micro 0 #1 June 23, 2006 got a question for you familiar w/ cross-braced canopy construction. why are the cross-bracing pieces of fabric only placed at certain locations going from the leading edge of canopy to the trailing edge, instead of all the way back? and since the cross bracing is only in certain places, how does that really render the canopy a 21-cell or a 27-cell or what-have-you? wouldn't cross-bracing that follows the whole cell, from leading edge to trailing edge create a firmer wing? i'm just having a hard time wrapping my pea-sized brain around the rationale for just having those little bow-ties placed sporadically in the cross-braced canopies... edit: is it a cross-port issue? (see pics) I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
AggieDave 6 #2 June 23, 2006 Good question. The design, as I understand it, isn't to fully create more cells, its to add structure to the wing. So what you see are the bracings going from the line attatchment points on the load bearing rib bracing to the non-load bearing ribs. The added structure gives the wing an ability to have a higher wingloading then a traditional canopy. This is due to less canopy distortion from the weight. Someday, if you have the experience, you may end up overloading a traditional canopy. You'll definately know what I'm talking about then. The spectre I jumped loaded at 1.9:1 comes to mind. Crossbracing doesn't make a canopy higher performance, it just makes the canopy take a higher wingloading. Now, the canopies on the market today with crossbracing are all high performance designs, though.--"When I die, may I be surrounded by scattered chrome and burning gasoline." Quote Share this post Link to post Share on other sites
CanopyPiloting 0 #3 June 23, 2006 The current cell structure (tri-cell) of modern cross braced canopies like the Velocity, Xaos and VX don't utilize the entire cell but future Daedalus designs will.....among other things. Quote Share this post Link to post Share on other sites
micro 0 #4 June 23, 2006 ah... it didn't even register w/ me that the cross bracing occurred (DUH!) at the line attachment points! so, if I understand better now, adding the cross bracing at the line attachment points allows you to sling more weight under a smaller canopy. it does this by adding more "rigidity" to the wing from the cross bracing, right? I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
Spizzzarko 0 #5 June 23, 2006 I would think that it would be a pack volume issue. CB canopies pack up big for their size, so if you added more material then they would pack up even bigger. Also you are only trying to keep the top skin from deforning so you don't really need a lot of material sewn to the bottom of the rib, but more sewn to the top. That is my hypothesis of why the CB's are triangular. Also, the less distortion you get in the wing the better it is going to fly. Look at the JSX pics that Jim put up, and look how little distortion there is in that canopy. I'm sure with a canopy like that an 80 series would flare out like a 150 non CB canopy but exponentially faster from a turn. I'm sure it would pack up like a 150 also! Quote Share this post Link to post Share on other sites
micro 0 #6 June 23, 2006 what's the advantage of getting rid of the stabs on that JSX? Or, perhaps the other way to ask, are the stabs redundant (wrong word?) or unnecessary on such a canopy? I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
Spizzzarko 0 #7 June 23, 2006 llok at the picture that I have below. You can se that teh CB's attach at teh line attachement point and then go off to one side or teh other. This "tricks" the top skin into thinking that there is a line attachment point on that nonload bearing rib. This creates a stiffer wing that can attain more speed because it is smaller. The more speed you have the further you can swoop. Does this make sense? Grant Quote Share this post Link to post Share on other sites
micro 0 #8 June 23, 2006 no pic attached, but that's the best explanation i've ever heard. it makes perfect sense! thanks man! edit-- it's ingenious, really! fascinating stuff! I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
Spizzzarko 0 #9 June 23, 2006 I am a computer GENIOUS! Quote Share this post Link to post Share on other sites
micro 0 #10 June 23, 2006 Dare-we-go!!! Thanks man. Who invented cross-bracing on canopies? Anyone know? I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
CanopyPiloting 0 #11 June 23, 2006 Quotewhat's the advantage of getting rid of the stabs on that JSX? Or, perhaps the other way to ask, are the stabs redundant (wrong word?) or unnecessary on such a canopy? Yes, there are no stabilizers on the current JVX or the future JSX. Less drag, more speed, more lift... Stabilizers on modern HP canopies only creates drag while they help hold the slider in the correct position for opening. slider stops near the nose and on the tail fix this problem. Again, I saw footage of a prototype canopy from another major parachute manufacturer that had no stabilizer and sail material......who would have thought? Quote Share this post Link to post Share on other sites
Spizzzarko 0 #12 June 23, 2006 PD had them in a canopy called the excalliber in the early 1990's. It was made of f-111 so it would lose it's porosity after awhile and lose performance. The jumpers of it also complained of hard openings. I think they scrapped it because it was really hard to make all the parts to it with the exacting specifications that it needed. Now with the laser cuters and cad drawings, they can be as precise as needed. I'm sure it was expensive to build then too. I also believe that there were some Russian canopies with CBing back then. The Rusians have usually been fairly progressinve with their parachutes. Grant Quote Share this post Link to post Share on other sites
micro 0 #13 June 23, 2006 QuoteQuotewhat's the advantage of getting rid of the stabs on that JSX? Or, perhaps the other way to ask, are the stabs redundant (wrong word?) or unnecessary on such a canopy? Yes, there are no stabilizers on the current JVX or the future JSX. Less drag, more speed, more lift... Stabilizers on modern HP canopies only creates drag while they help hold the slider in the correct position for opening. slider stops near the nose and on the tail fix this problem. Again, I saw footage of a prototype canopy from another major parachute manufacturer that had no stabilizer and sail material......who would have thought? hmm... i find this all so very fascinating... another question, if I may... and again, pardon if it's a bit on the ignorant side... what about stabs on medium performance canopies, say fusions, sabre2s and the like... will we see them not necessarily removed, but maybe reduced in size in deference to performance? I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
Spizzzarko 0 #14 June 23, 2006 just cut them off... I'm just kidding. The amount of drag reduction would be insignificant on the larger canopies. Quote Share this post Link to post Share on other sites
micro 0 #15 June 23, 2006 QuotePD had them in a canopy called the excalliber in the early 1990's. It was made of f-111 so it would lose it's porosity after awhile and lose performance. The jumpers of it also complained of hard openings. I think they scrapped it because it was really hard to make all the parts to it with the exacting specifications that it needed. Now with the laser cuters and cad drawings, they can be as precise as needed. I'm sure it was expensive to build then too. I also believe that there were some Russian canopies with CBing back then. The Rusians have usually been fairly progressinve with their parachutes. Grant so continuing the CB/suspension line attachment point thing... there really doesn't seem to be any reason why you would want to add a cross brace channel all the way back would you, since it would just add packing bulk, as one poster mentioned? unless of course, there is some residual strength in that that would keep the top skin from further distortion? obviously, i'm no engineer, i'm just trying to understand this shit in my head... I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
micro 0 #16 June 23, 2006 Quotejust cut them off... I'm just kidding. The amount of drag reduction would be insignificant on the larger canopies. oh fuck... should have read the whole post before taken the shears to my fusion 210 I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
Spizzzarko 0 #17 June 23, 2006 The new designs such as the Z bracing stuff may go all the way back, but the rear of the canopy is going to deflect with any flare input so why make it stiff? Maybe Jim will chime back in and correct my thinking. If we are lucky maybe Brian Germain will grace us with his input "The Zen of Cross Braced Piloting". Quote Share this post Link to post Share on other sites
Spizzzarko 0 #18 June 23, 2006 Thinking more about it, I don't think the chrod wise distortion that you are talking about is as important as containing the span wise distortion. The ribs of the canopy go from the front to the back (chord wise), and they prevent the canopy from distorting much in that direction. The Cross Braces (CB's) are preventing the top skin from distorting from side to side (span wise). If you look at a head on picture of a velocity compared to a stilletto, you will notice that the top skin inbetween the ribs on the stilletto is bulbous and distorted, and the velocity is much flatter. The top skin on the stilletto that is not facing directly up is not producing as much lift as the material that is on the top of the cell. The top skin that is facing the side of the canopy should be producing lift to the side. If you have a 100' stilletto you will not have 100' of the canopy top skin producing verticle lift. CB's keep the topskin flatter allowing more verticle lift to be attained. Quote Share this post Link to post Share on other sites
CanopyPiloting 0 #19 June 23, 2006 I leave it alone for now. If you guys get a chance to see or fly a Daedalus JVX, GLX or GLS please do. Seeing is believing... www.daedaluscanopies.com Quote Share this post Link to post Share on other sites
micro 0 #20 June 23, 2006 well, by the time I have the requisite jump experience for such a high-performance canopy, who knows what sort of technology will have surfaced by then? just amazing... I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
Spizzzarko 0 #21 June 23, 2006 "Knowing is half the battle!" Quote Share this post Link to post Share on other sites
cessna54tango 0 #22 June 24, 2006 any of you guys jump an excaliber? on of the guys at our dz has one and we bring it out on special occasion. its pretty cool. it has 3 sets of risers ( not tripple risers). one to each line set. its a 200 sf 21 or 23 cell i forget f111. it is the best flying f111 canopy ive flown. turns are made best not by toggles but by yanking on the center risers. funny stuff. also the pilot chute is attached to the slider and goes through a hole in the center of the canopy. so when you pack the thing and you take the slider up, you pull this pilot chute line through the top of the canopy and pack it. also the lines on this bastard are loooong. its like the canopy is a mile away from you. so the pilot chute line is that long also, its funny when you deploy. you pitch, wait a moment, wait a little longer, then wait just a hair more then look back to make sure the pc isnt on your back then wait just a little more then it snags teh bag off. good stuff. awesome swooping the thing, you just need to make sure you grab the right set of risers when going for rears smizo Quote Share this post Link to post Share on other sites
micro 0 #23 June 26, 2006 Quoteany of you guys jump an excaliber? on of the guys at our dz has one and we bring it out on special occasion. its pretty cool. it has 3 sets of risers ( not tripple risers). one to each line set. its a 200 sf 21 or 23 cell i forget f111. it is the best flying f111 canopy ive flown. turns are made best not by toggles but by yanking on the center risers. funny stuff. also the pilot chute is attached to the slider and goes through a hole in the center of the canopy. so when you pack the thing and you take the slider up, you pull this pilot chute line through the top of the canopy and pack it. also the lines on this bastard are loooong. its like the canopy is a mile away from you. so the pilot chute line is that long also, its funny when you deploy. you pitch, wait a moment, wait a little longer, then wait just a hair more then look back to make sure the pc isnt on your back then wait just a little more then it snags teh bag off. good stuff. awesome swooping the thing, you just need to make sure you grab the right set of risers when going for rears smizo lol! shit, just reading your post made me anxious! haha! "no, wait for it... really, it'll be there, I promise... " I miss Lee. And JP. And Chris. And... Quote Share this post Link to post Share on other sites
SkymonkeyONE 4 #24 June 27, 2006 Hey, bro. You are talking about a ParaFlite Evolution, not a PD Excallibur. The original evolutions had three sets of risers and a center-line reefing system. Later Evolutions had regular sliders. The reason for the three sets of risers was that the lines were attached span-wise. PD Excalliburs were 21-cell crossbraced canopies. The smallest one was a 120. Mine was a 150 and I bought it brand new. There were several people at my dropzone that also jumped ParaFlite Evolutions in sizes 160 and 140. Chuck Quote Share this post Link to post Share on other sites
masterrigger1 2 #25 June 27, 2006 Chuck, Danny Page had one there, but I think it was a larger one. Blue Ones, MELSkyworks Parachute Service, LLC www.Skyworksparachuteservice.com Quote Share this post Link to post Share on other sites
