Subject: Re: Flow Form enlargement Message-ID: <16923@umd5.umd.edu> From: jeffy@syrinx.umd.edu (Jeffrey C. Burka) Date: 11 Nov 92 03:28:53 GMT Organization: University of Maryland at College Park In article <1992Nov6.102854.8017@jarvis.csri.toronto.edu> irving@white.toronto.edu (Irving Reid) writes: >I've had a close look at the big flowforms Art Ross from Vancouver >builds. He has built a few in the 500-1500 square foot range, along >with smaller sizes. 1500 feet^2? That's a BIG kite. >The main change is to make the airfoil thinner and move the high point >forward. There's not a lot of science necessary; flowforms are >relatively forgiving about cross-section. Guessing from only having >seen his kites, the body proportion is roughly 3-4 units span to 5 units >chord. He also uses longer "legs" than the book plans show, partly for >stability and partly for effect. By legs I suppose you mean the keels? 5:4 sounds like most of the flowforms I've seen; mostly but not quite square. (sort of like a TV screen) >Cell width (the spacing between ribs) doesn't scale linearly for either >flowforms or parafoils. For 30 square feet it shouldn't be a problem, >but for larger foils you need to put the ribs proportionally closer >together to get the cross-section to keep its shape. As I recall, the 252 has 8 cells. I know everything up to and including the 30 have 4 cells. What about the 60? >For 30 square feet, try a cross-section about 12(of the chord) deep, >with the highest point maybe 10back from the leading edge. This is a >fairly radical departure from published plans, but then the published >plans don't fly quite as well as one would like. Sounds like a *very* radical departure. In fact, if memory serves (I don't have a copy of the book handy), isn't that more like the Flow Form II (Steve Sutton's design) in Margaret Gregor's book, as opposed to what she refers to as a better kite, the "Flow Form I"? Any hints on venting? Thanks for all of your suggestions. They've been quite helpful. I'm still at the "what am I getting myself into" stage, but I'm still eager to try building the kite. Unfortunatley, it'll be anothe 2 or 3 weeks before I can order the fabric. Got any suggestions (Pat, are you out there? This means you!) for dealing with, laying out, cutting, etc., the large pieces of fabric for the top and bottom of the kite? I mean this in terms of laying it out, marking, cutting, etc. I'm not really used to huge pieces of fabric, but I have no interest in a little flow form...;-) > - irving (Hey! I finished my Masters, Moved, and got a New Job!) - Congratulations! Jeff -- |Jeffrey C. Burka | "Show what you are / Be strong, be true | | | Time for you to / Be who you are." | |jeffy@syrinx.umd.edu | --Happy Rhodes | = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Subject: Re: Flow Form enlargement Message-ID: <1992Nov11.112140.1822@jarvis.csri.toronto.edu> From: irving@white.toronto.edu (Irving Reid) Date: 11 Nov 92 16:21:40 GMT jeffy@syrinx.umd.edu (Jeffrey C. Burka) writes: >In article <1992Nov6.102854.8017@jarvis.csri.toronto.edu> irving@white.toronto.edu (Irving Reid) writes: >>... He also uses longer "legs" than the book plans show, partly for >>stability and partly for effect. >By legs I suppose you mean the keels? Sorry, I should have been more precise. I meant the extensions off the back of the kite, like where the legs are on Martin Lester's Legs flowforms. Tails might be a better name, but they're not really that either. On the other hand, the keels on the big flowforms I've seen are also modified; like the cross-section, they get thinner as the kite gets larger; perhaps 150f chord or so. I'm kind of guessing at that, so don't bet the farm on it. >>Cell width (the spacing between ribs) doesn't scale linearly for either >>flowforms or parafoils. For 30 square feet it shouldn't be a problem, >>but for larger foils you need to put the ribs proportionally closer >>together to get the cross-section to keep its shape. >As I recall, the 252 has 8 cells. I know everything up to and including >the 30 have 4 cells. What about the 60? The rough numbers I've heard (for parafoils) is that cells shouldn't be more than ~10 inches wide; flowforms usually go larger, but the wing won't hold shape very well if the cells are as