pchapman

... and the Skyhook is a whole bunch of other things too... proposed space transportation, gadget in a sci-fi game, rock climbing tool, imaginary device used to fool people, and probably a bunch more things, perhaps more than we need to list.

The Skyhook is Rigging Innovations reserve pilot chute, and has been for decades. I think some other company later started calling some other product a Skyhook too.

I've long liked risers that have a downward facing tab in addition to any upward facing ones. I would think this greatly reduces chance that a fast descending slider (that comes down onto the riser) will be able to push the toggle down and out of place (despite the solid covers most rigs now have for the top of the toggle.) It doesn't stop a slider ring from slamming down onto the riser, just should reduce the problems from that. But that doesn't help you specifically with the existing risers; and toggles with a downward tab are rare. (And Pilots aren't exactly known as slammer canopies.) Mirage used to have a design like that but a recent Mirage rig I saw no longer uses that idea. I have a nice set from Flying High (Canada) that uses a downward tab. Chuting Star has the Paraavis toggles that also use that feature. Not sure who else makes toggles like that.

Everyone chips in with comparisons of course. So here's mine: Skydive Toronto last year was doing 100 a day on the best days of summer, with 4 C-182s. However, the instructors' knees agree that getting a Caravan again this year was a good thing.

A couple sources are the Irvin Recovery Systems Design Guide AFFDL-TR-78-151, and the Parachute Recovery Systems Design Manual by Theo Knacke for the US military. Both are online... somewhere, and have been mentioned on dz. Attached is a pdf I made of the Altitude effect section of the more recent Knacke manual. It isn't ideal for our purposes but gives some idea of altitude issues. The rate of increase of opening force with altitude does depend on the design of the parachute, and whether the load is light (like a person) or heavy (like a bomb) relative to the size of the parachute. The research shown only applies to unreefed round canopies. I would imagine that the reefing of ram air parachutes would decrease the sensitivity to altitude, but would not change the basic principles (like higher true speed and energy when up high) or that higher altitude openings get harder.

All Skyhooks get tacked with seal thread. Just that early on it went through the bridle, while later it would go through holes in clear plastic plates on either side of the metal hook device, to keep the tacking in the right location.

I'm not sure that it changes where the leg straps go, but by pulling forward on the main lift webs, keeps a flexible rig from lifting away from the jumper's back, especially when legs come up for a sit fly. This reduces the size of "the hole" from the back.

Perhaps a tunnel trained student? Not sure how US AFF works but in Canadian PFF, a student with 20 minutes of tunnel can do a Level 2 that's 1:1. The original poster's profile doesn't mention location though.

We have relatively few people doing skydiving equipment sales in Canada, and without a point-and-click ordering interface, so a lot of skydiving specific stuff one orders from gear stores in the US like Para Gear, Chuting Star, Square One, Aerostore, or other places. Get together with a few friends to share shipping costs and order the stuff you need. Since demand is low at any given location, one might find standard items like goggles or a basic alti at a local DZ, but one isn't going to have racks of helmets to try out. I notice that 'Danger' at Skydive Swoop does sell Bennys. He has had a small shop at the DZ for some years. (http://www.dangerwear.ca/SkySystems/Benny.html) Full Protecs one might find at or through a kayaking or similar water sports store. Skateboard shops tend to have the half shell only - but who knows, they might be able to order others in.

And for something like $10 more, one can get the more advanced liner for the Benny, which is a real, sewn helmet liner, and not just layers of foam that eventually peel off from each other a little at the edges. That's fairly new; only noticed it available last season. The other option usually mentioned is the ProTec. It has the simple layers-of-foam style liner. If doing a ProTec, get the full shell, not the half shell.

Yes indeed. But presumably that wasn't in the middle of your DZ's landing area .... Easily possible in tall grass during an off-landing or something like that though. If one has a lot of horizontal speed, and the terrain is rough, what are the options? Just my thoughts: If the terrain is really rough, one might just have to flare as fully as possible, then drop it in and roll and tuck. If the landing surface is not too rough but uncertain, I might try an 'upright slide', trying to stay somewhat upright or standing while sliding (even if legs forwards), so one is scrubbing speed and unloading the canopy to allow it to continue to fly as the speed decreases. Then if one's feet hit something they can't slide over, one can pitch forward into a roll. (Which is easier if one is already twisted somewhat sideways, as people tend to do during a good sliding landing, unlike the direct butt slide style.) This is in comparison to a low slide with hips just off the ground, in which case if an obstacle is encountered, one may just crumple up against the obstacle.

Regarding slides: If I may elaborate more, so is any landing if screwed up. So is any parachute jump. So you don't do certain things, unless you have reasonable skills to do those particular things. So if you don't feel you are ready to start sliding landings, then you are correct and wise to avoid them! If you haven't been able to get rid of all vertical velocity, and are coming in steep, then a PLF is the best you can do. If you have planed out, and can't get rid of enough horizontal velocity to run it out, then (if the ground is smooth), a slide is the best you can do. If you have a lot of horizontal and vertical velocity when about to impact, there's no method that really works well, but a PLF and then tucking tight is about the best you can do. So if you are not sure you are going to touch down with near zero vertical velocity, getting ready for a PLF is still the best thing. A slide is only if you are confident that you'll touch down with low vertical velocity, and the ground is smooth enough to allow a slide. Even a moderately experienced jumper, jumping in non turbulent conditions, can carry out a slide safely because their flare is repeatable enough to provide a low vertical velocity. While one can't avoid errors all of the time, most major errors in the flare should be spotted early enough in the process for the jumper to prepare for an immediate PLF. Hope this helps.

