Date: Sat, 19 Nov 1994 06:06:17 -1000 From: Silas@silasm.demon.co.uk (Silas Murray) Message-Id: <895080345wnr@silasm.demon.co.uk> Organization: Clitheroe Computer Company Subject: Flexifoil - Power Questions. How do you work out how much pull a certain size of Flexifoil will produce in a given wind? - I recently got a catalogue from Flexifoil international, and I`ve got a few questions: Why is it that 10`s pull 4x harder than the 6`s (as stated on page 9) - why not 40 percent more as the sizes would suggest? - Would 2 6`s pull a little harder than a single 10, because you would then have 12 feet of kite? or do you need 4 6`s to get the same pull as a 10? What is the Aspect ratio that is given for each ot the Flixi`s in the catalogue (but not the other kites I notice), is this related to the pull the kite has? - I can`t seem to find much of a mathmatical relationship between the aspect ratios and lenghts of the flexis - is kite weight involved. I`m assuming all flexis are the same width (I`ve only ever seen my own 6 footer!) is that right? It`s all a bit confusing! - I`m obviously missing something, but I can`t seem to find any info on this in the FAQ`s. Reason I`m asking is because I`m wondering what to but next. In some ways I regret having bought the 6 (only 10 days ago! - I`m *HOOKED* and need more pull! ;-) ) and wish I`d gone straight for 10`s. Do I buy more 6`s, ditch my 6 and start buying 10`s to stack, or stack different size kites? (not the best solution from what you good folk of rec.kites have told me.) Any help much apprectiated. _/_/_/_/ _/_/_/_/ _/ _/_/ To find your kite _/_/_/_/ _/_/ You have to find wind _/ _/_/ in which to lose it first. S;)as _/_/_/_/ _/_/_/_/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 19 Nov 1994 14:32:56 -1000 From: dickbell@netcom.com (Dick Bell) Message-Id: Organization: NETCOM On-line Communication Services (408 261-4700 guest) Subject: Re: Flexifoil - Power Questions. Silas Murray (Silas@silasm.demon.co.uk) wrote: : Do I buy more 6`s, ditch my 6 and start buying 10`s to stack, or : stack different size kites? (not the best solution from what you good : folk of rec.kites have told me.) Silas, Probably your best solution now is to borrow two more 6 ftr's and stack the 3 together. In winds of 15 mph + you will find that the kites are a hand full. I normally stack 2 6 ftr's during the strong spring winds. After a few hours flying the beast you sure can tell how winter has put you into bad shape. Your body will hurt for days. :-) Again, just borrow a couple more kites and see how you like it. It will be cheaper that way. -- -------------------------------------------------------------------------------- Dick Bell dickbell@netcom.com Dallas, Texas = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 19 Nov 1994 14:13:07 -1000 From: paul@bfield.demon.co.uk (Paul Bloomfield) Message-Id: <155453271wnr@bfield.demon.co.uk> Subject: Re: Flexifoil - Power Questions. Silas, These are my opinions on flexi's (I fly 6x6' or 1x10') In article: <895080345wnr@silasm.demon.co.uk> Silas@silasm.demon.co.uk (Silas Murray) writes: > > How do you work out how much pull a certain size of Flexifoil will > produce in a given wind? You try it - there's no substitute for experience! > Why is it that 10`s pull 4x harder than the 6`s (as stated on page 9) - > why not 40 percent more as the sizes would suggest? The longer an aerofoil is compared to its width (front to back), the more efficient it is. This is why gliders have long thin wings. > - Would 2 6`s pull > a little harder than a single 10, because you would then have 12 feet > of kite or do you need 4 6`s to get the same pull as a 10? Flying 4x6' is a totally different experience from 1x10'. It's not just the pull that matters, it's the way the pull comes in. In a big wind, a single 10' can snatch you off your feet as it accelerates across the wind. The pull on the stack will come in more gradually... This is an inadequate description: you have to try it to find out. > > What is the Aspect ratio that is given for each ot the Flixi`s in the > catalogue (but not the other kites I notice), is this related to the > pull the kite has? This is the ratio of the wing's length to its width, as described above. It is simple to calcualte for a flexi, for a delta (with non-constant width) it is harder and less relevent anyway. > - is kite weight involved. No > I`m assuming all flexis are the same width All I've ever seen are. I'm not sure about the 16', which used to be in the catalog, but I've never seen for real. > Reason I`m asking is because I`m wondering what to but next. In some > ways I regret having bought the 6 (only 10 days ago! - I`m *HOOKED* > and need more pull! ;-) ) and wish I`d gone straight for 10`s. What to do next is find some other flexi flyers, and try their rigs. Where are you based? There is more to flexis than pull alone - controlling a 6 stack in a light wind is one of my favourites. > > Do I buy more 6`s, Yes, you will then have an impressive looking stack. > ditch my 6 No, any flexi is better than no kite atall! > and start buying 10`s to stack, or Buy one, a solo 10' is my favourite flexi. Find a freind or two, and you'll have a stack. I'd like to meet the man that can take more than 10 minutes of a 4x10' stack, so sharing isn't a problem! > stack different size kites? (not the best solution from what you good > folk of rec.kites have told me.) I agree, don't bother. > Any help much apprectiated. No problem! Paul Bloomfield | paul@bfield.demon.co.uk London, England | CompuServe 100420,142 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 19 Nov 1994 14:10:05 -1000 From: travell@comics.enet.dec.com (I want to Go Fly a Kite!) Message-Id: <9411200010.AA23570@vbormc.vbo.dec.com> Organization: Division of Applied Sciences, Harvard University Subject: RE: Flexifoil - Power Questions. >Why is it that 10`s pull 4x harder than the 6`s (as stated on page 