JohanW

What Kallend called deviatoric distortion. Johan. I am. I think.

I appreciate your opinion, and it applies to some possible formations. But to say the 71-way could not ever have been a formation, based on the spacing only, is not what I would want. If the spacing had been perfect, and if the grid would have worked, that would have been good enough for me. That's my opinion. There is something to be said for (and I included this possibility) requiring grips for any official record. You will then need something else for bigways. Effectively, you (Robi) also don't want to allow dimensional distortion. That means either taking grips, so you're limited by length of arms (with or without extension noodles), or introducing calibrated distances. Johan. I am. I think.

Fundamental questions: Do we allow angular distortion? Do we allow dimensional distortion? Do we allow crooking (bent lines) in the formation? Do we allow skewing in the formation? Do we want criteria based on calculations at all? When I find the time, I may draw up some examples. I think Robi has a point that one ought to be able to look at a photo of a nice formation and say 'they got it' but frankly, I don't see how you can keep that objective with no contact formations. James might have something with the lines, but what would you call acceptable and what is over the line? James, what is your idea exactly anyway? It may have limitations or not be finished yet, but care to throw it out? Johan. I am. I think.

The calculations aren't that hard, and besides your average laptop computer has a ridiculous amount of computing power anyways. I do not think this will be a problem. Image pattern matching for automated picking out of heads might be computationally intensive, I don't really know about that actually. I was referring to the task of fitting the grid over the formation for Kallend's method. I'd think that's quite an intensive task. Your method does. Kallend's does not. Hmm interesting point... again, we'll have to see what it does for the numbers once we have the app. I'm thinking that if the front diagonal is bent, the rms of the horizontal lines will be higher as everyone will be flying closer together, so that should work out, right? Actually, I think the RMS of one of the diagonals is going to be higher, not of the horizontals. But I think you have to decide if you want to allow for it at all. Personally, I can imagine skewing and crooking that does not make the formation look *very* bad. For now, I'd like to focus on the criteria itself, and not start compensating for things. We can always test on photoshopped formations, so you don't need to take marginal photos and go compensating. (That's what I'd like for now. Feel free, of course.) Johan. I am. I think.

More results from the Dutch jury. Wing diamond normalised split diagonal overall sigma .1683 Base diamond normalised split diagonal overall sigma .0998 The base gets under 10%! Bases rule too!

Honestly Prof, I'd be a lot more impressed if you attached a photo of the formation.

Allowing angular distortion makes sense. I would propose we accept that as a given that any set of criteria must satisfy. Costyn's distancing does this, taking grips (noodled or not) does this, diamond grids allow for this, square grids do not (a rectangular grid would). Allowing dimensional distortion also makes sense. I would propose we accept that as well. Costyn's distancing, when normalised, complies, taking grips complies, both square and diamond grids allow for this. What is a 'best fit grid' ? I'd say the one, allowing for both kinds of distortion, that offers the lowest RMS error. (BTW, RMS stands for root mean square; it is basically averaging absolute errors, on steroids.) Fitting that grid sounds like a job a computer should do, really, though you could project a photo on a wall (so you can vary the size of the formation a bit), overlay an iron wire grid that can be flexed (to adjust the angles), mark the four (you only really need three actually, for any formation) corners (they define the grid position, size, orientation etc.) and go back to the computer anyway for the calculations. (You probably still have to point out the 71 heads in the picture to the computer manually. I don't see this as a problem.) But the programming from that point is going to be a lot easier and shorter and the calculations are over a lot quicker (I don't know if that would actually be a bottleneck when using it for debriefs, but if we can prevent having to have a supercomputer for realtiming this, let's do so. it means someone gets to play with a lot of iron wire as preparation, but if we can play with spray paint we can do this*). Calculating an RMS error in the end returns a value that is probably best expressed as x% of the size of one side of the diamond used. So normalising again, to prevent having to go back to calibrating distances. We then get to haggle over what value would be acceptable.

So, what was it? Or would it possibly have been a matter of sending a photograph that is just so stunning there's never going to be any discussion? How does one contact Guinness? James, Jeff, someone? Johan. I am. I think.

And look at that! They would have had no grid discussions !?! Why don't we qualify as airplanes BTW? We got wings! Sure, we're gliders, but gliders are aircraft too! (Don't let them hear that, though. ) Johan. I am. I think.

The averages should have been the same. More or less. They are not. A picture taken from a different angle (to the side or from behind or in front) should not affect the diagonals should it? They will become steeper (from the sides) or wider (from front/behind) but relatively they should stay the same. If you move away from the center of the formation, at a constant height, in the direction of either the / or the \ diagonal, that one will have a constant spacing. The other one will get tighter. Effectively, you are rotating the formation with regard to the camera. Take a look at Scotty's debrief photo. It's definitely taken from an angle. That's a good one to do some calculations on BTW, I'm getting on that. Johan. I am. I think.

Would you consider French canopies? Parachutes de France actually has some decent models these days. Do not get a Springo, but an Electra is a nice canopy. Have heard (second hand only) good things about the Electra XS (which is an entirely different animal). Johan. I am. I think.

You mean there's a record up for grabs? Would four Otters count? They were in the same frame on, oh, any number of photographs. Johan. I am. I think.

OK, the results of the jury are in. The wing 9-way diamond scores 2.7331 cm horizontal avg and 1.7208 cm diagonal. The base 9-way diamond scores 1.8429 cm horizontal average and 1.5585 cm diagonal. I have calculated as if these were two distinct formations; theoretically, they should have the same values for those numbers but they obviously do not. Maybe the infamous aspherical lens distortion? Just angle differences? Wing diamond normalised horizontal sigma .0416, diagonal .2544, overall .2213 Base diamond normalised horizontal sigma .0737, diagonal .1130, overall .1045 So for these two formations, overall standard deviation of the normalised distances seems to give a usable number. The cut-off value would seem to be around .15 to .20 (or would it still be reasonable to say the wing diamond 'got it' ?) Horizontally, they are not even half bad, but this does not affect the diagonal score really. That's good. I think this method starts working from 5 flyers; I have no idea yet [how] the cut-off value increases with the number of jumpers. And what this really needs now is an interactive computer program where you can drag the flyers around and see what the values do in (almost) real time, because I have no idea how the calculated value would be for perfect but skewed formations, crooked ones, indistinct blobs or other abominations. That may be the quickest way actually to determine if this method is valid, robust, accurate and generally correct and useful. Also, testing on some of those formation photos in an earlier thread might not be a bad idea. I'll see if I can find that thread. Do not expect results on that this year .. A possibility would be to split diagonal distances into / and \ for normalisation. You could calculate away quite some skew that way, I think. If all you have is a picture taken at an angle anyway, you might want to do that. Johan. I am. I think.

As long as we don't forget it, can we for now disregard it? As well as the 3D vs. 2D complication? For now, I would rather have criteria that work as intended, no false positives, no false negatives, on a slightly simplified model of the formation. Johan. I am. I think.

Not yet, need a little more time. But I am at the office, so expect results soon.

If you have mathematical criteria to apply to a 2D map of a formation, I think you can extend them to work on a 3D map. Measure distances in 3D, then start normalising, averaging etc. like you would in 2D. If a formation is skewed, it may still satisfy some criteria almost as well as when it would not be. Other criteria may not have this property. Skewing the grid may be defined as acceptable, just as rotating and scaling need to be (see above). I think there can be formation attempts that do not use predefined criteria, but you'll never fly an accepted, official record that way. If that's not what you want anyway, no problem. Sometimes you do, sometimes you don't, I think. A friendly fun 4-way RW counts points until separation instead of in 35 seconds, doesn't it? Johan. I am. I think.

I don't think they'll work either, at least not for 100-ways. But they might be workable for 4-ways, or highly skilled 9-ways. There's no reason to rule out something that doesn't work for all sizes if it works for some sizes. I say we try it before we dismiss it. Walmart, Walmart - what's the Euro equivalent of that? We'll figure something out.

You mean exactly like an RW formation? Not to mention CRW, where you can do this to somebody else? They would not need stretch, you just don't fly them at full extension. (They might need to be longer than a foot.) That's why you take foam and not bamboo. You could have them break when stretched - but make one mistake and your grip is gone, you've just taken out the entire formation for the remainder of this jump. I don't know if the flappage would actually be a problem. Maybe for taking grips, but I suspect not for holding it. RW experience, skills and mindset really, really help in flying this thing I think. I'd like to test it some time, see what it does in the real world. Johan. I am. I think.

So, how does one judge a wingsuit relative work formation, resulting in a binary outcome - we got it, or we did not. The grid idea as used in Elsinore needs a lot of computers, time and people to implement (channelling Jeff here, not necessarily correctly) and, with current skills, allows for a maximum formation size of about a 16 way diamond. For bigger formations, say a 100-way wedge, it's still very usable for debriefing purposes, I think, but, again with current skills, you'll never get a completed formation. This need not be a bad thing; skills improve. An alternative is to put a diamond of appropriate size over each participant and see if the formation blots out all the sky behind it (assuming ground-to-air). This allows for crooked, skewed formations, which may or may not not be desirable. Then there is the method with everyone touching a grid, be it chessboard or diamond style. That way madness lies, I have to give Yuri he showed that, when taken to the extreme. And you have to account for extremes. Or we could go back to requiring grips. And to a 5-way world record. Not discounting the possibility. But imagine the effects on the glide ratio and the safety of the formation. Yuri would have a stroke because of the first, and I would not be in it because of the second. There's things to be said for either of those. It's extreme, but it's clear cut. You might allow grips on soft noodles. Extend them a foot from hands and feet and allow the formation to skew and breathe just a little. Then separate and deploy .. can you build a formation with feet noodles only? Actually, yes, you can, but I still worry about the effects on the safety of the formation. No idea to what size you could (safely, or at all) build with current skills. A possibility I threw out in a private conversation earlier is requiring grips for official records (I have a hunch the FAI might accept that) and judging bigways subjectively. Score Elsinore 8.8 out of 10 and accept it'll never be an official record. Personally, I don't like it. But if it's the only way of flying a 100-way, it'll do. I like flying bigways, even if only for the pretty pictures. Then there's Kallend's idea: I would actually really like to hear him explain in layman's terms what this means and just how easy this is. Calling John Kallend! Discuss .. Johan. I am. I think.

And thank you, and congratulations, on what you achieved. It was great to be a part of. So, we did not complete the formation in strict adherence to our stated objective. In my opinion, we do need a different objective for next year, because this one is unattainable. I have long let go of the stated objective (about Monday afternoon of the event

Mark himself told me he needed the experience as an organiser/plane captain. Note he did not himself fly base for his sector. Next year, he may be free to do what (I think) he does best in the world. This year, he was not. (Mark, if I misrepresented what you told me, please hit me in the head and correct.) Johan. I am. I think.

I fly a Triathlon. Which doesn't mean I don't consider myself a high performance pilot. And aren't they all fun jumps? Which does not mean you can't enjoy doing *your* best. I do enjoy the occasional jump with a pocket rocket, or the occasional jump where the result counts, too. But if *your* jumping works for *you*, and you consider me pushing the envelope, that's all good.

Wingloading helps to turn diving twists into a spinning mal. But planform is a major factor as well. You really want to avoid the more radical elliptical designs just yet. I have insufficient experience with Sabres 2 to unrecommend them on the basis of being elliptical, turn-happy, dive-happy suicide machines. I do feel they have a recovery arc that is longer than would be appropriate for you at this time. I (heart) Silhouettes myself for people with your amount of experience (including myself at that time); something like a 210 sounds about right for you. Your friendly online canopy nazi (who has never seen you jump

She hasn't mentioned that to me, and she does sometimes like me to pack for her. Is this recent? She does have a Mirage G4, according to her profile, ISTR her rig being the one with the bloody split D-bag and the sewn corners but I'm not all that familiar with Mirages. Do they have a square bag (seen sideways) you can pack grommet to pin without problems? Doesn't seem to fit with the split bag; it's split because it fits the container shape that way. I know my Atom doesn't have a square bag. I have a vague recollection of I think Espen (haven't read from/about him in ages ..) making a custom rotated bag for his Atom; I know I'm not packing my rig grommet to pin because of the bag shape. Well, and because I don't have any problems anyway

No. We play well with others. Johan. I am. I think.