Date: Tue, 24 Oct 1995 04:19:41 -1000 From: Dan Whitney Message-Id: Organization: Delphi (info@delphi.com email, 800-695-4005 voice) Subject: Re: Venting a kite: aerodynamics or wild guessing? I have flown a kite called the exterminator built by Fred Adler, He vents the L/E and the trailing edge, The vents are aprox. 1" Iam not a kite builder but this method seems not to take away from the sail design or the way the kite flys. Give it a try on your next one. dan = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Tue, 24 Oct 1995 04:24:55 -1000 From: djskites@aol.com (Djskites) Message-Id: <46isvn$30v@newsbf02.news.aol.com> Organization: America Online, Inc. (1-800-827-6364) Subject: Re: Venting a kite: aerodynamics or wild guessing? >Does anyone have experience with venting high wind kites? My main idea is to reduce the kite's pull to a reasonable amount in order not to let it self distruct. After trying to teach in extreamly high winds in Fanoe this past summer, we resorted to using the cut method to see what worked(wasn't my kite) So we cut, and the kite flew terrible. From that I knew what not to cut, and that is what I called the target zone. By holding out the bridle and looking for dead center in each side of the sail, I figure this is where most of the pressure is going, if you vent that, you effect the flight charicteristics of the kite, so venting near that point, the wind essentialy hits the "target zone" and then bleeds off to the vents. I do not claim to know aerodynamics, or it's terminolgy, but flying and cutting and making kites for years, I was able to get lucky on my first production vented design, the "Vented Tramontana". Vented high wind kites should be for high winds. Some use small vents, and still pull like a truck in over 25 and are expected to fly in light winds. This one needs about 12mph to fly or more and can handle over 3o(and that is high!) with ease! This new design if adjusted properly has been tested in the kickin winds in Dunquerk France recently. I estimated over 35 mph.I had trouble walking against the wind! A girl in my class was able to fly it in those winds! Now, we couldn't stall on her setting, but she could do precision and practice team with her team mates without being pulled using 150 lb Lazer pro line. By adjusting the bridel, we could get stalls and an occasional axel, but we had more pull of course. The rain didn't help though! If any one has seen a Tramontana(Kite lines Summer/Fall 1995 Vol 11 no 3 Page 8), I vented the two large black panels that extend from the top spreader to the keel and the two small white panels above the Air Wing Battens. Most who see it comment on the amount of venting used. The title of this thread is true, for me it took both, and a little more of the latter. I am trying to vent another one of my kites, I hope I get as lucky as I did with this one! Good luck cutting and I hope this helps Dodd Gross North and South America Importer/Wholesaler of HQ & Fizz Sport Kites Master Instructor Flight School World Tour Flight School Instructional Video Series \\\\\\\\\\\\Disclaimer/////////////// Because of my involvement with the above products and services, my views and statements may be seen as biased. I can assure you I am a flier FIRST! Quote of the month "Hay alquien aqui que hable ingles?" = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Mon, 23 Oct 1995 23:45:20 -1000 From: hpeeters@vub.ac.be (Herman Peeters) Message-Id: Organization: Brussels Free University Computer Centre Subject: Venting a kite: aerodynamics or wild guessing? Good morning all, last week I finished building the 'Titlis', a 3 meter span fully battened high aspect delta (plans available soon). I'm playing with the idea of building a high wind version as well. So far, I haven't been able to find some general idea behind dimensioning the vented panels on high wind kites. Apart from small vents at the tips, to prevent flutter, vents appear about everywhere on a kite in every thinkable shape, sometimes just determined by aesthetics. Possibilities that come to mind: Parallel to the spine: / \ / | \ / | \ /* | *\ /**** | ****\ / **** | **** \ / **** | **** \ --------****-----------------****-------- Perpendicular to the spine: / \ / | \ / | \ / | \ /*************************\ /*******************************\ / | \ ----------------------------------------- Triangle (Raaseri style): / \ / | \ / | \ /* | *\ / ** | *** \ / ***** | ***** \ / ******* | ******* \ ------*********----------*********------ Reverse triangle: / \ / | \ /** | **\ /**** | *****\ /****** | *******\ / ***** | ***** \ / *** | *** \ ----------*------------------*---------- Center panels: / \ / | \ / | \ / | \ / **** | **** \ / **** | **** \ / **** | **** \ ----------------------------------------- Does anyone have experience with venting high wind kites? My main idea is to reduce the kite's pull to a reasonable amount in order not to let it self distruct. