pchapman

In that case, those may be some of the world's first booties?! (Even if there's so much other fabric out there to try to outfly...)

So where was the deployment handle? (Is that it visible in the BOC location? Is it a pullout?) I'm not sure from the photo, but it looks like the suit had straps under the feet to tension the legs, but no toe cap coverage, so it doesn't quite qualify to be a very early version of booties.

And similarly: -- Different main lift web length adjustment method, using different hardware. (Much easier to adjust.) Minor: -- No Skyhook to Skyhook to Skyhook II or whatever the latest version is called (hologram, anodizing, clear plastic cover with hole for safety tie, more labelling, etc) Non-physical changes: -- New manual (For the Sigma rig and canopy; not just a Tandem Vector II manual that showed some archaic methods plus some incomplete add-ons for the Sigma.) -- New reserve packing method (Propack not a special flatpack.)

While some Canadian skydivers finish their season early, start late, and travel to Florida or Arizona sometime in between, there are others who jump when it snows: =================================== You know you're a Canadian skydiver when... ... the first couple hours of jumpable weather are spent clearing the runway of snow that drifted in since the runway was cleared yesterday ...you struggle like a first jump student to gather your canopy after landing, even when you're on a tiny crossbraced one, because of standing on a slick crust of snow in high winds ... you're bit tired after partying for 4 hours since sunset, look at your watch, and realize it is only 9 pm. ... a dragging pilot chute after landing collects snow that ends up compacted to a snowball inside ... you check out your swoop distance by looking back at the marks through the snow ... everyone agrees the temperature is "nice" at altitude when it doesn't drop below -10 C ... you jump in mukluks (Peter tandem.jpg) ...you start doing superman belly landings in the snow (Marc swoop.jpg) ... you build snow walls to swoop into (Paul swoop.jpg) ... you look like a bank robber with a full face mask (Craig mask.jpg) =================================== Of course you could be in parts of the USA or a bunch of other countries and still do many of these things. Photos are from the jumpers at Skydive Toronto!

As a Canadian that could even get me more riled up than if I were American.

As a side note -- not to derail this thread -- I just have to add the caveat that the above doesn't apply in the US for US built TSO'd gear, even if owned & jumped by a foreigner. There are some messy details and interpretation issues too. FMI, USPA has an article on it, as does dz.com (by Tom Buchanan). The rule is a bit odd but that's the way it is. (So a Canadian in the US with a Vector III & PD reserve must follow a 120 day cycle, while someone from Lower Crapistan with a harness hand woven from yak's hair can jump it with a longer repack cycle if that's legal in his country.)

Yes, true. But your original point still stands: I'll agree that there isn't much point in pulling the reserve handle if one is under one's reserve already. Unless one is trying to prove to those on the ground that you, as a newer jumper, are able to properly follow through on reserve procedures! That's not an invalid reason. Last weekend I had my first actual parachute malfunction, on a Skyhook equipped Sigma tandem. A tension knot sent me into an increasing spiral that I couldn't fix or counteract. I got my hands on both handles, but wanted to wait (theoretically) with the reserve pull until I was sure I (a) had a good cutaway and (b) could determine whether I liked the freefall situation (stability OK? fixable quickly or just get the reserve out?). (Part (b) only applied because I knew I had decent altitude available.) But it was just theoretical as nothing in the RSL & Skyhook system came accidentally disconnected. I wouldn't want to chop without already having the reserve handle in my other hand. As soon as the cutaway cable slid out, lots of stuff was clearly moving rapidly behind my head, so I waited it out, and in seemingly a moment the reserve was open. The reserve handle stayed where it was, happily in place in its velcro. Nobody on the ground worried about that decision. But since it was jump #1998 for me, nobody was worrying about me being a newbie either...

ISSUE 1: LAG Nice, I glossed over the yellow dot issue and missed that. That apparent use of the raw speed data gets rid of the problem (that I had erroneously thought might exist) with using the yellow line averaged data that lags by 2-3 seconds. I wonder if the averaged speed is really needed at all by the Vigil. Maybe it is just for making a pretty graph on the ground. In which case, they could better have done the averaging by using raw data data from the seconds before and after the point being calculated, instead of just the seconds before it, to avoid that 2 or 3 seconds of lag. That's something one can do after the jump, but not in real time during the jump. ISSUE 2: LARGE SPEED CHANGES = ARTIFACTS? Since it turns out to be a wingsuit flight (by a big guy), with slow flight and then wings-collapsed flight at the end, that explains some of the large variation in the speeds shown at the end. But if the Vigil is using the raw data after all (red trace not the yellow), then it is still seeing 50 to 220 mph, which seems more range than I'd expect. Thus the issue of artifacts from body position (or wingsuit wings) doesn't entirely go away. If one thinks the extremes of 50 and 220 are too much, then from the graph it seems like one might be able to fool an AAD about speed for say 2 or 3 seconds, just like one can fool a Protrack or similar. It is good that (at least in this case) any extremes in speed are accentuated rather than diminished. BUT all that is a weak conclusion based on just one jump, with a wingsuit which likely will have more than the usual effect on pressures over one's back. (I'm not picking on Vigils, all this is just of interest in the general field of measuring skydivers' speeds and altitudes.) Thanks for sharing the graph, Blindbrick.

Interesting plot! While I've seen Protrack and Neptune readouts, Vigil readouts are rarer. What were you doing on the dive? Looked like you were doing about 130 mph once up to terminal. (Without knowing how the device is calibrated for altitude and temperature.) Then there's a dip to 95 and jump to 160, even in the smoothed data. Unless you were doing something interesting, I guess those are artifacts of body postion? My Protrack, on the outside of my helmet, usually shows huge unrealistic spikes in speed when tracking away from an RW jump. Interesting to see, if my guess is right, that something similar is happening with an AAD buried in one's rig! Also, the averaging / smoothing that is applied does create a lag of 2 to 2.5 seconds, very roughly, in the speed. I assume (but don't know) that the averaged speed is the same one the Vigil is using for its firing calculations. Note that the averaging does not fix the very wide spikes of what I'm guessing are artifacts from changed body position. The raw speed data suggests you went below Vigil firing speed (the red horizontal line I believe) at about 36 seconds. That raw speed data was very smooth in the seconds before and after. But the smoothed data that the Vigil is using, doesn't show you slowed down enough until about 39 seconds. At around 80 mph 3 seconds is worth 350 feet in altitude. Which doesn't matter up above 2000 ft where you had your canopy open, but it can matter below 1000 ft near firing altitude. Hmm, I wonder how that sort of lag is taken into account by the AAD. Although the raw speed reading bounces around a lot (based on rate of change of pressure) at least the altitude reading (based on pressure) doesn't fluctuate as much. Both altitude and speed are of course needed for an AAD. (And I'm ignoring for the moment whatever Vigil says about it's own method of calculating time remaining to firing altitude.) Perhaps altitude is fairly reliably measured, using pretty much raw pressure data (or with minor filtering), but it seems like its derivative, speed, needs more smoothing and even in smoothed form doesn't as closely resemble reality as desired. The lag could affect both the issue of low pulls (jumper slowed down before the firing altitude but device doesn't know that yet), and the issue of firing after a low cutaway but no reserve pull (jumper accelerated to firing speed but the device won't know that for a couple more seconds). At steadier freefall speeds, however, the lag won't be an issue. The body position artifact issue could however come into play. I had often thought about the limitations of devices like altitude alerts ("don't trust all the numbers"), but not so much how similar issue affect lifesaving AAD's ("trust them"?). The assumption had been that a position within the parachute container would create better raw data than one on the back of the hand or outside a helmet, subject to much more varying wind blasts at different angles. This is all good food for thought. I don't have the answers yet, and the AAD companies aren't telling us their secrets. I don't think I'm ready to design one yet...

First bid is at 3 if you allow paragliders -- The Renegades paragliding acro team in Europe. (Now with different sponsorship and a different name, which I don't recall.) e.g., Planed at http://members.aon.at/renegades/dd_3er_st._hillaire_dd.jpg and death strap fun at http://www.stubaicup.parafly.at/images/renegates_2.jpg

The accident is getting talked about on the International Aerobatic Club email list. There's some good review going on about spin recovery techniques, aerobatic practice altitudes, and setting a bailout altitude. There's a fair bit of criticism of the pilot in question, for messing up the spin recovery. He had sufficient height but not a lot to spare and he left the power on initially after falling out of his maneuver, thinking he could recover anyway given that aircraft's characteristics. Whatever the merits of this, it was wrong in that he couldn't get it recovered in time. A 1500 foot hard deck isn't much and it is still impressive that he got out in time from that level, so at least he gets points for a quick bailout.

That wording does sort of make it sound like you are putting blame on the jumper... But yes it does seem to me that a jumper's position under a draggier baglock can depend partially on the jumper's actions. A jumper might initially be pulled shoulders-high under a baglock, or into a stand. Whatever the percentage chances, if it is only to a shoulders-high position, if the jumper then rotates their legs forwards (whether expecting opening shock or to get a better look or whatever) they may end up more in a sit or stand position, presenting less drag area and accelerating to a higher speed. If one is in a standing type position, it may be prudent not to admire the view for too long even if altitude is sufficient. Airtwardo mentioned being able to slow down for reserve opening because he didn't have an RSL. And on DZ.com I've heard of a baglock clearing itself, in a messy manner, after the jumper was stood up for some time. A very hard opening resulted.

Billvon compared the swoopers who, if they hit, may be more likely just to give the earth a glancing blow, to the "I'll be very careful" group, who are more likely to panic toggle whip into the ground. No objections! But I'll note, however, that it looks like the definitions being used are that those are EXPERIENCED swoopers versus INEXPERIENCED careful-approach people. The swoopers wouldn't as safely get to that glancing-blow level if they just started whipping out 270s off student status. Obviously some structured progression can help. In the same vein, someone can be an experienced and safe non-swooper, if they have taken the time to do some of those canopy control exercises, so that they aren't at great risk of the low emergency toggle whip. Either way, rapid downsizing makes it more difficult to progress. The swoopers shouldn't try to jump to the hard core swoop level instantly, and the non-swoopers shouldn't be satisfied only with very conservative approaches. Some people need to be held back a bit, others need to be given a push! PS - Dan Preston's idea about eyes-closed turn practice up high (and in clear air) is an intriguing one. Maybe good for getting a feel of the timing and non-visual cues.

I decided to vote "Other". The "expected outcome" might be defined by the mean outcome or most likely outcome, depending on how one chooses to define it. That's clearly a harsher definition than most people assume, otherwise I couldn't believe that 31% of current voters really expect that the jumper is likely to die from his choice! If this Cobalt 105 scenario applies to a certain Chris-Ottawa fellow [with this thread being based on other recent ones involving him], I figure the expected outcome is no injury beyond a twisted ankle some day. Part of the issue is whether someone plans to swoop hard. Since so many want to do so early in their careers, our thoughts about downsizing these days are often coloured by that assumption, which is often a true one, but is also a worst case scenario of sorts. If Chris does decide to start learning 270s on his own during the next couple hundred jumps, maybe I'd change my vote. Last weekend Chris dropped by the DZ I'm at. His landings were OK standups, although with clearly visible minor issues no worse than any other jumper with under 200 jumps. Given that he isn't planning on doing 270 degree swoop approaches, and isn't mixing it up with an Otter load of other jumpers, there isn't a huge danger there. He did dig the bottom end of his flare while focusing on landing by the tuffet on a load where we were having an informal bet on doing accuracy. [

I noticed that one BBC report on strange laws has a note that the report has been amended, to remove some items in the original report which they could not subsequently verify.

When newbies are doing their first freefall, it is about making them more comfortable for a particularly stressful jump -- knowing that they aren't goint to be "too low" after 5.01 seconds helps them focus on their task. (Even if they are supposed to pull whether stable or not.) What you are talking is important but comes into play later on -- getting students mentally comfortable with lower altitudes, once they already can easily physically exit stable and pull. More of an issue for AFF students obviously. And NWFlyer - thanks for looking through the SIM for the details of the wording. I had only skimmed it.

Interesting. So far it looks like the US Clear & Pull may or may not be interpreted as a 5 sec delay. Different DZ's do different things. As for altitude, I do like having extra for 5 sec delays, and make sure the student knows it to help reduce their anxiety. At the DZ I'm at, the 5 sec delays are from the same altitude as the 10 second ones, and even then there's some spare height built in.

From a thread in the General Forum called "5 Second Delays, Dammit.": Not being in the US I don't know the USPA SIM well, or the reasons for particular decisions. It seems that the traditional 5 second delay has been replaced by a "clear and pull". For both methods, as soon as a successful one is done, I believe students immediately move on to a 10 sec delay, where they have some more time to get used to stable freefall. Anyone know the justification for the clear and pull? For a student, a Clear & Pull may just be like a Training Ripcord Pull jump (or Training Throw Out or whatever it may be called depending on equipment) but "with a real handle". That way the student doesn't change their actions at all. Once that gets the student over the nervousness of their first freefall, they go right to 10 sec where they have more time to regain stability if they have a problem. I've seen plenty of 5 second delay students get head down or over on their backs, for whatever reason, maybe from an exit that would be fine with a static line to start a deployment very quickly after exit, or from general stiffness and moving around, or dearching when going for the handle. When there's only 5 seconds, it seems there's time enough to flip over, but no time to correct it, so watching their openings can be fun. So is that the reason for doing a Clear & Pull and then a 10 sec delay? In other words, with the 10, there's more time for some problems to appear, but more importantly they have time to at least fix an exit mistake before having to pull?

Downsizing is the perfect dz.com topic to discuss when one is bored! Has Chris been defensive?: Probably. But he seems to be getting thick skinned and thus inoculated to the dropzone.com way of doing things. Everyone has to take their lumps as soon as they post here. Some people don't like seeing others downsize rapidly as they'll have to watch carnage later: Don't worry about it, Chris, that's just for big turbine drop zones, where it would be depressing to see people colliding and biffing in all the time. At a smaller dropzone, really serious injuries are rare, although there is the occasional sacrifice to the swoop gods. Plus nobody worries about you potentially cutting off 20 other people at once. Keep your little home DZ safe. If you want to create carnage, head to some big US drop zone for the holidays and do it there! :-) Do I care or coach those trying to downsize quickly? Sure. Even if I'm not too tough on people trying to downsize, I want them to really understand the risks. It's not enough to say "you'll be dangerous". That just makes people defensive. One has to help people understand specific reasons why the risks may be going up. Chris wrote: I think the point is that being unskilled or a dumbass under a lightly loaded and large canopy is less likely to result in serious injury. But it is a good point -- even those on big canopies, who plan to downsize slowly, shouldn't be complacement about their skills and should improve for their own future benefit. So even if "you are surviving your first landings on the 105", I'd have no problem choosing to criticize every detail of them. Face it, if one is flying a hotter canopy, especially if one is not really proficient with it, the risk of landing injury is higher. Maybe not much when one is "being careful" with straight in landings. It is the off-DZ landing in bad terrain, or the emergency maneuvering at low altitude to avoid another jumper, where the risk is higher. One simply has to accept that if one is going to play that game. For myself, I'm so glad that there was no anti-downsizing agitating back when zero-p was new. I got to fly a Jonathan 92 a few times (at 1.8 WL) when I had 200 jumps, when I usually just jumped accuracy canopies. Not everyone sticks around long enough in the sport, and makes enough jumps per year, to satisfy those who want you to downsize through half a dozen canopies doing 500 jumps on each one... It would be nice to make people get excited about their existing bigger canopy. The only cure for boredom shouldn't be downsizing. Many need to find something to focus on: They could do those different landing exercises that are recommended before downsizing, and focus on flying their canopy consistently and to an accurate, well flared landing.

Yeah, if one takes a normal upwind jump run, and has the canopy open up facing upwind, then it is little surprise that (if the canopy turns at all), it "tries to turn downwind". No more surprising than the fact that a mouse at the north pole knows exactly which way to run south! But other than that, the shear explanation (Kallend & Billvon) sounds good.

D-47 wrote: How did one work that, not cutting away, but using a PC? The old standard, as I understood it, was to not use a PC if not cutting away, and use a PC if cutting away.

Re Nick dG I'll allow for someone who is historically minded (like Nick dG) or has a more of a scientific rather than a marketing mentality, to get just a little offended by stunt people who don't seem to appropriately credit those who came before them. In a scientific paper one would cite all the previous related stunts and how they were similar or different from one's own. But it isn't science, it is marketing and self promotion. I haven't checked to what degree Travis publicly acknowledges that others have done the stunt before. The expn.go.com site article does mention that Travis is not the first, so it is encouraging that the concept has gotten out to the media. (Travis had an interesting variation in hook up method, that actually puts more of the onus on his buddies, who weren't there just to hold the chute like for others. Maybe we skydivers should recognize Scott Palmer too, for being the active hookup guy.) It's not always about being the first. Last time I did a good swoop in front of spectators at the DZ I thought it was a damn good swoop, even though thousands of others have done even better swoops. Travis did a good stunt anyway. But I upset at the terrible example Travis set. The pictures clearly show that he threw away the Red Bull can in freefall. Aren't there littering fines in the US? Even in Puerto Rico? People will think skydivers are a bunch of crazy litterbugs...

True. But aerobatic pilots in the late 90s at least got a little more interested in canopy strength and speed ranges. That was after the 1996 Sukhoi 29 accident where the pilot bailed out at very high speed and blew all the lines off his canopy. Maximum speeds were no longer just a theoretical thing. I wonder if the newer pilots nowadays recall that anymore.

That Skydivingmagazine one has 15 entries per page. The Paragear ones have more space per entry, and thus fewer entries per page. The Skydivingmag one has fewer columns: Date, owner's name & address, manufacturer, type, serial, service location, work performed, certificate #. The Paragear uses more space per entry, as there are boxes for both the type and serial number for each of the reserve, rig, and AAD. (Just going from memory about a new one I saw earlier this year.) So the Paragear one is better if you like a lot of space and putting in a lot of detail. The Skydivingmag one is closer to the traditional style one I had from 15 years back, with more entries per page. (And I just use a second line if I need more space.)

This discussion has helped refresh my memory on low aspect ratio wings. As general comments for everyone: The Jalbert ram air wings in the NASA report Kallend referred to, were very low aspect ratio, about 0.65 to 1.0. That's a particularly low aspect ratio, which can explain the maximum lift not occurring until 30 degrees, well beyond the "normal" stall angle of an airfoil. When aspect ratios get very low there just isn't much of a "stall" in a conventional sense anyway. This is especially true of swept back delta wings where vortex lift is added. Either way, there is no longer a sudden point (when angle of attack is being increased) where lift suddenly drops off a large amount, drag continues to shoot up, and the pitching moment maybe even tries to pitch the airfoil nose down more than usual. The "stall" for a very low aspect ratio wing is a more gradual affair. As the angle of attack goes up, the lift just peaks and slowly starts to decrease. The vehicle, whatever it is, is less likely to suddenly drop and pitch nose down, but just start mushing, slowly becoming less and less efficient at flight, and descending if there isn't enough power to keep it flying level. For those who know something about aerodynamics: I agree that for low aspect ratios the lift curve slope is less steep (more angle of attack needed for the same lift), and the stall angle is higher, and the maximum lift at the stall angle tends to be a bit lower. Because of the complexity of aspect ratio effects, sometimes I think it is simplest when talking about airfoils just to talk about the ideal 2-dimensional airfoil (the same as an infinitely long airfoil). So one might talk about an airfoil that stalls at 15 or 18 degrees or something like that. Use that for one's basic discussions of how parachutes fly. But then put a disclaimer on the end that for a 3 dimensional airfoil, especially of a low aspect ratio like for parachutes, the actual angles and stall point will differ... (like all the stuff in the arguments in this thread).