Dan Gervae
FRIEND
You can also use a smart level to just measure degree difference between wings to get your dihedral. More accurate than pulling a string and measuring at the birdcage as far as I can tell but the "correct" way is to do the string method despite measuring from a very imperfect surface to a string attached to imperfect surfaces.
Smart levels are also super handy for setting washout and taking the trial and error out of finding what you prefer.
Is that .7 degrees between each panel or .7 degrees total dihedral? Just curious because I've heard higher numbers thrown around for total dihedral.
I'm thinking a good quality bubble level is more accurate than a digital level. They make machinist bubble level with some pretty extreme accuracy.
the bubble level was still off by .2 of a degree.
If you can read a bubble level to .1 of a degree I would be mighty impressed.
Not to say it is impossible. I used both a standard bubble level and then checked with a digital level to level my fuselage and while it was close, the bubble level was still off by .2 of a degree.
Or........ the bubble level was dead nuts on, and the digital level was off by .2......
FWIW ..... I use certain Milwaukee and Stanley bubble levels as they advertise .0005 (half thousandth) per inch accuracy ........ (there are machinist's levels even more accurate but not practical to use). That equates to .015 on a 30" spar center Piper. The digital level at .1° is .053 at 30" ........... If memory serves me correctly ....... 1° = .211 per foot, or .0527 at 30". I prefer bubbles for building and repairing and even in this case setting dihedral but prefer digitals for other not as critical measurements like control surface deflection.
Bubbles for accuracy, digital for convenience. Just sayin .............