Simple answer is that IF you are on a smooth surface, and IF you are experienced enough to know that your flare is going to leave you with essentially zero vertical speed, then a sliding landing can be quite safe. And safer than doing a multiple-tumble PLF at speed. The key is to not be coming down with much vertical speed at all, something that students especially can't guarantee, as they are still learning to flare right and may have canopies where the amount of time the canopy will plane out level, may be extremely small, making it hard to set down perfectly. Note that I'm saying a sliding landing. One may end up on one's butt, but the idea is to be twisted slightly and slide in more on one's thigh than making it a truly butt landing. (This isn't as easily possible with tandem landings though.) The jumper may also be sliding along only on their feet during the beginning and middle part of the landing, only ending up on their butt or thigh at the end when the speed has been scrubbed off. So overall, student butt landings still = dangerous and bad; while experienced jumper sliding landings = not done all the time but considered normal and accepted.

There are 7 pages of reviews of the Pilot in general all there. So there may be something of use in there but it will take some searching. Did you have something in particular in mind?

And about 12 seconds after reserve deployment to get out of the line twists. Just noting the point for those who keep saying they used the Skyhook and don't get reserve twists, implying that the Skyhook is, like so super duper fast and cool that you don't get twists. Well, fine, often one doesn't get twists, but sometimes it does happen. A few harmless reserve twists may be a lot better than opening hundreds of feet lower with no RSL. But I did want to point out that a Skyhook isn't a magical guarantee of no line twists on the reserve.

Yeah, that was Grimmie's post, I guess his friends told him to stop spoiling the fun. Of course it was all a joke. After all, why according to their web site would the Full Contact Skydiving Eastern Canadian competition be held in Alberta?

While the F-35 program clearly has problems, more so than even the typical hi tech program, the guy in the video - Pierre Spray - doesn't necessarily have the last word on anything. While I haven't done any fact checking, one perceptive comment on the web page includes the following: It's too easy to pile onto the F-35 now. "Do everything" planes have tended to have problems in the past. On the other hand, sometimes a large, capable aircraft has the stretch capability if the designers don't try to do everything at once, and thus run out of time to get the job done. Like the F-15, at one time "not a pound for air to ground", yet now available in capable air to ground versions too. So I'm not so much against some of the design compromises (well, maybe the VTOL thing is a stretch), as being against the F-35 just getting so expensive and still not able to fulfill its basic functions. Just an amateur opinion. My overall point is still that Pierre Spray isn't necessarily a prescient oracle, but maybe just someone who is a pessimist and eventually gets to say "I told you so!" for one project or another.

I wouldn't go so far. Sure, you are correct in the sense that if you don't make every jump a dedicated swoop jump into a marked lane, you won't progress as fast in dedicated swoop jumping into a marked lane. If that's your goal, two identical canopies may be ideal. But one could equally say, "Never do X type of jump because you'll hinder your progression in Y, any other type of jump." True but so what. I don't find it is any problem to go from an 88 to a 282 to a 135 to a 200 between different jumps. As long as one isn't totally new to a canopy one can land it safely and remember how to pack it right. Even a newbie should be able to land safely on two similar canopies 20 sq ft apart on any two consecutive jumps, if they are reasonably qualified to jump either canopy. If you are totally focused on a hard core swoop on a Velo, hitting the gates, or on a world class accuracy approach on a Parafoil 282, then yes, changing from one canopy to another is hindering progression in each discipline. I guess there's a difference in philosophy, to what degree one has to be getting better on every jump. One is allowed to jump for fun (and try to be reasonably safe) and not just relentlessly pursue a single minded goal.

I'm guessing designers were just conservative. Canopies were what we might call "open nosed". A big open nose worked. Canopies were big, slow, more porous, and so a large open area made sure the canopy stayed pressurized at all normal angles of attack. Only later did "closed nose" canopies start appearing. An early example of the tendency would be the PD Sabre. The top skin was brought down a couple inches along the "diagonal" that forms the normal nose inlet, without actually changing the nose profile. Only later did we get inlets that got smaller and more integrated into a fully rounded canopy nose -- more like those on crossbraced Icarus canopies. You still don't see noses like that on intermediate level canopies, and there's talk of how canopies with such small nose openings are poor in turbulence at low wing loadings and thus low airspeeds. (The Icarus 'diamond' nose opening may be small but in the center of the diamond has enough vertical distance that it handles whatever shift there may be of the stagnation point as angle of attack changes.) The consensus would be that fairly large nose openings are still important for good flight characteristics. Have a look at paragliding canopies though - they have done more with keeping nose inlets small, for a whole range of canopies and not just for the very high end market. They don't have the opening problem, but do have to deal with low wing loadings and turbulence. (Slightly earlier than the PD Sabre with its zero-p material was the short lived PD Excalibur in F-111. There was also the Paraflite Evolution, although with a lip extending up from the bottom of the inlet, not down from the top. Paraflite even mentions a patent they licensed for it, US 4406433, but what they had on the Evolution was not the fancy curved nose system seen in the patent.)

One can certainly get extra time tracking. I have averaged a repeatable 76-78 mph* on my ProTrack graph, for long periods of straight line tracking. That's for 6'1", 150 lbs at the time (admittedly a good body for tracking), in a tight RW suit with no booties. On a jump with no turns,it was 73 sec from 10,300', and deployed by 1900'. What those speeds translate into for time over the whole dive depends of course on exit & opening altitudes and to what degree one has to make turns to get home. I use a pretty standard body position with palms down, legs slightly spread, toes pointed, arms next to the body, but haven't tried to optimize it. I'm not sure about 'going steep before going flatter' in all of its interpretations, but it is certainly ok to angle a little steeper at the start -- after all, the airflow starts from directly below, so if you have some ideal angle of attack at .5 glide ratio, then to have the same angle of attack when starting, you would need to start off steeper. True at times, but one isn't going to be falling really slow just by cupping and not moving forward. So getting slow freefall speeds is still some indication of getting some sort of good track going, whether or not one is differentiating between best glide angle and lowest sink rate in still air. * ("SAS" value - adjusted to a standardized altitude, 3000' I think the device uses. Otherwise a couple mph more for true airspeed.)

Thanks Mike. Aviacom obviously hasn't been the most responsive company to work with, and you are sometimes left as much in the dark as are Argus owners & riggers...

A few comments on the ever fun world of Argus rules: 1. Units not serviced as required are already temporarily unairworthy according to the rules in most countries. 2. In the new bulletin , their definition of the period for the 4 year check appears different from the period I had been led to believe from on dz.com discussion. I was told (by a jumper, not ChutingStar itself) that ChutingStar was doing "end of the 4th calendar year", which is great for users with units built in January, but sucks for those with a December date. The ParaConcepts service center's statement on their web page (at least a couple years ago) had the statement This could suggest using a calendar year, or it could suggest that 4.999 years from manufacture is OK, but service is needed at 5.000 years. This new bulletin in saying 4 years + 3 mo suggests it is 4 years to the day, plus 3 months. This "3 months" was never in the manual and the issue has not been clarified. Do we take this manufacturer's offhand statement to be a changing of the rules, or something to be ignored as it wasn't what the bulletin was purportedly about, and wasn't presented as a clear and very significant change in what the manufacturer and service centers have stated before? 2a. The manual actually says the 4 year check is "Every 4 years (after the date of 1st use),", so technically one needs to know when it was first packed into a rig or turned on, not the manufacture date. 3. This point has been made before, but given that the company is still responding to the civil market a tiny bit, why don't they clarify or modify their rule to replace the battery at EVERY repack? This might be after 1 day in case of a mal or an accidental handle pull on the ground. Or it might be 180 days in some countries, or 365 in another. This seems inconsistent and designed just to screw around with their customers. 3a. However, the Chuting Star service center web page mentions that their Argus batteries are for the yearly battery replacement. Again one can ask, does one believe the manual or a service center as the as the authoritative definition? (Yeah, it could just be a web site typo for one of thousands of products they stock, but it is inconsistent with the latest manual.) 4. Units sent in for service will then be good for the following 4 years no matter whether they were serviced late. (So if you send it in year 7, it is good to year 11, not year 8 like a CYPRES.) This is in accordance with a statement on the ParaConcepts service center site. (That can be seen in the above quote, but was stated more fully and clearly on the website too, as a specific advantage over the CYPRES system.)

The manual does show the chest strap pretty high, sort of at sport rig chest strap level. Generally instructors on the dz I'm at, do indeed tend to put the chest strap a lot lower. Ref: http://www.unitedparachutetechnologies.com/PDF/Support/Rigging/INSTRUCT-003-Sigma-Student-Harness-Adjustment-Guide.pdf Edit: Who knows, other issues may come into play, such as how one positions the hooks at the shoulders, and how one fits the harness in general. Still, keeping the chest strap low is normal around here.

Nope. The Sigma manual, at least last year, only shows how to pack the old Dacron lined Sigmas. But it did help to make me aware that I was wrong in my recollection (a few posts back): on the Dacron lined Sigmas, the main brake line does pull down through the guide ring, while the secondary brake line remains above. So there was at least "something above" on the old Sigma canopies. The manual does not show how to pack the Vectran lined Sigmas that have been around for years. The UPT tandem manuals have at times taken many years to update -- even in the early 2000's they showed things like backing out of a King Air or standing on the step of a Cessna with the student hanging from the instructor, techniques that might have been OK in the 1980s but I doubt much after that. Anyway, just calling Bullshit on the notion that the manual is always correct or updated, even if it is worth checking.

Surf the ex President! Well, not bad for 90.