pchapman

Ahem. Your request is reasonable but the other things you wrote can attract some attention. I believe the USPA (for their members) upped the minimum pack opening altitude from 2000' to 2500' a year or two back. (I'm personally flexible with these things but anyway.) And I hope the Swift is at least a Swift Plus; those are old but still decent canopies at moderate loading.

An arch makes stability so much easier to attain, and is ideal for the newbie. But it isn't necessary as one builds skills. Flat is ok, even dearched is OK if you are actively adjusting and compensating. Asymmetries can be compensated for. (But it'll be easier if you stay completely symmetrical -- if you can't throw the left leg back, then the right should probably stay even with it for now. ) It may take some time in the tunnel to get the hang of basic stability but that applies to plenty of regular newbies too. Your bicycle may not have training wheels, but you can still learn to ride...

Yeah, I guess you have mandatory AAD's there and at most Quebec DZ's. Do you get exceptions for belly mount rigs and stuff like that? But just jumping with weird main canopies in more modern gear does make things nicer in various ways. (And I'm keeping my Dactyls, PZ-81, PC's, etc!)

And yes, I would most certainly bear 'some' responsibility for that. So everything needs to have a 'boss'? I thought I was out of this silly back and forth but this irked me enough to jump back in. Just because Douggs is experienced he is supposed to control the bridge? Set up checkpoints, gear inspections? Under what authority? (I haven't jumped the potato bridge so I'm not actually sure of procedures) If I'm hiking a trail along a cliff edge, and someone I don't know walks off the edge nearby, how would I be responsible? Or am I suddenly responsible if I happen to be the most experienced hiker within 50m? And are you also boss of your airport? Didn't know you controlled the airspace and all ground surfaces. I thought anyone could fly in to an untowered public use airport like Zephyrhills and pick up passengers. And how would you be responsible if they then passed over the airport up high and dropped a jumper? You might not like it, or there might be an FAA procedures violation (I'm not sure about US rules on notification of jumps), or you might want to improve things in the future, but would you actually be responsible? Anyway, Douggs happened to get lucky in that he was looking the right way at the right time, noticed something bad about to happen to someone he had no relationship with, and stopped it. Yay! That's basically it. Then you go smearing 'responsibility' around... Yeah, nobody wants bad stuff to happen. But your attitude smacks of someone in charge of things who is used to having some responsibilty and is getting used to controlling things. And sure, your job involves a lot of that. You don't get to be as carefree as us plain skydivers. But that doesn't mean that everything needs to be controlled and regulated, especially when well established rules and procedures already take care of things at an acceptable cost. Or else we'd all have to hire a more experienced jump buddy to keep an eye on us every day we skydive or BASE...

I think the negative attitude towards some trackers or tracking dives is simply that on some DZ's, a tracking dive is often a mess of people semi-randomly thrown together with little structure or training or rules or checks of skills. Tracking dives can of course be done with more discipline, and somewhere people will be practicing them repeatedly with care. Still, I get the impression that doing tracking dives isn't something most people concentrate on as a real discipline -- it's more just something fun to do occasionally.

Fair enough. But you've been around. Haven't you been in a C-182, the newbie pilot opens the door, and you're almost crossing the DZ but a couple fields off to the side? "What's the hand signal for 90 left then 90 right??" Having a pilot who can spot makes it easier for skydivers to do their spotting, and doesn't waste DZ fuel on go arounds.

So, does that mean Skydive City is now enforcing British nanny state gear checks before boarding? Or would you like to be sued because some dumbass skydiver doesn't check his gear properly before exit, something happens, and the family sues because it is now understood that in skydiving, the DZ is responsible for ensuring compliance with gear check rules? Hasn't anyone ever climbed into one of the airplanes you control (or stepped out of one) while having forgotten something really basic yet important? Jeez TK let it go. Everyone in BASE knows gear checks should be done, even if there isn't a controlling organization to put it in a manual. And I think everyone is aware of some the freedom vs. standards issues that exist both in skydiving and BASE, and can never be solved to everyone's satisfaction.

As WV177RG stated at the beginning of his post, a number of posts in the thread concerned Garrett vs PWC engine reliability, and that's what he addressed. It's a topic that draws heated debate. So he was addressing a topic that came up in the thread and added to that (with a lot of very relevant experience), that was also relevant to the original thread topic, even if it wasn't addressing the single and related question that revived the thread some years later.

Short answer: Can't help you with airfoils. Long answer, my thoughts on the topic: Part of the issue is that the performance of the airfoil is just a part of the performance of the 3-D wing, which is just a part of the performance of the whole system. For a conventional aircraft, one might know a lot about airplane design in general and then want to tweak the airfoil for a certain purpose. But the interactions between the airfoil and overall system are less clear for parachutes. One can't just pick up a standard aerodynamics text. The paraglider guys have a bigger industry with traditionally more sophisticated aerodynamics -- using CAD/physics models that don't just draw the constructed parachute but calculate distortions in flight and then presumably overall performance. I always wondered to what degree one could customize something like the X-Plane simulator to model a parachute. I know it has been done, but don't know if the parameters and aerodynamic modelling are sufficient for testing small variations. One is basically flying a tailless aircraft with a lot of anhedral and a VERY low set center of gravity! (If one is mathy and wants to approach parachute performance from the basic equations, one could find an old J.S.Lingard paper on parachute design. One or two from the 1990s are around. 'Simulation and control of guided ram air parafoils', a U of Waterloo student paper, is in the same vein.) Someone with basic airplane aerodynamics experience one might look at an airfoil and say "that's probably aft loaded.. with a lot of trailing edge camber adding negative pitching moment" and have some idea what that implies for an airplane ... but have little clue what effect it will have in practice for the parachute. If I could magically play with different canopy designs, I'd probably start with a bunch of different trim angles (and thus fore and aft center of gravity) and see what values are acceptable. After that I'd start with airfoil changes, eg chordwise location of maximum thickness, maximum camber, reflex at the back, etc., as well as nose openings. If you want airfoil contours to work will in the 2-D airfoil simulation programs, I think you'd want to have them really smoothed out. We just don't have airfoils that match the planned dimensions to a millimetre or whatever like a sailplane. Skydiving airfoils with their distortions etc are kind of dirty, so who knows maybe one just wants to run a simulation with the maximum allowed turbulence or surface roughness. Not sure what they allow adding in. This is all just off the top of my head. While I know a little aerodynamics I've never built any canopies. Interesting stuff you're working on.

Now that needs the back story told! Even if it would brand you as some kinda pinko Commie prevert in some circles, for aiding and abetting Fidel in enjoying a winter's day...

I did not know that Wings had a Q&A section on their rigging manuals page, that has some additional mini manuals in addition to 'the manual'. http://skydivewings.com/rigging-and-bulletins/rigging-manuals/ So the cutaway cable length is actually addressed in a pdf there.

This is trivial but for the record. I didn't see anything about the amount of excess cutaway cable appropriate for the Wings rig in their manuals (or on dz.com) so I asked the factory. They said: (A replacement handle from them was cut to a generic long length and had to be trimmed to match the rig.)

I like a good skydiving story... Still that was quite the dick move to push things that far! Especially when it turns out you really weren't current enough to carry out your original plan correctly and had to put a ride on their reserve. And you still came out looking like a hero, a dumb hero, but a hero nonetheless for saving your ass. I thought the game was up when the guy gave you the finger, thinking it was then that they recognized that you knew more then you let on. I remember the name from rec.skydiving so what could I expect. Thanks for sharing...

I think John got picky because Rob wrote "mostly", probably just using it casually and in a bit of a cynical tone about skydivers. But then John would object that Rob looks like he's suggesting that the factor with the greatest weight was "lazy skydivers" changing their body position. John probably gets a bit pedantic... because I thought that kinda was his job.

I bet he means that it used to be 120 days and now is 180, so that for a year round skydiver, what he saves in repacks roughly pays for membership. And the FAA wouldn't have changed to 180 without USPA prodding. (Although the PIA was in there too -- I'll have to let someone else better clarify their respective roles.)

And here's a pic I saved from Mirage's web site way back in 2002 [inline "Mirage-G4-vs-G3-velcroless-toggles.jpg"] They were happy to introduce a new velcroless toggle style.

Those look exactly like Mirage risers!!.. but not their current style. Look just like a pic I took of risers in 2008, I think as an example of one innovative riser & toggle design. The up and down tabs are a feature I like on tabbed toggles -- rather than 'all tabs facing upwards'. Up and down do a good job in preventing a toggle from just being pushed down and out and causing a toggle 'fire'. That being said, I haven't personally jumped that particular design. They build them differently now, with 2 upward tabs. I'm not sure Mirage has the best corporate memory. How could they not have recognized them? (Eg, recently a rigging customer ordered a split d bag from them like they used to make, but they messed up the order in a way that shows they don't understand how they used to make them. But that's just one data point. )

While it all should be obvious, it's good you pointed it out about the maneuvering relative the ground. If he does have a light system that points straight up, he wants to maneuver straight above and stay there. Which might mean, for example tracking 25 kt into a 25 kt wind from 270 at 9000', changing to 15 kt from 300 at 3000', changing to 5 kt at 000 in the last thousand feet. You just wouldn't want some messy day with 50kt uppers, 25 kts at 1500', dying off somewhere in between to zero at the ground (or a shear layer with 10 kts with a 180 degree dog leg at the ground). At least a freefaller has a high wing loading so to speak so won't instantly drift fully with a wind change. So there's some nicely graduated tracking there, backsliding aggressively if overshooting, maybe some hard sideslide adjustment, and hopefully only a little gradual heading change. (I haven't the historical winds aloft forecast for that day, time, and place to see what he really had to deal with.)

