• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.
Pumpkin drop event

Good reference plans for symmetric airfoil foam wings?

Duck

Active member
#1
I was doing some reading and came across the 'notforsale' Balsa plane. I love the design and was looking at making a foam conversion. I noticed the wings are symmetric and I have not built those before. What is your favorite technique for symmetric airfoil wings?



I did come across this pair of articles on the FT site:
https://www.flitetest.com/articles/making-fully-symmetrical-w-ings
https://www.flitetest.com/articles/designing-smooth-symmetrical-airfoil-wings

That will be my first try but I was wondering if there are other techniques that people have used successfully.
 

bracesport

Well-known member
#5
@Duck - the flat-sided aerofoil will be easier than the symmetrical one as there is a nice flat surface to work from - for a symmetrical wing I imagine you would crack the foam on the LE of both halves and then I would use and internal former in tandem with the spar to ensure the wing shapes symmetrically - if you want the TE edge sides to be curved rather than straight you can remove the inside paper and the foam will curve on the formers nicely - hope this helps! :D
 
Last edited:

Merv

Well-known member
#7
@Duck, I have also struggled to get a good wing, one without being misshapen or twisted. With a flat bottom wing, I use the standard FT method, place the spar, then fold the wing and glue the trailing edge. On a symmetrical wing, I fold the wing first and glue the TE. After the glue cools, I spread the middle of the wing and insert the spar into the wing. This method, consistently gives me a good wing, the same shape on the top and bottom of the wing.
 

Duck

Active member
#8
@Duck, I have also struggled to get a good wing, one without being misshapen or twisted. With a flat bottom wing, I use the standard FT method, place the spar, then fold the wing and glue the trailing edge. On a symmetrical wing, I fold the wing first and glue the TE. After the glue cools, I spread the middle of the wing and insert the spar into the wing. This method, consistently gives me a good wing, the same shape on the top and bottom of the wing.
Merv,

So you aplly glue to the spar, expand the wing and slip the spar in from the edge? I would not have considered that. Do you have a video of the process? It seems like it would go fast amd getting alignment right before the glue sets would require some careful prep. Cam you share more details of your process?
 

Merv

Well-known member
#10
Merv,

So you aplly glue to the spar, expand the wing and slip the spar in from the edge? I would not have considered that. Do you have a video of the process? It seems like it would go fast amd getting alignment right before the glue sets would require some careful prep. Cam you share more details of your process?
Yes. Only applying the glue is the last thing done before inserting the spar. Do a dry fit and make all the preparations prior to applying glue. I have some scrap pieces of wood that I use to hold the wing open and help locate the spar.

Sorry no video.