Author Topic: Need NACA profile for dagger board  (Read 2652 times)

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Offline Viking

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Need NACA profile for dagger board
« on: August 07, 2010, 10:37:11 AM »
I'm building a prototype mini and need a suitable NACA profile for the dagger board.
Any good suggestions for profile?

What about NACA 9?
Or is it too flat and with the max, widt too long forward?
Alternatively NACA 18?


BR Viking

Offline NicoG

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Re: Need NACA profile for dagger board
« Reply #1 on: August 11, 2010, 17:22:44 PM »
Good luck building, your own design ?
Pity nobody replies..
I must have some photos from the top, let me know if you need them...

Offline GDesign

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Re: Need NACA profile for dagger board
« Reply #2 on: August 12, 2010, 13:47:17 PM »
Hi!
Sorry to hear no one is really helping you out!
Try using this soft www.designfoil.com

The demo should be enough to compare the different sections, etc. It is a really nice piece of soft!

Regarding the foil. If the foil is used as a fixed daggerboard, no tacking or canting, the safe choice would be a 4 digit series, Naca 0012. If you require to make the section a bit beamer, to increase the inertia and make it stiffer, you can go for a 0014. If you can drop to a 0009 better!

Good luck!

Nico


Offline Florian

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Re: Need NACA profile for dagger board
« Reply #3 on: August 15, 2010, 23:23:04 PM »
Hi,
For the proto I am working on my brother and me looked at the foil shape for the keel. The keel I already had so I had to stick to the thikness of 35mm or so. Above that the keel does not really need to give lift, just as less resistance as possible. At 0 degrees angle the longer profiles where better and at higher angles are better due to less surface area. I found the naca 0011 and 0012 giving the best results. Not to much resistance at 0 degree and low resistance at angles up to degrees I found reseneble.
We also looked at some non naca profiles but without taking lift in account they performed less.
A dagger board might be different becouse it should give lift and in case of 2 daggerboards asymetric would be the best I guess. Also about the exact numbers I don't know anymore. I just looked at it once and made a decision what I was going to do and than forgot about it most of it but I hope it helps you a little bit.
If you are really interessted in this stuf you could also send Halmar an email, he also knows some programs to compare profiles.

Regards Florian

Offline NicoG

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Re: Need NACA profile for dagger board
« Reply #4 on: August 16, 2010, 20:15:41 PM »
Very old fashioned profiles, but they are thick,and proven. So as you are not spending 100K on the proto, youre not hiring a designer. So a 0012 should be fine :)

any photos/drawings ?

Offline NicoG

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Re: Need NACA profile for dagger board
« Reply #5 on: August 17, 2010, 19:29:21 PM »
BTW, for assyms look into the LS serie.

Offline SYDE

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Re: Need NACA profile for dagger board
« Reply #6 on: September 18, 2010, 23:41:32 PM »
If you want to dig into it more, you can google xflr5.  You can go a long way with this tool.  0012 won't give you a competitive section in the protos.  But you can always upgrade.

Doug

Offline Viking

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Re: Need NACA profile for dagger board
« Reply #7 on: March 26, 2011, 13:07:26 PM »
Thanks for all your waluable input's.

I'll start with the NACA 0012 and take it from there.
One mentioned the NACA 0009 i'll have a look at that too.

There will only be one daggart board so I wound make it assymetric.

BR Viking