From: andrew@tug.com (Andrew Beattie) Subject: Re: Chevron progress Organization: /usr/lib/news/organisation Date: Sat, 1 Jun 1996 13:25:52 -1000 Message-ID: I had such a positive response to my postings about my my trials and tribulations with the Chevron that I thought I'd fill you in on the latest one. Whilst it has been fun to turn up at no-wind festivals and tease everyone with the 13m^2, it's not very parcatical when the wind does show, so I decided to make another 5m^2, much along the lines of the the black and white one has just managed to crawl by the slowest possible snail mail to John Gabby. First problem was fabric. I had quite a lot of fabric in various stages of being delivered to me, but none actually within my posession, so when I got the chance of some 1/2 oz Red Icarex, I jumped for it. I've still retained the Chevron graphic, it's sewn into the panelling, but it's somewhat subliminal - a red Chevron on a red background... The Chevron graphic is designed not only to look good and to show which way it's going, but it also to make good use of the fabric. The idea on the 5m is that the widest part of the rear panel is the same as the width of the fabric, and you should be able to fit two front panels across a width of fabric. It's not as easy to work this out as it sounds. The front panels are different widths front and back (carefuly calculated so that the chevron graphic on the front is aligned with the graphic on the back, so that the colours don't shadow each other). The leading edge panels arn't even parallel, they taper slightly, so it's a pig of a job trying to work out if a top panel tapering one way and a bottom panel tapering the other is going to fit in the fabric available. The upshot of this is that on John's 5m, there was a lot of waste because it didn't *quite* fit on the fabric as planned. Some *very* small changes and it's spot on for this kite. I paid particularly close attention to the amount of waste. I don't actually know how much fabric I used (I keep meaning to measure what I use, but never remember...), but I do know how much I wasted: I gathered up all the little scraps and it weighed 46g. Taking the 32g/m^2 as gospel, that's 1.4m^2. Hmmm... it was ever such little scraps, but it's still somewhere around 10 *sigh* I've been looking at building kites with Mylar(*) bladders, which I can use either air-filled (for playing in the water), or Helium/air filled (to replace the heaviest structural component in the kite with something a little lighter...). For this, I need easy access to the interior of the kite, to service the bladders, so I contacted YKK and bought myself 200m of bulk zip. This isn't exactly a barrel of laughs to sew onto the kite. You can't do it with the zip closed, because it's on the trailing edge as you seal up the kite, so you don't get any registration marks to tell you how you're doing. It was a bit of a struggle, but I'm pleased with the end result. The zip is the lightest dress zip I could find, it weighs 10g/m, so it's around 100f the weight of the kite (not including air). It's a small weight penalty, but it's interesting to note that its all at the trailing edge. I think that this kite is even *more* stall resistant than John Gabby's one. People commented about how high it flies, (while I thought it looked poor, 'cos the lines were too heavy...), but I couldn't make it collapse due to over flying no matter how hard I tried. I think that the slight shift of C-of-G meant that when it stalled, it basically sat back by it's self without reference to the bridle and glided till it ready to fly again. (*) It's not actually Mylar, but it's a similar film... I had hoped to use the experience of John's kite to get the primary bridle perfect first time, but life's not like that. It worked OK, but I had to fiddle with it this evening to get it "just so". I've changed the cross bridle a little. The kite is now even flatter across the middle, yet it seems to turn even tighter and with even less input than John's 5m. (I say "seems". I'm pretty sure, but John's 5m is 8 timezones away, making cross comparison a little difficult...) During the day, it was never very happy in a tip-stand position, but I've adjusted the tips to make them flatter too and a brief test suggests that this has been successful. As usual, it's for sale so that I can afford to build the next one. (I'm running kinda short of things to fix or improve, but I've got work to do on other sizes...) First person to offer US$450+shipping secures it. (if you want to see it, have a look at the 5m at the bottom of http://www.kfs.org/kites/chevron and think "red") Andrew -- Chevron Performance kites: http://www.kfs.org/kites/chevron = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: gaffer@pat.rec.com (Andrew Beattie) Subject: Re: Chevron progress Date: Sun, 2 Jun 1996 21:34:29 -1000 Organization: I need to put my ORGANIZATION here. Message-ID: <833787269.7592.0@pat.rec.com> In article , Andrew Beattie wrote: >During the day, it was never very happy in a tip-stand position, but I've >adjusted the tips to make them flatter too and a brief test suggests that >this has been successful. Successful? Nope. Sure, it fixed the tip-stand problem, but it stuffed up the steering. It would curl up round the leading edge excessively. Ken Knight observed that it looked like a seahorse when turning. It was very light wind, but it didn't seem to be pulling like it should. (kinda difficult to judge after flying the 13m^2...) Time for some tuning. I changed the A-lines (nearest the leading edge), I changed the C-lines. I changed the tip bridle, I changed the A-lines some more. Then the C-lines again. Then a different tip configuration. It went >From bad to worse (and of course, I'm doing this while everyone can see it). Eventually, I got it right. The magic has returned, but it waited until everone had gone home... *sigh* Andrew = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: KITEJAG@MOTHER.COM (John Gabby) Subject: Re: Chevron progress Date: Wed, 5 Jun 1996 05:03:19 -1000 Organization: Mother.COM Message-ID: <31b59e28.87862478@NEWS.MOTHER.COM> On Mon, 03 Jun 1996 07:34:29 GMT, gaffer@pat.rec.com (Andrew Beattie) wrote: >In article , Andrew Beattie wrote: >>During the day, it was never very happy in a tip-stand position, but I've >>adjusted the tips to make them flatter too and a brief test suggests that >>this has been successful. > >Successful? Nope. Sure, it fixed the tip-stand problem, but it stuffed up >the steering. It would curl up round the leading edge excessively. Ken >Knight observed that it looked like a seahorse when turning. It was very light >wind, but it didn't seem to be pulling like it should. (kinda difficult to >judge after flying the 13m^2...) > >Time for some tuning. I changed the A-lines (nearest the leading edge), >I changed the C-lines. I changed the tip bridle, I changed the A-lines some >more. Then the C-lines again. Then a different tip configuration. It went >from bad to worse (and of course, I'm doing this while everyone can see it). >Eventually, I got it right. The magic has returned, but it waited until >everone had gone home... *sigh* > >Andrew Ahh, the humility of Andrew but certainly not humiliated...on this side of the pond the Chevron is being flown and well received by everyone who picks up the handles. This past weekend I even let an importer of brand X foils have a go at the Chevron...his analysis was three words, the first of which is banned by decency freaks...the other two are merely "great kite". Dave Culp had a similar reaction, though a little more polished. I suspect that pull on the Chevron is relative to what Andrew was flying before...the new five comes on so gradually it almost doesn't feel like it's pulling...a quick look at the speedometer will confirm that all is well...the kite just doesn't feel like it pulls hard...but it sure is fast and sure does point high...in my mind the important stuff! = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: mm95-16@Swansea.ac.uk (Chris Dearden) Subject: Re: Chevron progress Message-ID: Organization: Swansea University Date: Wed, 5 Jun 1996 06:23:19 -1000 First person to offer US$450+shipping secures it. Andrew,i know we haven't got as mouch money to spend as those on the other side of the pond , but could at least give some prices in proper (pounds Sterling) , so I can plead to my manager to buy It = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: Andy Wardley Subject: Re: Chevron progress Date: Tue, 4 Jun 1996 23:04:34 -1000 Organization: Peritas Multimedia Message-ID: Andrew Beattie writes: >I had such a positive response to my postings about my my trials and >tribulations with the Chevron that I thought I'd fill you in on the latest >one. [...5m Red Chevron...] I flew this at Basingstoke and while I'm no expert foil flier, it was obvious to the untrained eye that this kite is really something. The most impressive thing was the ridiculously small turning circle (the kite almost snakes around itself) and the inability to fold the kite up, even for a lutz like me. >As usual, it's for sale so that I can afford to build the next one. (I'm >running kinda short of things to fix or improve, but I've got work to do >on other sizes...) First person to offer US$450+shipping secures it. If I hadn't spent all the money I have (and a lot of money I don't have) on the impending nuptials (78 hours and counting), I would have snapped this bargain up. If you're looking for a foil and want something that delivers everything that a commercial foil does (and more), then I would think seriously about making Andrew an offer. I have no commercial interest, blah, blah, disclaimer, blah, blah with Andrew other than an interest in seeing what he comes up with next. Cheers Andy Andy Wardley || . Hacker, digital artist/designer, webmister, brave warrior thricefold decorated in the winky wars, best mate to the rich and famous, no really, I mean that. I luv you, you're my best mate.... For a good time, http://www.peritas.com/~abw = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: Andrew Beattie Subject: Re: Chevron progress Date: Thu, 6 Jun 1996 12:40:06 -1000 Organization: Division of Applied Sciences, Harvard University Message-ID: <9606062340.aa07822@tug.com> > I flew this at Basingstoke and while I'm no expert foil flier, it was > obvious to the untrained eye that this kite is really something. The > most impressive thing was the ridiculously small turning circle (the kite > almost snakes around itself) and the inability to fold the kite up, even > for a lutz like me. In fact, this is a bug. I don't mind it snaking up on "extreem" input, but it was doing it on "reasonable" input. I think that it's fixed now. I messed around with the cross-bridle trying to fix it, but I think that the real problem was with the primary bridle - I think that it wasn't powered up enough, so it didn't have sufficient internal pressure to cope with the amount of steering effort coming from the cross-bridle. I've managed to retain a similar steering response - I want to describe the feel as "twitchy", but maybe I've been flying 13m^2 too long... > I have no commercial interest, blah, blah, disclaimer, blah, blah with > Andrew other than an interest in seeing what he comes up with next. The cheque is in the post.. Andrew This is signature number 100 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = From: Andrew Beattie Subject: Re: Chevron progress Date: Fri, 7 Jun 1996 13:55:18 -1000 Organization: Division of Applied Sciences, Harvard University Message-ID: <9606080055.aa00452@tug.com> > I suspect that pull on the Chevron is relative to what Andrew was > flying before... No. It simply wasn't flying right. There is a lot to be learnt about tuning and I'm only just beginning. - There are compressional problems in low wind with the first Chevron (John's 8m), I put it down to cell-size and cross-bridle issues at the time but now I'd like to play with it more, because I think I might be able to tune it out on the primary bridle. - When I first flew the 13, I thought it was spot-on, but I went back to it months later and made significant improvements. - The 7m^2's improved with experience. The first ones had little power, but I learned how to get more out of them. When I eventually catch up with Matthew Hurrell, I'll make the changes I've been trying to persuade him to make for several months... - The first 5 (where I took a big leap to my own profiles rather than a simple derivative of the Sputnik-4 ribs) was very odd out of the bag. It overflew, it had no power, it would fold towards you during a depowered dive, worst of all, it would simply fall out of the sky if you turned down rather than up. It was out of this mess that I managed to tune the canopy that John raves about. - On the latest 5, I re-calculated all the plans in the light of the lessons learned from John's kite, in the hope that it would work first time, but no, the power was down, the L/D wasn't good enough, the stall speed was too high, it would curl round the leading edge. It took all weekend to sort it out, yet this is the sort of state it was in when it impressed Andy Wardly. Several people have asked me about plans. The above is one of the main reasons that I don't want to produce plans at the moment. The kites are simply not ready for that. The difference between an excellent kite and a crap one is entirely within the hands of the person who's tuning it. mm95-16@Swansea.ac.uk writes: >> First person to offer US50+shipping secures it. > > Andrew,i know we haven't got as mouch money to spend as those on the other > side of the pond , but could at least give some prices in proper (pounds > Sterling) , so I can plead to my manager to buy It I buy my fabric and Spectra in US$ and most of the kites go to the USA, so I work in dollars. US50 is around 300 quid. Andrew If you fly stunt kites to win competitions, you won't understand, but if you fly to give pleasure and entertain the audience, you might find AoxomoxoA -- Marty Sasaki Harvard University Sasaki Kite Fabrications sasaki@noc.harvard.edu Network Services Division 90 Melrose Street 617-496-4320 10 Ware Street Arlington, MA 02174 Cambridge, MA 02138-4002 phone/fax: 617-646-1925 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =