Main spar bow

[Rynoth]

The act of clecoing in the skin to the rear spar acts to straighten the rear spar, thus pulling the main spar straight via the ribs. If you progressively drill/cleco the ribs from the rear spar going forward, this will additionally make the main spar tend to go straight. That said, putting some pressure to make the spar straighter before drilling wouldn't hurt, I think.

[wlarson861]

I think you need to try the Sonex method before you start bending the spars straight. put the skin on the wing and use lots of clamps,(I used Cleco clamps) to hold the aft edge of the skin even with the aft spar edge. If everything prior was done right the main spar will be bolt straight and the leading edge of the top skin will line up with the spar cap exactly where the plans show. In other words the main spar will be pulled straight by the aft spar pulling all the ribs which pulls the main spar with them to line up with the straight edge of the rear spar. When you build the wing vertical on saw horses the main spar sags a lot under it's own weight, when the first skin is added and the edges of the skin and rear spar are aligned the bow in the main spar just goes away.