pchapman

Interesting to see the differences in terminology in different countries. Already mentioned were: USA "pack opening altitude" UK "opening" (with some variation in interpretation) In Canada for the CSPA it is the minimum altitude at which the "parachute must be activated". "Activated" could be interpreted different ways, whether it is first starting to pull the PC (only starting to activate it), or perhaps better, letting go of the PC.

One cause is the PC getting knotted closed, if the bridle entangles with it. That's similar to the example given about the handle getting caught up in the base of the PC. A knot could be from a bad throw, bad packing, or even just very bad luck due to the vagaries of airflow and parachute inflation. Attached is a photo of a PC as we found it after someone came down under his reserve. The bridle wrapping around the handle kept the handle below the rest of the PC, keeping it from effectively inflating. EDIT: Note the photo shows an entanglement on a PC with a lightweight tube handle, although it is of the more vulnerable center-attachment type, not with the attachment tape coming out of both ends, which might help reduce the snag chance.

Airtourer. The name just popped into my mind. No idea why. Knew it wasn't a British Bulldog. I looked at a lot of airplane books when I was a kid. Honestly only after thinking of the name did I check "Airtourer" in wikipedia to see if it might be right.

I notice the 1993-1994 Para Gear catalogue does show Glide Path Nova's down to 99 in size, and PD Sabres were down to a 97 minimum. Stilettos were advertised but must have been brand new as no sizes were listed yet. I don't know what time of year the Para Gear catalogue is published, but it suggests a few small canopies were available in 1993. Others would know better how rare it would be to actually find people flying such small canopies at the time.

Thanks! One almost forgets somebody has to have actually written these songs at some point! Ron Marshall - what was his role in Canadian skydiving?

Clarification please? More strict, for the US military specifically? In the old pre-oxygen days DC-3 pilots would just take their plane up higher to put any drunk combative passengers to sleep...

Anyone know the lyrics to an old skydiving song which might be called "I'm going in."? Seem to recall that the protagonist went tracking across the country and kept going until he went in. I always assumed it was a classic but I haven't been able to find the lyrics. It wasn't in the one long skydiving songs thread (#974560).

To add to this: I SUGGEST MAKING A DOWNWIND RUN BEFORE A SHORT FINAL INTO WIND: I think one source of fear is the problem not being able to see behind you while facing into the wind yet being pushed back. You can't very well see where you are getting pushed. Very scary! But you doesn't to have to try to "back in" from opening altitude down to the ground! (Even if you are told instead to crab in, from upwind and to the side, it is tough to look back over your shoulder to see the target.) Although hopefully the spot was far enough upwind, perhaps after opening you do want or need to hold into the wind for a long time, ensuring that you stay upwind of the DZ. But then when it is time to decide on an approach, you can start a long downwind run from well upwind. (It doesn't matter if that downwind run is for the original target area or for a big alternate field like Billvon suggested.) Heading downwind you'll be screaming over the ground, but you can see where you are going. Maneuver yourself to above a safe landing area, making sure you get there at a fairly low altitude, just enough for you to make a 180 turn onto a short final approach into wind. You decide what a safe turn altitude is, given your experience. I'm not saying to hook it hard and low in turbulence. But you don't want to start your final at 500', and end up being blown backwards quite a ways, again trying to look down backwards between your legs to see what you'll hit. If you get onto final at only, say, 50' to 200' you won't have time to blow back very far, and you'll stay within the safe landing area you chose. And by those lower heights the wind speed might have gone down a little. (To be fancier about this, and you want real accuracy, do the crab approach from ahead and to the side. It is tricky to manage well, but can be accurate, and is still easier than backing up straight.) All this is just what I liked to do, even when I was inexperienced. I've never heard anyone discuss this technique, so I don't know whether others would recommend it. This isn't just for newer jumpers; I've seen some tandem instructors who really could use the technique when caught by high wind. > IT'S OK TO JUMP BIG CANOPIES IN HIGH WINDS: For years my only canopy was an accuracy canopy, and even at 0.65 wing loading, back when I had 200 jumps, I basically never stood down a load when others were jumping and the planes were taking off. (Eg, 170 lbs suspended under a 265 sq. ft. 7-cell ) These days it seems common enough for people to be scared away from jumping because their "parachute is too slow" or their "wing loading is too low". I don't want people to hurt themselves, nor am I saying that anyone should be airborne during gust fronts or other extreme conditions. But I do want to say that it is quite possible to consider jumping a slow canopy in higher winds to be normal. One has to pay more attention, both to the spot and canopy flight, and it is less fun than in low winds. Yet "being pushed backwards" by the wind isn't necessarily something terrible. Wind speed typically decreases near the ground, so even if backing up significantly at 200', one might only be backing up very slightly at 50', and come down essentially vertical for the actual landing. Admittedly if one is actually still moving backwards more than very slowly right at landing, it does make landing injury more possible. I wonder if there was more acceptance of jumping with larger canopies in high winds, back in the 1980s when when 200 or 220 sq ft canopies were normal, well before everyone expected to be able to penetrate through any wind under small ZP canopies.

1. To me it would be more descriptive to call it a main PIN COVER FLAP bulletin, not a MID FLAP bulletin. ... although yes they are part of the same assembly, and Sunrise call it the "mid-flap pin protector" in the main text of the bulletin. 2. Gemini described a situation that seems different from what the bulletin addresses. a)The bulletin modifies the last couple inches at the tip of the pin cover flap. b) The bulletin mentions a line catching "under the mid flap". Given their terminology it isn't quite clear where that happened, especially given the confusion over the mid flap vs. pin cover flap terminology. c) Gemini told about a case where a line apparently caught in the soft fold area where the pin cover flap turns into the mid flap. All a bit unclear to me. 3. Sunrise doesn't make it clear how making the tip of the pin cover flap more flexible will solve whatever problem we're talking about. Sounds like it would just make it easier to have the pin cover flap pop open. (But something unclear to me isn't necessarily unclear to them.) 4. What's different with the stiffeners or construction of just the W1-1EXT, W5-1EXT, & W4 listed in the bulletin? (Not that they have to tell us.) I just like having bulletins give a little bit of real rigging insight.

So on a PC in a deployment bag, do the crown lines stow in elastics inside the top of the bag? Or how does it work? That's the way I guessed it could work when putting a PC into a bag a couple years back.

Quoting from John Sherman's article: Technically it is right, but the pressures are even lower closer to the front of the canopy. So by mentioning the thickest point at all, it shows a lack of understanding of aerodynamics. Wrong. One of the myths of aerodynamics. It doesn't matter what the air somewhere else is doing. There's no "keeping up" involved. I can't offhand teach the right way to describe it, but the air speeds up to get around the curved airfoil, and the pressure drops as the air speeds up. Huh? I'm not sure what a "strong" boundary layer is. Approaching a stall the speed of the air in the boundary layer is particularly slow and about to break away from the airfoil, leading to large areas above the airfoil of disturbed turbulent airflow that isn't zooming across the airfoil in neat, straight, fast lines -- that would produce lift. A strong boundary layer to me would be one with extra energy injected into it, such as from vortex generators. Because there's extra energy and speed in the airflow, it would have less tendency to separate and go turbulent, and thus delay the stall to an even lower speed. If turbulent air does have an effect on the boundary layer, which makes sense as it will mess up the smooth flow of air, I would not want to already be close to the stall, with an airflow about to break away from the airfoil and lose me a lot of lift. I think Mr Sherman knows something about aerodynamics but isn't really current on synthesizing it all, and has let a few incorrect concepts creep in. I did an aerospace engineering degree but am not in the business so am a bit rusty. In addition, FWIW, I'll also side with billvon and pilotdave's posts. For Mark about 'pressure gradient' vs ' boundary layer': One has to be careful with the term because when aerodynamics types talk about 'the' pressure gradient, they usually mean the static pressures front to the rear of the airfoil, the pressures that help speed up or slow down air in its journey over the airfoil. I think you're describing the gradient of the dynamic pressure going outward -- the wind-on-hand type pressure. So for your quote: Obviously it can be both depending on how far you climb out. But yes next to the fuselage, well away from the nose of a larger airplane, there could be, who knows, an inch or two of boundary layer where the air's speed has been slowed quite noticeably by friction over the aircraft, and expanded from a very thin layer up at the nose. I recall tales of people on the catwalks on top of Zeppelins. Well back from the nose it wasn't very windy to crawl, somewhat windy if crouching, and quite hard to stand up and walk, as one stuck oneself more and more out of the slowest parts of the boundary layer which was a few feet thick. The layer slowly grew over the length of the large aircraft. In other words, if a door were available, doing camera slot from the side of a Zeppelin would be easy.

Hey, come on Chris, if you're gonna post and stir things up let's at least hear your side.

