model RC racing yacht uni project beguinners help

Discussion in 'Boat Design' started by squires500, Feb 25, 2009.

  1. squires500
    Joined: Feb 2009
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    squires500 Junior Member

    thank you very much ivor it has certainly given me a much clearer picture of how to start.
    ive also managed to get your website to work last night and it is very informative.
    thanks for the help. i really had no idea where to start.
  2. ivor Bittle
    Joined: Feb 2008
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    Location: England

    ivor Bittle Junior Member

    RC yacht

    You seem to have taken my hull design on board and to have found my website. It must be ideal for your project.

    If you can design a hull you need a design sequence for the rest. The starting point is to choose an area for the rig, that is, the total area of the sails. No amount of physics will give an answer to this and you need to look at successful designs of small yachts like the Fiesta and the Victoria. The mast height will be about 20 inches.

    I think that you will be expected to use a Bermuda rig and this means that you must share the sail area between the main and jib. Use my “Physics of sailing” on my website to make an argument for how you make your choice. You should be able to use it in your write-up.

    From there on everything that you need is in my book “The RC yacht explained” and it is in the university style.

    The first step is to design a fin and then to optimise the weight of the bulb. That is quite straightforward if you follow my design methods. There is a chapter on the shape of the bulb.

    It would pay you to read “making sense of aerofoils” if only to understand your fin.

    When you come to mount the mast and fin remember that the centre of sideways lift of a hull bare is very close to 40% back from the stem. If you have trouble locating the mast and lead relative to the 40% point ask me again.

    Ivor Bittle
  3. ivor Bittle
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    ivor Bittle Junior Member

    Yesterday I watched a fleet of Fiestas and Micro Magics racing.

    The Fiesta is larger than I recall it at 24 inches long with a 37 inch mast. The Micro Magic is 500 mm long with a mast about 750 mm high. The beam is 175 mm. The sail dimensions are given in detail in Look in Class rules. Both the boats appear to have area ratios of about 60% to 40% between main and jib.

    The underwater parts of the Micro Magic look a bit agricultural to me and it is beamier than the Fiesta.

    In this thread someone said that these little boats bob about and this is true. My impression was that you would be hard pressed to find a way to bring science-based design to bear on these little boats.

    Ivor Bittle
  4. Tcubed
    Joined: Sep 2008
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    Tcubed Boat Designer

    Science can be brought to bear on tiny sailboats just the same as any other boat. It's just that a lot of formulas change.

    My most successful design was 30 cM long non RC monohull and it would ,within a suitable wind strength window, plane upwind.

    I have also observed that most model sailboats (even those made professionally) suffer from basic design flaws, that could have been prevented by correctly understanding and applying the correct (at that scale) mathematical principles.

  5. FlyingFish
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    FlyingFish Junior Member


    How was the project done?

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