Initial Wing Rigging

12/9/2007

To start rigging, I had to somehow think up of a way to dry mount the wings in such a way that, I could adjust on all axis. I came up with a timber framework as seen in the pics. The cheapest way to do this was by using stock 2x4's and ripping them in two.

Initial rigging: It could be said that this stage of the build would be exciting, since things would visually start to come together, but I found it extremely tedious work. So tedious, that after 2 days [actually approx 11 hours total] I have only just completed leveling the upper on all axis, to the point where I'm satisfied.

Step 1: was to align the upper wing centrally at the cabanes, and to dry fit the cabane brackets where they theoretically 'should' reside, then clamp. Incidence angle was then confirmed at 1.5 deg [actually, it said 0.0 on the digital level because the fuselage is shimmed 1.5 deg tail high so I can then level everything to 0]. Incidence was then checked going down the wing, and adjusted accordingly.

Step 2: Trammel to tail post. I measured from a fixed point near each wing tip to the tail post. Initial measurement was off by 2 inches! So I checked with a straight line laser to see if the fuselage had a banana problem, all was well there. Then I checked the line of sight through the two 3/8 cabane fitting bolt holes to the tail post, sure enough, it was slightly off. To remedy this, I pivoted the wing so the center lines of the wing were off one way at the front spar, and off the other way at the rear spar, I didn't measure, but it looks to be off the center line when looking at the center bracket by about 3/16. I dropped a plumbline either side of the trailing edges [where the center bow will start], and the distance between plumbline and upper longerons either side is minimal - and I now have equal distance to the tail post. Because of pivoting the wing, I had to of course, re-level the angle of incidence throughout.

Step 3: Level wing span-wise. I had been looking around for a surveyors transit, I also asked at the local EAA chapter, but to no avail. Then I noticed the prices of laser transits had plummeted over recent years, so I bought one from Harbor Freight for the princely sum of $59. I wasn't sure of the accuracy of the built in vials, so I calibrated by using a Stabila high end level as reference. It transpired that the built in levels were 'close', but close isn't good enough when spanning a 24 ft wing span.

Finally, I cross referenced/adjusted all three steps again for good measure. I do have a water level that I purchased last year, but was told by a local veteran builder that due to friction, water in the tubes can give an inaccurate reading. Still, I am toying with the idea of using it - just for yet another cross reference...

Next will be mounting the lower wings. I know I have problems there, due to one rear wing bracket being off center slightly...more to come.