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Tips on building SFG's for 75.5" Extra 300

AKfreak

150cc
Hey there guys. I'm curios what are some of things one needs to consider when building SFG's for an airplane. Obviously I could just copy a known design (like the EF stuff), but without a wind tunnel to test, and the aeronautical background to engineer a set, how do you know how big to build them? Also what shape, how thick, ect..?

On my Showtime 90, the SFG's are mid wing (and they are airfoilish), and they work extremely well. On all of the EF, 3DHS, AeroBeez, ect.. they are all on the tips. I saw somewhere where someone here built some on a YAK-55, so I think it can be done with a little effort.

Any advice would be helpful, thanks again for your time. AKf
 

3dNater

3DRCF Regional Ambassador
It is not really rocket science when building SFG's. The idea behind them is to just keep air from delaminating off the end of the wings. You get wing rock when wing tips are stalling... meaning there is not enough air flowing over them to generate lift. The SFG's just act as a fence to force the air over the wingtip that would otherwise be going somewhere else. The size after a certain point is likely aesthetic rather than actually useful.

Here is where my buddy and I made some for an aerobeez 73" yak. http://www.3drcforums.com/showthrea...0cc-ARF-Airplane&p=52593&viewfull=1#post52593

Here is the pdf file Brigg made for this plane. Keep in mind that it is customized for the Aerobeez yak and may need some adjustments for another plane based on the airfoil and wing shape.

View attachment side force generators.pdf
 

AKfreak

150cc
Thanks for the link and file. I knew they make the rudder more effective, but for correcting wing rock, WOW. I will be making some for mine, no doubt it will bot fly without them. Did you make yours out of one solid piece?

I was thinking of making my with stick hardwood like the ones in this video.
[video=youtube_share;z2ThUfuyiPU]http://youtu.be/z2ThUfuyiPU[/video]
 
Last edited by a moderator:

3dNater

3DRCF Regional Ambassador
You could do it either way. We just used light ply in one piece. It was a lot simpler and I think the weight difference is negligible.
 
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