Carbon Spar/s

Discussion in 'Laser Class Politics' started by Rob B, Dec 6, 2005.

  1. Rob B

    Rob B Active Member

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    After some thought and discussion of sail design change ideas I have decided that I'm 110% against allowing carbon top sections in the standard rig. Why? Well currently us, em , "heavier" folks currently get an upwind advantage in the heavier breeze and we get eat up by the lighter guys downhill. So, some of us get to enjoy better finishes when the breeze is up. With a carbon top section the heavy folks uphill advantage will go away and we will find ourselves in a lose/lose situation to those within the "competitive" weight range.
     
  2. Murphs

    Murphs New Member

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    luckily they wont be used on the std rig (although i think it will happen one day)

    im fully against them and im on the lighter side for a full rig (170ish pounds i think, we dont use that crap over here :) )

    the stiff lower section and the bendy top section is ugly and not very effective at all
     
  3. bouyracer

    bouyracer New Member

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    I am 100% for carbon fibre rigs,
    Race results should not be influenced by the weight of the sailor.
    Skill of the sailor is whats it is about!
     
  4. Rob B

    Rob B Active Member

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    The problem is this. The boat was designed for a 180 lb sailor. The full time or "professional" laser sailors today keep their weight under 170. Us "average" sailors can still be competitive in the 200 lb range in windier conditions, (given the pros are not in town). The carbon spar will cater to the lighter weight, (average) sailor and make the class more narrow. Thus turning sailors away. Don't get me wrong I like my opportunities to share the course with the pros, but I also like to get some silver at home.
     
  5. glasky

    glasky Member

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    It would be cheaper to race in weight divisions like the windsurfers used to do.

    A carbon topmast, if introduced with radically different bend dynamics, would necessitate a sail re-cut and quite possibly a re-design to a stiffer bottom section as well.

    It would probably require a total new rig like on the byte to make it work.

    Stiff lower sections at maximum pre-bend with a flexible (glass not carbon) tip have worked well on 18 ft skiffs, but this is a stayed rig scenario. The new Byte rig appears to work well but also appears to be engineered in a completely different way to that of the current Laser rigs.

    Should ask Julian Bethwaite about this re-engineering rather than try to re-invent the wheel.
     
  6. Rob B

    Rob B Active Member

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    All of that would be REAL healthy for the class. :mad:
     
  7. Murphs

    Murphs New Member

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    i can confirm that the carbon top section project has been abandoned, the builders/world council wont proceed with them until they are proved to be unbreakable, and some were recently broken in france.

    there is a number of other options they are exploring
     
  8. OliLaser

    OliLaser Guest

    I am completly against having carbon fibre at the top of my boat (full rig) however for the 4.7 it would be ok because the sailors dont weigh much more than the boat anyways and would give the C2 byte some compition.
     
  9. LooserLu

    LooserLu LooserLu

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    Hi,
    there is something curious, that I learnt at my studies for civil-engineering:

    If a bar gets a high compression load (F) to the centerline in the length, it will break suddenly in reason of a physical phenomenia that the famous mathematican from Switzerland Leonhard Euler (1707-1783) found first. 1:1 translated we say "Buckling of Euler".

    The compression load at the Lasermast is generated by the Cunningham.
    The maximum point-force for this Euler-buckling [F=EIππ/l² ("l" = length of the mast, without the length inside of the hull and "I" is the so called "Modulus of Inertia", "π"is the number "pi") ] is only factor ~4 higher for a bar made of carbon-fibre than for an aluminum-bar.
    My calculations are based to a Modulus of Elasticity (E) for Aluminum of 72 kN/mm² and a Modulus of Elasticity (E) for carbonfibre of about 300 kN/mm².
    Alumium handles the energy that is loaded to the bar better than carbonfibre can do (although the bearing strenght of carbon is much higher). Carbonfibre hasn't a linear elasticity and can suddenly crack like glass.