wide or wider than they are high. >>For 30 square feet, try a cross-section about 12(of the chord) deep, >>with the highest point maybe 10back from the leading edge. This is a >>fairly radical departure from published plans, but then the published >>plans don't fly quite as well as one would like. >Sounds like a *very* radical departure. In fact, if memory serves (I >don't have a copy of the book handy), isn't that more like the Flow Form >II (Steve Sutton's design) in Margaret Gregor's book, as opposed to what >she refers to as a better kite, the "Flow Form I"? With all the parafoils and flowforms I've seen, the rule seems to be the larger the kite, the thinner (proportionally) the cross-section. If you're careful with the vent holes in the ribs, you can always build it thicker and then just pull the top off and resew it to try a thinner section; this saves 9/10 of the work of building a new foil. >Any hints on venting? Sorry, no. Anyone else? >Got any suggestions (Pat, are you out there? This means you!) for dealing >with, laying out, cutting, etc., the large pieces of fabric for the >top and bottom of the kite? I mean this in terms of laying it out, marking, >cutting, etc. I'm not really used to huge pieces of fabric, but I have >no interest in a little flow form...;-) My answer to this is running on a bit, so I think I'll work on it a bit longer and post it separately to get the big audience. - irving - = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Subject: Re: Flow Form enlargement Message-ID: <16923@umd5.umd.edu> From: jeffy@syrinx.umd.edu (Jeffrey C. Burka) Date: 11 Nov 92 03:28:53 GMT Organization: University of Maryland at College Park In article <1992Nov6.102854.8017@jarvis.csri.toronto.edu> irving@white.toronto.edu (Irving Reid) writes: >I've had a close look at the big flowforms Art Ross from Vancouver >builds. He has built a few in the 500-1500 square foot range, along >with smaller sizes. 1500 feet^2? That's a BIG kite. >The main change is to make the airfoil thinner and move the high point >forward. There's not a lot of science necessary; flowforms are >relatively forgiving about cross-section. Guessing from only having >seen his kites, the body proportion is roughly 3-4 units span to 5 units >chord. He also uses longer "legs" than the book plans show, partly for >stability and partly for effect. By legs I suppose you mean the keels? 5:4 sounds like most of the flowforms I've seen; mostly but not quite square. (sort of like a TV screen) >Cell width (the spacing between ribs) doesn't scale linearly for either >flowforms or parafoils. For 30 square feet it shouldn't be a problem, >but for larger foils you need to put the ribs proportionally closer >together to get the cross-section to keep its shape. As I recall, the 252 has 8 cells. I know everything up to and including the 30 have 4 cells. What about the 60? >For 30 square feet, try a cross-section about 12(of the chord) deep, >with the highest point maybe 10back from the leading edge. This is a >fairly radical departure from published plans, but then the published >plans don't fly quite as well as one would like. Sounds like a *very* radical departure. In fact, if memory serves (I don't have a copy of the book handy), isn't that more like the Flow Form II (Steve Sutton's design) in Margaret Gregor's book, as opposed to what she refers to as a better kite, the "Flow Form I"? Any hints on venting? Thanks for all of your suggestions. They've been quite helpful. I'm still at the "what am I getting myself into" stage, but I'm still eager to try building the kite. Unfortunatley, it'll be anothe 2 or 3 weeks before I can order the fabric. Got any suggestions (Pat, are you out there? This means you!) for dealing with, laying out, cutting, etc., the large pieces of fabric for the top and bottom of the kite? I mean this in terms of laying it out, marking, cutting, etc. I'm not really used to huge pieces of fabric, but I have no interest in a little flow form...;-) > - irving (Hey! I finished my Masters, Moved, and got a New Job!) - Congratulations! Jeff -- |Jeffrey C. Burka | "Show what you are / Be strong, be true | | | Time for you to / Be who you are." | |jeffy@syrinx.umd.edu | --Happy Rhodes | = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =