Date: Fri, 9 Feb 1996 12:23:24 -1000 From: pchandler@sidewinder.win-uk.net (Paul Chandler) Message-Id: <42@sidewinder.win-uk.net> Subject: Leading Edge (no - not the shop in Leeds!) I have made a few soft quads (3m2 and 5m2) to a design by Chris Sands that was published in The Kiteflyer (UK) last year and both fly really well providing good traction for buggying. I have been toying with the idea of moving up to Icarex for the next project and have also been thinking how I might improve on Chris' work. Chris' design calls for a cut-off leading edge that is open (no gauze) but I want to round off the leading edge and use gauze to improve the aerodynamics of the wing. This set me to thinking that if I could use some sort of 'valve' on the inlet it would help it to stay inflated in low wind situations. What I had in mind was to attach a rectangular flap to the inside of the gauze but only sew it down the front of the ribs, leaving the top and bottom of the flap free. This would allow the flap to bow inwards to allow air in, but when it tried to get out again (due to decreased outside pressure) the flap would press against the gauze and effectively seal the leading edge. I plan on including some cross cell ventilation to distribute the internal air pressure evenly when the leading edge is sealed (did try some ascii drawing but it looked cr@p). The original idea came from a large round spiked fish (a ground bouncer) that I saw which had this type of arrangement on the air intake in it's mouth. I would imagine that it would be more difficult to inflate at first due to the slightly restricted air flow, but once inflated would be more stable. Is this theory sound? Would this work in practice? Has it been done before? Answers and any other help would be greatly appreciated *before* I commit needle to Icarex. ___ _ | Paul Chandler / \ | | | | O )__ _ _| | | York Kite Flyers | __/ \| | | | | | British Buggy Club Member | |( O | |_| | |_ | |_| \__|_|\___/|__/ | pchandler@sidewinder.win-uk.net = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 10 Feb 1996 06:19:21 -1000 From: ahclem0013@aol.com (AhClem0013) Message-Id: <4figi9$9lp@newsbf02.news.aol.com> Organization: America Online, Inc. (1-800-827-6364) Subject: Re: Leading Edge (no - not the shop in Leeds!) In article <42@sidewinder.win-uk.net>, pchandler@sidewinder.win-uk.net (Paul Chandler) writes: >What I had in mind was to attach a rectangular flap to the inside of >the gauze but only sew it down the front of the ribs, leaving the >top and bottom of the flap free. This would allow the flap to >bow inwards to allow air in, but when it tried to get out again (due >to decreased outside pressure) the flap would press against the >gauze and effectively seal the leading edge. I plan on including >some cross cell ventilation to distribute the internal air pressure >evenly when the leading edge is sealed (did try some ascii drawing >but it looked cr@p). > > Why not from the top of the mesh so it hangs down completley covering the intake? Most importantly, if you don't try it, you will not know! oxodean = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 10 Feb 1996 07:29:25 -1000 From: birdofplay@aol.com (BirdofPlay) Message-Id: <4fikll$b4k@newsbf02.news.aol.com> Organization: America Online, Inc. (1-800-827-6364) Subject: Re: Leading Edge (no - not the shop in Leeds!) Paul, This is a great idea for keeping the kite inflated, however, when you wipe out and whack the kite into the ground inadvertantly you will discover that your seams will be exploded into space. ou will be left with a pile of glad rags. Even if you are super human enough to never crash it's going to be tough to get it back in the bag ! It's simply a matter fluid dynamics. Maybe your idea would work with some sort of velcro safety valve which would pop open in high pressure situations. Hope this helps. Hey I'm not expert - just though i'd stick in my two pence or do you say tupence ? Bob Neitzke birdofplay@aol.com http://members.aol.com/birdofplay = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 10 Feb 1996 12:06:44 -1000 From: Paul Chandler Message-Id: Organization: Buggy to Death Subject: Re: Leading Edge (no - not the shop in Leeds!) In article <4fikll$b4k@newsbf02.news.aol.com>, BirdofPlay writes >This is a great idea for keeping the kite inflated, however, >when you wipe out and whack the kite into the ground inadvertantly you >will discover that your seams will be exploded into space. ou will be left >with a pile of glad rags. Even if you are super human enough to never >crash it's going to be tough to get it back in the bag ! I always thought that you stood a better than even chance of exploding the seams if you crashed a soft kite straight into the ground anyway? 