pchapman

Simple version:

Is it OK on a belly mount to have a short cross connector, between 2 of the 4 L-bar links only, built from 550 cord that's wrapped 12 times to create the cross connector?


Long version:

I'm trying to better understand cross connectors, and don't know what is actually normal practice.

Some designs go between the snaps, some are longer and go inside the pack between the links. Is the inside-the-pack version considered the better style?

Poynter (7.83) describes the standard design of 3/4" tubular inside 1" tubular.

But there's also a pic of one that's like some I've seen where the cross connector is a length of 550 cord wrapped around multiple times, for a total of 12 strands for the one I have. The design looks professional - ends knotted with stopper knots and servings to keep it neat.

This design is acceptable, is it?

What about short vs. long cross connectors?

Poynter mentions longer ones inside the pack to avoid getting a face full of connector on opening, but the ones I've seen are short, just long enough to go between the links on the reserve. I'm not sure how one would pack a longer one, with slack in it, to keep it neat in the pack and not getting in the way of the reserve.

You'll have to check the manuals but I seem to recall that Aerodyne mentions tacking their soft links in the Icon manual, but not in the Smart manual. (Smart reserves come with their soft links.)

In any case, not being under FAA rules, I tend to leave reserve soft links un-tacked, just stretching them to try to seat them. I prefer having them inspectable.

Remember all those rigs with rapid links that had no bumpers and no tacking? Links rotating, lines sliding around, contacting the barrel? I never liked that much but I guess when the reserve was used everything usually lined up properly and didn't cross-load the link (across the short dimension). Definitely uglier than un-tacked soft links.

My experience in Canada was that repack rates didn't really change when we went from 120 to 180.

Perhaps a rigger might have decided that it was a good time to bump his rates up by $5 in any case, but generally the longer repack cycle was a non-issue. (Individual results may of course vary - as seen by one previous post from a Canadian)

So how about the oldest sport reserve in production,
excluding rounds,
excluding tandem reserves?

Flight Concepts still advertises the range of reserves that includes the Fury.

Does Precision make the Raven any more? They don't advertise it. (One can argue whether the -M counts as the same parachute as a Raven or Super Raven but I guess the TSO is the same?)

I'd guess one of those two groups of canopies would be the oldest solo, square sport reserve in production.

Quote

You can minimize your civil liability footprint by adhering to not just the FARs, the BSRs and the manufacturer's recommendations, but by also trying to stay with in the norm of what is acceptable procedure by the industry.

True. The tricky bit is when the accepted practice in the industry is below the level of the FARs or manufacturer recommendations.

If the manufacturer recommends no front loops out the door with a tandem, but all the experienced instructors do them, that can put one in an awkward spot.

Quote

Probably not this one, either.

HW

Flare puppies !!!

Seems a little cruel to use ... before they even had had a canopy that would flare.

Quote

Quote

loop from Cypres is rated at 180 kilograms or 398 lbs.
When full length fingertraped that makes a tensile strenght of about 800 lbs.

Airtec seems to differ with you on that.
[...] Here they specify 450lbs for the breaking strength of a loop and

Hi Sam and Andre,

I thought I knew the answer but now I'm not sure!

Sounds like confusion over the strength of a completed loop vs. that of the material itself.

The Cypres 2 manual mentions 450 lbs for a Cypres LOOP (and shows a photo of a completed loop) -- which is basically what 980's link shows.

My spool of Cypres material says "185 kp" on it, i.e. kilopond or kilograms-force. That would suggest the 400-450 lbs value is for the MATERIAL.

The Cypres Rigger's Manual mentions the MATERIAL: "Cypres loops are made from polyamide nylon cord and are specifically designed for
use with the system. This is an innovative, very thin material with a diameter of
1.8mm and a breaking strain of approximately 180kp. "

It sure does seem that it takes less than 800 lbs to break a loop, but I haven't calculated the numbers a novice rigger might apply on a torquing device. And loops only seem to break at their apex so I think there's the issue of thin cord slicing through thin cord with a tight bend radius, that is reducing the strength factor. Don't know how much.

I'm tending to believe that the material is ~400 lbs, so the full loop is ~800 in the ideal world, but Cypres sure isn't very clear in their writing...

