Help me to choose the best division of spars - Rokkaku Horizontal Spars

Hello Everyone.... Hope you all are doing well...

Guys, I really need your help here.

I have a Rokkaku which is 230cm wide and 300cm tall and I have broke my Upper Horizontal Spars last time, due a small accident. So, now I'm confused in which I'm going to replace it.
Last time, I used 9mm CF Tubes in 3 parts (3 x 77cm long spar) to make it 230cm long, because I don't had the spars more than 100cms long. This time I'm thinking to use 10mm CF tubes to add some strength.
Since I have some left outs of other tubes of same thickness and fixed 100cm long spares, I was thinking of below options to make it 230cm long....
(I use Smaller CF tubes as ferules to connect with each other that fits inside perfectly)

1. Either I add 15cm tube at the extremes with 100cm tubes in the middle.
2. Or put the 15cms in the middle and the 100cms at the extremes. I don't have anything left that is 30cms long to put in the middle.


3. Should I make it 3 parts as I did before. (77cm-77cm-77cm) In this way I have to use 3 new tubes and then cut down to 77m. Whereas in other two methods, I utilize just 2 full spars of 100cm tubes with some left outs.

The only thing I'm concerned about is while making the Bow for the rokkaku. At the same time more efficient, not to break early.

So friends, please suggest me the best way to put it in and what works better.

Thanks. :)


  • Hi! Sousube

    I will prefer solution No 3. I would like to avoid any joint at the center if possible.
    (77cm-77cm-77cm) or 65cm-100cm-65cm

    ~ Erich.
  • Hi Eric, I watch you lot in FB. Your 360s are cool.
    Thank for the suggestion Eric. In that case, my Rok is 200cm long at the lower side, so I use two 100cm tubes connected at the centre. Will that be any problem.
  • Hi Sousube,

    Eric for sure knows quite well large size ROK

    BKT Blue Kite Team also has surely a great know how and testing activity on ROK over 3 m

    if your ROK is in a style similar to Holy Man with holes or "vented" the lower spar has much lower stress

    probably you could be interested by previous discussions dealing about ERBK .... ERBKT

    SMAC from Italy
  • Hi @Sousube,

    There are many possible combinations, there is no right or wrong, it is just a choice, you want light weight? Strong pull? Minimum lift? convenient when fixing or Travelling.

    It is ok to have a joint at the center if you can properly reinforce the joint, and you need to find out all the weak points.

    @SMAC, thanks!


  • Thanks @smac and @Erich.... Yes @smac, Mine is the style of Holyman...
    I will do as you said... Catch you soon guys...
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