Hatz Biplane Association

After putting on my leading edge (top wing) I noticed a slight warp from wing root to bow. Will this be eliminated when I rig the wings?

Michael
N838MM

I laid my wings out flat and adjusted the drag/anti-drag wires before I installed the leading edge.
At that point you should be able to set the wash out on the plane without any trouble.
Jeff Moore

I had my EAA chapter visit last October 2009 and was asked about washout. I did some research in the archives and internet and could find no reference to building in any washout while constructing the wings. I'm not that far along but I guess some washout can be put in at the N struts.

I too am building the wings flat, trammeling, by adjusting the drag anti-drag wires and then gluing on the leading edge skins.

Michael, the better question might be what will the leading edge look like when the wing is pulled flat. If your warp is slight and the leading edge does not deform when you pull the wing flat you should be O.K.

Lyman

The top wing has a little wash. When laid out flat the trailing edge is about an inch off the table at the wing tip bow. I can push it down flat with one hand. The fabric is not on yet. I am going to release the drag/anti draw wires and re trammel and see what happens.

Thanks

Michael
N838MM

From my learnins, biplanes don't use wash out. With both wings flat and at the same angle of incidence, in flight the lower wing causes the upper to have a higher angle of incidence relative to airflow. That causes the upper wing to stall first and give the same basic effect as wash out; that is, creating a gentler stall and leaving the lower wing ailerons effective.

If you use metal leading edges, I would think you can rig the wings level to a degree. You may experience some deforming of the leading edge metal if you're too far out of plumb. If you use ply, better lay 'em straight when you're gluing them up, cause they aint moving when your done. They are stiff! I know of a guy who first mounted and rigged his Waco wings to the fuselage before he glued on his wooden leading edges. But then, it was a taper wing Waco and they are a b*#@ch to level on a table.

Mark T
#493