Date: Thu, 22 Dec 1994 08:13:30 -1000 From: era_pul@ki.ericsson.se (Peter Ulfheden ) Message-Id: <1994Dec22.181330.9944@ericsson.se> Organization: Ericsson Radio Systems AB, Sweden Subject: Re: Steering multiplier plan Ronald van der Putten (rvdp@xs4all.nl) wrote: : reason for that? My guess is that as long the kite generates enough pull : you will NOT encounter this 'drawback'. I guess this is true. : closed loop at the bottom, which of course is VERY dangerous if you have : to let go of the kite. : Perhaps there is a possibility to release the kite at point Q? I'm sure too, that it would be dangerous to fly one built with no thought of the safte aspects. This is perhaps something you people, at rec.kites, can help me figure out how to solve. : > : > : > K K K = Line to kite : > | | A,B,C = Pulleys : > | | e,f = One line running in pulley A : > &Q Q& a,b = One line running in pulley B : > |\ /| c,d = One line running in pulley C : > | \ / | & = Knot : > | \ / | H = To handles : > | e\ /f | : > | \ A / | : > | \O/ | : > |a | d| : > | & | : > | / \ | : > | b/ \c | : > | / \ | : > |B / \ C| : > \O/ \O/ : > | | : > | | : > | | : > H H : Are there any length restrictions in lines a, b, c, d and f? Not really, as long as the knots doesen't enter the pulleys at full arm movement. : and how about : the strength of these lines. I'm not a expert in mechanics, but I think, if : you gain a bigger line length difference you have to pay somewhere else. You pay by having to exercise a bigger force *difference* in your arms while turning. : PS: Is this system great to use with a buggy, or what? Yes, why not? I think it can be useful when you see your self standing like a scarecrow with any kite. Peter -- []-------------------------------------------------[] | Peter Ulfheden | era_pul@ki.ericsson.se | | Amorinav. 3 | or petulf@saaf.se | | S-191 44 Sollentuna | Phone: +46 8 751 02 15 | | SWEDEN | Fax: +46 8 35 04 29 | []-------------------------------------------------[] = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Tue, 20 Dec 1994 21:34:15 -1000 From: rvdp@xs4all.nl (Ronald van der Putten) Message-Id: Organization: XS4ALL, networking for the masses Subject: Re: Steering multiplier plan Hi Peter, Unfortunately, I didn't follow the threat about steering large kites, and therefore this is the first time I see you steering system. There are a few things I don't understand, you are (in fact andrew did) talking about a force difference on the lines that can't exceed 25/75, any reason for that? My guess is that as long the kite generates enough pull you will NOT encounter this 'drawback'. Which brings me to the following; What if you have to let go? This system not only carries the weight of the handles, but also the weight of the Pulleys. furthermore, the system has a closed loop at the bottom, which of course is VERY dangerous if you have to let go of the kite. Perhaps there is a possibility to release the kite at point Q? > > > K K K = Line to kite > | | A,B,C = Pulleys > | | e,f = One line running in pulley A > &Q Q& a,b = One line running in pulley B > |\ /| c,d = One line running in pulley C > | \ / | & = Knot > | \ / | H = To handles > | e\ /f | > | \ A / | > | \O/ | > |a | d| > | & | > | / \ | > | b/ \c | > | / \ | > |B / \ C| > \O/ \O/ > | | > | | > | | > H H Are there any length restrictions in lines a, b, c, d and f? and how about the strength of these lines. I'm not a expert in mechanics, but I think, if you gain a bigger line length difference you have to pay somewhere else. Ronald PS: Is this system great to use with a buggy, or what? _______________________________________________________________________________ Ronald van der Putten, Heemstede, The Netherlands rvdp@xs4all.nl DoubleSpace....., Beyond the final frontier, To boldly go where no one has gone before. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Mon, 19 Dec 1994 22:44:45 -1000 From: era_pul@ki.ericsson.se (Peter Ulfheden ) Message-Id: <1994Dec20.084445.16262@ericsson.se> Organization: Ericsson Radio Systems AB, Sweden Subject: Steering multiplier plan Some time ago there was a thread about steering large kites. There were several solutions discussed the solve the problem with long arm movement to turn the kite. So, I've been thinking (well... sort of) about this. I have come up with this idea. I've built one, but I have not tried it on a kite yet. I have done some ground testing though and it seems to work. It will effectivly double your arm movement. A 50cm difference in the positions of the handles will give a 100cm difference at the flying lines. Andrew B. has politely pointed out that there is a drawback with this design. The force difference on the lines can't exceed 25/75This means that the pulley system will stop letting out line on the slack side when the force in that line drops below 250f the total pull. How much of a practical problem this is will have to be determined by practical tests. My guess is that it will also depend on which kite that is used. I will of course try it out myself as soon as weather permits. We are kind of out of kite season here in Sweden this time of the year. This reminds me to wish you *ALL* on rec.kites a Merry Christmas and a Happy Windy New Year. Tight Pulleys Peter 2 x Multiplier by Peter Ulfheden ================================ K K K = Line to kite | | A,B,C = Pulleys | | e,f = One line running in pulley A & & a,b = One line running in pulley B |\ /| c,d = One line running in pulley C | \ / | & = Knot | \ / | H = To handles | e\ /f | | \ A / | | \O/ | |a | d| | & | | / \ | | b/ \c | | / \ | |B / \ C| \O/ \O/ | | | | | | H H -- []-------------------------------------------------[] | Peter Ulfheden | era_pul@ki.ericsson.se | | Amorinav. 