9) - >why not 40 percent more as the sizes would suggest? - Would 2 6`s pull The pull on any aero-foil shaped kite is more-or-less 90 degrees to the kite top surface, and is almost wholly over the front half of the kite. On a flexi, the rear half pulls -towards- you, to set the kite at an angle to the wind without which there would be no lift (pull) at all. The ends of a loaded flexi are curved down towards you, the pull from these end sections is outwards, not directly away from you. This `outwards' pull tightens the kite and makes it more effective, but means that not every part of the length of the kite contributes equally to the tension in the lines that you see as PULL. On a ten footer, most of the kite is nearly straight with only the ends bent down. In contrast, much less of a six footer is nearly straight. Hence much less pull. >What is the Aspect ratio that is given for each ot the Flixi`s in the Aspect ratio is Span (10ft or 6ft) divided by the chord (width) of the foil. A six footer (6ft x 2ft) has an aspect ratio of 3. clearly the value for a ten foot kite in larger. A high aspect ratio wing with the same section is more efficient than a low acpect ratio. > - I can`t seem to find much of a mathmatical >relationship between the aspect ratios and lengths of the flexis Dont try too much maths, it makes the brain hurt.. :-) Buy a ten footer as well. There will be winds in which even the six footer is too big (though not very often). Also the six turns MUCH tighter than the ten. I can easily ground launch a six, even when it is inverted, but find it diffult to do at all with a ten. >stack different size kites? While I have stacked a six with a ten, they are much better with an eight between them, and better still all the same size. John Travell. Solent Kite Flyers is a NEW Kite club based around Southampton, UK, Contact me by Email "travell@kernel.enet.dec.com" for further info. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sun, 20 Nov 1994 19:20:04 -1000 From: coreykite@aol.com (Coreykite) Message-Id: <3apam4$g58@newsbf01.news.aol.com> Organization: America Online, Inc. (1-800-827-6364) Subject: Re: Flexifoil - Power Questions. In article <895080345wnr@silasm.demon.co.uk>, Silas@silasm.demon.co.uk (Silas Murray) writes: >What do I do with my flexi's? (Pardon the paraphrase.) I humbly respond: I've been flying flexi's since 1977. Love the 6er in stacks. Moves good and you can add or subtract to control the power. The 10 in light winds handled by a good flyer is beautiful to watch and oh so graceful. Flying it is an even better feeling. Like being one with the power of the wind. I've read the other 4 postings and those folks explained the science pretty well. Shut off your computer and get out there and fly that flexi some more. None of us knows as much about flying as we think we do. aoxomoxoa coreykite@aol.com = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Tue, 22 Nov 1994 17:21:52 -1000 From: dstabb@epix.net (David Stabb) Message-Id: Organization: epix.net Subject: Re: Flexifoil - Power Questions. In Article <155453271wnr@bfield.demon.co.uk>, paul@bfield.demon.co.uk (Paul Bloomfield) wrote: >Silas, > >> I`m assuming all flexis are the same width > >All I've ever seen are. I'm not sure about the 16', which used to be >in the catalog, but I've never seen for real. My old catalog shows the 12 footer to be 27 inches deep, whereas the smaller kites are 24 inches deep. >> stack different size kites? (not the best solution from what you good >> folk of rec.kites have told me.) > >I agree, don't bother. Actually, stacking different size flexis can be both fun and instructional. The usual way to stack the kites is with the larger kite to the outside of the stack. This way, maneuvering seems rather natural. There is less stress on the spar joints also. You'll find that you aren't able to make quite as large control movements as you are used to with the big kite alone. For something different, stack them in *reverse* order. This is best done in a light wind - I find that an 8 footer with a 6 footer behind it, both with light wind spars makes a good stack. Be sure to tape the spar of the smaller kite *securely*. What will this do? It will increase the pull dramatically. The pull of the smaller, outside kite will tend to spread the larger kite apart. (Use 5 to 6 foot training lines for the stack) While edge precision suffers, the airfoil efficiency increases and you're in for some exercise in fairly light wind. dstabb@bix.com Good Morning, Good Afternoon, Good Evening. dstabb@epix.net How difficult it is to tell when you're dstabb@aol.com locked in a tiny room with no windows dstabb@ilc.com and artificial lights. ____|)avid = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Mon, 28 Nov 1994 12:28:08 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Re: Flexifoil - Power Questions. [Quick followup of bits that others have missed...] Silas@silasm.demon.co.uk writes: >Why is it that 10`s pull 4x harder than the 6`s (as stated on page 9) - >why not 40 percent more as the sizes would suggest? The 6' has 2 fibreglass tapered spars, they bend under strain. The 10' as 2 similar (identical?) tapered spars, but a solid carbon centre section that hardly bends at all. It is the much increased length of the straight centre bit that delivers the extra power. >What is the Aspect ratio that is given for each ot the Flixi`s in the >catalogue It is The square of the span of the kite divided by the area. For a rectangular kite like a flexi, this is the same as span/depth. High aspect ratios are generally more efficient. Flexifoils have some of the highest aspect ratios around (soft kites can't cope with much above 5) Andrew -- Kite FAQ's: ftp.hawaii.edu:/pub/rec/kites/faq) For sale: 10' Flexis with std & UF Spars. I've had some trouble with my news feed. Sorry if this isn't too timely... = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =