andyhughes

Thanks for the replies so far - but keep the info coming if there are any other designs out there that were/are being used. The reason for the the info request is more for historical reasons - being a rigger and missing out on the earlier years of the sport. I've never seen trim tabs in the flesh, and very seldom come across 2-1s... Actually, i'd also be interested in pics/designs of 2-1s too - if anyone has anything... pchapman - that is a good photo, thanks - I can't work out how it locks though (is it just the two grommets that make a friction lock?)

I'm interested in hearing about the various designs used to construct CReW trim tabs. I.e. what hardware combinations etc... Would be cool to see some photos of different designs too.

The British Parachute Association (BPA) have a bunch of training manuals available both online and as hard copies.... http://www.bpa.org.uk/training-and-progression/canopy-handling/ Check the following: * CH Manual - Basic canopy handling * CP Manual - Basic canopy piloting

Anyone got any photos of the paper seals? How do they work? (i'm pretty happy using the lead ones, but i do like the sound of the paper ones)

Anyone got Aerodyne's version of the Sensei yet? How does it compare to the Velo? Presumably Sensei will now be measured using the Aerodyne method (whereas it was developed using a measuring method similar to PDs according to the bigairsportz site).... ... so does this mean a Sensei 111 = Velo 120 in terms of both physical size and handling? (having trouble getting any info out of the manufacturers)

Both the Poptop and para cushion manuals are in the www.ukskydiver.co.uk Rigging Documents section... link here... http://www.ukskydiver.co.uk/cms/index.php?option=com_docman&task=cat_view&gid=320&Itemid=240

It is in the UKSkydiver.co.uk documents section... http://www.ukskydiver.co.uk/cms/index.php?option=com_docman&task=cat_view&gid=133&Itemid=240

Looks like it was too easy a question having the measurements of the links when dissconnected ... It would have been too evil to post the photo with them hooked up though. God only knows why Aerodyne made reserve and main links look identical - a real pain the arse having to dissconnect and measure to be sure the correct links are on the reserve.

Hi, In the attached photo there are two Aerodyne soft links, can you identify which is the main, and which is the reserve link (or are they both the same?!)? Please vote :). (btw - line lengths are as follows: left = 5 inch, right = 5.5 inch).

There is now also a comprehensive index of service bulletin on the UKS website, which complements the Rigging Section. Fully searchable - very useful. http://www.ukskydiver.co.uk/cms/forums/viewforum.php?f=97]

Problems are fixed... it now works with IE too... Happy days :)

Nice one. Thanks for the info. Andy

In terms of the way the fabric is loaded, makes sense for the top skin and bottom skin. But for ribs and d-ribs, is there any specific reason why these are also cut on the block with tapes at 45 degees (aprox) to the chord line or is this just "market convention". We don't see bias cut ribs with tape parallel/perpendicular to the chord (which may reduce amount of tape neeeded), and was wondering why?

I've not been in the sport long enough to see any of these... but i've read about a few models of square canopies that were constructed on the bias. Apparently there were problems with this construction method (hence the block construction used in pretty much all modern squares), and i was wondering exactly what the problems were exactly?

good point mark. the 500lb strength of the adaptor will probably go first. Regarding my estimation of 910lb for the stitching, i have 2 questions: 1. Would you say that was realistic. I am not sure what extent the webbing would be damaged by the super close stitch pattern. 2. Would you say that the strength of the bartack would be the same across the direction of stitching as the same direction? How much would it differ?

Ok, so lets break out the calculator here a second… for this chest strap mod there are 3 bartacks, that looked to be around 42 stitches each… so this would give 126 stitches. So if type-e thread was used we would have a theoretical (shear) strength of 126 * 8.5lb = 1071 lb. Take off 15% for thread wear (from sewing), which gives us a max strength of 910 lbs. That is less than half of the strength of the single layer type-17 used to make the strap: a load that I would say is fairly achievable? Hence the alarm bells… If this mod was done using FF, then we would get a junction strength similar to that of the webbing. But I’m not sure how much trust I would put in a harness system with a theoretical max load of 2000lb on the chest strap… I’d certainly prefer 2 layers.