3 | or petulf@saaf.se | | S-191 44 Sollentuna | Phone: +46 8 751 02 15 | | SWEDEN | Fax: +46 8 35 04 29 | []-------------------------------------------------[] = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Wed, 21 Dec 1994 20:04:53 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Re: Steering multiplier plan >There are a few things I don't understand, you are (in fact andrew did) >talking about a force difference on the lines that can't exceed 25/75, any >reason for that? Let's look at the thing under full turning: > K K > |g h| > | | > & & > |\ /| > | \ / | > | \ / | > \ e\ /f | > \ \ A / | > \ \O/ | > b\ |a d| > \O& | > | \ | > | \c | > | \ | > H \ C| > B \O/ > | > | > | > DH Let's say that we've got 4kg pull on handle D and 0kg pull on handle B (we're trying to pull as hard to the right as we can). Because C is a free-running pully, the tension in line c and line d must be equal. c is 2kg and d is 2kg. The pull on B is Zero, so b hangs slack. The pull on a is all of c, plus half of the zero pull on B, so the tension in a is also 2kg. The pull on A is split 50/50 between e and f, 1kg each. The total tension on g is e(1kg) + b(zero) = 1Kg The total tension on h is f(1kg) + d(2kg) = 3kg This isn't just a limitation of Peter's implementation. It can be proven mathematically that you can't beat it. You can't get better than this without a *compressive* member in the system to push the "slack" side forward. You reach the 75turning faster but you can't get past it and believe me, you want the full 100to get a Peel out of a tip-stand. You owe the Kite Oracle a perpetual motion machine. Andrew -- Kite FAQ's: ftp.hawaii.edu:/pub/rec/kites/faq) o /\ Kite Jumping For sale: 10' Flexis with std & UF Spars. |_ \/ is for andrew@tug.com AoXoMoXoA (_\ M O R O N S = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Thu, 22 Dec 1994 11:31:00 -1000 From: Joachim_Wiechmann@ol2.maus.de (Joachim Wiechmann) Message-Id: <199412222331.a5770@ol2.maus.de> Subject: Re: Steering multiplier plan Hello Peter, [some stuff about minimizing steering movements deleted] I could imagine another drawback concerning force vectors: As all forces point either in the direction handle-kite or somewhat to the center pulley there will probably occur a resulting force dragging the lines towards each other. You might test that using longer flight lines in your kite simulator. I wish you (and all rec.kiters) a Merry Christmas and a Happy New Year, too. o<:-)} (no convincing Santa Claus, I'm afraid...) Joachim = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Fri, 23 Dec 1994 05:56:05 -1000 From: pbc@condor.circa.ufl.edu (Philip B. Chase) Message-Id: Organization: CIRCA, University of Florida Subject: Re: Steering multiplier plan In article rvdp@xs4all.nl (Ronald van der Putten) writes: >From: rvdp@xs4all.nl (Ronald van der Putten) >Subject: Re: Steering multiplier plan >Date: Wed, 21 Dec 1994 08:34:15 +0100 >PS: Is this system great to use with a buggy, or what? yes, it looks very interesting aside from Andrews point on the 75 423936mit and the safety concerns. As for buggying, I have a trick that I have been meaning share with the list. So far I have only circulated this privately for fear of getting flamed for idiocy, but I have tried it and *it works*. If you have tried buggying with kites that require a lot of displacement to turn you frequently find that you cannot move your arms far enough for an up turn. Meanwhile you can easily get the displacement for a down turn, but monsters like the big peels sometimes don't have the room to turn down. You want to do up turns more often than down turns. The solution to this problem is to switch the handles so that you left hand pulls the right handle the right hand pulls the left handle. The hard part is that you have to learn to fly the kite backwards. I DO NOT advise doing this around people, light poles, trees, or any other object that you would not want to hit. A good drop zone is also valuable and make sure you use quick release, because you will want to release when the kite is in a dive and you get confused. Once you have learned to fly backwards, get into the buggy (remember, *LOTS* of room) and try it. Once the fear is gone you will find that upturns are much easier and down turns are still easy. For my 10m2 peel it really balanced the required displacement with the available displacement. Anybody ever try this trick? Anybody kill a kite doing it? ;-) I swear it works! Philip Philip Chase * pbc@ufl.edu * 904-392-2007 * FAX: 904-392-3760 * U Florida NetWare help >>>>>>>>>> http://grove.ufl.edu/~pbc <<<<<<<<<< NetWare help = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =