Fast Build Scale Model

Discussion in 'Projects & Proposals' started by rwatson, Dec 11, 2011.

  1. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    Out of the moulds

    Pulled it off the 'nest' yesterday, and started adding side panels on the cockpit.

    Balsa is hard to beat as a lightweight, self fairing material.

    Model weight around 8 kg, so its looking good for the final test weight of ~19kg


    http://schoolroad.weebly.com/model-dev-page-4.html
     

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  2. rwatson
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    rwatson Senior Member

    Slow Progress - but finishing Topsides is underway

    Moving house, shed renovations have slowed me down considerably, but some progress has been made.

    Fairing of topsides has commenced, and completing the removable cabin is underway
     

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  3. rwatson
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    rwatson Senior Member

    Model Research Note - plain FG panel not ideal for model

    After all this time, I have to report that the concept of plain FG panels makes keeping the scale weight down extremely difficult. If you build them thick enough to the self fairing and self supporting, they are just too heavy.

    I am currently working on version 2 of the scale model, and having vastly more success using 2mm hi-density foam with FGlass on both side.

    The weight saving with greater stiffness is extraordinary.
     
  4. Fanie
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    Fanie Fanie

    Elementary my dear Watson :D

    That's one hell of a big "model" unless the chairs and ladders I observe are also models ?

    Awesome job, would have liked to be able to give you some more rep points there.


    If you're already working on the next model.... is this what you do, model making, or what's the idea ?
     
  5. rwatson
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    rwatson Senior Member

    No, the model making is a means to an end.

    The first one was of a hull shape that got superseded by a new version of the full size design, and I have that 'on hold' for the moment.

    The second one is of the Version 2 full scale design in foam, to see if we can derive any performance hints from it. One thing we found was that the curves on the forefoot are very tight.
     

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  6. Fanie
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    Fanie Fanie

    Hulls have feet now :D

    Neatly done. Do you actually put these to water and test them ?
     
  7. rwatson
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    rwatson Senior Member

    Please God - eventually. I have the scale model size outboard, Radio Control, servos etc. sitting in the cupboard for the last 12 months

    I also have GPS camera to record the wake patterns, records hull speed during power and sailing.

    So many plans .... so little done.
     
  8. Fanie
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    Fanie Fanie

    LOL.

    What's the radio control for, don't you take them out yourself ?
    Certainly looks big enough ?
     
  9. rwatson
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    rwatson Senior Member

    I could one on each foot.

    Seriously though - 1:5 scale is the smallest you can go (1.5 metres) if you want any semblance of reality between the model and the full scale.

    With the amount of work it takes on the small one, building a full size 28fter is the next stage, just for testing.
     
  10. rwatson
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    rwatson Senior Member

    Finally - 'not so fast model build ' ..

    ... floats on her lines with minimum ballast, and the GPS Camera mechanism finally works

    She only just snuck in to scale weight using foam. Solid glass sheeting would never have worked.

    The color scheme is garish for easy photography, and the finish is 'adequate', but the thing is finally ready for the first day of calm weather for powered trials.

    Latest pics at http://schoolroad.weebly.com/rpgmodel_11.html
     

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  11. michael pierzga
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    michael pierzga Senior Member

    To accurately simulate real life sailing trim, You should pick up a couple cases of these 1.15 beer cans and stow them appropriately.
     

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  12. rwatson
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    rwatson Senior Member

    Yes, true, I think I should invoke the true spirit of boating in the model phase.

    I have the scale model "model" passenger trained to help out with the hard work ;)
     

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  13. dskira

    dskira Previous Member

    Why you think that? Transom in the water is not always bad, it make the buttocks straighter, give volume aft needed for speed which can happens with good wind. Also in case you put a small engine outboard it can be very helpful to have some added buoyancy in the water. I am a firm believer of buried (to some extent of course) transom. The way the water leaving the transom appear do not always bring a lost of speed.
    In 1973 I tank tested a ultra light quarter ton with buried transom, and we didn't find much difference while built against the same model with transom out. ( I know Mariner case, but it was not the transom "per se" other problems was added. And 12M are heavy displacement)
    On fair weather, we always sinked the transom of the Flying Dutchman into the water to gain acceleration.
    Nice job on the basket construction for the model. Next time I will try that. seams to be accurate and liberate the interior of all the framings. Pretty neat.
     
  14. rwatson
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    rwatson Senior Member

    The suggestion was made by a qualified engineer, and my experience with low speed sailboats from dinghys to 28ft is that a buried transom creates severe drag. It wont even have a spinnaker.

    It is probably different for high sail ratio craft, but this design is not in that league.

    I thought so too initially, but I am inclined to agree with PAR these days, and I think I will convert to traditional methods for the actual build.

    You lose a lot of fine control over small parts of the hull, and it increases the fairing work required, as I found out with the model.

    I am hoping to use a lot of the actual interior framing as part of the build mould to save doubling up work, but I will feel a lot more comfortable being able to see the lines from the outside as the panels are pulled down onto the moulds, and make sure that the shapes are correct.

    Its true that I will have to turn the hull up the right way, strip the moulds out to do a layer of glass over the entire inside. I did hope to avoid that, but in the interest of accuracy, I think I will stick to tradition.
     

  15. rwatson
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    rwatson Senior Member

    Switch slapper

    Having fun making a reliable servo controlled water cooling switch and GPS camera activator. I love the way I just have to 'slap' the switch on or off. I should put a face on the switch ;)

    The great thing is that the Contour camera has a magnetic on/off switch, so I can control it with a couple of strong magnets activated by the servo arm

     
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