SkiD_PL8 0 #1 April 21, 2005 I was thinking about this a minute ago maybe you guys can clear it up, or point and laugh, whichever you prefer. Is weight only important for initially building speed and then it hinders performance once you plain out? Greenie in training. Quote Share this post Link to post Share on other sites
johnny1488 1 #2 April 21, 2005 It's kind of complicated, and different for each canopy. I have always thought that if you could ditch your weight 3/4 of the way through your swoop, a bit at a time, I'd imagine you could go quite a bit further than with all the weight. Weight increases speed, but also increases the stall speed of a canopy. But the short answer is fat = fast. Johnny --"This ain't no book club, we're all gonna die!" Mike Rome Quote Share this post Link to post Share on other sites
DrewEckhardt 0 #3 April 21, 2005 QuoteI was thinking about this a minute ago maybe you guys can clear it up, or point and laugh, whichever you prefer. Is weight only important for initially building speed and then it hinders performance once you plain out? Higher sectional density means you'll have a higher terminal velocity and take longer to slow down. Quote Share this post Link to post Share on other sites
johnny1488 1 #4 April 21, 2005 But higher velocity increases the force your drag imposes, or something. The faster you go, the faster you slow down. Johnny --"This ain't no book club, we're all gonna die!" Mike Rome Quote Share this post Link to post Share on other sites
sirenoremac 0 #5 April 21, 2005 Its a similar issue to fall rate. Momentum v. Friction. If you keep the same profile presented to the wind while increasing your mass, you will go farther than if you were going the same speed with less mass. The friction or drag that the wind creates is proportional to velocity, and surface area (coefficient of drag as well). If these stay the same, but mass increases, you have more energy, therfore more "cutting power" through the wind. Assuming the canopy performs exactly the same, which it won't, you will go farther by having more weight. Quote Share this post Link to post Share on other sites
johnny1488 1 #6 April 21, 2005 Quote Assuming the canopy performs exactly the same, which it won't No there's the problem right there. Johnny --"This ain't no book club, we're all gonna die!" Mike Rome Quote Share this post Link to post Share on other sites
SkiD_PL8 0 #7 April 21, 2005 QuoteI have always thought that if you could ditch your weight 3/4 of the way through your swoop, a bit at a time, I'd imagine you could go quite a bit further than with all the weight. Which is exactly what I was wondering. I didn't consider the fact that losing the added mass would also decrease your momentum. I wonder if the fact that with less weight you would have a lower stall speed would outweigh the loss of momentum from dropping the added ballast. Greenie in training. Quote Share this post Link to post Share on other sites
cobaltdan 0 #8 April 21, 2005 eric butts and i hatched an idea a few years ago to build him pants with water bladders. The bladders would put an extra 50# on him. the intention was coming out of the corner he would pull the plug on the bladders and the port would be sized to drop all the water in the time of a full swoop.... akin to being in a glider and dropping water ballast. it would definitely give a swooping advantage...but is it worth the trouble. dan<><>Daniel Preston <><> atairaerodynamics.com (sport) atairaerospace.com (military) Quote Share this post Link to post Share on other sites
SkiD_PL8 0 #9 April 21, 2005 If it allowed you to add distance to a swoop yes. I am sure the PST guys wouldn't mind adding a few more feet to the world record. Greenie in training. Quote Share this post Link to post Share on other sites
raymod2 1 #10 April 22, 2005 QuoteIts a similar issue to fall rate. Momentum v. Friction. If you keep the same profile presented to the wind while increasing your mass, you will go farther than if you were going the same speed with less mass. The friction or drag that the wind creates is proportional to velocity, and surface area (coefficient of drag as well). If these stay the same, but mass increases, you have more energy, therfore more "cutting power" through the wind. Assuming the canopy performs exactly the same, which it won't, you will go farther by having more weight. Don't forget that more suspended weight means you need more lift. And increasing lift (which is achieved by a higher angle of attack at a given velocity) also increases induced drag. So you have increased momentum which will keep you swooping longer but you will also have increased drag which will tend to shorten the swoop. It must be hard to predict which effect dominates (or whether they cancel out) and that is probably why the pro swoopers are experimenting with weights. Quote Share this post Link to post Share on other sites
sirenoremac 0 #11 April 22, 2005 Yeah, it's definitely a complex issue, and one that is more than likely very canopy dependent. However I would be willing to bet that the added momentum has a greater effect than the induced drag. The real issue is how the wing's performace changes at higher velocities, and at higher wingloadings. That is bound to be the hardest thing to analyze, with the only practical option being to do so empirically. Now if canopies were completely rigid wings, we would be in much better shape performance-wise, but I imagine the openings would be slightly uncomfortable . Quote Share this post Link to post Share on other sites
Bartje 0 #12 April 22, 2005 It is not any more an exact science. One type off canopy in a difference size but with the same wl can give different results. Different kind of canopies with the same wl give even more different results in flight characteristics. Even in swooping, you will see that swoopers will take extra weight for the speedrounds but for distance they will take a bigger parachute. Even this can be discussed now since the last worldcup. Greetz B. A FreeFly Gypsy Quote Share this post Link to post Share on other sites
Rdutch 0 #13 April 22, 2005 QuoteQuoteI have always thought that if you could ditch your weight 3/4 of the way through your swoop, a bit at a time, I'd imagine you could go quite a bit further than with all the weight. Which is exactly what I was wondering. I didn't consider the fact that losing the added mass would also decrease your momentum. I wonder if the fact that with less weight you would have a lower stall speed would outweigh the loss of momentum from dropping the added ballast. It might work, but you cant use it in competition, your exit weight has to match your landing weight. Ray Small and fast what every girl dreams of! Quote Share this post Link to post Share on other sites
SkiD_PL8 0 #14 April 22, 2005 QuoteQuoteQuoteI have always thought that if you could ditch your weight 3/4 of the way through your swoop, a bit at a time, I'd imagine you could go quite a bit further than with all the weight. Which is exactly what I was wondering. I didn't consider the fact that losing the added mass would also decrease your momentum. I wonder if the fact that with less weight you would have a lower stall speed would outweigh the loss of momentum from dropping the added ballast. It might work, but you cant use it in competition, your exit weight has to match your landing weight. Ok, well it is kinda pointless now lol. Greenie in training. Quote Share this post Link to post Share on other sites
breadhead 0 #15 April 22, 2005 Quote in competition, your exit weight has to match your landing weight. Can you point out where you found that in the FAI/IPC rules?? ftp://www.fai.org/parachuting/competition_rules/cpiloting_2005.pdf I can't find it, but that could be just me. Quote Share this post Link to post Share on other sites
Rdutch 0 #16 April 22, 2005 QuoteQuote in competition, your exit weight has to match your landing weight. Can you point out where you found that in the FAI/IPC rules?? ftp://www.fai.org/parachuting/competition_rules/cpiloting_2005.pdf I can't find it, but that could be just me. It might be something the IPC slipped on and diddn't print, but discussion was made and the idea of using water for weight and releasing it during your swoop was the idea. It was quickly pointed out that it wasn't possible because the exit weight and landing weight had to be the same, maybe they forgot to put it in there written, so take advantage of it if you want. If you do it right you can get away with it one time. Ray Small and fast what every girl dreams of! Quote Share this post Link to post Share on other sites
