#7 Pre-Rig

When I found that neither set of wings would rig up with the original cabling and not have the rudders binding significantly, I realized I would have to re-rig the entire glider.....meaning I needed to cut ALL the rigging cables and remove them. I ended up doing this using a cutoff wheel on my ¼ inch angle grinder. I had to really be careful not to nick the brackets or tubing but it worked OK. I cut off one end of each negative wire cable leaving a cable bushing on the other end. I used two of these pieces, each with a cable bushing on the end and a cut cable end on the other and clamped them together using the electrical clamp nuts called for in the rigging part of the instructions. I end up with an adjustable cable with bushings on both ends that I used to hold the wing from folding down while I checked the upper and lower spars for parallel alignment.

The photo below shows the right wing set up on the fixture and if you look close you can make out the plumb bob off the leading edge wing joiner on the left hand side of the photo where I am checking for parallel alignment of upper and lower leading edge spars and also the 14” stagger.

You may also have noticed the tape on the floor which I used to mark all the reference points called out for on the pre-rigging sheet in the plans. Here is a shot of what I mentioned can happen in the last post if you don't watch which bolt you're using where (permanently compressed strut).

I have done a bit of sourcing research trying to find the part shown in this photo that is used throughout the Easy Riser rigging brackets. It is called a rivet nut and various other names depending on the manufacturer. The longest barrel length I could find anywhere to date is approximately 0.5 inches. Somewhere, Larry Mauro apparently sourced one with a barrel length of nearly 3/4” which doesn't seem to exist anywhere I've tried looking. He may have had it special order. The ½ inch ones which are readily available, are used on this glider frame in the brackets with only a single cable attached as shown here.

One of my goals in this project is to find sources for all the parts needed to make an Easy Riser from the ground up so I would like to find the longer rivet nut even if I have to find a manufacturer willing to make a custom run of them. Below is a shot showing the longer rivet nut with the half cable bushing which is what requires the barrel length to be nearly 3/4” long since a second cable bushing will need to slip onto the end of it for the quick disconnect negative wire attach point during set up.

That completes the pre-rigging. Next, I need to wrap all seven ribs on the upper left wing panel using the knot shown in the original addendum the plans included for rib stitching (which I also plan to do after attaching the fabric). Wrapping the entire length of the rib keeps the cap strip from pulling off the foam core.  This is probably most important in rough landings where the wing spars might collide with a stationary object whereas rib stitching functions to keep the fabric attached to the ribs.  The other three panels I had already finished rib wrapping from the original build. This shot shows the left upper wing panel propped up on saw horses ready for rib wrapping.

Somewhere I thought I remembered the instructions including wrapping the ribs but could find no reference to it anywhere in the large plan drawings or the rib stitching addendum. I used the same knot shown in the addendum to wrap the ribs. Here is a shot of the last knot being tied on the final rib.  I later decide this is totally redundant since the entire glider will have to be rib stitched after covering and sealing anyway which will accomplish the same thing.

Ordered the fabric glue to do a test on the frame with the old glue intact to see if it would be compatible with the new glue. The tests were good which means it will not be necessary to completely strip all the spars of the old glue. The old glue was Super Seam that came with the original kit. This was really good news since stripping all that glue would have been a real job.

The local EAA chapter has a Tech Counselor that has volunteered to help me attach the fabric to the first wing and shrink it. This requires me to get the trailer ready to haul wing panels so I have been spending most of the time working on that, hence, not much progress on the wings. My next post will include the material order list for the covering supplies I will need through the top coat paint.