Designing a Surfboard Fin

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wandererfan
Posts: 4078
Joined: Tue Nov 06, 2012 5:42 pm

Re: Designing a Surfboard Fin

Postby wandererfan » Sat Apr 19, 2014 12:12 am

triplus wrote:I tested both versions of the macro on Ubuntu 13.10 using latest Development Release and can confirm that flat spot. It looks OK as Wire and converting to sketch gives predictable results. Converting to BSpline adds that flat spot.
Could I get a step-by-step please? I can't reproduce the flat spot or the Coin error. This is what I'm doing:
1) Macro v2.0 from [wiki]Macro_Airfoil_Import_&_Scale[/wiki]
2) input file: NACA0007.dat, options: DWire, chord=100
3) run Draft DWire to BSpline tool on result
My results:
NACA0007.png
NACA0007.png (161.04 KiB) Viewed 2024 times
And for NACA0012.dat:
NACA0012.png
NACA0012.png (160.25 KiB) Viewed 2024 times
I must be doing something wrong (right?).

wf

OS: Ubuntu 12.04.4 LTS
Platform: 64-bit
Version: 0.14.3435 (Git)
Branch: master
Hash: 61919e89abdd7630e3893e33374eb303cd0fe726
Python version: 2.7.3
Qt version: 4.8.1
Coin version: 3.1.3
SoQt version: 1.5.0
OCC version: 6.7.0
User avatar
wandererfan
Posts: 4078
Joined: Tue Nov 06, 2012 5:42 pm

Re: Designing a Surfboard Fin

Postby wandererfan » Sat Apr 19, 2014 12:20 am

wandererfan wrote:I can't reproduce the flat spot or the Coin error.
I found the Coin error message, but only in the terminal window, not the FC display.
triplus
Posts: 9475
Joined: Mon Dec 12, 2011 4:45 pm

Re: Designing a Surfboard Fin

Postby triplus » Sat Apr 19, 2014 12:42 am

wandererfan wrote:
wandererfan wrote:I can't reproduce the flat spot or the Coin error.
I found the Coin error message, but only in the terminal window, not the FC display.
True. I forgot to mention the error is shown in terminal not in FC.
This is what I'm doing:
Dwire is fine but converting to BSpline produces this on the screen:
naca.png
naca.png (9.22 KiB) Viewed 2020 times
I used the exact same procedure as you said you used.
triplus
Posts: 9475
Joined: Mon Dec 12, 2011 4:45 pm

Re: Designing a Surfboard Fin

Postby triplus » Sat Apr 19, 2014 12:55 am

What is interesting using Pad on created BSpline produces result as if flat spot was not there. Maybe this is just "visual glitch" or some setting in preferences that controls visual representation for BSplines?

If it is a bug i guess it is a bug in some library responsible for visual representation where newer version is used on Ubuntu 13.10 and bug does not affect older library used on Ubuntu 12.04? Anyway it looks like it is more of an "visual representation" bug and not something affecting other tools in FreeCAD for example creating drawing view produces expected results without flat spot too.
triplus
Posts: 9475
Joined: Mon Dec 12, 2011 4:45 pm

Re: Designing a Surfboard Fin

Postby triplus » Sat Apr 19, 2014 1:31 am

Yes it is purely visual setting in preferences affecting this behaviour.

@woodbuddha just go under Edit -> Preferences -> Part design -> Shape view -> Tessellation. Set it to this 0.02 and you should achieve what you are after!
woodbuddha
Posts: 35
Joined: Mon Jan 06, 2014 2:30 am

Re: Designing a Surfboard Fin

Postby woodbuddha » Mon Apr 21, 2014 6:48 am

Thanks Guys. Problem solved with the changing the teselllation to 0.02%

WB
Florian
Posts: 2
Joined: Wed Jul 30, 2014 10:22 am

Re: Designing a Surfboard Fin

Postby Florian » Wed Jul 30, 2014 10:36 am

Hi, I just starded with freecad and use it for designing a sailboat rudder. Very usefull info here, helped mee a lot. But besides the flat spot I had as well (fixed) there seems one more problem with converting the wire to a spline, the trailing edge witch is flat on my foils from xflr 5 becomes funny when using a spline. Are other peaple experiancing the same or is there a easy fix for that? Right now it looks better to me to just use a wire with a lot of point so the flat spots become neglectable.
Attachments
trailingedge.png
trailingedge.png (218.66 KiB) Viewed 1863 times
Florian
Posts: 2
Joined: Wed Jul 30, 2014 10:22 am

Re: Designing a Surfboard Fin

Postby Florian » Wed Jul 30, 2014 10:45 am

After closing the trailing edge gap the problem is solved, althoug the TE gap is in the foil by default and might be there for a reason. Not sure if I ant it there or not, for construction it is probable better if it is there.
Looktree
Posts: 34
Joined: Thu Dec 04, 2014 7:53 pm

Re: Designing a Surfboard Fin

Postby Looktree » Thu Dec 04, 2014 9:17 pm

Dear Florian,

have you managed to solve this "problem" somehow?
I do have the same with a kiteboard fin at the moment.

THX
Uwe
woodbuddha
Posts: 35
Joined: Mon Jan 06, 2014 2:30 am

Re: Designing a Surfboard Fin

Postby woodbuddha » Mon Jan 19, 2015 2:45 am

Hi Florian,

Yes I get the same thing happening to the TE of my foils as well. How did you resolver the problem?

TK