Date: Wed, 27 Jul 1994 00:25:21 -1000 From: paul_b2@sfov1.verifone.com (Paul Butterworth, Software Designer, London.) Message-Id: <1994Jul27.022521.1029@sfov1.verifone.com> Organization: VeriFone Inc. Subject: Flexifoil stack wobbling & which spars for stacks Hi, Whilst on Holiday I saw some strange behaviour from my stack of 2 6 foot flexi's. In certain winds they started to wobble in opposite directions. I became slightly worried about this as I didn't think that it could be doing them any good. I read in an old message in Hawaii that wobbling can be caused by sand in the sail, but if there was any it was very minimal. O some occasions the sails were a bit wet, but not every time. Also which spars do people recommend whilst stacking, is it OK to use one of each, and if so would you put the Ultraflex one on the top kie or lower one? If anyone has any ideas they would be appreciated. Paul ---------------------------------------------------------------------- Paul Butterworth /\ You haven't lived until you've VeriFone (UK) Ltd. / \ flown a stack of Flexifoils! paul_b2@verifone.com < <> > 100114.230@compuserve.com \ / rec.kites pbutterworth@cix.compulink.co.uk \/ May the wind be at your back! ------------------------------------\--------------------------------- + \ + \ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Wed, 27 Jul 1994 13:43:36 -1000 From: mark@murder.demon.co.uk (Mark de Roussier) Message-Id: <775377816snx@murder.demon.co.uk> Organization: damage Subject: Re: Flexifoil stack wobbling & which spars for stacks In article <1994Jul27.022521.1029@sfov1.verifone.com> paul_b2@sfov1.verifone.com (Paul Butterworth, Software Designer, London.) writes: > Hi, > Whilst on Holiday I saw some strange behaviour from my stack of 2 > 6 foot flexi's. Hi Paul ! I'm not sure what to say about spars, but one thing to try to stop the wobbling ( a resonance effect of some sort I'm sure ) may be to play with the lengths of the stacking lines. I'd probably try making them shorter first. I fly a couple of ten footers with 5ft 10" stacking lines, and this has not been a serious problem. -- Mark de Roussier ( murder@cix... ) ************************************ A nice man is a man of nasty ideas. Jonathon Swift. ************************************ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Thu, 28 Jul 1994 11:17:31 -1000 From: chris@sound.demon.co.uk (Chris Lamb) Message-Id: <775458090snx@Sound.demon.co.uk> Subject: Re: Flexifoil stack wobbling & which spars for stacks In article <1994Jul27.022521.1029@sfov1.verifone.com> paul_b2@sfov1.verifone.com (Paul Butterworth, Software Designer, London.) writes: > Hi, > Whilst on Holiday I saw some strange behaviour from my stack of 2 > 6 foot flexi's. > In certain winds they started to wobble in opposite directions. I > became slightly worried about this as I didn't think that it could > be doing them any good. I read in an old message in Hawaii that > wobbling can be caused by sand in the sail, but if there was any > it was very minimal. O some occasions the sails were a bit wet, but > not every time. I've had this before and was allways due to damp/wet sails. Also check the length of your stacking lines, are they even? > > Also which spars do people recommend whilst stacking, is it OK to > use one of each, and if so would you put the Ultraflex one on the > top kie or lower one? Put the Ultraflex on the end of the stack this will help with launching of the stack. Bear in mind, if it was at the front the rear kite would stop the spar from flexing more the the standard spar at the rear. > If anyone has any ideas they would be appreciated. I have lots of ideas but I don't think anyone here would appreciate them. O--------------------------------------------------------------------------O | "Hello. My name is Inigo Montoya. You killed my father. Prepare to die." | | - Inigo Montoya "The Princess Bride" | O--------------------------------------------------------------------------O | Anytime I see something screech across a room and latch onto someones | | neck, and the guy screams and tries to get it off, I have to laugh, | | because what is that thing. | O--------------------------------------------------------------------------O | Duct tape is like the Force: | | It has a light side and a dark side and it holds the Universe together. | O----------------------------------O----------------------------O----------O |InterNet - Chris@Sound.Demon.Co.Uk| QWERTYUIOPASDFGHJKLZXCVBNM |Chris Lamb| O----------------------------------O----------------------------O----------O = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Mon, 1 Aug 1994 06:37:00 -1000 From: gaffer@ibmpcug.co.uk (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organiszation Subject: Re: Flexifoil stack wobbling & which spars for stacks >paul_b2@sfov1.verifone.com (Paul Butterworth) writes: > Whilst on Holiday I saw some strange behaviour from my stack of 2 > 6 foot flexi's. > In certain winds they started to wobble in opposite directions. Whilst wet foils, funny wind, sand and the position of the moon all play a part, the cure to this is mostly in the hands of the flier. Let me talk you through a typical senario: >From launch, the top foil starts to fly, but the bottom foil is stalled. The top foil pulls the bottom foil forward, making the bottom foil fly, but as much as the top foil helps the bottom foil to fly, the bottom foil drags back on the top foil, causing the top foil to stall. The bottom foil shoots forward, the top foil stalls back and the cycle starts again, with the bottom foil pulling the top foil out of the stall, while being pulled into a stall it'sself. I've also seen a related senario with 6's where the ossciulation is side-to-side rather than back and fourth. The cure is to stall all of the kites together (easily done by walking/running forward during a dive), which will stop the fighting and gently pulling them all out of the dive together. You owe the kite oracle a lilo filled with jello Andrew -- This is not the account that I usually Email from. Please continue to use my usual addresses, thankyou: Work, computer stuff, demands for payment -> gaffer@rec.com Play, kite stuff, party invites, offers of Pizza -> andrew@tug.com = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =