As mentioned in the last entry, I will be working on ribs for a while. (Also, I have another project going for the next month or so, so progress will be slow.) With all the ribs formed, they must be fitted and stiffened. Image 1 shows stiffeners being added to ribs on the right wing. Next the front and rear spars were supported as needed to ensure they were straight with no sag. To check this, the front and rear spars were marked by drawing a line on the outer flange a fixed distance from the web. A fine string was then attached at each end of the spars with the same offset from the web. Next, supports were installed and adjusted to ensure the thread stayed on the lines drawn on both spars. Once this was accomplished, rib mounting began. However, care must be taken to ensure that the rib-to-spar flange is set at exactly the correct angle to meet up with the rear spar without excessive twisting. This meant that flanges needed to be adjusted as needed.(There is an art to this) Once the forward holes were drilled, the aft spar attachment could be made by fabricating brackets at the proper angles and drilling. Care must be taken to ensure the spars stay straight and level while doing this.
