#6 Repair and Prep For Pre-Rig

Drilling and riveting the upper wing was easy because both spars were new and had no holes so I just drilled using the gussets as my hole template. When I went to align the lower wing on the fixture, I found that the impact had tweeked the lower panel enough to where I felt I needed to move the internal strut location to reduce the chord spacing back to it's original. I decided to accomplish this by moving the LE gusset location outboard toward the tip by ¼ inch. I cut new LE gusset plates that were longer than the originals so that I could still use the three original rivet holes in the spar. This shot shows the rivet holes I must hit exactly if I want to avoid ordering new material to fabricate a new diagonal strut and also the pre-bent LE spar (big incentive here to find a way!).

Here's the new gusset in place (now hiding where I need to drill the rivet holes)

In order to drill and exactly hit these old rivet holes in both the lower wing spars and internal diagonal strut (which I am re-using since they were not bent) I had to find a way to do this using the newly made larger gussets. There is a tool they call a “hole finder” which I borrowed from one of the EAA members but I found it to be too, thick and stiff to get under the gusset without moving it out of position. I made my own out of much thinner material I cut out of some scrap sheet metal with a metal shears.  I put two pop rivets in the one end forming a long tweezers-like tool. On the hole finding end, I clamped the ends together and drilled a rivet hole through both and then installed a rivet into one of these holes only, the other hole ends up on top of the gusset and acts as my drill template.

This next shot shows the finder ready to insert into an existing hole.

Once this is done, I slip the gusset into position as shown here and mark the hole location for drilling.

A word about other tools...... I wore out a pop rivet gun and the only symptom apparent was I started having more and more rivet stems break off leaving a long stem sticking out of the piece but not long enough for the tool to grip and finish the pull. I then had to break off the tail and drill out the rivet and install another rivet. Here's the old tool....

These are only $20 tools so it's not a big deal until you spend your $20 and get home and actually use the new one when you realize they aren't all made the same. The one I wore out was cheaper looking but actually worked much better because of the handle design. The new one has a handle spread in the open position that is made for someone with hands the size of large dinner plates so in order to squeeze the handles it becomes a two handed operation for us “normal” people.

Shop around.

Repair and re-assembly of both upper and lower left wing panels is now done.

Right wing panel pre-rigging

The next photo shows me attempting to get the upper right wing in position over the lower right wing which is positioned in the floor frame.

It's a good idea to make at least one reference mark on one of the spars relative to the fixture on the floor just in case something gets bumped accidently. The plan directions are a bit sparse as to how to do this and I found that suspending the upper wing in rough position was the easiest thing to do. You can see the cords coming down from the garage rafters.

Next I just followed the Pre-Rig instruction sheet of the plans to set the wing stagger (top panel forward of the bottom panel) and dihedral (top panel outboard of the bottom panel). The stagger is set at 14 inches and the dihedral is set to 6 inches.

Once I got it on the mark in the upright position, I used Pony clamps to hold the brackets in position and also made a reference mark on the spars then installed the struts including the rudder. Next I folded the wing down to check for binding. My wings weren't perfectly parallel when folded down but there was no binding and the upper wing plumb lines were withing an 1/8 inch of the marks so I called it good enough and drilled through the brackets into the spars to rivet them in place. If you were building the wing you would not yet have the bottom brackets set but I'm doing a repair and they are all riveted in place already. I think this is the weakest part of the plans. It is difficult to get all this done and get it to come out right. Later on, during final assembly there is reference to a) extending or lengthening the spar plugs when you mount them in the spar ends and also b) bending the spars to get things to fit. I believe if there was a better way to do the Pre-Rig, you would end up with everything coming out right. The other source for error is the plan calling for a flat floor to set the lower wing panel spar rotation (this sets both the sweep and the dihedral for the spar end that is pre-bent. The plan specs this to 1/16 of an inch........over a 14 X 3 ft area.....it would need to be REALLY flat to get the end of those spar ends to within a 1/16 of an inch of the spec the plan calls for.

That completes the left wing except for using the rib stitching knot to wrap the upper wing ribs and to strip the old glue from the lower panel spars and internal struts. Removed all the external struts and stored the wing panels in prep for the right wing.

Right Wing Panel Pre-rigging

The lower right wing panel is the only one left with it's original covering intact. There were some significant tears on the bottom of this panel that you can't see here. Hmmmmmmm, to strip or repair? I already forked out the money for cloth to cover all four wings and this would be nitrate/butyrate dope vs the Polyfiber covering system I have pretty much decided to use which would be a difference in weight.

I decide to strip it. This photo shows the hardest portion (it containes the strapping tape, the adhesive on it is really tough).

