[jcoyier]

Easy Riser glider frame repair diary

UFM Easy Riser repair diary including airframe re-rig and re-cover process. This is the foot-launched glider version, not the motorized version. The start date on this blog is April 2013.

History of this EasyRiser glider (report #1)

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). On the maiden flight, pilot error into a whip stall after launch resulting in a dive into 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.

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. Comments specific to the repair of this EasyRiser are welcome in this topic.

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. 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. There fabric was not rib laced or stitched since I had no plans to ever fly it powered (made that decision after receiving the kit). The next post will include my initial assessment after removing the covering on all four panels.

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Easy Riser glider repair report #2

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.

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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.

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

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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).

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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.

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

[jcoyier]

Easy Riser repair report #3

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. 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 two choices; 1) nitro dope and compatible glue or 2) Polyfiber which is a water-based system involving an epoxy primer prior to the glue. At this point I'm going to try the Polyfiber process on the left wing panels which have both already been stripped of covering.

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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;

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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.

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Here's the 1 1/2 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 1/16th 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.

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[jcoyier]

Easy Riser glider repair #4

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.

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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:

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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".

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

[jcoyier]

Easy Riser Repair #5
    (Wednesday, May 15, 2013)

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.

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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.

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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.

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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.

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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!

[jcoyier]

Easy Riser repair #6
    (Wednesday, May 29, 2013)

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!).

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

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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.

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

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

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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....

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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.

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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.

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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.

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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.

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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.

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

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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.

[Merlin]

That hole finder is slick. Looks easy to make too.

[jcoyier]

Easy Riser Repair #7
    (Thursday, June 13, 2013)

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.

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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.

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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).

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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.

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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.

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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.

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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.

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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.

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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.

[Bill Cummings]

That hole finder is slick. Looks easy to make too.

Jcoyier,
Was there a + or - tolerance (if so what was the max deviation?) that you noticed after drilling the holes after locating the them with your “hole finder?”

Sorry for the construction of that question but asked another way---
How far off, if at all, were the hole alignments?
INTERESTING STUFF!

[jcoyier]

Bill,
Re: accuracy of the hole locations using my hole finder......I didn't measure. The hardest thing for me to control using it was holding the curved gusset down, tightly onto the tube. Since half of the hole finder has to be under the gusset, there was error on the final hole. From what I remember it might have been 1/32" which is right at the limit of getting a pop rivet to cram into both the gusset hole and the tubing hole. Since my finder arms where much lighter material than the expensive aircraft tool finders, this error was much less, in fact, I could not really even use the commercial hole finder I borrowed from the local EAA chapter shop for this application. It is more limited to flat pieces.

Merlin,
Thanks!, yes it was WAY easy to make.

[jcoyier]

Easy repair #8

The covering supplies arrived. Here is a shot of nearly $1000 worth of chemicals including the glue, the sealer, the UV paint and the top coat paint plus the thinner for these products.

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I hope to have some left over that I can sell to the EAA chapter here. They go through this stuff like water. Decided to have the Tech Counselor help me do the upper left wing panel and then I'd take it from there. Started by putting anti chafing tape on all the potential rub points on the frame that would have fabric contact. I had taken a stab at what I thought would be adequate for taping over sharp areas. Not good enough per my Tech Counselor Ernie. He showed me how this needed to be done. No real tricks here, just had to think about how to best cover the topography with as little tape as possible. Here's a shot of the wing panel after I finished re-taping the root rib gussets. The rest of the panel shows what I thought would be adequate. I had to remove all of what I had done and re-do it right.

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Here are some examples of what the anti chafing taping should look like if you are doing a good job of it.

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The next step was to apply the leading edge filament tape. I used the directions specified in the original plans that call for three span-wise lengths spaced 3 inch center-to-center from the leading edge of 1.5” filament tape.

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The purpose is to help minimize the fabric droop between ribs when the fabric is tightened up during the ironing process and the coating process. After the filament tape is applied it is really easy to bump it with a hand or something on the table or saw horse it's setting on and fold the tape onto itself. After you do this it is really hard to separate the tape. This happened multiple times to me during the process and each time I had to use MEK solvent on a paper towel to redissolve the tape glue so that I could pull it apart again. I could not completely fix an area once this happened but decided it wasn't bad enough to redo it. This shot shows it prior to several accidental collapses that had to be separated.

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Next, my Tech Counselor highly recommended I cross brace the ribs midway between the trailing edge and the last row of filament tape. He supplied me with the approved material which was 1/2” wide cloth tape designed specifically for this. I don't think this was necessary since the filament tape and gluing the fabric to the ribs really doesn't allow for any movement of the ribs after the covering is complete anyway but I went ahead as instructed and did it. This shot shows me finishing up the cross bracing tape.

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We got to a dead end here as soon as we had tacked down the fabric on the bottom of this wing panel. We were noticing a reluctance of this material to shrink. It became obvious the more we tried to shrink it that it was pre-shrunk polyester cloth....something you might get at a fabric store. When polyester cloth is pre-shrunk, there is about 10% of shrink left in the cloth and it takes a hot iron to get that last 10% (something around 350 F). This won't work for covering material on a "conventional"airframe because you want all of that shrink margin to get a decent, tight and smooth covered surface. However, this is not a "conventional" airframe, far from it. The Easy Riser airframe is extremely fragile and weak relative to the techniques and materials used on stiffer, more constrained airframes. My tech counselor has had no experience with this type of frame so I'm back to re-reading the instructions sheets. Once I re-read them it was apparent that pre-shrunk material was, in fact, what UFM used to cover the Easy with. I had saved some scraps of material that I had from the initial covering I did years ago and put them to the iron set at about 300F. There was almost no more shrinking going on at that temp. The plans mention a very crude reference to shrinking once the cloth is in place. It says to set the iron on "wool" and go for it. You will know if it's too hot because it will melt the material. So.......the Poly Fiber manual talks about 350F being the highest temp you ever want to take polyester cloth. Beyond this, the fibers actually begin to relax and then finally melt outright. My conclusion here is that the original kit cloth was, in fact, pre-shrunk polyester fabric which weighs in at about 1.5 oz/sq yd, significantly lighter than the lightest material you can buy from aircraft supply shops. The method UFM describes in their plans basically talks about hand stretching the cloth as best you can and gluing it down while holding tension. Had I read the plan instructions more closely and tested the scraps I had kept from the original material, I could have saved myself a lot of labor and expense. Although, because my tech counselor assumed he was dealing with a standard covering process, he applied the fabric loosely when we glued the pre-shrunk material so it could not have been salvaged as the bracket holes were consequently in the wrong place. The photos that follow show the various steps I will now be doing over again with pre-shrunk material.

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This shot shows the cuts made for one of the strut gussets using a Weller soldering gun with the blade tip. This was slick and was right on the mark since we made a template pattern before making the cuts.

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Here's what happens when you don't make a template and get in a hurry.

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A shot showing the rough tension prior to the heat shrinking. This one is the root bay....notice how loose it is. With standard unshrunk polyester, this will shrink up tighter than a drum if you take it all the way up to 350 degrees F.

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Here is the Tech Counselor starting to heat shrink the fabric. Notice how loose he strung it. His assumption was that it was standard, unshrunk polyester fabric and very soon after this concluded it was pre-shrunk fabric that I would have to strip and toss.

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The next report will take me back to the beginning of the covering process where I will use standard uncertified light fabric material which I ordered from Spencer Aircraft Supply in Washington.....another ~$400 receipt. I will then discover the airframe is way too weak to support the standard shrinking process and soon be right back to pre-shrunk polyester (basically dress lining material).