pchapman

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Posts posted by pchapman

  2. Finally an all purpose scary-story thread! Great for wasting time, writing or reading.

    Regarding the kid who grabbed the wrong rig:
    Quote

    I chew his ass , not for taking my gear, but for not checking it over before putting it on.



    Even though one may think "the kids today...", it reminds me of a story from the 80s, from the rigger I apprenticed with:

    This rigger does some work on a customer's gear, repacks the reserve, and leaves the gear at the DZ for pickup. The customer later comes by, gets the rig, and goes jumping. Maybe a week or two later the customer sees the rigger again and says, "I want to pay for the work, but I didn't see a bill when I got the rig back. How much do I owe you?"

    The rigger replies, "I left the bill under the reserve cover flap."

  3. I think more emphasis should be on the issue of the burble, than the simple linear distance between main and reserve bridles.

    I like the idea of going a little shoulder low when deploying a reserve past a PC in tow, to angle the reserve PC launch outwards. The idea is not so much to get the reserve PC pushing out into the airflow to get away from the main bridle. I don't think the PC will get very far to the side before it gets swept away by the strong relative wind from below, especially if the firing angle is still close to vertical.

    Instead, the idea is to get a consistent launch, placing the PC into cleaner air, instead of accepting the randomness that sometimes happens when a PC is deployed in a burble.

    (Of course things one theorizes at the computer aren't always practical when altitude is disappearing fast. But I could image going a little left shoulder low when my left hand came in to the reserve handle. After a good launch, I'd theoretically try to get my shoulders level again for a more symmetrical reserve inflation.)

    While many, many times reserves have fired past PC's or other junk in tow, there are enough cases where they haven't. One hears of one bridle 'wrapping around' another, something that might have started with a PC whipping around while making its way up through the turbulent, churning air of the burble.

    I'm not sure to what degree spring loaded pilot chute hesitations (due to the burble) have lessened using modern high strength pilot chute springs. I've seen some nasty AFF videos with a PC bouncing all over the student (although its a big burble with 3 people).

    To appeal to higher authority, I'll throw in a quote from the Great Bearded One (billbooth):
    Quote


    Unless you have a lot of experience with internal, spring loaded pilot chutes (and therefore know how to "break the burble" at pull time to get them to deploy without hesitation), don't assume that pulling a reserve ripcord while falling "stable" at 1,000 feet at terminal velocity, is high enough. A pilot chute hesitation can easily eat up 500 feet or more. (We are all so spoiled by hand deployed pilot chutes.)


    It makes me think!

  4. Quote


    A friend had one 'blow' on opening too...



    What stuck in my mind from the manufacturer's video on the Z-Po was how carefully it was packed. While I don't recall the specifics, it may have shown the nose being carefully rolled, the slider carefully positioned, and the tail carefully and tightly rolled.

    All that seemed to be a big hint about how the thing might be expected to open!

    (Not unexpected really, for a Sabre-like canopy from the early Sabre era.)

  5. What hasn't been discussed much in this thread has been the degree to which the downsizing 'guidelines' were intended to be MANDATORY, ADVISORY, or something in between.

    I'd feel really sad at the loss of opportunities to newer jumpers if any downsizing chart became MANDATORY.

    If it were ADVISORY only nobody could be stopped from doing anything, but the chart would still be a useful teaching & learning tool if it is well thought out and supported by the industry.

    Some instructors (like myself) who started some years ago, never did go through a proper downsizing progression, making it more difficult to make specific recommendations for newer jumpers. Some industry guidelines would be handy to 'back up' anything one tells a newer skydiver. A recommendation to a newer jumper would be less likely to be seen as a personal attack.

    If rules were mandatory, I'd want to see exceptions allowed, perhaps using sign-offs by senior instructors, perhaps only for limited periods of time in order to 'try out' a canopy. Abuse of the system would be a potential problem.

    Jumping a canopy 'a few times' is different than jumping it 'all the time'. A jumper may be more conservative and not complacent with a canopy they are trying out for a short while, which helps keep the risk from rising too much. Even if you argue that the risk per jump is high, the total added risk may be relatively low because of the limited number of exposures to that risk.

