ruthers

An eagle films the world below. (Not DSE :-) ) http://www.photographybay.com/2013/09/30/watch-this-video-of-an-eagle-with-a-gopro-strapped-to-its-back/ I wasn't sure whether to post this here or in videos - but that area seems to be for uploading, I'm just linking to what a friend sent me.

If the rod section can be built instead with a short section of double surface, then most of the weight and bulk advantages might be gained. A main canopy with half the bulk (and cheaper to make since there is a lot less fabric!) sounds great, bring it on!

I'm not a fan of the typical snag magnet gopro mounts. If people are going to use the camera, it might be better with something like this: http://www.chutingstar.com/newgear_en/square-one-gopro-top-mount.html Or perhaps better would be a mount more on the front of the helmet, perhaps shaped like a truncated cone/pyramid, with a recess for the camera to velcro into, with the back face of the camera almost against the helmet.

Were the main risers loaded with body weight during the "table test"? Perhaps the extra friction at the left side 3 ring loop when the risers are loaded, and the resulting increased friction inside the cutaway cable housings would then require more force to achieve left side riser release than would be available through the backloading of the collins lanyard by the red thread-attached skyhook/PC which you described.

The RWS RSL pin can certainly bend too. I was quite surprised to get a call from the guy packing my Vector 3 (with skyhook), saying that the pin was bent and he has to replace it. I had looked at the pin and reserve closing loop the last time I jumped it and didn't notice any bend. I haven't seen the bent pin yet (the replacement is still in the post) but will be interested to see it. I really can't imagine how it got bent. I haven't been jamming against doors or snagged it, but somehow it got bent. Bit of a worry -I guess the reserve closing loop must have been close to breaking point.

what was the nastiness of the seated harness? Do you mean in terms of getting the deployment bag out, up and away cleanly, or nasty in terms of forces on the body?

That's why I proposed the idea. I guy on the paragliding forum has been trying it out for a couple of years, slightly different system but same principle. I also thought that one problem might be that with toggles normally stowed with the "point" (which is set into the brake set eye on the line to give deployment brake setting) upwards, the anti twist housing would only start at best a toggle length above the 3 rings (and might still get twisted up. But if the point of the toggle faced downwards, the housing could go closer to the 3 ring.

Has any manufacturer ever tried to make risers which could prevent the brakes locking due to line twists? I'm thinking in terms of a system like this: longer risers, with built in hard housings for the brake lines. The long risers (how long would be necessary to ensure that,say 90% of cases of line twists would be on the risers (where the hard housings would keep the brakes running freely) and not on the lines (where the twists lock the brakes and result in loss of control of the canopy)?) would ensure that the twists happen on the risers and not the lines. The brake set cateye and toggle stowage would need to be down at the bottom of the riser, closer to the 3 ring. Of course, a longer lower control line would be necessary to account for the lower installation of the brake set loop and toggle stowage.

Thanks John.

Do you mean that to achieve 75 pounds of extraction force, with a Cd of 0.65, a PC with 25 square feet of surface area? What airspeed and density was assumed for this calculation?

10% seems like a very stringent requriement. If a PC could only make 10% more than the weight, that would mean that once the bag was free of the container, it would only accelerate away from the jumper at 1/10th of a G. If the distance to line stretch is say 3.5m, and you want to achieve that distance in say 1 second (is that reasonable/too short, too long? How much of the TSO 3 seconds is typically taken to go from a taut PC bridle to full line stretch? ), the bag needs to accelerate with respect to the jumper at about 0.7G. So the PC would need to be pulling the weight of the bagged canopy plus 70% to achieve this. Doesn't that mean that any PC able to pull enough to acclerate a bag fast enough to get it it line stretch in a reasonable amount of time should easily extract a bag even with bag weight plus friction of say 50%-70%? Or did I misunderstand John's intent with the test? Cheers, Hamish

Hi Jerry, Yes, I did watch the youtube and looked at the photos. My sincere apologies if my questions have offended. Perhaps by phrasing as questions, it might have seemed critical. I'm not trying to criticise at all - I am very impressed by the simplicity and apparent good function of the system. Just asking the questions as I was visualizing the function to understand it all. Once again thanks for the offer and the responses. Hamish

what happens if a situation as may have happened with the tandem fatality a while ago, where on a low pull, the cypres cut the loop, and the main opening shock may have ejected the reserve freebag and back loaded the skyhook? i.e. if the pull on the reserve bridle is from the freebag side and not the pilot chute side, will the pin disengage or will the pin perhaps get bent? A convoluted sequence I guess, but Murphy's law has a habit of lurking. Without a collins lanyard, the above would mean that the reserve freebag would not be released from the RSL, which is still attached to the (not yet cut away) risers. Perhaps that's a better outcome than a 2 out anyway?

Paul, thanks for the explanation. At first when I read your post, I was thinking that having the ring around the closing loop could mean the closing loop could get broken by a pull on the RSL (such as from a failure of the RSL side riser/3 ring), releasing the reserve into what is potentially still a mess. But then I realised that of course the RSL pulls the reserve pin anyway, which is why there is the need for a Collins Lanyard type of function. Will be interesting to see how the new Strong Tandem system's MARD works, as that has been advertised but I haven't seen details yet.

Just reread this thread, if anyone is still interested to discuss: is the RAX pin disconnect sensitive to the direction which the pc/bridle pulls? I'm not sure what would happen if the jumper has a total (caused for example by being unstable and getting main pc bridle wrapped somewhere), pulls their reserve ripcord, the reserve pc launches but again due to instability the first pull on the bridle pulls to the right, pulling the tab out of the pocket. Would the bridle now be locked to the RSL, which is stuck to the risers and hence container since the main is still closed? Perhaps I misunderstood the sequence of the RAX opation. Cheers, Hamish