CoolBeans

Do you know if iFly at Union City (N Cal) is opening anytime soon?

Would you know how much actual force is pushing down vs how much is pushing up?

I think that's a guy actually, long haired guy rolling pink rig.

How does one clear the stabilizers? Honest question.

Check this very useful article: It depends on you, your age, agility, the type of dropzone you jump at etc. I'm still on big canopy. One time I went to brand new dropzone with new to me landing pattern and jumped unknown, rental gear. I messed up the landing badly. Well, it was on 210 canopy so after all I had sore butt for a week and sore ego. If I had done that on smaller canopy I would have been in much worse shape. Don't rush anything in skydiving, for real mate. What's more important is how many landings in variable conditions one had, like 0 wind, strong wind, cross wind, landing with many other people around you on final etc etc. It's better to experience all the first things and errors on bigger canopy than smaller. It's better to face plant landing on bigger canopy than smaller. Have you face planted yet? :) Have you had other people cut you off on final? Have you landed still or backwards on final? That happens if wind is very strong and you get 0 or close to 0 forward speed on final. Have you landed different patterns, have you landed on different dropzones? Have you had any experiences that scared you or other jumpers around you yet? Have you landed down wind yet? Have you had people overtake you in the pattern? Have you landed off dropzone yet? Do you know good and bad places off the dropzone to land if shit hits the fan? Have you ever had to abort or modify a turn in the pattern because you noticed other people last moment? There are many things that don't happen normally but they do happen occasionally. It's best if you are familiar with these so that way you can operate with 100% focus and 0 panic. Everybody makes mistakes, it's best to experience them in more favorable environment and walk away from them with scratches and bruises than broken bones. If you keep jumping, you will land down wind sooner or later. You will be in busy pattern once and see people too close to you on final. It's likely you will face plant one day etc. etc. Again, best to get familiar with all odd scenarios on bigger canopy. Everything is fine now, you repeat same or similar comfortable landing in comfortable conditions. There will be that one day when something will happen and you want your brain trained and prepared for that. Maybe you will track too far and can't get back to the dropzone, maybe there will be other people close to you in the pattern and you make the turns late or so many other maybies. I don't recommend you do anything sketchy on purpose. I'm just making you aware that odd things happen and every time you experience those, you learn and you open little doors in your brain that make you more humble and more prepared skydiver. Also, if and when you decide to change the canopy, I recommend you do some hops and pops first so that way you are alone in the pattern and don't have to worry about the traffic. That will help you get used to the way new canopy flies in safer environment.

I would imagine canopy manufacturers know very well what kind of forces act on slider during the deployment. Would you know if there's any publicly available research or publications about that? Approximately, how big is the force pulling slider down during canopy inflation?

https://uspa.org/downloads/minimum-age-to-skydive#:~:text=For all U.S. tandem makers,18 strictly the minimum age. Go to that one drop zone!

Or you could do some base jumping :o By the way, do non-USPA drop zones allow younger jumpers?

Does anybody have old, unused risers, preferably 23 - 25 inch long that they would be willing to donate for the project? I'm building a prototype.

olofscience has good ideas and understanding of the problem. Let's say 5 m stretch is the value that makes real difference. I'm an engineer. I'm asking if 0.5 m makes a difference? What about 5 cm, does that make any difference? Many glorify Dacron lines. I read different values for how much Dacron stretches, but let's say Dacron can stretch up to 10% and average line length is 120 inch. That gives us 12 inch of stretch. If shock absorbing risers could stretch by 12 inch and you used Dacron lines, you would end up getting 2x benefit of Dacron lines. Now, any of you tell me if that's worth the hassle or not. There are many other aspects one could look at. Have a look at these diagrams of soft / hard openings: https://www.pcprg.com/g-forces.htm . Let's think out loud, if one was to use shock absorbing risers + Dacron lines and had a hard opening. At around 6Gs mark the chart would be flat (absorption of energy into lines/risers) for maybe 100 or 200 miliseconds. Then once lines and risers reach full stretch, Gs would keep growing and get absorbed into the jumper's body. My question is, would you rather get hit with 12 Gs in belly to earth orientation (left picture) or hit with 11 Gs in potentially straight up position (right picture)? Would that extra 100 - 200 milisecons delay at 6G be enough to put jumper into upright position without braking their neck immediately and better prepare them for incoming stronger hit? Would it make a difference between broken spine vs sore neck? Those are all of the questions I'm asking myself to understand if it's worth pursuing this idea.

You guys are talking about completely different solutions to hard openings that are not related to adding shock absorbing component to risers or harness. They are all valuable but please keep them in separate topics. Otherwise it gets difficult to follow the discussion. Also, remember that multiple solutions can exist at once, they are not competing against each other.

Do Dacron lines affect performance of the canopy in a noticeable way? Let's say I'm talking about Sabre 2 190 sqft. How different would fly Sabre 2 190 sqft with Dacron lines vs one with HMA, Vectran or Microline? Also, can ANY canopy be relined with Dacron lines?

That! You just need to push through it, it gets much better and easier with jumps. You can always do coach jumps too - that way you have another person with you on the jump.

I had a shoulder surgery, torn labrum. Got 6 bolts into my shoulder. Bioabsorbable Suture Anchors to be specific. The shoulder is like new now, I'm jumping and I don't need no braces. I retained 100% of the mobility and range. But I took that project very seriously, I made sure I had decent insurance, extra cash on a side, I picked the doctor, the hospital, I picked the rehab center and was following the program very religiously. I was back in the sky about 10 months after the surgery. Good luck, it can be done.

If a friend of mine wants to do the tandem - what criteria would I have to fulfill as a fun jumper to be around and jump together? Just curious, don't judge. It can be either with another video jumper or without them. Either way.

he didn't even bother to buckle up!

That's what I found so far, simple review from somebody who did 2 jumps on it :)

It sucks a lot the gear was stolen. I just thought the first picture was really cool!

Guess what, Asians make even more than Whites. And Hispanic make even less than Blacks. https://iwpr.org/publications/gender-wage-gap-2018/ Why is nobody crying about that?

What if I add 2 inch fold of the webbing around the breaking point, so once it breaks the risers are still usable? That's exactly what I'm explaining from the beginning. Think of "Shock absorbing risers" just like regular risers that break at specified load, except, they can break multiple times at staggered loads and you can still land them afterwards.

I figured I could do some basic testing in garage conditions. I would need to get a hold of some old 3-ring system and some old risers that I could reuse to make a prototype. Does anybody know what's the easiest/cheapest way to go about obtaining old/used risers and 3-ring systems? I'm in California / Bay Area.

Let's start from the basics, the source of the problem is how many Gs are experienced by the jumper. Simply let's say, <6G the opening is ok, 7G - 12G would be pretty hard, 13G+ would be life threatening. That's just rough guidance. In any case, we are dealing with abrupt slowing from approx 120mph down to approx 20mph, that's a difference of 100mph that needs to be dissipated. If the parachute opening completes within 0.3 sec it will put 15Gs on the jumper. If we can do anything to extend that process to e.g. 0.6 sec it will put 7.5Gs on the jumper. That's what's most important here. If shock absorbing risers can maintain the process of tearing for the duration of only 0.3 sec they will eat up 7.5Gs that jumper won't experience. Or in other words, they will make jumper experience 7.5Gs over 0.6 sec instead of 15Gs over 0.3 sec. As a side note, 0.1s opening would take 45Gs and 0.2s opening would take 22.5Gs. 22.5 is better than 45, ain't it? Dacron lines do pretty much the same thing, they flex extending the opening duration and eat up Gs. Advantage of the shock absorbing risers is that during normal operation they don't flex like Dacron lines do, they only flex on super high Gs

Uneven risers in case of hard opening are pretty much guaranteed. However, I bet anybody who went through serious hard opening would have traded that for uneven risers. Uneven risers leave pilot with two options, either pull one riser to make them even or cutaway. I suspect one could also correct uneven risers with toggle input, obviously that depends on how badly uneven the risers would be. Small improvement to help with uneven risers would be to put flexible element inside the folds so that way after stitches are torn, the flexible part would still maintain original riser length. The outcome would be same or very similar length risers but flexible. Although, they wouldn't flex all that much as normal canopy flying wouldn't put 7G+ forces. I've done some simple calculations: a = 6G m = 200 lbs ; F = 5339 N m = 180 lbs ; F = 4805 N m = 160 lbs ; F = 4271 N m = 140 lbs ; F = 3737 N m = 120 lbs ; F = 3203 N m = 100 lbs ; F = 2669 N ____ a = 8G m = 200 lbs ; F = 7119 N m = 180 lbs ; F = 6407 N m = 160 lbs ; F = 5695 N m = 140 lbs ; F = 4983 N m = 120 lbs ; F = 4271 N m = 100 lbs ; F = 3559 N ____ a = 10G m = 200 lbs ; F = 8899N m = 180 lbs ; F = 8009N m = 160 lbs ; F = 7119N m = 140 lbs ; F = 6229N m = 120 lbs ; F = 5339N m = 100 lbs ; F = 4449N ____ a = 12G m = 200 lbs ; F = 10679N m = 180 lbs ; F = 9611N m = 160 lbs ; F = 8543N m = 140 lbs ; F = 7475N m = 120 lbs ; F = 6407N m = 100 lbs ; F = 5339N As you can see, the forces are all over and because of that shock absorbing risers would have to be rated for very limited weights. Shock absorbing riser rated at 5339 N would tear for 100 lbs jumper at 12G and for 200 lbs jumper at only 6G. The important data points are around how many Gs does hard opening vs normal canopy operation put on the risers.

I've been thinking of simple riser design to absorb some of the hard opening energy. In a similar way that crumple zones work in the car. Those zones could be for example: 7G, 7.5G, 8G, 8.5G, 9G, 9.5G, 10G etc. Below is my simple prototype, in real world, using modern technology, those zones could be integrated into the riser (webbing) itself. I believe professional name for that is tear webbing or shock absorbing webbing. Disadvantages? crumple zones could break unevenly which would result in uneven lengths of risers crumple zones could break when not desired, for example during high performance low turn after hard opening crumple zones would leave jumper with extra long risers which, depending on design, might not be landable anymore and may require cutaway crumple zones will have tolerance that will change over time; ones that initially were designed to tear at 7G after years may tear at 6G which could happen unexpectedly during high performance maneuver in order to operate properly, those risers would have to be rated for very limited body weights, e.g. 150-155 lbs only torn risers would have to be replaced which is extra cost for jumper Advantages crumple zones should not affect base riser strength crumple zones would absorb some of the hard opening energy risers with crumple zones should be very similar to regular risers and wouldn't require any other equipment modifications risers with crumple zones should behave exactly like regular risers in < 7G conditions; no extra flex should be observed risers with crumple zones could potentially be beneficial in fast spinning malfunctions as they would lengthen the risers making the spin slower What do you think? I think some other industries already use similar approach, e.g. Petzl ASAP`SORBER https://www.petzl.com/US/en/Professional/Mobile-fall-arresters/ASAP-SORBER _________ Assumptions hard opening that would require extra shock absorption is above 7G any regular canopy maneuvers are below 6G crumple zones should preferably be numerous and short, as short as possible ; that way if 1 zone tears at undesired moment, it shouldn't cause too much damage

Ok, so now I'm the softie then.