June 2018Painting issues continued with the right wing and to be honest, after all the trials and errors, I can't say I've mastered the art of shooting Ranthane. There are many, many variables, and different ones for different colours. Anyway the wings are done!
For the most part the right wing was a repeat of the left. There is no pitot but the aux fuel tank is in the right wing.
First task was swapping the wing rotisserie. Should have built two was the thought going through my head as I invisioned poking a hole or worse in a finished wing!
Some additional tapes are also added where the tank straps and flanges are close to the fabric.
And I think that's it for this section :)
All that remained to do on the left wing was the leading edge and the registration. Who knew that three weeks later I'd be pulling my thin hair out trying to get the maroon to work (see Painting& Finishing section).
Other than that the work was straightforward.
Measure and pull fine-line tape.
I did consider painting the maroon first, but this would require masking a perfect line as there's no way the Ranthane white will cover the maroon.
Registration under the wing is optional in Canada but if you elect not to have it, minimum 12 inch letters must be used on the sides.
CF-CLR (as opposed to C-FCLR), large under wing letters and 6" letters on the fin is period authentic.
I cut the backing after positioning the registration and then apply one letter at a time. Difficult to get it to go down without some small bubbles but they disappear with time.
December 2017Ideally I would have made two wing rotisseries which would have allowed the concurrent completion of all the gussets, doilies, tapes Poly and paint. In the real world I switched my one rotisserie over to the left wing to do the rib lacing and then carried on, leaving all that to look forward to on the right wing.
Despite all the care, we did manage to place one stitch over (behind) instead of under an aileron cable. This meant that half that rib had to be stitched again. Anyway this was the only faux pas so not too bad. At least we caught it before it was a big deal.
020" 2024 T3 to be precise. I made two craft card patterns and then cut out 4 reinforcing plates (two left and two right).
I made a bunch from .020" 2024 T3
Despite this there were still a couple of things that didn't show up until the silver went on.
Finally, after getting the hangar up to a decent temperature, the top coat goes on. Next is the registration under the wing and the leading edge accent colour before I transfer the wing stand to the right wing for a repeat performance.
That was the last opportunity for 2017 really. As I write, the temperature outside is -25C so I'll be finding some tasks I can do at home unless and until the weather warms up a bit.
With the basic wing structure complete, the next step was to ensure they fit. So I test installed the wings and lift struts.
In retrospect I should have used a smaller diameter tube to form the skins.
So I rigged up my work bench again to try and get an easier fit.
The factory used Pk screws to attach the leading edges. This was done for the sake of expediency and hence lower cost. I'm not in that much of a hurry (obviously!) and there was a good chance that some or many of the holes in the ribs would be stripped requiring larger screws, tinnerman nuts, or double holes.
As I've stated eslwhere, I'm not a fan of putting Pk screws into aluminium without at least a tinnerman nut, and so......
I found that a 1/8" drill bit just cleaned up the existing holes nicely so I opted to use AN470AD rivets.
I used this long drill bit to pick up the upper holes,
I used my rivet squeezer to attach the bottom edge first. Note I also flattened the small flange at each rib location to get a smooth transition.
Rivet gun and bucking bar for the top rivets.
and then the upper surface. The mid-span lap joints turned out nice.
All in all I was very pleased with the way the leading edges turned out.
I installed the aileron pushrods and secured them so they don't flop around.
Given that I'm using rib lacing in place of the original steal clips, I elected to just tape the whole exposed rib flange.
Many if not most of the clip holes in my ribs were like these. (below)
Bottom line is that, like the Pk screws in the leading edges, wire clips were used in production because they saved time, not because they're better. So rib stitching it is.
So now ready for fabric....
Chalk lines are pulled and I use fine line tape to reference (to pencil a line) the centreline around the wing tip.
Later I shrink each lightening hole with the small iron.
I cut to expose the strut attach points so I can attach the wing stand.
This will be the most visible edge so I did my best to get it straight.
Lots of heat forming with the iron at 225 to remove creases in the fabric (I opted to have the fabric folded to save shipping costs but the result was more creases), and form it around the leading edge.
The 2" joint is then made. Need to work fast and pull the fabric tight and to the chalk line to get it as straight as possible.
The wrinkles show which areas to shrink first, ie which areas need to move in which direction (you need to be there!)
Using copper house wire to get the profile of the false spar.
it's easy to Poly Tak in place.
I ended up with both the top and bottom locations marked on the straightedge so I could then transfer the locations to the tip and mid-span.
I basically had two choices, use pop rivets, or stitch just the rib flange. Both require drilling a hole in the rib flange (because the original martin wire stopped just past the spar).
