Murray Parr wrote:Clear tubing filled with water across the wing span works well, also, if you can colour the water with something it would be easier to see the level. Follow the plans closely too.
This works extremely well provided the fuselage is also perfectly square to the world. It really only guarantees the wing tips are equidistant from the center of the earth.
If the fuselage is tilted 1/8in, while the tips are level with each other, that translates to nearly an inch out of wack. Not that you could ever tell you were sitting crooked in that configuration. The biggest caveat to not having the wings perfectly leveled is some smart-ass at a fly-in getting down on one knee and eyeballing for some side-to-side discrepancy using the tailfeathers as a guide. You might go with that.
My preferred method was to lay a laser level across the longerons pointing at one of the tips and measuring the distance from the little red dot to the wing skin. Repeat for the other side and compare notes. Adjust the wings till the distance is the same. Leveling the fuselage is not necessary with this method. It would work just as well in space. Hopefully the tail is on straight.
Flying with one wing low due to poor technique and not bad rigging here @Area 51%