Building the Fokker D.VII Top Wings
After test fitting the wing to the fuse, I decided to inset the root rib 1.5" to prevent interference with the lift tangs on the center section. A small root fairing will cover the gap between the wing and center section.
The root rib was braced to prevent distortion from taut fabric. Standard brackets could not be used because the spars must remain free of rivets on the ends so they will slide onto the center section spars.
The top wing differs from the bottom in that it needs a tubular trailing edge to carry the aileron. It is important to slide the aileron hinges onto the trailing edge prior to attaching it to the ribs.
The wingtip is braced to the outer compression strut and rib. A gusset secures it to the trailing edge.
I overlapped the skins instead of butt-joining them as on the lower wing. The overlaps aren't very noticeable on the top wing and are less work to install.
The more straps the better when it comes to riveting the leading edge skins. I found two straps on each rib worked fairly well. The straps were rotated to a new position as each rib was riveted.
I caught a set of four ratchet straps on sale at Harbor Freight, they are light duty but came in handy for this task.
The ailerons are blocked out on the bench similar to the other control surfaces. The ribs are bent up from flat stock like the rudder ribs. Biggest difference is the copper tube trailing edge that is formed same as the wing trailing edges.
The left aileron was used to lay out the other one to assure they are identical. Both tip bows were bent with the 14" form in the same session so they are duplicates.
The tip bows are secured to the ribs with gussets and the spar tip is drilled and coped same as the rudder spar. Be sure the hinges are installed prior to riveting the ribs to the spar.
First aileron required about four hours construction, second one was half that. I thought gussets would be required at each rib for rigidity but the aileron is quite stiff, and very light, as designed. I secured each rib to the trailing edge tubing with a 3/32" pulled rivet after the coped ends were wrapped around the tubing.
Left top wing is compete. Still need to fabricate horns for the ailerons but will wait until the control cables are installed.
The aileron horns are intended to be identical to the one on the elevator, an eyebolt and spacer. But whereas the elevator pushrod terminates with a fork, the aileron control cable has a rod end bearing. Pairing the rod end bearing with an eyebolt seemed awkward at best to me. Also, the eyebolts for the aileron horns were shorted from my kit, so instead of waiting for replacements to arrive, and because I didn't care for the standard design, I went another direction.
Here is the conventional aileron horn I fabricated. Additional plates and braces were also constructed to support the cable housing. I have no idea how this was intended to be built because there is no kit documentation on this area.
The horn is .062" 6061 reinforced with 3/4" x 3/4" 6061 angle. The entire assembly is riveted to the second aileron rib.
A gusset ties the horn to the aileron spar and it ended up very rigid.
I like it.
A couple more detail images since there aren't any in the kit documentation.
I refined the aileron cable attach bracket backing plate on the second wing.
Because I didn't want to permanently install the aileron cable and have it hanging loose from the wing during the covering process, 3/4" PEX tubing was added to the wing so the cable could be pushed through the wing for final assembly.
The PEX is lightweight and flexible with a 1.0" OD which makes it easy to drill supports to secure it. The tubing was safety wired to a couple of ribs via support brackets and will live anonymously in the wing from now on.
Construction of the top right (final!) wing panel is underway.
Right top panel is ready for the leading edge. All rib tubing is gone and the rib jig has been dismantled!
Building Log for Sam's