    My own experiences are probably not much different than that of others who started in the sport more than 10 years ago: For example, at 200 jumps, with only 11 jumps loaded over 1:1, I got the chance to borrow and jump a Jonathon 92 loaded at 1.8, on a hot, no wind day.

    It was great fun to do a few jumps, although my run-outs weren't the prettiest. An ideal situation? No. Fun, exciting, and a good learning experience? Yes.

    Had downloading rules been in effect, I could never have made such jumps. I'd feel guilty, sad, and hypocritical if I automatically denied others from having that kind of experience!

    These are personal feelings only, biased by my own experience. They may not necessarily be appropriate these days, but I hope someone else out there has similar thoughts.

  6. Sometimes any additional qualifications or achievements one might have in skydiving can be spun in a much more positive way than just being a weirdo skydiver.

    For example, instructor ratings, a rigger rating, or success at competition.

    A specific achievement sounds better than general skills, as the acheivement is better condensed into a few words on a resume.
    (E.g., it's hard to explain how ones good qualities resulted in great sport skills given X number of jumps. It's easier to say that one competed in the Open category at the National Championships, whether or not that really meant much.)

  8. The one previous thread I know of on the Evolution and Super Evolution is:
    http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1299075;search_string=%26quot%3Bsuper%20evolution%26quot%3B;#1299075

    I'll repeat and expand on what I wrote in that thread. I only have about 20 jumps on the Super Evolution 140.

    It's a fun canopy to fly, but outclassed by more modern canopies. Because of its line configuration it can do things other skydiving canopies can't do. Because it is so unusual, it is not useful as part of a newer jumper's downsizing progression. I bought one cheap as a spare canopy, just because it is fun and different. The standard caveat about such a canopy is that it no longer manufactured or supported by the manufacturer.

    SPECS
    -- Max weight recommended by Paraflite is 180 lbs for the 140 size.
    -- For the "140", Paraflite's specs call it 154 ft sq. when the slightly drooped outer cells are included. (The drooped cells replace stabilizers)
    -- The canopy does pack up very large compared to others of its quoted size -- so be careful of container sizes. (E.g., a later quote from Paragear stated the Super Evolution 140 as being 483 cu. in., while a Sabre 170 is quoted at only 451. Paraflite itself says 435, but the larger number is much more believable.)

    CONSTRUCTION
    -- The Super Evolution is an odd canopy. The lines cascade from side to side, attaching to almost ever rib for the 21 to 23 chambers, depending on size (vs. 18 for a "9 cell" canopy). There are A, B, and C sets of lines, each going to their own riser. (Actually, the front riser splits about half way up, in a "Y" configuration, to create the "third riser") Although there are no D lines, there are still plenty of lines. When pro-packing it is a messy job sorting the lines down at the canopy, as one is dealing with groups of 10 or 11 lines on each side at the canopy, instead of groups of 5 for a normal 9-cell. It's not the sort of canopy to give to a novice to pro-pack.
    -- If someone had to change a worn-out 3-riser set up to a regular 2-riser system, I'd bet that it would be acceptable. The canopy should fly fine with the A and B lines all squeezed on the same set of front risers of a normal 2-riser system. The geometry isn't going to be messed up that much, since normally in flight the A and B links are only a few inches apart horizontally.
    -- The 3 riser system is accompanied by a 6 grommet slider. It is non-collapsible, and in-flight stops above the links, restrained by front to back lines between the suspension lines. These 'silencer' lines are designed to stop the slider from flapping. This looks weird when packing, and remind me of CRW cross-connectors.
    -- The risers that come with the canopy are not 'reinforced risers'.
    -- The Spectra lines are very soft compared to those used by other companies, and so are a little easier to snag.
    -- Only the top skin is zero-p. (The non-Super version had no zero-p.)

    FLIGHT
    -- Openings seemed a little squirrelly on the Super Evolution 140 I flew, often diving into 180 or even 360 degree turns. The person I bought it from was a little spooked by the openings but it never bothered me. The turns were at the end of the opening sequence and never gave me line twists.
    -- The canopy has a tight recovery arc, typical of fast canopies of the day. Excellent for low, toggle whipping hook turns before landing, which these days surprises spectators. (Such turns are considered dangerous.)
    -- Unlike a regular canopy, where pulling the front riser pulls down both the A and B lines, on the Super Evolution, only the A lines are pulled down. Yanking a front riser down quickly can easily cause the nose of the canopy to fold under. I completely avoid front risering the canopy at low altitude, whether doing it smoothly or not.
    (The instructions say that the risers are designed to limit the amount that the front riser can be pulled down, and that pulling both front and middle risers down may collapse the leading edge. I find it odd that there's no warning about just pulling front risers down.)
    -- At altitude, yanking down a front riser to collapse the nose on one side can be fun. The fast spiral dive that results can be prevented by opposite brake if one is quick. Letting go of the front riser will allow the nose to return to normal.
    -- Very fast turns can be accomplished by hauling down a middle riser, which quickly destroys the lifting capability of that side of the canopy. Pulling both middle risers down produces a fast descent with the canopy still mostly inflated, but slightly 'accordioned' from front to back. Again, it's something fun to try up high. This maneuver is a "B-line stall", in paragliding terminology.
    -- My impression is that it doesn't have as good a flare and landing as a Sabre 135. Still, it was no problem with my weight (150 lbs + gear= approx 170 lbs).

  9. I just read in a European paragliding magazine (Fly & Glide) about a replica of a Barish Sailwing being flown.

    The Sailwing gets mentioned in histories of the development of parachute technology as the first wing style gliding canopy flown, although it was actually flown as a paraglider and not as a parachute deployed from an aircraft. It was a mostly a single surface design, unlike a two surface ram air wing. The year was 1965 or 1967 according to different sources I've seen.

    The replica was built in France by Francis Heilmann, who has a long tradition of sewing spectacular flying costumes for the annual paragliding festival at St. Hilaire, France. (He has aslo built some skydiving wing suits.) For the Sailwing, no plans or detailed construction information were available, even though Heilmann was in contact with David Barish. So it is a replica based on photos. It does use modern paragliding fabric.

    Barish went to the St. Hilaire Coupe Icare festival in September 2005 to see the canopy fly. At least the way the replica was built, it flew acceptably although reportedly somewhat unstable in turbulence. It managed a 3:1 glide ratio.

  10. Quote


    (c) If installed, the automatic activation device must be maintained in accordance with manufacturer instructions for that automatic activation device.



    While that is the well known bit of regulation that applies, anyone trying to weasel out would use this semantic argument:

    If a jumper is wearing an expired Cypres, he would say, "This is not an AAD. It was until it expired. Now it is a bunch of scrap, which just happens to have a part of itself wrapped around my reserve loop. Actually I consider the unit to be an electronic game -- I use it to play 'follow the flashing red light' on it's one button." :)

  11. While I've been warned an occasional time, I was grounded only once, for one day of the weekend.
    It was for exercising poor judgment in being on a load that took off a couple minutes after sunset.

    While we could legally jump until 1/2 hour after sunset (Transport Canada regs), the DZ has a rule of exiting the aircraft no later than sunset. A few minutes leeway is tolerated. The rule leaves a little margin for safety and lets the pilots land in time on the unlit grass runway. (They are also legally limited to 1/2 hour after sunset.)

    The sunset C-182 load just wasn't getting assembled quickly, so while I was ready to go, others were "almost finished packing" and so on. In the end I just wanted to get that sunset jump I had been anticipating!

    When we finally boarded, I felt the situation was safe enough (eg, the skies were clear so it was relatively bright), and we wouldn't break the law. I kept the process going because nobody else said "No", and I figured the DZO wouldn't find out. The pilot was willing to go along with it, as were the other jumpers.

    But I got punished largely because I was the senior jumper on the load and was a senior instructor at the DZ too. I had wanted to forget all that, and for that load, just be a jump-hungry fun jumper, willing to push the limits a little. The DZO argued that I couldn't ignore all my experience and had to show some leadership. It was an issue of roles and responsibilities. (The pilot got grounded too.)

