Zoomzoooie
Well-Known Member
I will be modifying the wing somewhat on my one of kind 85% Cub project. There are no plans for this design although it is similar to a few others, but the builder used a scale outline very close to a real cub.
This plane was flying at one time according to the guy I got it from who also knew of the builder. I got the fuselage and wings, but the lift struts are missing so I have no idea what the rigging was set to.
I won't be doing anything until next year, but I'm working on drawing up plans and reference notes.
The wing is very similar in design to a J3 Kitten. I believe it's a USA35B airfoil with a flat bottom and wider cord at 53". The wing construction is all wood with plywood sheeting leading edges, cable X braces and steel tube compression members. With the covering on, the wings had very little flex. I placed each wing on leveled saw horses and found they had very little to no washout.
The ailerons are piano hinged at the top with a flat angled leading edge allowing the aileron to move down and the linkage is differential moving up more then down. The tip rib is outside of the aileron.
See pic.
The modifications will be extending the leading edge plywood sheeting up to the main spar to increase slow speed and lift performance as well as adding flaps. The flaps will also hinge out of the way for wing folding.
With no information on rigging for this wing design I am not sure what to set the wash out to. I think there should be washout for safer slow speeds.
I cannot find rigging info for the J3 Kitten which would be a good place to start.
The real Super Cub has about 2.5 degrees of washout, but this seems excessive for a low power, slower flying plane.
Since the wing will have minimal flexing once recovered, which will reduce the amount of "adjustable" washout, I want to set the wing to a specific washout angle before adding the extra leading edge sheeting and covering.
I think if I don't do this and try to set washout during rigging it will create torsion to the leading edge sheeting and covering possibly creating diagonal waves in the covering. The wing does have lots of flex without the covering.
I saw information stating washout was set by lowering the leading edge incidence. This does not sound right to me. Doing it this way in effect reduces dihedral and incidence from what I can see. With 1 degree dihedral in each wing it would most likely cancel out the dihedral. Shouldn't washout be set by raising the trailing edge to maintain the overall incidence over more of the wing?
Any thoughts on the amount of washout and procedure would be appreciated.
This plane was flying at one time according to the guy I got it from who also knew of the builder. I got the fuselage and wings, but the lift struts are missing so I have no idea what the rigging was set to.
I won't be doing anything until next year, but I'm working on drawing up plans and reference notes.
The wing is very similar in design to a J3 Kitten. I believe it's a USA35B airfoil with a flat bottom and wider cord at 53". The wing construction is all wood with plywood sheeting leading edges, cable X braces and steel tube compression members. With the covering on, the wings had very little flex. I placed each wing on leveled saw horses and found they had very little to no washout.
The ailerons are piano hinged at the top with a flat angled leading edge allowing the aileron to move down and the linkage is differential moving up more then down. The tip rib is outside of the aileron.
See pic.
The modifications will be extending the leading edge plywood sheeting up to the main spar to increase slow speed and lift performance as well as adding flaps. The flaps will also hinge out of the way for wing folding.
With no information on rigging for this wing design I am not sure what to set the wash out to. I think there should be washout for safer slow speeds.
I cannot find rigging info for the J3 Kitten which would be a good place to start.
The real Super Cub has about 2.5 degrees of washout, but this seems excessive for a low power, slower flying plane.
Since the wing will have minimal flexing once recovered, which will reduce the amount of "adjustable" washout, I want to set the wing to a specific washout angle before adding the extra leading edge sheeting and covering.
I think if I don't do this and try to set washout during rigging it will create torsion to the leading edge sheeting and covering possibly creating diagonal waves in the covering. The wing does have lots of flex without the covering.
I saw information stating washout was set by lowering the leading edge incidence. This does not sound right to me. Doing it this way in effect reduces dihedral and incidence from what I can see. With 1 degree dihedral in each wing it would most likely cancel out the dihedral. Shouldn't washout be set by raising the trailing edge to maintain the overall incidence over more of the wing?
Any thoughts on the amount of washout and procedure would be appreciated.
