Widgeon 0 #1 November 15, 2005 What would cause this? I've now seen on several canopies (Xaos27 72, Velocity 84, and a VX89) once the pilot started his/her turn, the tail seemed to buffet and flutter all over the place. All three canopies were in good condition as were the lines. These incidents took place at different DZs and in different conditions. The only constant I observed would be that these pilots used alot of risering for their turn technique, and two of them were unaware it was even happening. The only thing I can think of is some kind of contradicting combinations of inputs like opposite harness to turn direction with risers. I don't know but it is some scary looking shit. Quote Share this post Link to post Share on other sites
Brains 2 #2 November 15, 2005 USUALLY, the reason is brake lines that are too short. When pulling on the fronts with toggles in hand the tail is pulled down also. Brake lines can shrink over time from heat/friction. Having not ever flown a canopy of those sizes and imagined wingloadings associated with them, i would find it hard to believe the pilot had not noticed tail buffeting. Never look down on someone, unless they are going down on you. Quote Share this post Link to post Share on other sites
dragon2 2 #3 November 15, 2005 The first thing a lot of canopy coaches do (at least the ones that've been to our dz) is freeze-frame video of everyone's swoop and look at the tail. Turns out most brake lines are too short! Velo's and Xaos's too ciel bleu, Saskia Quote Share this post Link to post Share on other sites
Spizzzarko 0 #4 November 15, 2005 This can also be caused by the brake lines being to long. Long brake lines can allow the tail to position it's self more in a full flight position when pulling on the rears. This phenomenon is called reflex. John LeBlanc informed me of this, when I was questioning him about e-lines. Quote Share this post Link to post Share on other sites
Widgeon 0 #5 November 15, 2005 Negative..........Brakes were plenty long. You can still see the bow on the vids. This isn't like the pulsing, thump, thump, thump you see on a sabre2 or something, this a weird, fierce vibration like effect. You got me... Quote Share this post Link to post Share on other sites
Widgeon 0 #6 November 15, 2005 Thats a maybe. Thanks. Quote Share this post Link to post Share on other sites
frost 1 #7 November 15, 2005 Was it consistent? I mean was it noticed repeatedly on jump after jump on the same canopies with the same type of turn? This is my opinion only and may be totally false but... May be there was some odd outside air conditions in addition to an uneven air distribution inside the canopy (especially after distorting it so much by the front riser input)? At the speed of the dive the air flowing over the top and bottom skins could couse the flatter of the non-rigid wing. It IS just a piece of fabric after all and not having full pressurization will cause it to behave strangely especially at higher speeds. Edited to add - ask them to perform a few harness turns, see if it happens again - that may help prove or disprove my theory - as the canopy distortion is minimal with harnes input.SoFPiDaRF - School of Fast Progress in Downsizing and Radical Flying. Because nobody knows your skills better than you. Quote Share this post Link to post Share on other sites
marks 0 #8 November 15, 2005 mike, nobody knows, if you ask 10 different peeps you will get 10 different answers. i have yet to see one person fix it completly. i think it was first noticed on the vx, it is more noticable on that canopy. ive heard peeps say that the velo does not do it, well it does i have seen it, just not as bad as i have seen the vx do it. it seems to usually happen to older canopies, but i have seen it happen on new ones. it seems to get worse at higher density altitude's. it also seems to get worse after the canopy has been wet. i dont think there is a ryme or reason that somone defenatly knows what fixes it for sure, maybe it has multiple causes and multiple soulutions depending on the cause. but i do know for sure, no matter what peeps tell you, i have yet to somone come up with a single cure, or any cure for that matter, to fix this problem. i have noticed that my jvx doesnt do it. but there are alot of vx's and velo's that dont do it also. but there are alot that do. and there arent many jvx's out there yet. Quote Share this post Link to post Share on other sites
swoopster33 0 #9 November 15, 2005 A few years ago a friend of mine had his velo spin up on him just after starting the turn. It was a very bad deal, he ended up pulling the reserve at about 300 feet, the reserve opened in time, the guy lived, thats another story.... Just after that happend we took the canopy (velo 75) up to alt and did some high pulls. I was filming from behind him. We were trying to get the canopy to do it again, but with no luck. However, on the video we noticed the tail flutter that you are talking about. It happened several times. We sent the canpoy and the video back to pd. They tested the canopy and could not find anything wrong with it, however the tail flutter that we saw on the vid was never explained either. I have always been curious about what would cause it as well...... Quote Share this post Link to post Share on other sites
marks 0 #10 November 15, 2005 Quotehowever the tail flutter that we saw on the vid was never explained either. I have always been curious about what would cause it as well...... ya, they all seem to do it more when at higher altitudes. Quote Share this post Link to post Share on other sites
chachi 0 #11 November 15, 2005 i fly a vx and have never had this, any links to video would be appreciated. Quote Share this post Link to post Share on other sites
CanopyPiloting 0 #12 November 15, 2005 It happens for several different reason but I will list just a few... -D lines are too long (VX & Xaos especially!) -Brake lines too short -Brake lines too long -High altitude turns at high speeds Also, X bracing does not extend back passed the D lines to the tail so there is less rigidity there. Future canopies will address this issue. Quote Share this post Link to post Share on other sites
Hooknswoop 19 #13 November 15, 2005 I've had a FX-70 do that on a high altitude hop and pop. It did it from opening until after I made a turn, then it went away and didn't come back. Derek Quote Share this post Link to post Share on other sites
Widgeon 0 #14 November 15, 2005 QuoteWas it consistent? I mean was it noticed repeatedly on jump after jump on the same canopies with the same type of turn? This is my opinion only and may be totally false but... May be there was some odd outside air conditions in addition to an uneven air distribution inside the canopy (especially after distorting it so much by the front riser input)? At the speed of the dive the air flowing over the top and bottom skins could couse the flatter of the non-rigid wing. It IS just a piece of fabric after all and not having full pressurization will cause it to behave strangely especially at higher speeds. Edited to add - ask them to perform a few harness turns, see if it happens again - that may help prove or disprove my theory - as the canopy distortion is minimal with harnes input. Not really consistent at all. Weird. I've just been watching and trying to pick apart every decent swoop I see lately and when I started really watching, I saw it more often. Once in Deland last week and twice in Titusville on two seperate loads spaced out by six hours and a different wind direction and speed. The guy on the velo sold his Xaos27 78 about six months back because it happened to him on every jump. Called it the 'death machine' because it would start buffeting so violently after the speed picked up, that he had a hard time keeping control of heading. He said it felt like it was opening again. This is the first time I've seen this happen to him on his velocity, but he wasn't aware of it, just said the swoop felt kinda slow to him. Control inputs might be it. The guy I was talking about uses almost all riser in his turns as he feels he can regulate the dive better than with a harness turn. You may be right. The guy he sold the Xaos to jumps it here regularly and says he's got no idea WTF said velo pilot was talking about. I'd like to hear some more about this "reflex" theory. How dangerous can it get? Is it an indication you've done something wrong or just maybe a trim issue? I'm stumped. Quote Share this post Link to post Share on other sites
Widgeon 0 #15 November 16, 2005 And you've probably already been jumping one for a year! Quote Share this post Link to post Share on other sites
murps2000 86 #16 November 16, 2005 Check out the video of the Ranch pond swooping comp from 2001 and you'll see at least one example of it. Can't remember exactly where in the video it is but it's there. Quote Share this post Link to post Share on other sites
grega 0 #17 November 16, 2005 take a light piece of paper or ZP fabric put out the window in the moving car and tighten the front edge with fingers (pulling apart, not too much so you don't rip it). the paper that is trailing will flatter the same as the trailing edge of the canopy does. It hapens because the paper fabric isn't tight over whole surface and it just "folows the turbulence" the front edge or whatever is causing it. Same with the canopy if your trailing edge isn't tight (isn't producing any lift and/or is loose - lines too long) it will flater in the canopies turbulence. If you tighten it (pull the control lines) it will stop... what is causing this? i noticed it when pilots were landing with rear risers and the toggles had alot of slack so while they puled on rears, trailing edge was completely loose and started flattering..."George just lucky i guess!" Quote Share this post Link to post Share on other sites