    Fair enough, I pushed significantly past a well known DZ limit, got caught, and did the time for it.

    Did it serve its purpose? Yes. The DZO clearly showed how far is too far at his DZ.

  12. My limited experience suggests that there already is a decent paragliding site out there, so it may not be worth trying to split the market so to speak.

    I only check PG sites very occasionally, as I haven't flow my PG much in recent years. Anyone with more experience might have better opinions.

    So what's out there already, that are in the english language?

    The best I know of is PARAGLIDING FORUM (www.pgforum.com)
    While it isn't as sophisticated as dropzone.com, it uses reasonable software and seems to have a moderate following. I'm not sure of its origins, but the moderators and users seem to be spread out a lot -- not just all USA or all Europe.

    Then there's also Kinsley Wong's Big Air sports (http://www.web-partners.com/paragliding/)
    It has been around a long time, with what seems to be a decent US following, but the forum format is very simple, crude, and not easy to follow.

  13. Quote

    5 ways??? How do you get 5 People in a 182? You guys must be TINY



    It depends on the 182. Later 182s, with the wider body and rear window are roomier. Modifications such as wing tip extensions can increase the gross weight enough to take 5 people averaging average weight or slightly less with a low fuel load.

    A 182 with 5 jumpers can be packed. If one knows how to fit in, however, I find it often more comfortable than sitting crammed chest-to-container along a hard centerline bench in a King Air, or tilting sideways, shoulders jammed, in Twin Otter side benches. Climb time is naturally longer in the 182.

  14. At an accuracy meet I was climbing into a 182 along with a jumper from the USAF academy, who had never jumped a piston Cessna. Naturally he needed some help in figuring out the seating arrangement.

    Anyone with piston Cessna experience knows that the strut gets a lot use, with people holding it, leaning on it, or hanging right off it.

    The young jumper asked, a little wide eyed, whether he could touch the strut when climbing out!

  15. Quote

    Or if you were "on" your back but decided to start kicking out, wouldn't you be alternating from belly to back every half twist? Or is there some physical phenomenon that causes the jumper/harness to always orient back to earth during a hard linetwist spiral?



    Two ideas come up:

    1) If one is alternating on-belly and on-back while twisting up or untwisting, one may both remember and talk about the on-back part more, because that's the more disturbing situation to be in. "No s___, there I was, on my back, spinning...."
    It's sort of like remembering and complaining about all the red traffic lights one gets, while forgetting that one also got plenty of green lights.

    2) There may be an aerodynamic tendency to stay on one's back: When suspended from a canopy, a jumper's typical position is effectively massively dearched, so in a high speed spiral, the jumper tends to be stable when in a back-to-the-wind position!

    The stability wouldn't be as strong as in 120 mph freefall, but I'm guessing it could still be a factor with a small canopy that spins up after opening, even with brakes set.

    Hmm, this then suggests the idea that using body positions for a freefall barrel roll, might help in getting the untwisting started. Wonder if it would work?

    The video of the VX jumper shows him fighting quite a while to get the untwisting started. Very roughly, I timed 6 seconds to spin up into 4 line twists, 13 seconds of struggling to start to untwist, and only 5 1/2 seconds to undo all 4 line twists, once he got the untwisting started.

  16. Quote

    Were round parachutes used as mains on tandems ?? Or was the tandem invented with ram-air ??



    People played around with the idea quite early: A photo in a French parachuting book shows a tandem done under a large round canopy at Guyancourt, France, in 1937.

    (In "Le Parachute" by Borge and Viasnoff, 1977)

  17. Round canopy technology may not be evolving in skydiving, but does get attention in other fields. Pilot emergency rigs and the military have already been mentioned. The military of course uses aerodynamic decelerators for many things other than dropping people. The military & their suppliers get pretty detailed with their designs -- computational fluid dynamics of unsteady flows, etc.

    One additional area of continued round canopy design is in paragliding (& hang gliding), as most paragliding emergency parachutes are rounds.

    Things that have been tried have been slotted double cap designs, multiple cell designs, steerable single riser systems, pulled down apex annular designs, cold & hot rocket deployment, integrated pilot chute & bag, single-use shock absorbers, etc. I won't try to explain all that, and I don't have the terminology right in all cases. Some items relate to canopy design, others to the overall parachute system. Some of the items are common, others never became popular. It's not a hotbed of activity, for many designs are pretty much standardized now, but there has been evolution in the last 15 years.

  18. Quote

    are the drouge release handles on sigma tandem called primary and secondary? which is which?



    Finally after some years there's a true Sigma manual online at RWS. (Not just a Vector Tandem manual plus some additional material describing the Sigma equipment, as it was before.)

    The new manual labels the blue left side drogue release as Primary, and the orange right side release as Secondary. [Section 2 Chapter 1] The section on normal procedures is kept short and only mentions pulling the blue handle.

    That being said, I figure drop zones can choose their own preferred pull procedures depending on the level of student involvement in the process.

  19. Quote

    At my dz we show them Bill Booth's tandem video, then they fill out the paper work, including a quiz, and register, after which we brief them on equipment and exits.



    To expand on this (as I instruct at the same DZ), the students are actually shown 2 videos, one on the legal & waiver aspects, one on tandem jumping procedures in general. Together, that's 40 minutes.

    Tandem exit procedures for a C-182 take a little more time to demonstrate and practice in the mockup. That's in comparison to relative ease of "getting up and walking out the door" for a large turbine a/c.

    Tandems take more time at this DZ as tandem clients are treated more as students: they learn to check an altimeter & pull for themselves (although a pull-time altimeter check is prompted with taps to the left arm). Depending on the instructor, they may learn to wave off, or how to cooperate with the instructor on turns in freefall. One can debate it forever: there's stuff the slung meat doesn't NEED to be told, on the other hand, it is nice to go a little further and involve the client in the skydive.

    One problem is that the extra time taken per student is difficult to turn into a competitive advantage. I'm not sure that this aspect is "sold" sufficiently on the web site or in phone conversations with prospective students.

  20. Quote

    Ahh.. the lost art of spotting....CSPA rules sez,a wind drift is to be thrown before 1st. load of the day,



    Technically it does say "wind drift indicator or rate one turn". (Canadian PIM 1, Sec. 3.3. No change for many years.)

    So drop zones have an alternative to a WDI.
    But when I go to a Canadian DZ flying a Twin Otter or King Air, I don't seem to recall seeing either... :)

    At the DZ I jump most at, we still use WDI's. A bit of a bother but they are very good at showing the winds!

  21. Quote

    It seems nearly impossible to have it occur unless it was put on your back that way. I realize you performed a gear check, but it seems to be the only way. I've been proven wrong before so it happening afterwards isn't ruled out. Does there happen to be video of the jump?



    Nope no video.

    As it is hard to come up with ways for the rings to flip through during freefall or opening (or even, say, while hooking up in the aircraft), it comes back to the question whether I got in the airplane with the flip through. I can't avoid that question but I just can't see myself having missed that during inspection & gear up.

    I still need to talk to the other tandem instructor on the C-182 and to find the records of who packed the rig. And I'll play around with tandem 3-rings next time I'm at the DZ.

  22. This weekend as an instructor on a tandem jump at near maximum allowed weight, I discovered one riser's 3-ring to be partially 'flipped through' after opening, where the middle ring had slid back part way through the large ring, and the middle ring was angled well forwards rather than vertically, as was the bottom of the riser itself. This configuration greatly reduces the lever effect of the 3-ring system. The yellow cable was jammed up against the AMP fitting and riser, with a slight bend in the cable, although not actually being sucked through the grommet.

    Under canopy, the top of the small ring can normally be moved with only a couple pounds of pressure (showing how little force there is on the white loop), but this time I found I couldn't budge the small ring while squeezing the riser and small ring with one hand.

    I landed OK with my first jump student. The middle ring shows distinct indentations where it was 'hammered' by the large and small rings during opening. The indentations are much deeper and sharper edged than the minor flat spots that occur on the middle ring over the course of many jumps. I think the middle ring is slightly distorted (bent, not ovalled), but it's hard to tell by eye. The cutaway cable is nicked and kinked slightly.

