From: andrew@tug.com (Andrew Beattie) Subject: Single Skin Chevron Organization: /usr/lib/news/organisation Date: Sat, 20 Apr 1996 09:19:15 -1000 Message-ID: A few weeks ago, I found myself at a bit of a loose end and without anything to fly, so I thought I'd throw together an idea that I'd wanted to explore- A Single-Skin Performance kite. As always, I drew on other people's experience, as well as my own ideas. I had been impressed by John Travell's single skin+ribs 4-liner, and I also liked Peter Lynn's ribless Trillobyte design, and I had been pleased with the 5m^2 Chevron, so I put all the ideas together and started designing a single skin (no ribs) 5m^ Chevron. I had no idea whether it would work, and didn't really want to waste 5m of Icarex (to say nothing of the fact that I didn't *have* 5m of Icarex to hand), so I grabbed some Carrington seconds that were lying around, and the 5m^2 plan and started cutting, marking and sewing. On a Chevron/Peel/Sputnik, the bridle lines attatch to a v-line sewn into the rib, which distributes the strain. With no ribs, the plan was to sew a reinforcing line down the rib positions, and attatch the bridle directly to that. I would increase the number of bridles per "rib", cross my fingers and hope to get away with it. I've never particularly enjoyed doing the reinforcing - it's a fiddly job, but with so much of it to do (every rib, rather than every second or third one), I figured it was time to make it easier. I took a file to the bottom of the foot of my beloved Pfaff and started to file a groove (I've been unable to locate such a foot in a local shop yet). Taking a look at my progress, the file appeared to have done little more than make the surface a little shinyer. *sigh* It seems that Pfaff make their feet from Chrome Vandium or the like. About an hour later, I had a little groove in the foot... This made life a lot easier. I could sew much more quickly, while retaining the same poor precision as before ;-) What about the profile? I don't know. I figure that the top of a Chevron profile comes down too much at the front and would fold under. I figure I want something fairly flat. I just sat down with a Chevron profile and sketched the sort of shape I thought I wanted. How to bridle it? I just marked off on my sketch where I thought the bridles should go, with more to the front than the rear, and measured their positions. A 17bridle works well on the Chevron, so I picked a bridle length (same as the chord of the biggest ribs, and wrote a program to calculate the distance >From a point this distance down and 17back from the nose, for each of the bridles on each of the ribs. The program produced a plot file (similar to those used by PLOT.EXE on Stunt Kites 2.0), which I could lay on some wood, bang nails into and use as a bridling jig. Then all that was left was the simple task of bridling. There are 25 ribs with 7 bridles each. I figured I wanted the lightest possible line. I considered using my rather thick sewing thread, but Kiteability was selling 20lb Dyneema at Blackheath, so I came home with 1200 feet of it and set to work. Later calculation showed that this wasn't enough and I had to phone back and order more! I did some testing and found that their 20lb Dyneema (which is bearly thicker than my thread) actualy breaks past 30lb, but the bridle knot breaks at around 16lb. 556 knots later(!) (including stopper-knots), it's ready to fly. It doesn't work very well. Here are some of the issues: Structural integrity. It tends to form ribs across the kite (the bulges go at 90 degrees to the normal direction. Maybe if the ribs bere closer (or it had more bridles), it would bulge the other way. Aspect ratio. The aspect ratio of a normal kite is less in the air than on the ground, because the fabric bulges along the cells, bringing the tips closer together. This kite bulges the other way, so the chord becomes less and the aspect ratio goes up. It gets pushed too far. The tips seldom work at all. Bridling. It's bridled too far forward, and/or the nose is too far down, as soon as the apparent wind stars coming from the front, it tucks under. --- Basically it's pretty crap at the moment, but it's saving grace is that it is *completely* adjustable. If I don't like the shape of the rib, I adjust the bridle. If I tips don't fly right, I'll just cut them off! More later, if it actually works in the end... Andrew -- Microsoft is to Software as McDonalds is to Cuisine = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: jburka@Glue.umd.edu (Jeffrey C. Burka) Subject: Re: Single Skin Chevron Date: Sun, 21 Apr 1996 06:13:47 -1000 Organization: Project Glue, University of Maryland, College Park, MD Message-ID: <4ldmrr$gn@geog25.umd.edu> In article , Andrew Beattie wrote: >Structural integrity. It tends to form ribs across the kite (the bulges go at >90 degrees to the normal direction. Maybe if the ribs bere closer (or it >had more bridles), it would bulge the other way. Y'know, Andrew, I bet you could get rid of those bulges by quading the kite... ;-) Jeff -- |Jeffrey C. Burka | Pithy, insightful quote to be inserted when one | |jburka@glue.umd.edu | occurs to me. *If* one occurs to me. | |http://www.wam.umd.edu/~jeffy/html/home.html | = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: era_pul@ki.ericsson.se (Peter Ulfheden) Subject: Re: Single Skin Chevron Date: Mon, 22 Apr 1996 23:46:08 -1000 Organization: Ericsson Radio Systems AB, Sweden Message-ID: <4li8t0$r2d@erinews.ericsson.se> Andrew Beattie (andrew@tug.com) wrote: [snip] : A Single-Skin Performance kite. As always, I drew on other people's : experience, as well as my own ideas. I had been impressed by John [snip] : 556 knots later(!) (including stopper-knots), it's ready to fly. Well, I wouldn't call you lazy Andrew. : It doesn't work very well. Have you had a look at the Parawing *UL* ? It uses something that resembles profiles. Consider a Sputnik/Peel, remove the bottom skin and the part of the profiles that is below the reinforecement line, attach the bridle where it usally goes. The PW UL also has a small chamber in the front that is inflated like a normal chamber. This chamber extends to about 250f the profile length, the rest is single skin. I don't know if someone still uses the PW UL. Any one else? : Basically it's pretty crap at the moment, but it's saving grace is : that it is *completely* adjustable. If I don't like the shape of the That doesn't go for a the PW Peter -- []--------------------------------------------------------[] | Peter Ulfheden | Peter.Ulfheden@ki.ericsson.se | | Amorinav. 3 | or peter@hmab.se | | S-191 44 Sollentuna | or petulf@saaf.se | | SWEDEN | Home: +46 8 92 99 01 | | | Fax: +46 8 35 04 29 | | GSM: +70 594 02 15 | Office: +46 8 751 02 15 | []--------------------------------------------------------[] = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Message-Id: <199604231838.UAA22739@vbormc.vbo.dec.com> Date: Tue, 23 Apr 1996 09:48:03 -1000 From: travell@comics.enet.dec.com Subject: Re: Single Skin Chevron >Andrew Beattie (andrew@tug.com) wrote: > >[snip] >: A Single-Skin Performance kite. As always, I drew on other people's >: experience, as well as my own ideas. I had been impressed by John >[snip] > I tried a while ago to post an entry containing a URL for the page where Andrew has kindly put a picture and short write-up of my kite. I will try again. http://www.kfs.org/kites/trav It is a 4-line kite, with a complex! bridle. Not qhite as many knots as Andrew has tied, only 16 ribs and 6 points per rib, total 96 at the kite, with slightly more than half that joining the primaries and secondaries. It flies VERY well, and does NOT suffer the lateral creasing Andrew appears to be seeing. It's major problem is the lack of internal pressure allowing the outer cells to collapse from the leading edge back to about 30hord when the kite is moving fast through the air. The picture says a lot. John Travell. Solent Kite Flyers is a Kite club based around Southampton, UK, Club fly-in's 2nd and 4th Sundays each month. Contact me by Email "travell@comics.enet.dec.com" for further info. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: Rodger Duffett Subject: Re: Single Skin Chevron Date: Tue, 23 Apr 1996 16:39:20 -1000 Organization: University of Cape Town Message-ID: <317D9458.30C3@ray.uct.ac.za> Andrew Beattie wrote: > > A few weeks ago, I found myself at a bit of a loose end and without anything > to fly, so I thought I'd throw together an idea that I'd wanted to explore- NASA worked on a single skin steerable parachute once upon a time! I believe that some rec.kiters were working on a kite version of this. I saw one made by Chuck van Eekelen in Holland. It was a low aspect ratio triangular type shape. Apparently it pulled very hard but at that stage of development did not control very well. Cheerio -- __________________________________________________________________ Rodger Duffett Internet Address: rodger@ray.uct.ac.za Dept. Radiation Oncology Telephone : +2721 404 3135 Radiobiology Section University of Cape Town Groote Schuur Hospital South Africa = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: pdjnjvt@knoware.nl (Peter de Jong) Subject: Re: Single Skin Chevron Date: Wed, 24 Apr 1996 03:14:38 -1000 Organization: Knoware Internet Message-ID: <317e2911.408971@news.knoware.nl> On Tue, 23 Apr 1996 19:39:20 -0700, Rodger Duffett wrote: >Andrew Beattie wrote: >> >> A few weeks ago, I found myself at a bit of a loose end and without anything >> to fly, so I thought I'd throw together an idea that I'd wanted to explore- > >NASA worked on a single skin steerable parachute once upon a time! I >believe that some rec.kiters were working on a kite version of this. I >saw one made by Chuck van Eekelen in Holland. It was a low aspect ratio >triangular type shape. Apparently it pulled very hard but at that stage >of development did not control very well. > >Cheerio > Saw it on the beach last weekend: A blue / black (modified ?) Rogallo. about 4 m2. ( Like the one in the Rogallo section of the P. Book of Kites with the capsule under it, page 82 in the dutch version; but with an added mid section.) Flying fine while there was so little wind you could 360 a 10 m Peel. It didn't seem to have any control problems. Plans seem to circulate but I haven't got them yet... ( sorry Mark & Gary : maybe later....) Regards, Peter Greetings from Holland Peter de Jong A&F Custom Kites Werkhoven NL * 900f the time the opposite of GOOD is not BAD but WELL INTENDED * = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: hpeeters@vub.ac.be (Herman Peeters) Subject: Re: Single Skin Chevron Date: Wed, 24 Apr 1996 23:45:50 -1000 Organization: Brussels Free University Computer Centre Message-ID: > Plans seem to circulate but I haven't got them yet... > ( sorry Mark & Gary : maybe later....) > > Regards, Peter Peter, I noticed some plans of a kite like that on: http://www.hol.nl/~telead/nasaplan.html. Hope this helps = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: pp@win.tue.nl (Peter Peters) Subject: Re: Single Skin Chevron Date: Wed, 24 Apr 1996 23:30:22 -1000 Organization: Eindhoven University of Technology, The Netherlands Message-ID: <4lngne$7e6@svin09.win.tue.nl> <317e2911.408971@news.knoware.nl> In article <317e2911.408971@news.knoware.nl>, pdjnjvt@knoware.nl (Peter de Jong) writes: >Saw it on the beach last weekend: >A blue / black (modified ?) Rogallo. about 4 m2. >( Like the one in the Rogallo section of the P. Book of Kites with the >capsule under it, page 82 in the dutch version; but with an added mid >section.) >Flying fine while there was so little wind you could 360 a 10 m Peel. >It didn't seem to have any control problems. >Plans seem to circulate but I haven't got them yet... >( sorry Mark & Gary : maybe later....) Take a look at: http://www.win.tue.nl/~pp/kites/plans/ select the "Nasa Chute" link... Peter -- Peter Peters, pp@win.tue.nl, http://www.win.tue.nl/~pp/ Like kites.... look at http://www.win.tue.nl/~pp/kites/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =