BrianSGermain 1 #1 October 27, 2006 The different methods for handling turbulence depend more on the drag coefficient of the canopy as it relates to recovery arc. The smaller parachutes can maintain a high airspeed for a long period of time. This means that keeping the toggles up in turbulence is the way to go as a preventative measure, or even making smooth, coordinated turns to increase the average airspeed. This super-pressurizes the parachute, which makes it less susceptible to deformation due to turbulence. On larger parachutes, however, there is one difference. The canopy does not want to maintain an average velocity above the full flight speed. In other words, following a turn or dive, a large canopy will level off and diminish it's speed below the full flight airspeed for a short period of time. This presents an increased risk in turbulence. That is not to say that large canopies should not be accelerated above full flight speed in turbulence, just that any such maneuvers should be performed in a coordinated manner, and with a gradual return to zero bank angle so as to prevent the extra airspeed from pitching the canopy into level flight. All that being said, all parachutes will do better in turbulence if they are flown at full flight speed or higher. The problem with this kind of approach only comes when the pilot is untrained or unpracticed in the skill of quickly increasing the angle of attack to prevent the forward surge due to turbulence. A sharp application on the brakes of approximately 1/4th of the toggle stroke (regardless of bank angle) is usually sufficient to prevent the wing from surging to the low angle of attack that may open the door for a collapse. Does this change the standard procedure of flying a big canopy in brakes in turbulent conditions, yes it does. The governing dynamics speak for themselves. Airspeed creates internal pressure. Further, high airspeed creates the tendency for the wing (any wing) to remain in the back of the window and at a reasonably high angle of attack. Thus, flying at full flight will create a "dynamic stability" that will reduce the tendency for the parachute to surge forward. The key to making this effect work in a sustainable manner is to keep the speed high, which on large canopies presents an interesting problem due to the short recovery arc. There are times when the best choice is to keep the big canopies in the big containers, and wait for more favorable conditions. +Instructional Videos:www.AdventureWisdom.com Keynote Speaking:www.TranscendingFEAR.com Canopies and Courses:www.BIGAIRSPORTZ.com Quote Share this post Link to post Share on other sites
Swooopa-x 0 #2 October 28, 2006 Nicely put Brian. At 4800ft elevation and a very hot and dry climate i see a lot of turbulence. Ive been thinking about it for some time now and the : "post recovery slower than normal speed on the large wing" thought just cleared a whole lotta stuff up for me real quickly. Thank you. Not the traditional thought on the matter but a definite move forward. Tricky to implement at low experience levels but all the more reason for people to get experience... but that is another of discussion. Great post thanx again.People dont care how much you know until they know how much you care. Quote Share this post Link to post Share on other sites
chanti 0 #3 October 29, 2006 QuoteThere are times when the best choice is to keep the big canopies in the big containers, and wait for more favorable conditions. Hey Brian! When you talk about big vs small canopies, what sort of size are we talking here for big canopies? Above 200 sq ft or above 120 sq ft etc? Also, does the same apply to higher vs lower wingloading? I.e. a 1:1 wingloading on a 120 is more susceptible to turbulence than a 1:1.5? -Chanti- Quote Share this post Link to post Share on other sites
rhys 0 #4 October 29, 2006 QuoteThere are times when the best choice is to keep the big canopies in the big containers, and wait for more favorable conditions. and it'd funny ho th tandems are always the last to quit in the dodgy conditions!"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix Quote Share this post Link to post Share on other sites
BrianSGermain 1 #5 October 30, 2006 The truth is, wingloading has more to do with it than actual size. However, anything over about 135 has a large enough volume for the air to "slosh around" inside the wing.Instructional Videos:www.AdventureWisdom.com Keynote Speaking:www.TranscendingFEAR.com Canopies and Courses:www.BIGAIRSPORTZ.com Quote Share this post Link to post Share on other sites
darkwing 5 #6 November 10, 2006 Quote...However, anything over about 135 has a large enough volume for the air to "slosh around" inside the wing. If the problem is sloshing related, maybe we should baffle big canopies, like they do tanker trucks. I'm not a fan of your "sloshing" theory though. This is a discussion that would be too long for us to have here. I look forward to chatting with you. Anyway, thanks for the lucid explanation on handling turbulence, which I will pass on to newbies. -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites
BrianSGermain 1 #7 November 13, 2006 Actually, there are a number of baffle system ideas being tested, but the most significant difference seems to be created by keeping the air inside the wind with airlocks, and or flying fast to create a "seal" against the relative wind.Instructional Videos:www.AdventureWisdom.com Keynote Speaking:www.TranscendingFEAR.com Canopies and Courses:www.BIGAIRSPORTZ.com Quote Share this post Link to post Share on other sites