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Tue, 24 Oct 1995 09:20:26 -1000 From: sasaki@netopd.harvard.edu (Marty Sasaki) Message-Id: <46je9q$rt@netope.harvard.edu> Organization: Harvard University - OIT/NSD Subject: Re: Venting a kite: aerodynamics or wild guessing? In article , hpeeters@vub.ac.be (Herman Peeters) writes: |>last week I finished building the 'Titlis', a 3 meter span fully battened |>high aspect delta (plans available soon). I'm playing with the idea of |>building a high wind version as well. So far, I haven't been able to find |>some general idea behind dimensioning the vented panels on high wind |>kites. The easiest way to do this is to make a kite entirely out of screen material. Then tape pieces of fabric or plastic to the screen. You can then experiment to your heart's content with the placement and size of the vents. Of course, I have never done this. I always make complete kites that sometimes work and other times fail miserably ;-). |>Does anyone have experience with venting high wind kites? My main idea is |>to reduce the kite's pull to a reasonable amount in order not to let it |>self distruct. You can vent a kite so that you can do snap stalls and axels in high wind. Good luck with your experimentation. -- 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 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Tue, 24 Oct 1995 20:09:55 -1000 From: Chuck.van.Eekelen@net-engine.nl (Chuck van Eekelen) Message-Id: Organization: NLnet Subject: Re: Venting a kite: aerodynamics or wild guessing? djskites@aol.com (Djskites) wrote: >This one needs about 12mph to fly or more and can handle over 3o(and that >is high!) with ease! 30 MPH is HIGH ! ? Guess you don't live in Holland. Average is 7-18 (inland) and 12-24 on the Beach. Come fall and spring 31-38 is not exceptional and 25 is rather common (again inland). You can actually have 45 mph winds once every so often on the beach. Imagine a 2-stack of SpeedWing Super's ? (You're absolutely right I leave my 5 sq. meter QuadriFoil in the bag in these winds) So I guess your definition of high winds DOES depend on where you live :-) greetinx, Chuck Go Fly a Tornada in a Hurricane ! __ ____ / \ / | \ /--- \____\/____ Wandering through the thick fog, wondering where my kite went. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Wed, 25 Oct 1995 09:10:05 -1000 From: g.umlauft@magnet.at (Gertraud Umlauft) Message-Id: <611450878.33531640@magnet.at> Organization: magnet Online Service Subject: Re: Venting a kite: aerodynamics or wild guessing? >I was able to get lucky on my first production vented design, the "Vented Tramontana". I read Dodds informations about the Tramontana with much interest. I have made a Tramontana with vents. I must confess, I chose the place for the vents from the view of the design. So I made a stripe of 3cm mesh arround the big panel in leef form. BTW, I thought a little bit about what the vent at that possition would cause ( it was not only the beauty that made me locating the vents at this point). I know from many kites I made with vents during the last years, that vents near the tunnel (the zone of the sail from the standoffs to the nose - I do not know the english name of this part) make the kite slower and that vents near the leading egde reduce pull. So this place for the mesh met both zones, it slowed the kite down and the pull was very much reduced. The kite now flies in very strong winds with a modest pull, he makes all a normal Tramontana makes, including stalls, slides, axels and so on. The only I am not satisfied with, is that the kite with 3cm stripes of mesh need so much wind to fly properly, that I nearly cannot use it in winds we have in Vienna. But in our summer holydays in South France (Festival in La Franqui) it was sometimes the only kite to use in those strong winds. If I make another vented Tramontana, I will make the stripes of mesh only 2 cm. Other vented kites I made were three Edge - one with the triangle hole, one with mesh in the triangle and the small stripe going from the triangle to the leading edge, and one with more mesh at this stripe. They oll performed very well, the second version I used often in the last years competitions in winds over 15 km/h. Than I made a Cicade after the book Stuntkites with only a 10c m stripe of fabric on the outside