rigging65 0 #26 November 18, 2003 QuoteThat's odd. I've jumped a few times without brakes stowed, and each opening has been a slammer... Hmmm...could be that it's a bit out of trim and leaving the breaks unstowed just magnifies the problem? I don't know the answer to that one...I do know that I've jump FX's, Xaos', Sabres, Falcons, Monarchs, Triathlons, and at least a couple more, and not stowing the breaks has always slowed it down for me! Could be canopy dependent though.... "...and once you had tasted flight, you will walk the earth with your eyes turned skyward. For there you have been, and there you long to return..." Quote Share this post Link to post Share on other sites
breadhead 0 #27 November 18, 2003 Just don't forget PD's main suggestion: "Avoiding turbulence is the best policy."! Quote Share this post Link to post Share on other sites
sammer 0 #28 November 18, 2003 QuoteJust don't forget PD's main suggestion: "Avoiding turbulence is the best policy."! That's a good idea but I think where I jump the only way to avoid turbulence all together is to never jump. I like my AFF instructor's main suggestion better: "Just buy a really small canopy and you won't notice it as much" Quote Share this post Link to post Share on other sites
AndyMan 7 #29 November 18, 2003 I just a relatively new Stileto, and have no reason to think it came from the factory out of trim... A perfectly good explanation could be that I'm nuts. _Am__ You put the fun in "funnel" - craichead. Quote Share this post Link to post Share on other sites
PhreeZone 15 #30 November 18, 2003 Talk to Kris on this. His Stiletto only had about 200 jumps on it when it blew apart. PD found it to be grossly out of trim at that stage already.Yesterday is history And tomorrow is a mystery Parachutemanuals.com Quote Share this post Link to post Share on other sites
AggieDave 6 #31 November 18, 2003 That's for sure, PD has some of the best quality control in the industry, but shit still happens. There are sometimes also other variables invovled that may create "fun" issues. Andy, you know how to check the line trim yourself, I assume, it might be worth a check.--"When I die, may I be surrounded by scattered chrome and burning gasoline." Quote Share this post Link to post Share on other sites
rigging65 0 #32 November 18, 2003 QuoteI just a relatively new Stileto, and have no reason to think it came from the factory out of trim... Hmmm...shit happens?? Sorry, best I could do. Canopies often have their own unique temperament (even within the same model family). They're made by hand, so they're certainly not all identical, and this can lead to individual canopies having individual personalities. QuoteA perfectly good explanation could be that I'm nuts. We all are, man, we all are.... "...and once you had tasted flight, you will walk the earth with your eyes turned skyward. For there you have been, and there you long to return..." Quote Share this post Link to post Share on other sites
meatbomb 0 #33 November 19, 2003 My pet hate canopy myth is: "Rounds don't steer" [rant] BOLLARKS!!! The rounds at my club, which, yes, we still jump first timers with, have roughly a 10mph forward speed, and just as much steerability as squares. Providing the winds in in limits, you can go where you want with a round. When I'm doing student talkdown I often get the students to do a downwind, base leg, and into-wind leg, exactly like a square parachute would. There is so much ignorance out there, because most people have never even seen a round jumped nowadays... Phew...[/rant] --- Swoopert, CS-Aiiiiiii! Piccies Quote Share this post Link to post Share on other sites
trigger 0 #34 November 19, 2003 Round is sound!.CHOP WOOD COLLECT WATER. Quote Share this post Link to post Share on other sites
VectorBoy 0 #35 November 20, 2003 QuoteRound is sound! Only if the plane is on fire! and that would have to be my side of the plane , otherwise I'm gliding this one out. Quote Share this post Link to post Share on other sites
kallend 1,635 #36 November 20, 2003 QuoteQuoteThat's odd. I've jumped a few times without brakes stowed, and each opening has been a slammer... I think it depends on the canopy. I jumped an FX w/o the brakes set and it snivelled for 1000+ feet. The faster the canopy flys, the more internal pressure it has, which helps it resist collapsing, and the more lift it produces, which helps it resist collapsing. The flip side is if it does collapse, you are going faster near the ground and have less time to fix it and you may hit harder if you can’t get it re-inflated prior to impact. More speed may make turbulence feel more intense, but that is only because you are flying through the updrafts and downdrafts (or rotors) faster. Kinda like hitting a speed bump slow or fast. Hitting it fast makes it feel harder, but the speed bump is the same size weather you hit it slow or fast. So the best method to keep the canopy from collapsing is the worst thing to do if those efforts fail and it does collapse. The worst thing to do in turbulence is go to deep brakes. This lowers the internal pressure of the canopy and you are more susceptible to the canopy collapsing. You are flying slower, which is good if the canopy does collapse, but it may not have collapsed in the first place if you have been at full flight. My plan for handling turbulence is full flight until it actually begins to fold up. Then what ever is necessary to get it to re-inflate, keep it flying straight, and keep it over my head. Of course the best plan is too learn where turbulence can most likely be found and avoid those areas or don’t jump in turbulent, gusty conditions. Derek The canopy's internal pressure is the dynamic pressure at the openings at the "front". In older canopies the openings really are at the front, but most modern canopies have the openings displaced downward quite a lot toward the underside. Therefore there will be a noticeable effect of angle of attack on the pressurization, over and above any effect of velocity. Lowering the AOA to increase speed may well end up lowering the internal pressure if taken too far.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
Hooknswoop 19 #37 November 20, 2003 QuoteLowering the AOA to increase speed may well end up lowering the internal pressure if taken too far. I agree. Front risers in turbulence is a bad idea. Derek Quote Share this post Link to post Share on other sites
relyon 0 #38 November 20, 2003 QuoteTherefore there will be a noticeable effect of angle of attack on the pressurization, over and above any effect of velocity. Lowering the AOA to increase speed may well end up lowering the internal pressure if taken too far. Not true. Internal pressurization is not dependent on the size of the opening though the rate of inflation is. Increasing the freestream velocity (speed) increases the internal canopy pressure proportional to the velocity squared. The orientation of the opening to the relative wind also does not matter as long as the stagnation point is in front of the opening and not on the top (or bottom) skin. Turbulence can greatly effect both external pressures (ie. on the outside of the top and bottom skin) and the stagnation point location, resulting in loss of lift and poor handling in such conditions. Bob Quote Share this post Link to post Share on other sites
cloud9 0 #39 November 20, 2003 How about this one. Semi elliptical, tapered, slightly tapered, elliptical and full elliptical. There's really no such animal as these and certainly they don't determine the performance of a canopy. Some of the modern semi elliptical novice canopies are more elliptical then the so-called full elliptical HP expert canopies. Atair has been trying for several years to teach this, only to be ridiculed and now Aerodyne is trying to teach the same thing and even get it standardized calling it the Planform factor. But the old myths are hard to break! Quote Share this post Link to post Share on other sites
Hooknswoop 19 #40 November 20, 2003 QuoteHow about this one. Semi elliptical, tapered, slightly tapered, elliptical and full elliptical. There's really no such animal as these and certainly they don't determine the performance of a canopy There are tapered canopies and, with the new Anglefire, elliptical canopies. We don't use F-111 anymore, but the term is universially understood and it works. QuoteThere's really no such animal as these and certainly they don't determine the performance of a canopy. Planform is definately a factor in performance. QuoteSome of the modern semi elliptical novice canopies are more elliptical then the so-called full elliptical HP expert canopies. True, which is why planform is only a factor of a canopy's performance, and not the only factor. QuoteAtair has been trying for several years to teach this, only to be ridiculed Atair has suggested that the terms should not be used, but has not suggested an alternative. They even continue to use the term "Elliptical" to describe the Cobalt on their web page. Quoteand now Aerodyne is trying to teach the same thing and even get it standardized calling it the Planform factor. Planform factor is a formula to oplace a numeric value on the amount of taper a canopy has and is much more descriptive of a canopy's planform. Until it is in common use, it won't be useful. I have a formula that takes into account type of line, wing loading, type of PC, and even if the slide is collapsed. It isn't very useful unless a large number of people use it and it becomes a basis of comparison, similar to wingloading now. QuoteBut the old myths are hard to break! Especially when they aren't harmful and were started and continued to be used by the manufacturers. Derek Quote Share this post Link to post Share on other sites
cloud9 0 #41 November 20, 2003 Quotewere started and continued to be used by the manufacturers. That's so true, but why? I was told don't know the validity that this was started because of so many spin ups on so called elliptical canopies. The manufacturers were trying to find away to change peoples perceptions. Kinda like the chicken or the egg thing. It would be nice to have something valid to help in making choices. Quote Share this post Link to post Share on other sites
kallend 1,635 #42 November 20, 2003 QuoteQuoteTherefore there will be a noticeable effect of angle of attack on the pressurization, over and above any effect of velocity. Lowering the AOA to increase speed may well end up lowering the internal pressure if taken too far. Not true. Internal pressurization is not dependent on the size of the opening though the rate of inflation is. Increasing the freestream velocity (speed) increases the internal canopy pressure proportional to the velocity squared. The orientation of the opening to the relative wind also does not matter as long as the stagnation point is in front of the opening and not on the top (or bottom) skin. Turbulence can greatly effect both external pressures (ie. on the outside of the top and bottom skin) and the stagnation point location, resulting in loss of lift and poor handling in such conditions. Bob I didn't write one word about SIZE of opening. I wrote about POSITION of opening, and if you read an earlier post (#17) in this very thread I wrote about moving the stagnation point away from the opening and onto the top skin. Jeez!... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
relyon 0 #43 November 21, 2003 QuoteI didn't write one word about SIZE of opening. I wrote about POSITION of opening, and if you read an earlier post (#17) in this very thread I wrote about moving the stagnation point away from the opening and onto the top skin. Jeez! You're quite right. My mistake and apologies. Bob Quote Share this post Link to post Share on other sites