Next I'll get the upper right wing panel and lay it in position over the lower panel in it's approximate fold down position and install the struts. Be very attentive when installing the struts to use the right bolt. There are two sizes within an eighth of an inch difference which is enough to compress 1” tubing permanently if you use the wrong one in the specified bracket. Since these remain in place on the finished glider, there is no need to worry about them later but I suggest that you color code them during assembly since you'll install them now, remove them when done and then re-install them during final assembly so there is ample opportunity to mix them up.  Note that the wing panels have the LE facing to the left here....same end of fixture requires the panels to face the opposite of the left hand wing panels.  That wraps up this entry.

#5 Diagonal Strut Install + Aluminum vs Foam Ribs?

The rivet backing washer idea worked out nicely.  I ended up not coming up with any slick way to cut the slot in the thin plywood rib plate.  Just drilled three holes in a row and shaved out the slot with a knife.  The next task after mounting all the ribs was to install the internal diagonal strut which requires you to hold it in place over the #2 rib and "eyeball" the location of the hole you need to cut through the center of the foam in that rib.  I tried but didn't get close enough and had to elongate the first attempt to get the strut to fit through. This strut was also raw stock so had to be wet sanded with 400 grit and treated (oxidized) with chromic acid solution same as the new LE and TE sections.

Had to fabricate a missing gusset for the internal diagonal strut (thanks Ron Enck!).  Don't recall what alloy we ended up using but it wasn't 6061.  I am certain it will be plenty tough for the job at this joint, it took quite a bit to form it around the TE using a broom handle as a mandrel.

I set the LE gusset and put a few rivets in to hold it at the set distance from the end of the LE at the root called for in the plans but let the TE position float a bit inboard of the set dimension indicated in the plans because it would have required me to file out the end of the strut significantly to fit at the spec dimension.

I can't rivet the other side yet since the wing is mounted to the floor frame.  Recheck that all the rivets on the top side of the wing are in and then remove the wing panel from the frame and flip it, laying it right back down on the frame with the LE tip section now up on the 2 1/2" block.  It should lay nicely on the frame with the ribs off the floor.

 I show the wing flipped here as I begin to complete the rivet installation on the bottom of the wing.  I have place one of the new aluminum stamped ribs next to the old, original wood/foam ribs to show the difference.  Just for fun, I weighed them prior to install.  The aluminum rib came in at 132g and the wood rib weighed 88g.  For 7 ribs per upper wing panel, that's 308g's more for those fancy aluminum ribs which I really doubt are any stronger than the wood/foam ones I'm using.  There are 26 ribs in the glider so that's over 2.5 lbs additional weight for those aluminum ribs.  I'm sure the reason they started using them was to offer a significant time saving in construction.  Myself, I will do whatever I can to keep the weight down. Looking back at original Easy Riser glider specs, says the glider alone should weigh in at only 50lbs (that's using dope to treat the 1.4oz Dacron cloth).  A 50lb glider is good, especially when I think about being able to only have to carry one side at a time over to where I will set up (that's 25lbs).  The idea here is to be able to still be doing this when I'm 80+.....I think it's realistic.   I am now looking to find a source for the foam they used in the event I ever need to fabricate new ribs.  Attended my first local chapter meeting of the EAA (Experimental Aircraft Association) and within an hour after getting back home, had successfully joined the national association and sent in my check for the local chapter dues.  What a gold mine of resources!

#4 Re-using Wood/Foam Ribs

Easy Riser glider repair #4
May 11,2013
Got side-tracked the last several days with all the hot, dry weather (feels like late June) in Oregon so I've been working on the Easy Riser trailer outside.

The left upper root strut is now riveted in place and I have to re-work the ribs in order to install them.  To remove them from the damaged wing, I had to drill out rivets holding them in position.  Here's a shot of one of the ribs after removal:

On most of them, the rivet stem stayed in the rib and the hole in the rib cap strip is now larger than it was originally.  To re-rivet with any hope of having the rivet head to grip under the cap strip, I decided to cut a slot in the side of the rib end cap, remove the rivet stem, slide in a rivet washer and re-rivet using a 3/8" stem rivet instead of the original 1/4".

Six more to go and I'll add another post.

#3 Wing Joiner Jig, Floor Wing Frame Jig & Fabric Search

Sorry for the disorganization of my reports....this info should have been in the very first post and begins with my retrieval of the trailer and glider/materials to my current home in Dallas, OR.

Tuesday, April 16, 2013

Went to Spiering's house in Banks and retrieved my EasyRiser in it's trailer. Nostalgia! It towed like a dream all the way back (with about 300 lbs tongue weight!). Washed off the box and trailer then opened it up and pulled out all the parts. The notes/receipts showed that I had ordered supplies to repair it except for the material (1.4oz Dacron) and chemicals. Began the process of figuring out how to proceed.

Wednesday, 4-17-13

Got the damaged wing stripped of covering and figured out after some thought that I was going to need to cut all four flying wires (3/32 cable) which I did with a cut off blade and my angle grinder. Buy a Felco Cable Shears, you'll need it later anyway.  These shears are God-send when needing to cut cable.  It turned out that the rear spar was bent at the root so I proceeded to remove it as well as the leading edge spar. The root plugs (wing connectors) were both frozen and I ended up using the cutoff blade to get them off. I couldn't believe how little adhesion there was of the fabric to the aluminum. I plan to make a jig to hold an 8” length of tubing so that I can safely run it through the table saw to make a splice insert for both the leading and trailing edge spar joints at the tip end. Trying to layout and mark the new spar to exactly hit the old rivet holes is going to be difficult. I'll try it first and then make new ones if I think I need to. Got to decide on what materials to order and get the order in soon or I will be waiting for supplies to go any further. By the end of the day tomorrow, I expect to be very nearly ready to begin cleaning the frame for the upper left damaged wing.

Thursday, 4-18-13

Took out the right wing and set it up. I could barely attach the setup (neg. flying wires). Suspicious that it, too, was tweeked, I checked the rudder motion....it was binding noticeably and I think would not function to fly. I flipped the wing over and found myself looking at several significant holes in the covering caused during the crash....both upper and lower wing panels. I cut the flying wires and separated the two panels. I also noticed that ALL the diagonal struts are missing. There should be two for each wing...one at the tip and one at the root. I also remember there was fairing tape in the kit or at least I may have ordered it later for all the exposed struts, something UFM was making part of the kits. I have yet to find it. I measured the degree of bend in both upper and lower panels (trailing edge-TE and leading edge-LE). I did this without the diagonal struts in place but believe they would have made no difference in the measurements. Also, the bends were all consistent with what I expected would happen as a result of the known impact forces.

Things to do next:

1. Research covering process choices and order chemicals  (read plans and make a list).
2. Order the fabric (read the plans and get the amount right)
3. make both a LE and TE spar splice jig so you can cut these on the table saw
4. look into ordering a swaging pliers
5. start a blog for others to follow.

Friday, 4-19-13

Weighed the fabric found at the fabric shop shop near SE 122 and Powell in Portland which calculated to be ~1.5 oz/sq yd. Also weighed the old fabric from the kit which was also ~1.5 oz/yd. They looked nearly identical under my hand microscope. I placed the order for 45 yds of 48 inch wide white for approx $120 plus shipping. It was a generic liner material of 100% polyester.

Called and surfed the web to research what fabric glue to use and what prep the frame would need. Looks like there are two choices: either PolyFiber or nitrate dope. Ordered the Polyfiber process manual for $10 from Spencer Aircraft in WA.

OK, now that I've got that entry down we can continue where I left off with report #2.

I had a real scrub job to do on the LE & TE replacement spars I had ordered back in the late 70's to do the repair. They had been stored unprotected and had some corrosion and staining that I had to take off with 400 grit wet/dry sand paper. I researched covering process options and concluded I have three choices; 1) nitrate and butyrate dope (the Ceconite process), 2) the Stewart system which is a water-based proces and 3) the Polyfiber process which replaced the old Stits system and is solvent-based similar to the Ceconite process).   At this point I'm going to try the Polyfiber process on the left wing panels which have both already been stripped of covering.

   

The photo above shows the leading edge being treated with a chromic acid solution. This stuff is available from aircraft supply houses and is part of the Polyfiber process. As I understand it, you are actually “anodizing” the aluminum using a wet chemical process of dilute chromic acid. That's a drywall mud tray (stainless steel) and a $2 brush. I did about 2-3 ft at a time (7 minutes reaction time per section per EasyRiser original instruction plans). I made the mistake of joining the TE spar to the wing tip BEFORE doing this treatment and that made it really hard to complete the treatment. Treat all spars and struts BEFORE you assemble the to avoid this.

The next thing I needed to do was fabricate tubing joiners for both the LE and the TE (leading and trailing) edge spars where they are attached to the wing tip curved tubing. You cannot use the old ones because you would be drilling blind to hit the old holes.  Here's what I came up with;

I flipped this over and ran it through the blade on my little benchtop table saw after spraying the spar section with WD40 to help keep the aluminum from sticking to the blade. I used a Freud Non-Ferrous/Plastics 7 1/4” 56 tooth blade (about $40 at Home Depot). I estimated the slot needed to be about 3/16 wide so I had to make two passes. As you can see, the blade made it through the tubing before it passed through the end block on the jig which kept me from getting hit with aluminum shards (they're hot!). Did the same with the TE spar. Used the broken LE and bent TE for stock. I used this same blade on a small chop saw to make the 8” section required for the LE joiner (didn't have a pipe cutter big enough). Finished the cut with a hacksaw because the 7 ¼ blade couldn't get all the way through the tubing. I used coarse carbide paper to smooth the outside edges and corner of both joiners and then treated them both with chromic acid.