Looks like the rig is an old Vector I with velcro only and no tuck tabs for the reserve cover flap??

Pin checks sure are even more important with older gear!

The pin looks bent in strange ways. But there might be only 2 bends. Hard to tell in the cellphone shot, but part of the apparent bend is just from the zigzag that exists where the free end of the cable is ground off. So it could be one big bend up (from hitting a bench sitting down) and then another bend of the tip down (maybe from then leaning back and partially 'flattening' everything out again). Whatever the details, it sure is bent....

Same as Slotperfect at the DZ I jump at, with about 10 Sigma rigs.
That method gives good solid stows, better than regular elastics, without all the fuss of Strong rigs' design. Note that the canopies we are using are Sigmas with heavy Dacron lines - different from some tandem canopies. Shouldn't matter whether it's a Sigma or Vector II I guess.

Quote

Quote

it will not fire below 130ft AGL (or what it thinks is 130 ft AGL) since there is no time for the reserve to deploy.

I don't think the reason that it does not fire under 130 has to do with it not having time to open. It's for swoopers

I believe the first answer is actually the correct one.

"Below approx. 130 feet (approx. 40 meters) AGL opening is no longer useful. For this reason, CYPRES ceases operation below approximately 130 feet AGL." -- Cypres 2 User's Guide p 10 (and stated similarly in the Cypres "1" guide)

It's probably just confusion about a solo course (whether IAD, static line, or PFF) versus a tandem course.

Mind you some DZs may tell people to be ready to spend the whole day there; it isn't always as if a booking at 10 am means you have jumped by noon. Even for the solo courses, one has to distinguish between the time for the actual course vs. all the associated stuff -- registration, taking a test, waiting for one's load, gearing up, etc.

Places servicing Toronto are Parachute School of Toronto, Skydive Toronto, SWOOP, Niagara Skydive, and Skydive Burnaby. (And Grand Bend Sport Parachute Centre and Skydive Gananoque if driving more in the 3 hour range than 1-2 from Toronto.) Some are bigger, some are smaller, some have turbines, some don't, some are considered particularly strict with rules, but all are considered decent and safe places to go.

I'm not getting into the politics of which to go to as I've jumped at all of them...

One reply:

Quote

You can buy this
http://skyhivisuals.tripod.com/malfunctions.htm

Those photos are the old standard.

But one problem with them is that the camera angle on a few of the photos is from "ahead" of the risers, like from a belly cam, rather than "behind" the risers, as if one is arching and looking up at one's canopy.

Therefore some have the risers coming from the bottom of the photo to the canopy in the middle, and some have the risers coming from the top of the photos.

At my DZ those pics on the wall of the training room would sometimes get turned 180 degrees and then back again by different people. One either showed a view with the risers in the wrong place, or one showed the mal with the canopy facing the wrong way.

I could be wrong about it confusing students. But it sure looked confusing to me as an experienced jumper.

One important addition to all the detail Erdnarob provided:

The rapide links have a 5 times safety factor above the "safe working load".

So a #4 stainless isn't just "good for 615 lbs", but has an actual minimum breaking strength of 3075 lbs.

==================================

If one wants to delve further into all this:

For the other hardware, the values provided (such as 5000 lbs for a big harness ring) are Proof loads. I'm not absolutely sure but I believe that that is supposed to be below the yield point, or Limit load in aviation parlance. Any of that other hardware should be able to be loaded to the quoted level without damage, without exceeding the yield point and suffering permanent deformation.

Therefore the actual point of complete failure, the breaking point or Ultimate load, will be higher. (Roughly 50% higher depending on the metal and how the limits are defined.)

So five times the quoted numbers for rapide links still can't be directly compared to numbers for other hardware.

For a rapide link they care at what point it fails completely, while for a 3-ring, one also cares if it gets bent out of shape.

Chad, friend of mine, called me up early yesterday evening, looking for a reserve repack that same evening. He had just had his first chop, at slightly over a thousand jumps, and was looking to get back in the air for the rest of the long weekend (here in Canada) without having to borrow gear the whole time.

