DBTECH

You say 4cm or 1.6 inches; I say more. Also, one must consider the type of malfunction. Dave Brownell

Yes, you want a guaranteed first right side release first with an RSL in use. In my mind with a two inch longer RSL side cable, along with an aggressive pull/cut away, would translate to about a 65 ms (1/16 sec) second delay after the right side. (I'm assuming a two inch difference (0.166 ft) Anyone want to make a guess how far the right riser ring is above the harness ring when the left side releases? (assuming an aggressive pull/cut away) Dave Brownell

Another mfg? Any input as to who that may be? I own an early 98 Reflex (all AD's performed, of course) Skies, Dave Brownell

Carl said: I'm having a hard time picturing this. When you talk about "slider stop lines", do you mean the lines on whose ends the grommets end up resting when stowed? DB: Yes indeed And by rebound, do you mean that these lines reaching extension "boing" (forgive my misuse of technical terms) and force the slider part way down the lines before canopy inflation? DB: Take a piece of suspension line twelve feet long and attach one end to a fixed point. Attach a solid; let's say, three ounce weight to the free end. With yourself standing at the fixed point throw the weight away from yourself at 35 MPH. When it comes to the end of this line, what happens? 35 MPH (51 FPS) is the nominal speed of a bagged canopy "relative to a jumper" at last locking stow release. When will you be publishing this patent? DB; The patent application itself will probably never be published on a news group, but my article probably will------ I have written an article that will be posted/published at a later date, that is entitled; Fast openings/Slow openings--The Real Physics of slider rebound; plus invention revealed. (Patent Pending) By David B. Brownell Dave Brownell Mesa, Arizona Edited by dbtech on 5/18/01 11:09 AM.

Excerpt from article: Another way to reduce snatch force energy and the evils resulting from it, is to go with a smaller pilot chute. A smaller pilot chute will result in the bagged canopy reaching a slower speed relative to the jumper at last line stow release* This slower speed will result in lower slider stop line rebound energy. A smaller pilot chute will also lessen the chance of line dump. Dave Brownell

I'm Jumping a Cobalt 135 with a 21" ZP pilot chute, with my new design slider. Dave Brownell

No way six months! My custom color Cobalt 135 was done in four weeks! I believe they are running about 5-6 weeks now to your door. (custom colors) Dave Brownell

RE: Slider/slider stop line rebound Ongoing research/testing has been very educational, in so much as it has confirmed my theories/math on this phenomenon, which I claim is a major factor/source of those occasional, very fast/hard, brutal openings. We have also determined, that it's a factor, in most or all of, "so called" normal openings. I also believe that's it's a factor in line over malfunctions. At this point in time, I will reveal the fact, that it's really "Slider Stop Line Rebound" which results in the slider prematurely moving down the lines slightly, thus allowing the canopy to be ahead of the slider in the opening sequence. There are several factors that determine the amount/distance of slider rebound. The first is the amount of energy stored in the four slider stop lines at the point of maximum slider stop line tension/elongation. This energy is determined by the speed of the bag relative to the jumper at last locking line stow release, along with several other factors in the total parachute system, with deployment airspeed being a variable factor. This slider stop line rebound energy takes less than ten milliseconds to do it's evil deed! This event is over before the slider stops are hardly out of the bag! (10ms nom) The G forces on the slider during this time of slider stop line extension/rebound can be higher than two hundred G's! Another factor is the factor of aerodynamic drag of the slider, which opposes this rebound energy during slider stop line rebound. Having a faster inflating slider to appose the slider stop line rebound energy is an obvious plus. But what if we could reduce the amount of energy stored in the slider stop lines at maximum slider stop line tension/elongation, by a huge amount? And what if we could also have a faster inflating slider to oppose this now much lesser rebound energy. I claim that my methods have done both. (Patent Pending) I have reduced slider stop line rebound energy by 75%! I have also, theoretically, increased the inflation speed of the slider by a significant amount. Both of these factors, when combined, produce an additive/positive "double whammy." Yes, my big hope is for the reduction/elimination of those occasional very fast/hard, and sometimes brutal openings. I have written an article that will be posted/published at a later date, that is entitled> Fast openings/Slow openings--The Real Physics of slider rebound; plus invention revealed. (Patent Pending) By David B. Brownell Slow/soft openings, Dave Brownell

You may want to consider one of these in a 120 or smaller. http://www.extremefly.com/ Dave Brownell

I would tend to agree with this, as 1000 feet is only slightly less than one inch of mercury in pressure drop. Dave Brownell

I am very leery about adding mass to the apex of a hand/apex deployed pilot chute, as I suspect this mass could increase the chance of a PC malfunction. Yes, I know the jury is still out on this theory. When it comes to pilot chutes, I consider even the smallest increase in malfunction rate to be totality unacceptable. Dave Brownell

AndyMan said: My single biggest complaint is this: The tabs that are used to close the slinks constantly come out of my risers. These are little tabs that fit into a finger trap used to close off the cord. They're supposed to sit inside the riser out of the way. Mine constantly move out to the side, and there they catch the slider making it difficult to move. People tell me after a few months slinks develop a memory and don't move out anymore, but I've done over a hundred jumps on slinks and still have problems. DB: Tack the tab to the riser with E-thread with a fisherman's knot as I did when I used Slinks. I now use #4 Rapide links on my new Cobalt 135 Dave Brownell

Zennie said-- Wreck has a really high noise-to-signal ratio. 'Bout the only thing I use it for anymore is to try to get info when an incident occurs. DB: You mean a LOW signal to noise ratio. (much noise) Dave Brownell X recording engineer

Vector V-7 with canopies FS I have a 1983 Relative Workshop Vector V-7 harness-container, Cruislite main, and a Phantom 26' Reserve for sale. There is about 700 jumps on this rig. This V-7 Vector is in very good/clean condition despite it's vintage and number of jumps, as it's had much TLC over the last 17+ years. The harness size is for six feet, 175 lbs. nominal. There is a small BOC for the included 24' F-111 pilot chute, and a new deployment bag is included. The Cruislite main (220 sq ft) is "brown-tan-lt blue-TAN-lt blue-tan-brown," both top & bottom. There is some damage on one stabilizer, repaired with rip-stop tape only. The Phantom 26' reserve has been used only one time and has had all AD's performed. (new diaper and doubled upper Kevlar lateral band) (The mesh PH is ok) A very nice gear bag and extra reserve RC and cut-away pillow/cables are included. Asking $700.00 for all, but will break up. (reserve worth most) Dave Brownell Mesa, AZ

Post from Dave Brownell: The following is a series of letters regarding pull-out pilot chutes. Hello TK: (at the Relative Workshop) I don't know what your opinion is about pullout pilot chutes, but here is mine, in response to a question regarding rig conversion. I, personally, am against pull out's. (20+ years, jumper, pilot, rigger) As predicted, I have seen (watched) two near fatalities as the result of pullouts. Both were main-reserve entanglements. In both cases the PC's were held long enough to allow the bridle to half hitch around the pilot chute causing a PC malfunction. When I say long enough, I mean as short as maybe one half second or less! This may not seam very long, but consider the action/speed of the bridle being out next to the inflated PC. (perceived malfunction rate?) With a hand deploy PC you are holding the apex of the PC. There is only a horseshoe starting at your hand, and ending at the closing flap. When you release the PC the total horseshoe remains taught until pilot chute inflation. I have held on to my hand deploy for five seconds on several jumps with no problem. Would you want to do that with a pullout? As far as concern about the pin not being pulled? A 28" pilot chute has at least 70 lbs. of drag at 120 MPH. What's the likely hood of a misrouted bridle on a late-model rig? Buy the way, in both cases of near fatalities, both jumpers pulled their reserves around 1000 feet. In both cases there were entanglements with the main-bag that deployed at reserve pull. They both got reserve openings below 300 feet! On one, "garbage of the main" was pushed down to the jumper by the reserve slider, blinding the jumper! Sounds like fun time, HA! (bonus days included) I was witness to both of these jumps! Dave Brownell Mesa/Eloy AZ Dave, I'm with you on all counts. Here's a fact or two you can add to your list. We've done a lot of tests to determine the strength of the average jumper in the pull-out configuration. The strongest guys in our shop were not half as strong as the drag of a standard hand-deploy pilot chute. No contest there. In an ideal world, a hand-deploy is always thrown, and should not be held onto unless you discover someone over your back at that very moment. But when you must hold it, the worst that can happen is that the drag on the bridle pulls the pin. (which is what you get on every pull-out deployment!) If you're stable, the bagged canopy will stay on your back. (Dave, all of the maladies you mention are absolutely true.) With a pull-out pilot chute, you don't get the great, aggressive throw capability of the hand-deploy because you loose ½ of the throwing stroke just trying to pull the pin out of the locking loop. Without a good throw, the pilot chute could end up on your back in the burble. I personally have about 300 jumps on a pull-out system and on many of these jumps, I experienced pilot chute hesitations. I went back to hand-deploy and have not had a hesitation since. Dave, you're absolutely correct when it comes to two canopy entanglements. Here's how the scenario goes: They pull the handle and pin and then let go of the PC. The burble sucks the PC onto their back. They fail to look over their shoulder hard enough so the PC stays there. Eventually, and usually quite low, they decide to pull the reserve. Both canopies will usually deploy one after the other. And here's another problem. Most jumpers with pull-out systems loose their handle at least once during their career. Some don't ever find it on that given jump and end up pulling their reserve. Some don't pull anything. Before the days of AAD's, a significant number of jumpers bounced, Jeannie McCombs being one of the notables. I'm sure I could go on an on about the virtues of H/D over P/O, but life is short and so is the list of jumpers using the PULL-OUT System. Talk to you later, TK

