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 Post subject: test no3
PostPosted: Tue Oct 05, 2010 10:30 am 
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Joined: Sun May 23, 2004 4:32 pm
Posts: 98
board ist very well balanced now. the front straps are 5 cm further back. unfortunately i stopped gps tracking unintentionally, so, again, no good data.

again, i experienced the problem of not being able to pass all pressure given by the kite (speed3 19) onto the board. the back fins tend to give in when pointing too much upwind. not sure about the reason but i am pretty sure it is just that the back fins are too small (22cm each). i will try bigger ones the next time. 32cm should be enough.

sealing of centreboard box stayed in place this time.

h.


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 Post subject: Re: New Board Race 1 fin
PostPosted: Mon Oct 11, 2010 10:42 am 
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ready for the next test run.


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 Post subject: Re: New Board Race 1 fin
PostPosted: Wed Oct 20, 2010 9:04 am 
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way better with bigger fins. the board is still not performing well enough, but it is getting there. i am optimistic that the concept will work. it sure makes fun already. went out with my 12 and was medium powered. unfortunately not enough to push it to the limit. i am at 50° now.

h.


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 Post subject: Re: New Board Race 1 fin
PostPosted: Wed Oct 20, 2010 2:35 pm 
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50° upwind angle ?
or 50° tilting angle of the middle fin ?


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 Post subject: Re: New Board Race 1 fin
PostPosted: Wed Oct 20, 2010 3:05 pm 
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upwind angle. it is kind of strange. i don't know the reason yet. when i get going fast at around 55° upwind angle the board runs nicely, flat and ok fast. when i turn it further upwind it sometimes tilts windward side up and looses speed. i need to find out how to prevent that from happening. first thing i want to try is to mount some kind of bump under my straps to enhance my feets' angle when i am going upwind. plus i want to get rid of the third back strap. no need for that i think.


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 Post subject: Re: New Board Race 1 fin
PostPosted: Thu Oct 21, 2010 12:41 pm 
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sounds great 50° is a pretty nice performance,

as far as I know, last year, Bruno Sroka was riding at 45° upwind


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 Post subject: Re: New Board Race 1 fin
PostPosted: Thu Oct 21, 2010 2:43 pm 
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holden wrote:
upwind angle. it is kind of strange. i don't know the reason yet. when i get going fast at around 55° upwind angle the board runs nicely, flat and ok fast. when i turn it further upwind it sometimes tilts windward side up and looses speed. i need to find out how to prevent that from happening. first thing i want to try is to mount some kind of bump under my straps to enhance my feets' angle when i am going upwind. plus i want to get rid of the third back strap. no need for that i think.


I know the reason this is happening,

I used to race windsurf course board, the long ones.... when going up wind you had the center fin down, but in strong breeze you would get too much lateral force on the fin and it would tilt the board up on its edge to counter act this you would stand right over the centre fin but on the rail to keep weight on it but even then if you got a gust you would get pitched over.

to prevent it you could just reduce the area of the fin by pulling it up a little, but to be honest if you are getting 50 degrees then that is great already!


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 Post subject: Re: New Board Race 1 fin
PostPosted: Fri Oct 22, 2010 9:14 am 
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it is not only the angle, it is also the speed i am lacking. you can get these vmg values with a north ltd 2009 edging it a bit so you don't have to put all your weight on your back foot. it has to be better than that, right?

yesterday i had my final test run for this setup. i installed a rubber bump under each of the back straps to enhance board control. it helped. wind was solid, s3 12 dl well powered. waves were not too bad. this time i was able to go very well, board stayed flat on water, well balanced, load equally on both legs. as good as it gets. the board should have shown its best performance but vmg was not good enough. i mean, guys, there are two 32cm fins and a 36cm centreboard this should mean something.

but, i also had new findings. i was testing, again, all different positions for my centreboard and i had the strong feeling, that it creates a lot more drag than it is supposed to. when i put the centreboard all the way up, the board was fast. when extending the centreboard for about 10° it starts to create noticable drag. i think, what i feared in the begining came true. the turbulances of the centreboard get in the way of the back windward fin. that's just a guess, but i don't have another explanation for this.

this means: just one back fin. wish me luck!

h.


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 Post subject: Re: New Board Race 1 fin
PostPosted: Fri Oct 22, 2010 6:19 pm 
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good luck


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 Post subject: Re: New Board Race 1 fin
PostPosted: Sat Oct 23, 2010 9:01 am 
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thanks, dude!


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