Airfoil Question

[Zuriel Armstrong]

I have been reading some of the recent posts on foam wings regarding weighting down the wings after they have been cored.  It seems everone agrees, myself included, that this could cause the airfoil shape to be changed.  While reading some older Stunt News last night, I came across the pictures of Todd Lee's Mustang with the caved in ribs.  I know the leading edge retained it's shape, but after the high point the ribs are caved in.  So what is the big deal on rib/airfoil shapes?  I do not intend to change the symmetry of the airfoil or anything drastic like that.  I also assume weighting down the foam wings may not change the airfoil evenly.  Todd did do very well with this airplane and it made me wonder what the big deal is.

Thanks,

[James Lee]

Hi Zuriel
You noticed Todd's Sooper Sekrit airfoil....!!!!  Been a lot of comments on that over the years...   No, it doesn't seem to matter, but then he can wiggle that handle better than most....       And no, the airfoil wasn't planned that way!
Jim      

[Zuriel Armstrong]

Howdy Jim,

I was hoping you would see this one.  I've seen videos of his flights and, like you said, he can wiggle the handle pretty well.

[James Lee]

Zuriel
Actually, to comment on your original comment,  I will put the newly sheeted foam wing in the original cradles with weights on them and a board to spread the load...  this would be done before the wing is cored.  Actually, I think its easier to core a sheeted foamie than one that is not yet sheeted.  If the wing is cored before sheeting, weithing it after sheeting I think could cause a change in the airfoil shape.
Jim
 

[john e. holliday]

Myself after sheeting a foam wing after it was cored, it wound up in the trash.  After that I never cored one until all the sheeting had been put on.  But, it has been awhile since I have done a foam core.  I tried my own method of lost foam wing after seeing Bob's video.  It is great if you are going to use the same wing on every plane after that.  Also I never did put a ply spar in any of my wings.  Just had glass cloth and epoxy over the center section joint.  DOC Holliday

[James Lee]

Ty
Todd did a standard foam wing, but sheeted it like it was a D-tube with capstrips...   then a standard triple core horizontally plus vertically cored where the open bays are....    It did remove some weight....   and with the passage of time the dope kept pulling and the wing caved in...!   Makes for an interesting conversation piece, and throws the aerodynamacists into a tizzy!!  He just grins and picks up the hardware....
Thanks
Jim      

[Jim Pollock]

Jim,

At least Todd still has the old Mustang "B" model with the Sooper Sekrit airfoil he can fly.  I watched him fly it many times in Florida.  Is he building a new Lost Foam "B" model to replace the one Mother Nature destroyed in '03?

Jim Pollock   

[Crist Rigotti]

Jim Lee wrote:
Ty
Todd did a standard foam wing, but sheeted it like it was a D-tube with capstrips...   then a standard triple core horizontally plus vertically cored where the open bays are....    It did remove some weight....   and with the passage of time the dope kept pulling and the wing caved in...!   Makes for an interesting conversation piece, and throws the aerodynamacists into a tizzy!!  He just grins and picks up the hardware....
Thanks
Jim

It makes us realize just how important the airfoil is to winning.     It still boils down to the guy holding the handle, doesn't it? 

[Alan Hahn]

 Crist,
That certainly is the location of the weakest link in the control system!

[Dennis Pedersen]

If you have a set of cores that have been cored before sheeting just make a few wraps around the core plugs with some news print and slid them back in.This while hold the shape while you are installing the skins.I just did a set of Magnum cores in my vacum bag this way and all is fine.I built a jig to put the pilot hole through the wing to triple core after a wing has been skined and this really helps to prevent the loss of a nice new skinned wing.