Kris said: I would but I'm at a small DZ in Oklahoma where almost everyone jumps PD canopies. I would try a Cobalt but the biggest they make is a 170 and that's too damn small. DB: The current consensuses is that a Cobalt can be sized one size smaller than let's say a Stiletto. I'm 195 lbs. OTD with a Cobalt 135, and I'm getting great landings. WL= 1.44 lbs/sq ft. For this same wing loading with a Cobalt 170 you would have to weigh 245 lbs. OTD. Dave Brownell

Ric said: I'm scared when i go to the toilet after my mates been in there, man that kid smells. DB: Sh*t and flush should be in sync!! Dave Brownell

I would agree that Slinks would probably fail at a higher number than 3.5 Maillon Rapide links, (mini links) but not likely higher than #4's, and definitely not higher than #5's. My new Cobalt 135 came with #4's, which I consider to be the "ideal" Maillon Rapide link. As far as 3.5 mini's are concerned, I've always felt that they are pushing the envelope to much, with very little strength margin as compared to #4's. Keep in mind that #5's were the norm before 3.5's.. (mini's) 3.5's (mini's) are one half the strength of #5's! Number 4's fall in the lower middle. Note: A #8 Brass or 25mm stainless slider grommet will go over #4's with no problem, even with a boot. Dave Brownell Edited by dbtech on 4/30/01 01:58 PM.

Dutchboy said: Sounds like you need some kung fu shoes. They are very light with rubber soles without much tread. Perhaps when mine get a little more beat up I'll start wearing them when I jump. DB> You do not want rubber soles/heals for the reasons stated in my post. Less tread means nothing in this use other than less mud collection. A lower coefficient of friction counts here. Dave Brownell

*This is a brand new emergency parachute that is under warranty. If it doesn't work, bring it back. *Buyer/user beware; Seller is not responsible for injuries or death, resulting from use, misuse or abuse of this parachute. Seller also claims no specific purpose in mind, or out of mind whatsoever for this parachute. Seller proclaims; No warranties or guarantees of any kind expressed or implied for this parachute. *Hernia size is directly proportional to peak opening shock. Dave Brownell

After much exploration and research, I believe I have finally found an ideal shoe for skydiving. It is a Special Edition shoe made by K-Swiss, called a "Chillton." My goal was to find a VERY LIGHT shoe with a sole and heal area made with a VERY LOW FRICTION MATERIAL compared to any other sports shoes. A low friction material in the heal area would make for much easier jump suit leg removal. This same low friction material in the sole will make for better turf surfs. Data from K-Swiss> UPPER: Full-grain/synthetic leather combination or metallic fabric. OUTSOLE: New ultra-light EVA capsole. DETAILS: Streamlined stitched design with overlay strap. New K-Swiss metal eyelets and Shield vamp emblem. These shoes are very high quality, and look very cool. They are available in three colors. MSRP $70.00 Here's the URL for K-Swiss Be sure to check out the "Go 360* " To order, click on "Gear" then "Classics" then "Chillton." http://store.kswiss.com/rcs/kswiss/kswiss/Kstore/Chillton/product.jsp K-Swiss 31248 Oak Crest Drive Westlake Village, CA 91361 1-800-938-8000

Will asks: What are the advantages/disadvantages of the following 3-ring systems : * mini-ring type 17 * mini-ring type 8 * large ring type 8 I am looking to buy my first new rig, it will be mainly for freeflying, but also a little RW. What would you recommend and why? DB: Mini ring Type 17 with type 3 reinforcing tape is pretty much the standard now on most rigs. Mini ring Type 17 Integrity risers are pretty much out. Mini rings on Type 8 is a configuration that is not recommended by the RWS. Large rings (std rings) on Type 8 has the highest mechanical advantage and webbing strength/longevity. Here is one you forgot to mention; it is the configuration for type 17 that is the best, but is rarely seen. Large rings on type 17! This is the best mechanical configuration for type 17, but is rarely seen. I do have a pair of type 17 risers with standard rings that I built in 1987 that have 400+ jumps on. One of the openings was in the category of ultra brutally fast/hard. When I say ultra brutally fast/hard, how does stitches popped on dive loops, deformed delta/stainless connector links and broken lines sound!! I did not cut away, but had to land with rear risers, as both steering lines were broken! These type 17 risers with standard rings did not fail on this opening despite not having the type 3 reinforcing tape as used in currently manufactured type 17 risers! BTW: The canopy was a PD 210. I believe line dump was the cause of this monster opening. Now jumping a Cobalt 135 on Mini ring Type 17 risers. (I'm 195 OTD) Dave Brownell Mesa, AZ

For the record, I thought some of you may have interest in this question asked on rec.skydiving. db Jaime asks: >>Can anyone tell me anything about integrity risers? >>Thanks for your time. Integrity risers were first dreamed up because of the fear of riser failure only on the side with an RSL connection, during a very fast/hard opening, which would result in a main-reserve entanglement. (Yes, it has happened. Integrity risers are built without a grommet in the riser for the cable loop. Instead, there is a tab on the ring side of the riser that has the grommet. Integrity risers are installed on the harness ring in reverse (riser rings toward rig). Integrity risers are stronger because of their absence of a grommet hole. There are two negatives regarding integrity risers. The first is the fact that the loop mechanical advantage is close to half that of conventional risers, which in fact reduces the total mechanical advantage to close to half also. The reason that they have reduced mechanical advantage is because there is no longer a loop around the small ring, but a near straight line between the loop attachment point and the locking cable. There is in fact recorded cases, where under a high G spinning malfunction, where the release cable was pulled into the grommet somewhat, due to the higher forces, which resulted in a very hard release cable pull. When you consider this factor combined with the high friction of soft housings, you can see the potential of a deadly combination. This is not just my opinion, but is one shared by many in the industry. As far as stainless housings, I recommend keeping them clean, along with clean cables with a little silicone applied. Regular maintenance will keep them at a low coefficient of friction. The second negative is the possibility of not getting a riser release because of a combination of lower harness rings locations and a somewhat face to earth under a low drag malfunction. Rigs/harnesses made today are made with this in mind to assure high harness rings locations. I do not use an RSL, but I do like the strength advantage of a hole-less TY-17 riser. As far as a canopy with high spin rates associated with malfunctions being used with integrity risers, I myself have no problem with integrity risers, because of the factor of housing/cable maintenance. I once had a very fast/hard, brutal opening on my Spectre 170 with integrity risers. When I examined the loop/grommet/cable point there was no evidence of penetration of the cable into the grommet, which in my opinion, gave me a better "feel" for the total mechanical system. I recommend the use of the short metal excess cable housings installed in the stow channel in all risers, be it type 8 or type 17. These housings will prevent release cable capture/binding after a severe riser twist due to a severe canopy spin. 1/4" OD X 0.035" wall Teflon tubing works great also. One tack with Nylon wax cord 1/4"-3/8" from the inserted end holds it in place. I'm not trying to put down type17 integrity risers, as I have used them myself. Ultra blue skies, Dave Brownell DB Technologies Mesa, AZ

The following is a complaint that I sent to ABC news in response to a misreported event. RE: South pole, skydive expedition news text. We the skydiving community and the parachute industry are soooo tired of hearing the explanation to almost every skydiving fatality that, "the parachute never or failed to open." Have you people ever taken the time to get the facts as to why there was no open parachute? Have you ever considered the fact that in 90+% of these reported cases there was no activation of either the main or reserve parachutes for whatever reasons? Get and report the FACTS guys; we're tired of this crap, and so is the parachute industry. David B. Brownell (DB Technologies) (Commercial pilot / Skydiver with 1160 jumps) Mesa, AZ

Pilot chute retention idea> Here is an old idea that I came up with a number of years ago, that you may want to check out. It may indeed be a place where Velcro can be used very successfully over the long haul. I have used it on hundreds of jumps with very good success.--------> Install a piece of 2" X 2" Velcro PILE on the INSIDE of the BOC pouch, on the bottom container flap, so that it's edge is flush with the top of the PC pouch/opening. As close as possible to the PC's apex, on the PC canopy material itself; sew on a piece of 1" X 2" Velcro HOOKS. I use a piece of parapack .250" wider than the Velcro in both directions, as a back up buffer/sewing platform. I sew the velcro hooks first to the slightly larger parapack, and then sew the parapack to the PC fabric close to the apex. Some will say that the PC hooks will pick up grass, etc. I say, BS (the apex is pulled in) I've never had a problem with this. (and this was with non collapsible PC's) Dave Brownell