I wear cheap coveralls. Quick to put on, no spandex, velcro cuffs or all that crap. In summer they are still relatively airy, sleeves can be rolled up, or they can be dispensed with entirely on the hot days. (And accepting grass stains from slide landings.) Some coveralls are very heavy but the ones I found aren't bad. Some places sell used coveralls. Used military flight suits could be OK, but some get a little heavy with a million pockets all over them. I added velcro to a chest pocket to better hold earplugs, student tickets from dispatch loads, whatever. In winter the coveralls are baggy enough to allow sufficient layers underneath so it doesn't matter if cuffs aren't sealed.

It's starting to look like a new thread on turbulence will be needed elsewhere... (And I'm not very confident either about the John & Nancy quote.) Some of the many turbulence threads: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=256878; http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=458267; http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2502098; http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=759083; http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=2050501; http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=2051698;

Yet the rigs were presumably already in service? I.e., even if "very tight", they were already packed up and someone was expected to wear them. Unless Cossey had poor rigging skills at the time, he would have expected the rigs to be functional. Presumably, if they had no front mount D rings sewn on, they would have been used as pilot rigs by the DZ? There is still a lot that seems not to be known about the choice of rigs & canopies.

Supertacking a pillow is a simple way to do it. Some sewing can be done but it works better on older gear without fancier thick padding in the backpad. One end of the pillow doesn't even need velcro to allow access to the pillow to change the thickness. One can just have a flap of material that is sewn only at the two ends. It holds the foam in but can flex open enough to allow the foam to be changed if needed. I've also seen or built pillows that fit up against the reserve container, sewn and or tacked to the reserve container, not just the backpad. It may be trickier to do, but instead of creating a flatter container space, it makes one that is shorter from top to bottom, which actually works better to match the d-bags on smaller canopies. The one on my rig has the ends open, so it is easy to pull the foam out to switch thicknesses, or even remove the foam entirely and press the flap against the reserve tray.

Or cut a canopy down into some weird cutaway-only canopy. (I'm just waiting for a low wind day to finish that project...) This thread is getting derailed by us riggers who WANT to have closets full of junk!

Good question. Some old gear has historical value, or can be recycled. Riggers may be happy to get some old gear, to use for riggers' projects, riggers' sewing training, student training aids, etc. But eventually stuff does need to be thrown out. I also wonder about cadmium plated hardware. As for lead seals in rigging shops, I've kept them to take to the local household hazardous waste dump.

Leaving aside the whole Mr Cooper question: I don't know details but I'm sure the USA got into nylon production and fabrics for parachutes at least by the middle of WWII, so there must have been plenty of non-natural fibre ones around by war's end.

In my DZO's old rigging/storage trailer. Another rigger and I did some exploring! Although I had posted a few well used PCs for sale in the classifieds, we might just keep that canopy because it is a particularly interesting looking one. Do you have an in-air shot of yours? That would look good for this thread.

See the attached photo -- a ParaCommander on the floor, in a camouflage colour scheme that features bright yellow and other colours. Another dz.commer thought that that's the "pizza puke" colour scheme, but I don't know for sure. Is it?

Regarding the low supply of PC's: Well, I can't offer any new old stock PCs, but I have found some odds and ends that I can offer for sale. I've just put up an ad for a few PC style canopies (including a 'Russian' PC, Pap, PS-06), either in good but used condition, or well used condition. Colson and I are already discussing the sale of one. (Long after I and another rigger at the DZ raided the old rigging trailer for PC's for ourselves, I found some more and got the DZO to agree to let me sell them.)

Yes, speed increases with the square root of the wing loading change. (and the glide ratio stays the same) That's the basic, ideal calculation, but then, like Martini was talking about, you get into things like canopy distortion, lines and jumpers not changing size, etc. to mess things up. The basic theory is still a good starting point though.

We have a winner. Hmm, Danger, you probably saw that very canopy years ago in the time you were jumping at the same DZ as Steffani did. Still, it wasn't a giveaway. A whole 18 A-lines to contend with at the canopy. Not a canopy to give a newbie to propack! That kevlar (seen reinforcing the cell openings) was a hint towards ParaFlight. (For those unfamiliar with it, there are only A, B, and C lines, with lines cascading spanwise not chordwise, sometimes cascading twice, and three risers per side. At the time, in the early '90s, it seemed like Paraflight was thinking about paragliders when designing the Evolution. The Super Evolution 140 was weird but kind of fun to fly and one could do some tricks with it not possible on almost any other canopy.)