of the wings, the inner part totally with mesh- it needs strong winds. At a Big Brother I made a little vent in one of the inner panels. In pair Duo MozarTello (I fly with the swiss girl Monika Morgenthaler from the swiss team Lucky Landing Albatros) we use the Albatros teamkite (similar to Big Brother II) with every second panel vented. This kite flies in stronger winds with the same characteristic as the unvented version. I cannot explain,why all my vented kites are very good performing, I think it is a litttle bit of instinct to place the vent. And a little bit of trying make kitebuilding much mor interesting. Greetings from Vienna Gertraud Umlauft --- OffRoad 1.9g unregistered = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Wed, 25 Oct 1995 08:04:38 -1000 From: coreykite@aol.com (Coreykite) Message-Id: <46lu7m$rq5@newsbf02.news.aol.com> Organization: America Online, Inc. (1-800-827-6364) Subject: Re: Venting a kite: aerodynamics or wild guessing? As my little contribution to this thread... Venting on or near the Leading edge seems alot like slats on a airplane wing. These L.E. slats would increase lift (pull) at low speeds. Seems like the opposite of the goal as stated. Trailing edge vents would decrease pressure from the sail. Slowing the speed with dams would also decrease pressure. Critical sail areas would be the keel for directional stability and the wingtips for turning control. Experiment with the other side of the brain. aoxomoxoa coreykite@aol.com = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Wed, 25 Oct 1995 23:27:28 -1000 From: Rodger Duffett Message-Id: <46nka0$hup@ucthpx.uct.ac.za> Organization: UCT Subject: Re: Venting a kite: aerodynamics or wild guessing? In Cape Town 45mph is considered a gentle breeze ;-) So far most of the vented kites I've seen largely appear to be designed around making the kite look good! (Probably how most stunt kites are designed anyway if the truth be known ;-> ) That plus trial and error to optimise flying characteristics! Rare Air Kites (now based in Cape Town) make some nice vented kites. In particular the Wind Warrior does very well in Cape Town's higher winds. It has multiple triangular vents sort of parallel to the spine. Flys very nicely as a quad! I am working on a high aspect ratio delta (had discussions with Chuck van E. about it) called the FireFox. I intend to try a vented version with vents parrallel to the leading edge. More on this when it happens... BFN -- __________________________________________________________________ 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 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Thu, 26 Oct 1995 06:39:36 -1000 From: George Cameron Message-Id: <46odk8$5fj@lll-winken.llnl.gov> Organization: Lawrence Livermore National Lab Subject: Re: Venting a kite: aerodynamics or wild guessing? In article <46lu7m$rq5@newsbf02.news.aol.com> Coreykite, coreykite@aol.com writes: >As my little contribution to this thread... >Venting on or near the Leading edge seems alot like slats on a airplane >wing. These L.E. slats would increase lift (pull) at low speeds. >Seems like the opposite of the goal as stated. Look carefully next time you fly and you will see that the slats extend forward and downward from the L.E. of the wing thereby greatly increasing the camber of the wing with resultant increase in lift. The slots vents at the rear of the slats are there to provide some pressure equalization to minimize flow separation in this region. Fowler flaps (on the trailing edge) are slot vented as well to minimize separation over the highly curved upper wing surface. Just my $0.02 George Cameron = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 27 Oct 1995 00:00:15 -1000 From: hpeeters@vub.ac.be (Herman Peeters) Message-Id: Organization: Brussels Free University Computer Centre Subject: Re: Venting a kite: aerodynamics or wild guessing? In article <611450878.33531640@magnet.at>, g.umlauft@magnet.at wrote: > I read Dodds informations about the Tramontana with much interest. I have > made > a Tramontana with vents. I must confess, I chose the place for > the vents from the view of the design. Any chance on finding a web picture of this or other vented kites (I've seen the vented Raaseri and the Rev)? To continue the thread: I had a chat with an experienced kiter at the beach yesterday. He told me to leave the keel and wingtip area intact, but vent the center section. Shape of the panel didn't seem to matter that much as long as stability wasn't disturbed to much. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 27 Oct 1995 13:45:33 -1000 From: cvm@wirehub.nl (Corne' Verboom) Message-Id: Organization: JGC Dordtse Engineering B.V. Subject: Re: Venting a kite: aerodynamics or wild guessing? Chuck.van.Eekelen@net-engine.nl (Chuck van Eekelen) wrote: >djskites@aol.com (Djskites) wrote: >>This one needs about 12mph to fly or more and can handle over 3o(and that >>is high!) with ease! >30 MPH is HIGH ! ? >Guess you don't live in Holland. Average is 7-18 (inland) and 12-24 on >the Beach. Come fall and spring 31-38 is not exceptional and 25 is >rather common (again inland). You can actually have 45 mph winds once >every so often on the beach. Imagine a 2-stack of SpeedWing Super's ? >(You're absolutely right I leave my 5 sq. meter QuadriFoil in the bag >in these winds) >So I guess your definition of high winds DOES depend on where >you live :-) Sure does! Bragging about your favorite area? A few times a year I am in (Soutern) Alberta, Canada. Since they have over 50 mph (steady!) quite regular there (and a rare 60 mph), I never leave my 3.5m2 Sputnik I home!! But you're absolutely right, as kite flyers we are lucky to live in Holland ;-) ================= [ Corne' Verboom ] [ cvm@wirehub.nl ] ================= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 27 Oct 1995 04:47:00 -1000 From: alex.hesse@ius.gun.de (Alexander Hesse) Message-Id: <5wfVygSlNWB@alepoint.ius.gun.de> Subject: Re: Venting a kite: aerodynamics or wild guessing? Hi Herman, Herman writes: h> Does anyone have experience with venting high wind kites? My main h> idea is to reduce the kite's pull to a reasonable amount in order h> not to let it self distruct. I use for my Kite SYNAPSE a triangle shaped vent / \ / | \ / * | * \ / *** | *** \ / **** | **** \ / ***** | ***** \ / | \ ----------------------------------------- My experience with this vent in the centrum of both halfs of the sail is quite good. But i think that this way ist not the optimum. It could be better to vent the sail on two different places like this: / \ / | \ / * | * \ / ** *|* ** \ / **** *|* **** \ / ***** | ***** \ / | \ ----------------------------------------- You decrease the pull with the outer vents and decrease the speed with the inner vent (look at the article from Getraud Umlauft). You've also the possibility to mask parts of the vents to tune the kite for different windconditions. A generally Experience with vented kites is that the windwindow is a little bit smaler as it is with unvented kites. But I haven't a good explanation for that. A extra added difficulty for develop a god competition-kite is to have a smal overlap to the windrange of your unvented competition-kite. The way I vented the SYNAPSE allows to fly in a wind of >20km/h. Fly under that minimum Wind is possible but makes the kite less precise. Write about your Experience :-) Alexander Hesse (Pair "DON'T PANIC!") ALEX.HESSE@IUS.GUN.DE Krefeld, Germany ## CrossPoint v3.02 R ## = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 27 Oct 1995 04:47:00 -1000 From: alex.hesse@ius.gun.de (Alexander Hesse) Message-Id: <5wfVygSlNWB@alepoint.ius.gun.de> Subject: Re: Venting a kite: aerodynamics or wild guessing? Hi Herman, Herman writes: h> Does anyone have experience with venting high wind kites? My main h> idea is to reduce the kite's pull to a reasonable amount in order h> not to let it self distruct. I use for my Kite SYNAPSE a triangle shaped vent / \ / | \ / * | * \ / *** | *** \ / **** | **** \ / ***** | ***** \ / | \ ----------------------------------------- My experience with this vent in the centrum of both halfs of the sail is quite good. But i think that this way ist not the optimum. It could be better to vent the sail on two different places like this: / \ / | \ / * | * \ / ** *|* ** \ / **** *|* **** \ / ***** | ***** \ / | \ ----------------------------------------- You decrease the pull with the outer vents and decrease the speed with the inner vent (look at the article from Getraud Umlauft). You've also the possibility to mask parts of the vents to tune the kite for different windconditions. A generally Experience with vented kites is that the windwindow is a little bit smaler as it is with unvented kites. But I haven't a good explanation for that. A extra added difficulty for develop a god competition-kite is to have a smal overlap to the windrange of your unvented competition-kite. The way I vented the SYNAPSE allows to fly in a wind of >20km/h. Fly under that minimum Wind is possible but makes the kite less precise. Write about your Experience :-) Alexander Hesse (Pair "DON'T PANIC!") ALEX.HESSE@IUS.GUN.DE Krefeld, Germany ## CrossPoint v3.02 R ## = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =