rigging the wings

[Robert Bradbury]

I was lying in bed early today going through a few things about rigging the wings when something dawned on me. My rear spar is deeper than the stock
by almost one quarter of an inch. I'm not sure if the front was deeper but for
sure thicker which is irrelevant for my point, or rather, question.

Wouldn't this throw off your rigging using the methods as described in the
manual?? I guess I need to find out what is the actual debth of the spar and
remove the difference from the block we use on the end of the level ?

If I am correct and I think I am, this would have the wing at a higher angle than normal and also explain why the plane flys slower than most other float equiped T-carts . Hmmmmm??

[Robert Lees]

Re: rigging the wings

The washout depends upon the shape of the complete aerofoil (made up by the covering & ribs). The method for checking the rigging uses the lower spar cap as the measuring point. As far as the aerofoil is concerned, the spar is only there to mount the ribs (& covering) to.

So in theory, variations in the depth of the spar are not relevant.

The above assumes that the root fittings are somewhere near in the correct position on the deeper spar, but you could check the angle of the aerofoil at the root and at the washout location and make a comparison.

Does that help?

Rob

[Robert Bradbury]

Re: rigging the wings

The washout depends upon the shape of the complete aerofoil (made up by the covering & ribs). The method for checking the rigging uses the lower spar cap as the measuring point. As far as the aerofoil is concerned, the spar is only there to mount the ribs (& covering) to.

So in theory, variations in the depth of the spar are not relevant.

The above assumes that the root fittings are somewhere near in the correct position on the deeper spar, but you could check the angle of the aerofoil at the root and at the washout location and make a comparison.

Does that help?

Rob

I do not have the instructions in front of me, but I thought a level was contacting the bottom rear spar and a block 1 5/16" or so on the front of
the level contacting the bottom of the front spar.

What are you referring to as the lower spar cap, the bottom of the rib ?

Robert

[Robert Lees]

Re: rigging the wings

Affirm...when the wings are covered, the spar edges are not available for checking the washout. So the rib edges are used. The ones with the fabric stitches and/or wire clips attached.

Remember, the important aerodynamic features of any aeroplane are the outside surfaces. All that the inside features such as fuselage, spars etc do (aerodynamically) are act as spacers to hold the bolts in the right place.

[Len Petterson]

Re: rigging the wings

Is the rib of standard configuration = the same airfoil.
A thiker airfoil at the rear spar would make more lke the cub airfoil, dragy"
Len

[Len Petterson]

Re: rigging the wings

Is the rib of standard configuration = the same airfoil.
A thiker airfoil at the rear spar would make more like the cub airfoil, dragy"
Len

[Robert Bradbury]

Re: rigging the wings

Is the rib of standard configuration = the same airfoil.
A thiker airfoil at the rear spar would make more like the cub airfoil, dragy"
Len

I used standard stock BC12D stamped ribs.