DJL 235 #1 October 14, 2002 I'm trying to learn about canopies and figure out what aspects create which result. I was tryingt to find the inflated volume of the various canopies but there neither appears to be any info from manufacturers nor anything posted in discussion on this site. I'm guessing that there isn't a ratio that manufacturer's use (area,cell quatity:cell volume) or somethingruther... Why isn't this data available? -Doug"I encourage all awesome dangerous behavior." - Jeffro Fincher Quote Share this post Link to post Share on other sites
councilman24 37 #2 October 14, 2002 Canopy manufacturers cann't agree on how to measure surface area or compressed volume. At the last PIA meeting there were some proposals and the technical committee will be looking at this again. And rig manufacturers cann't agree on how to measure container volume. Imagine trying to get inflated volume of a canopy from these folks. They may very well be able to determine an approximation from CAD drawings but would it be assuming the panels are rigid? if not, inflated to what pressure? I don't know if any of the manufacturers have sophisticated enough models to predict the final shape in the air. It certainly isn't something that lends itself to actual measurement. It's of little interest or use to the buyers and users of parachutes. I recommend Parachute Recovery System Guide by T.W. Knacke for the truely masochistic. It has more physics and equations than you'd ever want to deal with. Give up the engineering and go skydive. I'm old for my age. Terry Urban D-8631 FAA DPRE Quote Share this post Link to post Share on other sites
ernokaikkonen 0 #3 October 15, 2002 Out of curiosity: Why do you want to know? Quote Share this post Link to post Share on other sites
councilman24 37 #4 October 15, 2002 Because he's an engineer who hasn't learned that skydiving is fun, not work! I'm old for my age. Terry Urban D-8631 FAA DPRE Quote Share this post Link to post Share on other sites
DJL 235 #5 October 15, 2002 Councilman is correct, except that for the fun part. Just trying to figure out a characteristic that would affect forward speed. This would actually just correlate to the cell height vs lenth at whatever loading. Volume could be figured out and the pressure could be, let's say, the same experienced at 1:1 loading in flight. But what's the point. Unless you're going to start making canopies using mathematical model, screw it. PEACE, Doug"I encourage all awesome dangerous behavior." - Jeffro Fincher Quote Share this post Link to post Share on other sites
ernokaikkonen 0 #6 October 16, 2002 >Councilman is correct, except that for the fun part. Yeah, who does he think he is, saying skydiving is fun??`>Just trying to figure out a characteristic that would affect forward >speed. This would actually just correlate to the cell height vs lenth at >whatever loading. There would be other factors, crossbracing being the first to come to mind. crossbraced canopies have less spanwise distortion --> smoother airfoil --> less drag --> more speed. Correct me if I'm wrong, people. Also I would imagine line material is a factor ; thinner lines --> less drag --> more speed. Then again maybe I misunterstood your whole point, me not being of the engineering type(much) Quote Share this post Link to post Share on other sites