'Cos the ground effectively seals the opening and - *BANG* !! > -- Paul Chandler = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sun, 11 Feb 1996 08:20:29 -1000 From: Adrian Pierorazio Message-Id: Organization: Queen's University, Kingston Subject: Re: Leading Edge (no - not the shop in Leeds!) On Fri, 9 Feb 1996, Paul Chandler wrote: > Chris' design calls for a cut-off leading edge that is open (no > gauze) but I want to round off the leading edge and use gauze to > improve the aerodynamics of the wing. This set me to thinking that > if I could use some sort of 'valve' on the inlet it would help it to > stay inflated in low wind situations. > > Is this theory sound? Would this work in practice? Has it been > done before? Eric Brackenberry (sp?) in Ottawa, Ontario, Canada has been building kites like this for a while. His traction kites have a totally enclosed front (think of a complete airfoil with no gauze at all) and they are inflated through a series of 'scoops' along the bottom of the kite. These scoops have the type of 'valves' you refer to and the whole thing seems to work quite well. He's able to fly indoors with these beasts because of the one-way valve idea which is difficult to do with most full size regular weight power foils (3/4 oz nylon construction throughout). Blowouts are not any more problem with his kites than they are with any other foil (that I know of) as crashing doesn't block the air inlets (though I guess the flaps do). Anyways, there's what I know about this. I think he sells his kites semi-comercially and they're beautifully constructed. Disclaimer: I have no connection with Eric Brackenbury's kites at all. I don't even own a buggy but, Eric is kind of a friend whose kite building impresses me a lot. Adrian Pierorazio = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sun, 11 Feb 1996 08:08:01 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Re: Leading Edge (no - not the shop in Leeds!) birdofplay@aol.com (BirdofPlay) writes: >It's simply a matter fluid dynamics. > >Maybe your idea would work with some sort of velcro safety valve which >would pop open in high pressure situations. I think that the thing that blows the kite is a shock wave, rather than a nice, easy-to-manage increase in pressure. Let me give you two bizarre data points: 1) Mark de Rossier dives a 10' flexi square into the ground. The shock-waves travel from the tips, to the centre of the kite, where it blew apart the middle of the cell (as opposed to tearing down the stitch perforations as you would expect). 2) Peter Lynn builds a velcro seal on the trailing edge, to blow first, saving the kite. The kite doesn't play ball - it blows apart half-way down the cell, before the pressure-wave has reached the trailing edge. This is not to say that the problem can't be solved, just that it's not a particularly nice problem. Andrew -- World Wide Web: http://www.kfs.org/kites Kite and personal email: andrew@tug.com (no binaries please) Web and mailing list administration: gaffer@kfs.org IRC: gaffer in #kites on EFnet = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 10 Feb 1996 08:11:38 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Re: Leading Edge (no - not the shop in Leeds!) pchandler@sidewinder.win-uk.net (Paul Chandler) writes: >Chris' design calls for a cut-off leading edge that is open (no >gauze) but I want to round off the leading edge and use gauze to >improve the aerodynamics of the wing. This set me to thinking that >if I could use some sort of 'valve' on the inlet it would help it to >stay inflated in low wind situations. *smile* I went through this too... It struck me at about 2am. I was very excited. I figured that it would slow down inflation, but maintain pressure during a lull. This should stop deflation during a luff, help stop the nose turning under, and maybe even allow a higher aspect ratio. Maybe you could even decrease the size of the vent. I phoned up Peter Lynn to tell him of my exciting new idea. Immediately, he quoted the patent that covered it. I seem to recall that it was on Jalbert's original parafoil patent. As with so many good ideas, he's already tried it. It worked exactly as I expected - much better luff and low wind performance. However, there was a downside - if you should happen to crash it into the ground, the air has no-where to escape and the kite explodes. Peter made two such kites. They destroyed both of them on the first day. Andrew -- World Wide Web: http://www.kfs.org/kites Kite and personal email: andrew@tug.com (no binaries please) Web and mailing list administration: gaffer@kfs.org IRC: gaffer in #kites on EFnet = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =