James Cook wrote: > On this video https://www.youtube.com/watch?v=XzF50wHhlnc two laser > levelers are used to set up vertical and horizontal reference lines > during a wing alignment.
You may be over-thinking this, if you're not building a "Super2". A water level is all you need for dihedral (http://www.n56ml.com/owings.html), and a plumbob and chalkline for aligning the tips to each other laterally. Later, you can use some of the water level tubing to make a manometer and test your airspeed indicator (http://www.n56ml.com/airspeed_calibration/). The sad thing is you can build the plane absolutely perfectly, and propwash will require you to add a trim tab to one aileron anyway. I fretted over mine and went to a lot of trouble to get the same kind of plane I'd have gotten without all that effort. But to answer your question, don't buy a level from Harbor Freight like the one shown at http://www.n56ml.com/kgear.html. After using that level to align both N56ML (which was perfect) and N891JF (which is on the squirrelly side), I recently used it at work to get some pictures hanging in a straight line on the wall... and noticed that the line curves! It's actually an arc that bends up about an inch at both ends off a 6' straight line! So there's no telling what the alignment really is on either plane. Bottom line is test whatever you buy against something "known straight" and at least give it a "reasonable test" before you use it. But for wing installation, it's hard to screw up with a water level and a plumbob... Mark Langford ML at N56ML.com http://www.n56ml.com
