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Thread: MICROMAGIC vs NANO

  1. #1
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    Default MICROMAGIC vs NANO

    Having consulted the NANO Rules, I just tried to compare with a similar length model like the Micro Magic.
    There are some data that may be difficult to cope with.
    The NANO Sail Plan aspect ratio is rather high compared with the Micro Magic.
    The Main Luff is 900mm against the 980mm of the total Micro Magic height
    My preliminary calculations for the Nano shows a possible Sail Area of about 1700cm against the 1450cm of the MM, it can be less if both sails become narrower like the rigid sails of AC catamarans.
    Similar righting moment of the MM can be obtained with a bulb of about 275g, but the height of the CE may requires more weight in the bulb to get similar stability against wind pressure.
    No calculations made, is just a guess.
    I wonder about stability !
    No further comments!

    ClaudioD

    Here below the comparative templates.
    Attached Thumbnails Attached Thumbnails Click image for larger version

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    Last edited by claudio; 05-30-2017 at 07:28 AM. Reason: added text

  2. #2
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    Default Re: MICROMAGIC vs NANO

    Claudio, I use a 350g bulb in my 500g Footys.

  3. #3
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    Default Re: MICROMAGIC vs NANO

    That was only a comparison when found out that the MM bulb is available as spare part and weight only 376g attached to a Fin of 134mm length. This may also justify a short mast !

    Personally I would try about 525/550g bulb to obtain a total displacement of about 750g (ratio 70%) compared with the 860g of MM (ratio 47% which is very low).
    Need to verify if the total construction can be obtained below 225g.

  4. #4
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    Default Re: MICROMAGIC vs NANO

    I went to check some parameters and got my personal idea.

    It is obvious that when a boat is getting smaller, the uncompressed construction weights become the predominant factor.

    Increasing balancing weight (bulb weight) to compensate the relatively high aspect ratio of the Sail Plan make things more complicate.

    Ending up with an heavier model will not help to get acceptable performances.

    Actually my Construction Budget is 340g, that's includes Electronics, Rig1, Fin, Rudder, Hull-Deck, Supports. It may be larger !

    Adding a bulb of 500g, the final boat will be 840g at the buoy.

    Unfortunately the weight Ratio will be rather low : 500/840 =59.5% - (Class M >70%).

    One may use a bulb of 600g and the Ratio will become : 600/940 = 63.8% that is better, but the boat will be heavier imposing a larger Sail Plan to get some sailing performances, etc.

    The sail plan considered is 1350cm, larger plan possible, but lateral stability will be critical.

    NANO, a difficult Model to build unless construction weights are smaller and mast height shorten.

    ClaudioD

  5. #5
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    Default Re: MICROMAGIC vs NANO

    While others talk about NANO, myself a tried to design a PICO for about 750g and 1350cm of sails ... hoping that she will not met too much wind !
    Attached Thumbnails Attached Thumbnails Click image for larger version

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  6. #6
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    Default Re: MICROMAGIC vs NANO

    Here the Chine Hull for PICO, although with more bulb weight and larger DSP, the ratio Bulb/Dspl is still below 65%
    Attached Thumbnails Attached Thumbnails Click image for larger version

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  7. #7
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    Default Re: MICROMAGIC vs NANO

    Recalling the Scale Factors when passing from one model to another. Volume rated at the cube of the scale and Surface rated at the square of the scale.

    Scaling down from an RG65 of 1000g and 2250cm of sails to a model of 500mm of length.

    650 /500 = 1.3 scale ratio
    the cube of 1.3x1.3x1.3 = 2.19 scale factor for the volume.
    1000g : 2.19 = 456g displacement for a 500mm long model .
    the square of 1.3x1.3 = 1.69 scale factor for sail plan surface
    2250cm : 1.69 = 1331cm
    Thus the 500mm long model should have a Displacement of 456g and a Sail Area of 1331cm.

    Mission impossible !!

    Calculations for the construction shows that the model will weight 330g without any bulb.
    According to the scaling factor the bulb weight will be 456g 330g = 126g, which is very very small.
    The bulb weight can be increased but the Displacement will increase also and far above the 456g calculated above.
    Assume to use a bulb of the same weight as for the construction : 330 + 330 = 660g.
    This could lead to the total weight of the boat of 660g, but 330/660 = 52% to ensure a lateral stability.
    A class M is around 72%
    Better to stay above 65% and in case of Wind increase the Sail Surface shall be reduced.

    The typical RG65 Main Luff length is: 1000mm : 1.3 = 769mm when scaled.
    The typical RG65 Keel depth is: 300mm : 1.3 = 230mm when scaled


    A model of 500mm length shouldl have the following parameters to ensure an acceptable minimum sailing capacity : weight Ratio : 550 : 880 = 62.5%

    DSPL 880g
    Bulb 550g
    Construction 330 g
    Main Luff 770mm max
    Sail Plan 1350 cm max
    Keel depth 230 mm min

  8. #8
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    Default Re: MICROMAGIC vs NANO

    Just a question, how much does the box influences the micromagic dimesions? I mean, how much effort goes into the boat design, for a large company like graupner? where do they put the priorities, in a really good sailing performance or the best boat that can be shipped at a reasonable cost (i.e. no 2m single piece tapered CF mast), produced cheaply and easily assembled?


    So basically the real question would be, is the micromagic a good comparison or benchmark for what would be a relatively "open" class?

    That said, I do like the NANO idea, and please keep the discussion going ....


    On a side note, I really like your chined PICO Claudio .... (I have a futinet footy), more info please?
    Last edited by Gio; 06-02-2017 at 12:24 PM.

  9. #9
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    Default Re: MICROMAGIC vs NANO

    Claudio -
    thanks for doing the math on the NANO comparison. It saved me a bunch of work since I can't find my notes of displacement and stability. They are around here somewhere - just couldn't find them on first try. Wife says I need to clean up and organize. Who am I to say "no" to her "suggestions? [Big Smile]

    Perhaps one of these days, I might get excited about the "FOOTY" class. In the meantime, I have a 2 meter catamaran that is calling my name and waiting for me to get the templates onto the building board ----before Christmas appears. "Oh My"

    Thanks again for doing the math and results.

  10. #10
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    Default Re: MICROMAGIC vs NANO

    Hi Gio,
    what do you mean by 'box' ?
    MM has some limitations and is a toy for me, but most of them are compensated by the low 'aspect ratio' of the Sail Plan with the Main Luff of 760mm against 900 mm of the NANO.
    The weight ratio do not play in favor for this model either if the Bulb is "apparently" weighting only 360g against a total weight of 860g. 41.8% is a very low ratio ! Far from 65% for an acceptable stability.
    Is floating and cheap...what ask more !
    Remember, waves and wind cannot be scaled.
    I do not consider it a benchmark.
    Benchmark for me means performances to be met, something to aim for !
    NANO idea is born for a 3D printing, what will happen when exposed to 12kt of wind I do not know.
    My posts were limited to explain what are for me the basic considerations for a stable boat.
    Cheers

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