Yes, the mod had been signed off by a master rigger. Any suggestions regarding the strength of a junction (see above post)?

Thanks very much for the info. I guess the main difference between those methods would be that strength of a bartack junction is much more directional than the "old school" method? But for things like the above chest strap and skyhook attachments etc that isn't really an issue. How would you estimate the strength of the bartacked junction? When the force is 90degrees to the stitch direction would it be aprox "number of stitches X thread strength"? How about when the stitch direction is the same as the load? (assume no point loading i.e. force and stitch direction are on the same plane)

I saw an interesting chest strap replacement on the weekend, would be interested in hearing comments/opinions on the mod… Container is a Javelin odyssey with chest rings and the strap was made from a single layer of type 17. The chest strap was threaded through the chest ring with 3 inches of turn-back. The attachment had a buffer (type 12 I believe). My initial concern was with the stitch pattern used to secure the turn-back to the chest strap: three vertical bar-tacks were used rather than the usual stitch patterns used on harnesses (although I couldn’t identify the thread type). Riggers, would you have repacked this rig? Would you be happy to make such a mod? Jumpers, would you be happy with this mod and trust your life to it?

That is probably because you are using thick thread on thin material (e.g. type-E on 2 layers of ripstop). On a horizontal-hook machine, when the needle thread is retracted, it pulls the bobbin thread upwards (and into the the fabric - providing the tensions are correct). Now since the needle thread is doing the pulling, and oriented in the direction you are sewing, the bobbin thread will have the tendency to align itself perpendicular to that, which makes the bobbin side look a little bit skewed. Try it yourself, by hanging one length of thread off a another loop - they will rest 90 degrees out of alignment. You may be able to play with the tension to reduce this effect, but the key thing is to make sure the lock-stitch is located in the right place (i.e. in the mid-way through the hole. The slight wonkyness is going to have an almost negligible effect on seam strength, which can't be said about getting the wrong tensions. Solutions: 1. use thinner thread (may not be appropriate) 2. use thicker material (may not be appropriate) 3. Get yourself a vertical hook machine (drop in bobbin style) 4. do nothing - even some the best made gear has the slight wonkyness.

Thanks for the reply. I can imagine how much of a pain in the arse that was. It is good to hear that it is do-able though. I guess that the complexity of such a mod prevents variable width double machines from being beingmade. > ...I changed the gauge to 3/8ths ... Is that for binding with 3/4 type III? What kind of spacing are people using for fully felled seams? I guess it depends on the application, but I'm using 5/16ths (basically the same spacing you'd find on jeans).

No pics i'm affraid, but it is such a simple idea the pics probably don't add anything to the description. That was my initial thought about the unshielded cable too, but not knowing exactly how the cable is routed it is difficult to argue either way. Perhaps it is partially shieled, i don't know - i'm sure someone who knows can chime in here... edit: the container I saw this on was an Atom Legend R.

> putting a grommet on the middle of the yoke That is what PDF do... a third teflon cable runs from the cut-away handle to release the connection to the slider connector bungee. From what i could see on the rig, the cable didn't have housing so didn't increase the bulk on the container....

Just a couple of quick questions re double needle lockstitch machines... The machines i've come accross (e.g. Singer 112 and 212) have the the needle seperation set at the factory. Realistically, how easy is it change the stitch spacing? Would it just require changing the needle-bar, or is there more to the conversion (i.e. changing bobbin case positioning etc...)? It even seems that the split bar models (Consew and Pfaff) are not capable of handling variable spacing: are there any machines that can do this, or is it the norm for lofts to have seperate double needle machines for canopy work and binding? Thanks, Andy

Item H5046 is what i've used in the past. the non-adjustable version is item H5040. http://www.paragear.com/templates/parachutes.asp?group=34&level=1 Edit: the listed force in the catalog are more or less the same as on the product (give or take some rounding).