The final thing to weld to the Flap Support Frame is an attach point for the flap return springs. The flaps have two long springs on each side of the Support Frame that attach to a couple of keepers and to the flap torque tube arms. The springs retract the flaps to the up position when the flap handle is lowered I suspect the flaps would retract just fine without the springs while in flight because the wind would push them to the up position when the flap handle is lowered. However, on the ground, while parked, the flaps would just hang down without these springs.
The 3/8" tube is slid in the hole and welded in place. To keep the springs in place, a couple of washers are welded to the tube on each side with about a 1/8" gap between them:
The washers trap the end of the two springs and hold them in place.
With the Flap Support Frame bolted into the Jig, the forward end was welded on. These were allowed to air cool completely before removing from the jig. The ends were then welded to the tubes through the 3/4" hole in the end of each flap support frame as pictured below:
That's it for the Flap Support Frame assemblies. Now its on to the Wing Root Support tubes.
The Root Support Tube has a bearing, similar to the one on the Flap Support Frame, to support the Flap Torque Tube at the wing root. It also has a guide for the aileron cable. The Root Support Tube bolts through the rear spar at the wing attach plate on one end, and to a cross member installed between the # 1 and # 2 ribs at it's other end. Therefore, it must have a plug in each end with a 1/4"-28 threaded hole in the center to accept the bolts. Here is a picture of the support tubes and end plugs:
It is really nice to have a friend and EAA tech counselor like Mickey Whittenburg. Mickey helped me make these plugs on his lathe. They were made from some 3/4" diameter steel rod, turned on a lathe, creating a "step' that slides in the tube, then drilled and tapped at the center for the 1/4"-28 threads. These plugs will be welded inside the end of each tube. Mickey showed me how to make one, then turned me loose to make the other three. What fun!!! I got to get me one of those lathes someday.
Here is a picture of one of the completed Root Support Tubes cut to proper length and the final end cap welded in place:
Curiosity got the better of me and I just had to see if everything was lined
up properly. One of the Root Support Tubes was bolted in place on one
of the rear spars and one of the Flap Support Frames was clamped in place.
The Flap Torque Tube slid in position with a little oil to lubricate
it:
In the picture above, the wing spar is upside down because it was the first one I grabbed, but it was fine for checking the fit of these pieces. I'm happy to say that it all lined up beautifully and the torque tube turns nice and smooth. I guess all of the careful measuring and triple checking everything paid off.
Next, I'll do the Aileron Support frames, so click here for that.
Click here to go to Aileron Support Frame
Click here to go back to Flap Support Frames page 1