A few months ago Vigil clarified the battery replacement requirements for the Vigil I, II, and 2+. It is 10 years + 3 months max from the Vigil manufacture date (not the battery manufacture date) Vigil Info-bulletin-Battery-replace-reminder-v2016.04.27 http://www.vigil.aero/wp-content/uploads/Info-bulletin-Battery-replace-reminder-v2016.04.27.pdf There's also a warning for Vigil II's, not in the manual, to leave it turned off for 12 hours after battery replacement. Background: -- basically me critiquing Vigil's vague and shifting instructions: I thought I'd mention it because there had been some discussions before about uncertain instructions. On dropzone, I had argued in 2015 that one could make a case for the Vigil 1 not needing it until the display required it, based on the wording in the current manual. Later Hackish talked to a company rep in Feb '16 and was told 10 years is a hard limit for Vigils. Degeneration emailed the company early in 2016 presumably and got the answer that it has to be done but the 10 years isn't an exact hard limit. Everyone was getting different answers. Even for the Vigil II, the manual was odd: It mentioned "10 years of use" in bold face, without clarifying what that meant. And we know that a unit might not be placed into service for months after the manufacture date.

Their new rule would suck for some people with vintage gear. For example, I know a guy with an Eastern European Talka rig with square main and Rogallo reserve from the early 1980s with uncoated cable. Or my buddy sometimes jumps a UT-15 round canopy & rig, and it uses uncoated cable. But I'd be OK if I jumped with Capewells or R-3's on a Paracommander rig? Would my friends be shit out of luck in the UK, or would it be easy to get a waiver? Plus of course there were the early rigs with 3 rings that used what looked like clothes line cable -- I'd be far more wary of that stuff 40 years later, even if it technically was allowed by the BPA. You aren't the BPA so don't speak for them but I gotta wonder about these things.

Interesting. I got a little mixed up when you said 'delaminated' as I interpreted that as meaning it was a coated cable, when I guess it wasn't. To be clear, correct me if I'm wrong: -- The jump happened with a rig that has a bare cable style cutaway cable (ie, must be a Strong Tandem unless there's some European rig I don't know of) -- The cable had a broken strand The bulletin said: -- The BPA subsequently banned non-coated cable for all rigs not just tandem The BPA didn't seem to say anything about the age or maintenance of the cable or describe the manufacturer's response or suggest any preventative measures or investigate the frequency of these incidents. (Or is that stuff hidden in one of their rigging meeting minutes, that are available on the web?) [Edit: I checked the BPA site; the minutes for the last 2 rigging meetings are not yet available. So there seems to be no public explanation of their action?] If there's scaremongering going on, it's the BPA: One nasty incident = Ban something! That being said of course we're interested in any failures that occur to a cutaway system.

Was wondering that. I wouldn't want to commit to a certain time and then find there's a strong low level shear. We skydivers don't normally have to maneuver relative to the ground in free fall ... One might get good practice having to add in some judicious use of forward or backslide to stay line up, despite inertia not allowing instant full drift. Anyone know how many practice dives he had been doing? Was he doing low pulls with two canopy BASE rigs or what? Admittedly I haven't checked out all the preparatory videos.

I see the kitesurfing kit uses glue (and alcohol swabs to clean the surface). And they claim it is good for paragliders too.

I lost one in 2012 on a chop .

You just don't give up do you? While some of us experienced people can forget some nuances of what it was like as a newbie, you are simply 100% wrong in ever recommending a sliding landing to someone who doesn't have their flare dialled in already -- which the OP doesn't. "All the pressure is on your tailbone and spine" if you drop down on your ass with any significant vertical speed, which happens if your flare isn't nearly perfect when your feet aren't under you to protect your spine. Now a well done sliding landing can have some twist put in, resembling a baseball slide, allowing more of a hit on the thigh (and twisting of the pelvis) rather than a direct impact on ass which pile drivers the spine. But again that's a more advanced thing to do once one has a finely tuned flare.