While he promised to make it up to me, this was one of those inconvenient rigging requests that mess up one's plans for the day. He was at one DZ, while I was at another 45 minutes away (just passing by after a non-skydiving weekend) for a couple jumps before having to get home at the end of the day. I figured I'd help him out, as Chad isn't some random annoying rigging customer, but a friend who shares an interest in some silly skydives -- wingsuit rodeo, Para Commander Mr. Bill, double tandem Mr. Bill, playing with my intentional cutaway rig, and so on.

So I agreed to head over to his DZ after jumping was done, but as it didn't look like I'd be on any good loads right away, I ended up packing up and heading out without another jump. Besides, "we" had C-182s, and "they" had a Caravan. I got to the DZ at 8:15 pm, just in time to make it on the last load. Sweet! Much more fun to jump at a DZ than only go there to do a repack. Chad kindly paid for my load, but stayed on the ground himself, chilling out and watching that last load.

As I deploy after a decent sitfly jump, the canopy goes off heading early in the deployment, the risers cross, and soon I've got a few line twists. The story follows a rather standard course here: on my back in a deep spiral, futile effort to fix, chop, flip to belly, open reserve, land in field with I and another jumper successfully chasing all the stuff, and getting a ride back to the DZ from a local yokel in the bed of his dirty pickup truck.

This was my first sport malfunction, although I had my first mal at the end of last season on jump #1998 on a tandem rig. (Plus there was a CRW related chop years earlier.) I guess I had had it coming, given that the main canopy is a Cobalt 75, kindly sold to me cheap by an experienced jumper who got tired of having to chop small ellipticals. (And upsized to a nice reliable Triathlon 99, which then spun up on her the same day I first jumped the Cobalt 75 -- that story at http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3105615; ) The Cobalt isn't my regular canopy but I've flown it a bunch this year, just because it is sporty and different.

As I joked, "Of course I like to jump it. What can possibly go wrong when someone sells you a 75 square foot non-crossbraced canopy for next to nothing?" Oh yeah, spinning mals.

The gods sometimes really do have a sense of humour. I had shown up at the DZ to pack the reserve of a friend after he made his first chop, and after I made it on the sunset load that he covered for me, I had my first sport chop.

Guess he's a demanding rigging customer, wanting proof that my reserve pack jobs work.

Chad and I are then found sitting in the hallway outside the manifest office, filling in the official CSPA Accident/Incident/Malfunction forms, as if we were kids called to the principal's office. And still laughing at another little skydiving adventure.

Quote

You know the difference between a Delta II and a Paradactyl?

The Delta II covers the whole car.

But the Dactyl is still big enough to cover your body...

Quote

The truth is with the cost of maintenance over a twelve year period, the FXC is no longer a cheaper alternative.

A good point. To expand on that:

FXC's are normally, what, a standard $200 charge for the 2 yr service (plus $ for any fixes)? Thus $100/yr.
Meanwhile a Cypres 1 averages out to say $80 for battery every 2 yrs and $160 for service every four, which is $80/yr.

(I'm ignoring taxes, depending on where you live, and shipping charges which are appreciable, but would be held down by shipping in bulk for DZ's. Cypres' may do better on that front due to weight.)

Also there's some DZ labour involved in doing chamber checks on the FXC's every 6 months, or even just once a season if the DZO slacks off a little.

Yes the maintenance actually comes out in favour of the Cypres. But upfront costs favour the FXC. I think used ones are available for $50, equivalent to almost nothing per year. Without getting into the time value of money, a Cypres is closer to $100 / year to cover the purchase price, tipping the balance overall in favour of the FXC.

Still your point is valuable - FXC's don't just sit there costing no money for maintenance, unless the DZO is unscrupulous.

Let's face it, I think a lot of the decision depends on the gear. If you are buying a bunch of brand new student rigs, the company will probably laugh at you if you asked for FXC mounting plates. And if you already have 20 sets of 1980's static line student gear, you are going to leave the FXC's in, and not spend $1300 per rig to install Cypres' (and sew in Cypres pockets.)

Quote

Check 5-7 of the riggers handbook

Thanks, I think that's the first reference to a written source in the whole thread.
On the other hand, that source does no better than just to say that "Small holes may be allowed, but consult the manufacturer's manual."

I'll go with those opinions about it being more common on canopies that are lightly loaded or on ones that open closer to a stall. When such a canopy is finishing decelerating vertically from freefall, it doesn't shoot ahead as quickly into fast forward flight, and so sometimes allows the pilot chute to drop right down and end up infront instead of streaming out behind.