    A couple questions:

    a) Anyone know of similar incidents?
    I haven't found anything quite like it in the dropzone.com archives, although it has been mentioned that jumping with a flip through could or has broken risers due to the non-normal forces on the system.

    b) What to do with the riser? Given that the white loop for the 3-ring APPEARS undamaged, does that mean that it IS undamaged or not? One theory is that if no torn strands are seen, and no elongation is seen compared to another loop, then there is no loss of strength. (I don't know anything about stress, strain, yield strengths, etc. in woven fabric material.)

    At the DZ, we've grounded the rig for the moment, and we'll talk with RWS after the weekend.

    ========== Other details:

    It was a tandem jump on an RWS Sigma rig with a Sigma 395 canopy. The student weighed 280 lbs (at least as reported by the student), with an instructor weight of 150 lb. With the rig weighing about 50 lbs, that's a total of 480+ lbs, getting close to the Sigma certification weight of 500 lbs.

    (No I didn't check what the canopy weight limits would be after density altitude corrections are taken into effect -- PD-designed canopies tend to have that kind of thing listed, although at the moment I don't have info on paper about whether that is applied to Sigma canopy for recommended or certificated weights. We were close to the limits in any case.)

    Droguefall was normal but fast as expected. (125mph SAS average on the ProTrack). The opening was hard but not unusually so. Openings on the Sigmas are noticeably harder as the passenger weights increase. In particular, there tends to be a harder jolt and shake at the end of the opening, which is what occurred. The opening was on-heading as usual.

    After popping toggles, checking airspace, getting my passenger comfortable, etc., I checked the 3-rings. To check them after opening was taught when taking the tandem instructor course 3 years ago, although it is easy to get casual about it because one expects the 3-rings to be fine. As I didn't check right away after opening, we were getting down a bit in altitude by the time I thought through the situation, although still above recommended tandem emergency procedure altitude.

    It seemed most likely that if the riser and loop withstood the opening, it would be fine under canopy. So I chose to land the canopy. Still, there was the disquieting notion that there might be a not insignificant chance that the loop could let go from damage during opening, which can lead to not being alive. No spirals for the student! (I coached the student through the steering during some of the flight while I squeezed the top of the small ring towards the riser with one hand -- that seemed worth trying even though the forces on the top of the small ring were probably so high that one couldn't keep the 3-ring from releasing.)

    How did the flip through happen? Flip throughs on tandem rigs do occur on the ground from time to time and have to be fixed during packing. I can't imagine that there had been a flip through that remained undetected by the packer or the instructor (me). Is there anything packing-related that might make a flip through more likely? Say, if a riser were a little loose over the shoulder (rather than snugly pulled down towards the main container & putting slight tension on the 3-ring assembly)?

    Could the flip through have happened in the somewhat jerky opening? Perhaps one riser rotated away from the pack, yet unloaded for a moment, allowing the middle ring to slip 'back' through the harness ring? Would the unloading happen as the main bag lifted and lines stretched, with some whipping back and forth of the risers, or later during some part of an asymmetrical canopy opening? I'm not quite sure.

  23. After deciding to post an ad, it would be useful to have a confirmation page that shows the final ad, before the posting occurs.

    This can be done with posting to the Forums and is a very helpful last check to see that all is alright, including the visual formatting.

    Lack of the feature really messed me up -- I saw an error after seeing what I figured was the preview of my ad, used the back button on the browser, fixed the ad, and posted. But as I hadn't seen a preview but the actual ad, then I had 2 nearly identical ads posted.

    When I tried to erase the first incorrect ad, it was impossible: It will stay posted, and show as "SOLD" for 3 days.

    I got myself into a bit of a mess!

  24. If one does loose a freebag, be careful when ordering:

    A friend ordered a freebag from a major manufacturer, and got just that -- the freebag, without the reserve pilot chute.

    The order taker must have been thinking in rigging terms, not in real life skydiving terms, and didn't help the customer get what they really wanted!

    (The freebag bridle normally is attached to the PC with a lark's head knot.)