    Under consideration of the other live-loads to the mast, the total-load under extreme conditions (like them, where the mast broke at France) this "buckling of Euler"-load perhaps is one of the reasons the top mast section can break.
    For the correctness of my reflection also it is important to know, at which area the breaking was. If the crack is at the end of the upper-mast-section, where the mast-parts are connected together my reflections maybe aren't complete nonsens.

    G'day
    LooserLu
     
  10. nybozo1

    nybozo1 New Member

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    Dear Laser Luuser,

    I too, have studied Civil Engineering.

    "Buckling of Euler"?

    Surely, you jest....

    Regards,
     
  11. nybozo1

    nybozo1 New Member

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    OK, I give up...see below.

    My question to you laser luuser is why would you present something so obsure and techincal as this on a sailing forum? No doubt, you have Shevy stashed some where and this is his way of communicating with us.


    Topic 6.1a: Euler Buckling - Example 1
    An 16 ft. long ASTM-A36 steel, W10x29 I-Beam is to be used as a column with pinned ends. For this column, determine the slenderness ratio, the load that will result in Euler buckling, and the associated Euler buckling stress. The beam characteristics may be found in the I-Beam Table, and are also listed below.
    [FONT=Trebuchet MS, Arial, Helvetica]-[/FONT][FONT=Trebuchet MS, Arial, Helvetica]-[/FONT][FONT=Trebuchet MS, Arial, Helvetica]-[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Flange[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Flange[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Web[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Cross[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Section[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Info.[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Cross[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Section[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Info.[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Designation[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Area[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Depth[/FONT][FONT=Trebuchet MS, Arial, Helvetica]Width[/FONT][FONT=Trebuchet MS, Arial, Helvetica]thick[/FONT][FONT=Trebuchet MS, Arial, Helvetica]thick[/FONT][FONT=Trebuchet MS, Arial, Helvetica]x-x axis[/FONT][FONT=Trebuchet MS, Arial, Helvetica]x-x axis[/FONT][FONT=Trebuchet MS, Arial, Helvetica]x-x axis[/FONT][FONT=Trebuchet MS, Arial, Helvetica]y-y axis[/FONT][FONT=Trebuchet MS, Arial, Helvetica]y-y axis[/FONT][FONT=Trebuchet MS, Arial, Helvetica]y-y axis[/FONT][FONT=Trebuchet MS, Arial, Helvetica]-[/FONT][FONT=Trebuchet MS, Arial, Helvetica]A-in2[/FONT][FONT=Trebuchet MS, Arial, Helvetica]d - in[/FONT][FONT=Trebuchet MS, Arial, Helvetica]wf - in[/FONT][FONT=Trebuchet MS, Arial, Helvetica]tf - in[/FONT][FONT=Trebuchet MS, Arial, Helvetica]tw - in[/FONT][FONT=Trebuchet MS, Arial, Helvetica]I - in4[/FONT][FONT=Trebuchet MS, Arial, Helvetica]S -in3[/FONT][FONT=Trebuchet MS, Arial, Helvetica]r - in[/FONT][FONT=Trebuchet MS, Arial, Helvetica]I - in4[/FONT][FONT=Trebuchet MS, Arial, Helvetica]S -in3[/FONT][FONT=Trebuchet MS, Arial, Helvetica]r - in[/FONT][FONT=Trebuchet MS, Arial, Helvetica]W 10x29[/FONT][FONT=Trebuchet MS, Arial, Helvetica]8.54[/FONT][FONT=Trebuchet MS, Arial, Helvetica]10.22[/FONT][FONT=Trebuchet MS, Arial, Helvetica]5.799[/FONT][FONT=Trebuchet MS, Arial, Helvetica]0.500[/FONT][FONT=Trebuchet MS, Arial, Helvetica]0.289[/FONT][FONT=Trebuchet MS, Arial, Helvetica]158.0[/FONT][FONT=Trebuchet MS, Arial, Helvetica]30.8[/FONT][FONT=Trebuchet MS, Arial, Helvetica]4.30[/FONT][FONT=Trebuchet MS, Arial, Helvetica]16.30[/FONT][FONT=Trebuchet MS, Arial, Helvetica]5.61[/FONT][FONT=Trebuchet MS, Arial, Helvetica]1.38[/FONT][FONT=Trebuchet MS, Arial, Helvetica]​
    [/FONT]The slenderness ratio = Le / r = 16 ft. * 12 in./ft./ 1.38 in = 139
    Notice that we must use the smallest radius of gyration, with respect to the y-y axis, as that is the axis about which buckling will occur. We also notice that the slenderness ratio is large enough to apply Euler’s buckling formula to this beam. To verify this we use the relationship for the minimum slenderness ratio for Euler’s equation to be valid.
    [​IMG]
    Or, after finding for ASTM-A36 Steel, E = 29 x 106 lb/in2, and yield stress = 36,000 lb/in2, we can solve and determine that Le/r = 89.
    The Euler Buckling Load
    is then give by: [​IMG], and after substituting values, we obtain:
    Pcr = [(3.14)2*29x106 lb/in2 * 16.30 in4/(16’x12"/ft)2] = 126,428 lb

    c) The Euler Stress is then easily found by Stress = Force/Area = 126,428 lb/8.54 in2 = 14,800 lb/in2. Notice that this stress which will produce buckling
     
  12. nybozo1

    nybozo1 New Member

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    OK...how 'bout "obscure" and "technical"

    think I'll go back to Sailing Anarchy where I belong.
     
  13. Merrily

    Merrily Administrator Staff Member

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    Is it true, Lu? Are you channeling DrLaser? :rolleyes: Are do you have cabin fever? I sure do.

    I hope "they" get those carbon spars ready in time for 2008. I wonder what the problem is. I have a perfectly good carbon mast on my Europe dinghy, but it is one piece. Maybe that makes a difference? There has to be a lot of bendiness in the top section and it's hard to mate that with the less bendy aluminum bottom section?

    Merrily
     
  14. Murphs

    Murphs New Member

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    i think you missed my point Merrily

    no carbon spars
     
  15. LooserLu

    LooserLu LooserLu

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    Well, 'nybozo1', first I want to say thank you for the great honor to be mentioned in one sentence with Shevy. :)
    Why you want to go back to that forum that you mentioned? ;)

    But, I have to say, I only had some email contacts with him in 2004, that's all. If he likes to talk with us here at TLF, I'm sure he will do by himself. And I know only very few persons, that not want that he comes back for some good discussions about our sport.

    TLF is a serious internet-forum and of course and I try the best I can to respect that. For me, I try to behave in that way, it is wanted here. Technical aspects of sailing the Laser, also in that way I tried to explain (believe me) in a low level-scientific way like above, I think is nothing that stay against the rules of using this forum and I hope the administrators of TLF do agree a bit to this. I try to say things as easy as it is possible. I'm not going to start a real lesson in engineering that only a few readers are interested in here, ok.