I've seen a light girl on a student gear with a spring loaded pilot chute have it happen a few times when nobody else on the gear was having the problem.

As for fixing it, yeah you don't unless you're really into canopy trashing and backwards flight.

Some Parafoil brake lines don't even have an eye; the jumper just does a daisy chain like knot to set the brakes.

If one has that situation, it leaves it up to the jumper to figure out the right position, and makes the brake line rather simple to make...

Quote

Quote

The root of this effect is in different dynamic characteristics of the canopy and the pilot: gust coming from the right will quickly push canopy to the left and tilt it due to its low mass, while the pilot stays in place, so the canopy turns left.

[...]
There is a wind gust from the right and you can see the canopy yaw to the right, that is, into the gust.

The following roll/pitch to the left looks like toggle input to me.

So there are different views of what a canopy might to when it meets a gust from the side. I'm guessing that is possible that both behaviours can occur at the same time:
a) the canopy yaws into the direction the gust came from (yaw stability), and
b) rolls away from the gust due to the different forces / inertia / mass densities / ballistic coefficients / or whatever factors you want to include, of the jumper vs. their canopy. (The behaviour yuri_base described.)

Without understanding the exact aerodynamics, it is quite conceivable that a gust could get the canopy swinging away from the gust, and then continue to swing side to side a bit until the motion damps down, but at the same time have it tend to weathervane towards the gust.

In my particular case the user is taking the PC out of service, because good sized holes had benn worn into it. Not sure how, as I wasn't the rigger before. Who knows, from the stains, it may have been pulled from a tree or something after a cutaway.

The best I can see so far:
- There's no standard number out there for hole size.
- A 'small' hole could be hand sewn shut.
- Hand sewing a patch on a larger hole might be feasible but fiddly.
- Any damage that is questionably large? Replace the PC. With appropriate skills it may be possible to rebuild the PC fabric using the same cap & spring.

All sorts of options are possible.

What is considered acceptable for torn holes in reserve pilot chute mesh?

I've come across an older PC where there is damage to the mesh. It's a soft type of mesh with hexagonal holes.

On the one hand, it isn't the way it was built and TSO'd. On the other hand, most things have acceptable wear limits. (E.g., consider all those Javelin PC's one sees with fabric looking rather porous and stressed from their packing method.)

I can't recall if anyone has suggested a specific limit to hole size.

I saw an interesting situation once in Canada. The DZO didn't have a commercial licence, but flew the occasional load. Everyone considered it normal. He figured it was justified because all the Operations Manual paperwork, which was approved by the government, shows him as the Chief Pilot.

The legality may be a iffy when it comes to having to fulfill all the applicable regulations. But he can say that the government, who knows what licence he has, specifically allowed the company to do things a certain way according to the Operations Manual, and that includes him flying...

Of course many people didn't really make any choice of handle -- they use whatever came with the rig.

Preferences translate into actual equipment only for those who bought a brand new rig, bought a new PC, or (very rarely?) actually had a rigger change handle types.

There's little point jumping in high winds if there are other associated risks -- like dust devils, an approaching thunderstorm, or really strong gusts.

But one could certainly work ones' way up, gradually getting used to jumping in stronger winds, in situations where the wind is judged by experienced jumpers to be unpleasant but not particularly dangerous.

One doesn't need to learn to jump when most others are standing down. But there are times the wind is strong, most people are jumping, yet some are afraid to jump and choose to stand down. They may be unsure of themselves, unsure how to plan their approach, or squeamish about any turbulence and bouncing around under canopy.

While nothing says one has to jump at any time, it can be handy to be comfortable with dealing with stronger winds.

So, yes, I'd recommend slowly starting to jump in higher winds. Coaching and advice beforehand could of course help. One needs to figure out what is just scary (because one isn't used to it or trained for it), versus actually dangerous.

For many years I jumped a big accuracy canopy and I never felt I had to stand down before others did. It just takes more planning, and does make the landing more of a challenge than easy fun. These days there seem to be enough newer jumpers who are afraid of moderately strong winds because they don't think they have a high enough wing loading, even when one could quite easily and safely go up with a student canopy, if one flies it right.