Here's the 1 ½ LE joiner after the cut.

Next, I assembled the wing frame onto the concrete floor in my garage. I used concrete screws and a concrete drill to attach firmly (didn't want to deal with accidently getting this frame kicked halfway through assembly. I used the original plan instructions (diagonal measurements) to get the frame exactly 10ft spacing and within 1/16^th inch on the chord width. Now both the LE and TE spars have been joined to the tip piece and riveted. The upper left panel is laying in place here ready for me to reform the bent gussets used to attach the root and diagonal struts.

#2 Assessing The Damage

I wanted to mention that if you look close at the photo in the first post of the left wing panels you can actually see the trailing edge took a significant set bend also as the leading edge impacted (I'm not certain what it hit) and my body kept going forward along with the hang cage.  I have not yet removed the right wing panel covering since I did not have the inboard and outboard setup struts to completely set up that wing.  I am hoping that when I do this, I will not see any other bent tubes and the tip rudder will move freely.  If that is the case, I'll have a much easier time getting this ship back in the air since I'll only have to patch the holes in the right wing lower panel vs recovering the entire 4 wings.  I am not hopeful however since when I did set up the right wing, the setup wires (negative load wires) were almost impossible to connect indicating more extensive tweeking of the whole airframe. I doubt that the flight struts (the ones you install once you expand the wing and attach the negative wires) will make any difference in this. I'll visit this later.

Another part of this project involves finishing the trailer I had fabricated when I first built the glider.  It's basically a plywood box with 1X2 framework, fiberglassed outside and carpeted inside on a Caulkins boat trailer.  Both ends are removeable.  More on this later.

Here's a shot of the upper left wing panel that ended up with a broken LE (you can see the rough end of the broken spar. I am removing the polyester/dope fabric along with the strapping tape...the tape stuck amazingly well and was very difficult to completely remove even after all these years. I guess being trapped inside the wing did not allow the adhesive to dry out.

Other readily apparent damage to the glider were tears in the lower right wing panel shown here;

This next shot shows a long gash on the underside of the left lower wing panel which I decided not to salvage with a patch (I stripped this panel).

Below is a shot showing the upper left wing panel TE spar at the root. The bend is out about 11/16” and is located right where I expected it would be, just inboard of the internal diagonal strut gusset. The strut was not bent at all.

Now to re-build the upper left wing panel.   To be continued.....

History of this EasyRiser glider

post date - 5-1-13
Ordered as a kit from John Moody/Larry Mauro in late 70's as a full motor package.  Completed the non-motorized glider portion of the kit using all the original kit materials (Dacron fabric, nitrate dope, 6061 T6 .035 wall aluminum tubing).  Here are a couple shots of the assembled wing prior to covering taken back in the late 70's.

 On the maiden flight (1982 I believe), I managed to execute a whip stall after launch resulting in a dive into a large bush from approximately 60 ft.  The frame was bent with the most obvious damage being the upper left wing panel leading edge which broke just outboard of the root, diagonal internal brace.  The trailing edge also took a set bend near the root and also bent parts of the left rudder frame.  I never did figure out what I had done to cause the abrupt pitch up other than I remember moving back in the control frame to slow down in what felt like some nice lift.  Very likely that I moved too far and too fast, being used to my flex wing, and the Easy responded.  I was not hanging from a suspension point, all I had for a harness was a hammock strung between the leading and trailing ends of the control cage which may have amplified the weight shift change.

My mission is to re-rig and re-cover the entire airframe.  My hope is that this blog will be discovered by other potential EasyRiser pilots/builders.  I plan to break the posts up into separate parts of the process of repair.

To begin, here is a photo of the left wing where you can see the upper panel leading edge spar is broken at the second rib out from the root.  I have not yet removed the fabric from the lower panel.

You can see this kit had the original foam/wood ribs which were soon replaced with stamped aluminum ribs in subsequent kits from UFM. The hole in the second rib was where the internal brace passed through it which I had removed after the accident.  You can also see the front end of the second rib is gone (broke off on impact).  On close inspection, I saw no other delamination of the fabric to the rib cap strips anywhere else on the glider frame which I thought was amazing given the impact it took to break the leading edge.  The fabric was not rib laced or stitched which I learned much later was really standard practice on any aircraft that is cloth covered.  The next post will include my initial assessment after removing the covering on all four panels.