    My point of interest to this aspect of breaking of a mast began with the story, a very good sailor from the US-west coast told in 2004. He told us here at TLF, he went out with his Radial in stronger winds and the upper mast-section bent. He told, that he went back to change this for a new one and went out again. He told, aft a while the new upper mast-section bent again. If I remember right his story, he changed the upper-mast section another 3 times at that afternoon... This story brought me to the opinion, that the likelihood is high, that there is a realistic (serious statistic) reason why this bending happens. One reason (but not alone!, there are a lot of other reasons that can be the reason in summary of a failure of the mast) is probably this buckling-phenomena.
    I started some "round-about"-calculations and found out, that the chance, that the likelihood for this phenomena not goes to zero and can be one (tiny) aspect of failure for an upper mast-section made of aluminum. But, I'm not the one, that can prove such an affirmation, because therefore I need a special test stand and exact information's about all the loads that an upper mast-section has to handle.
    Then, in 2005, here at TLF I read, the carbon upper mast-section also (suddenly) failures. Could it be, that this phenomena of buckling is one of the drops, that brings the barrel to flow over? I really do not know exact. But, this buckling-phenomena is there, no doubt. Also at other masts this "buckling"-load is there, but a full carbon mast behaves different than a mast that is made out of two (or more) parts.
    To say this clear, this aspect of buckling here, is not to be understand in the way the civil-engineers use it to calculate steel- or concrete-columns for that they do not break under the total loads. This columns should not bent, anyway. But for the masts, we want /it is appreciated that they bend (but not, that they bend so much, that they break under the total live-loads (also if they are extreme) it has to hold). The carbon mast is prepared/made to bend more than a mast made of aluminum. But it is the summary of all aspects (other aspects f.e. are: the imperfections that they have from gluing the carbonfibre together, sharp edges (like the end of the aluminum lower-mast-section) can destroy the carbonfibre by wearing) that let the carbon upper mast-section break.
    Maybe there is a need, to invent a new sort of connection of the under- and the upper-mast-section, I don't know.
    It is a really very-very difficult problem (with several unknown non-linear factors) to calculate the maximum load such an upper mast-section made of carbon has to hold save. Only with testing a lot of such carbon-tubes on a special test stand and doing some difficult statistical calculations, hopefully brings a trustful solution to the reasons of the failure. If this is done intensive and serious, of course there is hope for a carbon upper mast-section that will work perfect in 2007/2008.

    With my words I only want to express, how difficult it is to invent such a "simple" new tube for the Laser-mast and also it is really expensive. The people that construct such a tube know that all better than I ever would understand it and I have much respect for this people. I hope, with my words, the reader also comes to the view, that "life is not easy" for inventors.

    And Merrily, no, I'm not "channelling" Shevy. If I would do, he sure would be very angry with me. And I'm not "ill" (, I guess/hope). The only "illness" I perhaps have is, that I'm an engineer and Laser-sailor, that has to be in hibernation in the moment...;0)


    Ciao
    LooserLu
     
  16. rock steady

    rock steady New Member

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    Your dropping the big news on this topic MURPHS, can you tell us how you know?
     
  17. gouvernail

    gouvernail Active Member

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    Word has it, the Laser Enquirer has an article on page 49 of the Winter / May issue about Shevy, Laser LU, NYBOZO, and Merrily conspiring to bring recycled Kevlar Spectra reinforced spars made with recycled chocolate bunny based resins to the Easter Laser Regatta for testing by the entire fleet.
    The connection between the lower section and the top section will be improved and softened by insertion of a stuffed bunny in the top end of the lower section.
    JR has already promised to supply basket grass for lining of Laser cockpits so that no one's feet will be bruised as they jump for joy at the sight of the new top sections..

    This message was paid for by the Citizens Against Rationality and I approved this message.
     
  18. Murphs

    Murphs New Member

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    Gram from Performance Sailcraft Australia told everyone that was present at the Aus Laser Association AGM
     
  19. gouvernail

    gouvernail Active Member

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    Maybe I am asking you to start a new thread as this is off subject but.

    What is the format for your AGM?

    We used to have an AGM which was two meetings held at our two midwinters regattas. Our officers were nominated there and elected later by teh district secretaries. The meetings were held during a regatta dinner so a few hundred sailors actually attended and 10 or 15 provided input at each meeting.
    The class was controlled by the people who sailed in our largest regattas and the new officers were elected early in the sailing season.

    Currently we have a system where oficers are nominated on line and the elections ( if anyone is nominated) are held after the season ends.

    I am not trying to be judgemental about the realtive benefits of either system. I am just asking what you do.
     
  20. Murphs

    Murphs New Member

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    we have one AGM at our national championships annually

    financial report

    each state (district) reports to the meeting about progress and all that stuff

    then we have matters arising from the last meeting (i.e. if an idea was forwarded the year before, whats its progress)

    then election of officers, voting is done by 3 delegates from each state so all states are represented equally

    then general business
     

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