Date: Wed, 8 Jun 1994 00:50:38 -1000 From: R.J.Green-SE1@cs.bham.ac.uk (Robin J Green) Message-Id: <2t47pv$6b0@percy.cs.bham.ac.uk> Organization: School of Computer Science, University of Birmingham, UK Subject: Bi-elliptical formula + venting. In article , Kieran Sullivan wrote: > >why not have some kind >of simple valve which would allow air to flow into the cells, but would >resist air trying to escape? A flap of ripstop over the inside of the >air intake would work, it would close if air tried to get out. Darn good idea. I wonder if it'd actually get you any advantage? It'd cost virtually nothing to do (other than finding some form of crumple-proof valve. e.g. over a circular venting hole you'd have a larger circle attached top and bottom - not just bottom.) and it may solve some problems. I'll try it for a laugh. - Robin Green. P.S. I calculated the shape for a bi-elliptical kite last night. The formula I got for a rib width is (assuming a straight bridle line) rib length at Xcm = max_rib_len*sqrt(1+(X/wing_width)^2) | | 10 20 30 40 ... 180 190cm <- upper ellipse +---+---+----+----+----+--------+----+----+--- <- bridle line | | | | | | .. | | / | | | | | | .. | | | | | | | | .. | | | | | | | <- lower ellipse | | | | | | | max_rib_len = 84cm lower = 10cm upper wing_width = 190cm [ Aspect ratio = 4:1 which seems ok to me. The original kite the template was from - The Booster - is a 6:1 AR kite. ] This will generate the rib lengths for one ellipse for one half of the kite. You may want to generate a few more points between 180-190 cm to get the shape better. Now to decide on the venting and whether the 180-190cm cell will have an open leading edge or not. I think not. It's amazing what you'll find to do instead of revising. Now, it's a process of cutting out all those DAMN rib templates... aw, heck, get the computer to do it. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =