone a royality to use it, and therefore never published construction details. I'm afraid this has led to some poorly made pilot chutes as people have copied, but not copied EXACTLY, my original design. As a matter of fact, last Sunday, a jumper came up to me, said that he was having "pilot chute hesitations" on his Vector, and asked me to have a look. His problem, it turned out, was the same one I've seen countless times before...His pilot chute was made by "God knows who", and made incorrectly. I don't know about you, but one of the the scariest malfunctions I can think of, is a streamered main pilot chute that has enough drag to open your main container, but not enough drag to lift out the bag. What do you do? If you just lie there and wait, the ground may "rise up to smite thee". If you pull your reserve, your main is going to simultaneously deploy, and main/reserve entanglements are rarely much fun either. What to do...Easy, don't jump an incorrectly manufactured or adjusted pilot chute. So, how can you tell if your hand deploy pilot chute is OK? First, some basic definitions. 1. Apex - The center of the fabric part of your pilot chute. 2. Skirt - Where the mesh and fabric meet. 3. Base - The center of the mesh part of your pilot chute. 4. Centerline - One or two pieces of tape, of fixed length, that lead from the apex to the base. 5. Bridle - A piece of tape, doubled in the case of a collapsable pilot chute, leading from the base to the deployment bag. 6. Kill line - A single piece of line, on a collapsable pilot chute only, that runs from the apex, through the center of the pilot chute, and down through the bridle to the pilot chute attachment point at the bag, or in some designs, to the apex of the canopy. 7. Support tape - 4 pieces of thin tape, sewn to the mesh, leading from the base to the skirt. 8. Bias - Simply put, the direction the mesh stretches the most (a diagonal line, at 45 degrees to the little squares that make up most mesh used in hand deploy pilot chutes). Sorry for all that defining, but if you don't understand those terms, you won't understand what comes next. OK, now the easy part. If you want your pilot chute to always function properly, simply make sure, in the inflated state, that no part of the skirt is above the apex. In other words, make sure neither your centerline nor your kill line is too short. I pulled the apex on my hand deployed pilot chute for two reasons. 1. It makes them open faster. 2. It yields 11% more drag. However, IF THE APEX IS PULLED DOWN BELOW ANY PART OF THE SKIRT, THE PILOT CHUTE WILL NOT FUNCTION PROPERLY. How do I check that? First cock you pilot chute like you would during packing. Now hold your pilot chute UPSIDE DOWN by the bridle at the base. Simultaneously pull downward on the apex (handle) and each support tape where it touches the skirt. The apex should be equal to, preferable slightly "below", but never "above" the skirt. (Please remember, the terms "above" and "below", in quotes, refer only to the "upside down" pilot chute you are holding in your hands for this test.) Now look how your support tapes are sewn to the mesh. If they are sewn "on the bias" your pilot chute is properly constructed. If they are not sewn on the bias it means that the mesh halfway between each support tape IS on the bias and will stretch more than enough to allow the skirt to get way "below" the apex. Try it. It's like a round parachute with several different line lengths. It simply doesn't work very well. This extremely common construction error might not let your pilot chute fully inflate, or in extreme cases, inflate at all. If your pilot chute is "borderline" when it is new, then things will get worse and worse as it ages. Now to "adjusting" a correctly manufactured pilot chute. Kill lines are usually made out of Spectra (Microline). Friction generated during the collapse sequence causes heat, and Spectra SHRINKS when heated. This means that your centerline could eventually get short enough to prevent your pilot chute from inflating correctly. Use what you have learned above to recognize this situation, and correct it. This is just a BASIC primer on pilot chute construction, and does not address several other important design considerations such as fabric and mesh choices, and how pilot chute size vs. the weight of your main canopy affects seperation velocity, snatch force, opening shock, and malfunction rate. More about these another time.Bill Booth Dave replied: Wow, excellent advice. Tried the test and the apex is nowhere near the skirt. It's inches above. The end of the hackey handle doesnt even reach the level of the skirt. The support tape goes in the same direction as the lines of the mesh, not 45 degrees to it. You're saying this is improperly made? Do all "real" parachute manufacturers install the support tape 45 degrees to the mesh? Do I have some sort of homemade pilot chute? There doesn't seem to be any kind of tag or marking to tell me who made it. Watching the pilot chute as i pull it down through the air and let it inflate, I can CLEARLY see that the apex falls below the skirt. Until my incident, I wouldn't have know this is unsafe. The rigger I bought my rig from gave me a one year warranty on everything. If he hadn't been evicted from the DZ and his house, I'd get my money back. I am quite shocked he sold me potentially (or definitely) unsafe equipment. The good news is he's gone now and I don't have to deal with him anymore. Thanks for the info! I'm sure I'm not the only person relying on posts like this to keep me safe in the future. Keep it up! Dave Bill's reply: Your pilot chute is "unsafe" if it doesn't deploy your main correctly. What is "correctly"? You want your pilot chute to open your container and the pull your bag away from your container quickly, but not too quickly. If your pilot chute accelerates your bag away from you too slowly you have the potential for line twists because of the extra time your unsymmetrical deployment bag is exposed to the slipstream, or a bag lock caused by your suspension lines actually "blowing up" above your bag and entangling with it. Not to mention taking more altitude than necessary to deploy. If your pilot chute accelerates your bag too quickly, you have the potential for inertial line dump, high snatch force (when the canopy hits the end of the lines and is decelerated back to your speed), slider rebound (where the slider bounces off the slider stops and your canopy starts its opening sequence with the slider a few inches down the lines. OUCH), and a generally disorganized opening, increasing your chance of malfunction. The ideal separation velocity, that is the speed which the canopy is traveling away from you at line stretch, is 50 feet per second. An acceptable range is 30 to 70 FPS. If a pilot chute causes separation velocity outside that range, I do not considerate it "safe". How can you tell what your separation velocity is? You can look at a video of one of your deployments and count video frames at 30 per second. An acceptable time from container opening to line stretch is 0.45 to 0.75 seconds, or about 13 to 22 frames. Any faster or slower and you are "asking for it". Separation velocity for any particular system depends on the size, material, and construction details of the pilot chute vs. the weight of the bagged canopy. You of course also have to factor in deployment speed, what your lines are made of, and how you stow them. A very large pilot chute, constructed as yours is, might be perfectly "safe" with a light canopy. The construction details I gave you make the most efficient use of materials, and yield the most consistent results over the most number of jumps. Of course, if you pull the apex down far enough, no pilot chute, no matter how large, will do its job. That's what the "kill line" is supposed to do, isn't it...pull the apex down so far that the pilot chute totally collapses? Bill Booth Post Extras:

Pilotdave; Your pilot chute is "unsafe" if it doesn't deploy your main correctly. What is "correctly"? You want your pilot chute to open your container and the pull your bag away from your container quickly, but not too quickly. If your pilot chute accelerates your bag away from you too slowly you have the potential for line twists because of the extra time your unsymmetrical deployment bag is exposed to the slipstream, or a bag lock caused by your suspension lines actually "blowing up" above your bag and entangling with it. Not to mention taking more altitude than necessary to deploy. If your pilot chute accelerates your bag too quickly, you have the potential for inertial line dump, high snatch force (when the canopy hits the end of the lines and is decelerated back to your speed), slider rebound (where the slider bounces off the slider stops and your canopy starts its opening sequence with the slider a few inches down the lines. OUCH), and a generally disorganized opening, increasing your chance of malfunction. The ideal separation velocity, that is the speed which the canopy is traveling away from you at line stretch, is 50 feet per second. An acceptable range is 30 to 70 FPS. If a pilot chute causes separation velocity outside that range, I do not considerate it "safe". How can you tell what your separation velocity is? You can look at a video of one of your deployments and count video frames at 30 per second. An acceptable time from container opening to line stretch is 0.45 to 0.75 seconds, or about 13 to 22 frames. Any faster or slower and you are "asking for it". Separation velocity for any particular system depends on the size, material, and construction details of the pilot chute vs. the weight of the bagged canopy. You of course also have to factor in deployment speed, what your lines are made of, and how you stow them. A very large pilot chute, constructed as yours is, might be perfectly "safe" with a light canopy. The construction details I gave you make the most efficient use of materials, and yield the most consistent results over the most number of jumps. Of course, if you pull the apex down far enough, no pilot chute, no matter how large, will do its job. That's what the "kill line" is supposed to do, isn't it...pull the apex down so far that the pilot chute totally collapses? Bill Booth