I choose to use lacing emulating the cap stitching guidance in AC43 -13. The stitches end up slightly offset but otherwise a good result.
I did the same thing on the top surface, immediately forward of the aileron bays. A single stitch around each rib flange, where there is no lower rib flange.
Masking tape helps in locating the holes from the opposite side.
So we're about 1/4 into the left wing lacing task, and I've also started covering the ailerons. I see much brushing and taping in my future!
More than two years since my last update to this section. Up until early this year the only wing components to get attention since 2015 were the drag wires, which I primed and painted (using up some mixed Ranthane).
I decided to lay out both wings with the objective of assembling them simultaneously. Eventually I fabricate a Rotisserie but initially I set the spars on sawhorses.
With the compression struts and jury strut attach in place, I started figuring out rib locations.
A few are obvious where they go, others not so much. It seems all we have is an 8 x10 sketch showing relative locations. Ribs with an "R" part number have the web to the right and flanges to the left (and vice versa).
Every adjustment needs at least one other adjustment in order to change squareness or straighten the spars. So, for example, to adjust the spars aft at one station, loosen the two wires at the aft spar and tighten the pair on the front spar. Anyway, ya needed to be there!
Photo right is the old rear spar. Note the four crushed areas from the previous installation. Crushing in the important root area is not good and one of the reasons I made new spars.
At the factory, all the ribs were located and attached with the aid of a spacing jig. I use measurements from the old spars as a guide, holes in the leading and trailing edges, and ultimately my square and clearances to position the ribs laterally.
As you can see here, the nails are not sufficient and the angle ends up cutting into the rear spar. No biggie in the tip area I guess, but easy enough to fabricate something more suitable....
All the little steel angles are installed being careful not to alter the location of the hinges.
I also used tape aft of the rear spar to help straighten the inboard trailing edge ribs.
With some help from the guys on the Taylorcraft Forum and a more detailed review of my old spars and leading edges,
the correct configuration was determined.
Looking at the old leading edges shows these angles were glued in.
So with 800 and some odd nails driven home, with the exception of the leading edges the wings are assembled.
I need to offer them up the the fuselage and a rolling stand needs to be made.
So I bought some 3/4" square tubing to make a rolling rotisserie.
Not particularly elegant but should get the job done.
Also made a rolling/rotating stand for the root end.
And that's where I'm at with the wings.
To be continued.....
Wing leading edges were obviously and typically the subject of much action over the years not to mention the dings and dents from moving and storage. So I set about making new ones
Small flange is made on the upper and lower edges
There's actually quite a bit of info floating around on the web about different methods people have used for leading edge fabrication. I didn't want to be different but the Tcraft leading edges are asymmetrical top to bottom ie the skin stretches further aft on the top than on the bottom of the wing. Anyway my solution is sort of a hybrid of what others have done. I only used the electric winch in place of another set of hands. Even I was surprised how well it worked!
The square is used to line up the marks and the tube bolts are tightened to clamp all.
Press the button and the leading edge is 80% formed (see video above). Let go of the button when the bench lifts off the ground :)
Now I have the drag and a-drag wires to clean up and I believe all the parts are ready for both wings.
For now I won't be assembling the wings because they take up too much room.
After priming the "specialty" ribs, the parts and repairs were riveted together.
Here the root rib doublers are riveted in position prior to final assembly of the inner and outer ribs
The inner and outer ribs are "shoehorned" together and literally snapped into place. Note the bucking bar I made. This slides in from the front and is used to buck the top and bottom original 3/32 flush rivets and the ones I added for the repairs. My finger tips were sore for weeks after assembling the root ribs!
The etching production line:
Addressed by dressing back material, increasing the radius and improving surface finish.
Many more cracks repaired like this:
Another paint-a-thon and everything except the leading edges is now ready to assemble the wings (which I won't start for a while for a couple of reasons including the fact that the hangar will be too cold in the depths of the Thunder Bay winter.
Just the leading edges left to do... repair the tips and fabricate new for the rest.
July - November "Rib Fest"
No way I would have thought I'd still be working on ribs and wing parts... for months, but that's pretty much what I've been doing. First, all these parts had to be stripped and cleaned, and with years of glue, dope and paint, not to mention surface corrosion, it turned out to be very time consuming. During cleaning of course the deformations, cracks and other damage became evident along with the unacceptable previous repairs.
I tried various chemical and mechanical means to strip and clean the ribs and ended up with a three stage process (five if you count alumiprep and alodine prior to priming).
I made a tray from a 5 foot length of 6" HVAC duct, shown here with the fuel tank straps soaking. Each rib was soaked in varsol overnight to soften up the layers of masking tape (unbelievable how well 40 year old masking tape sticks!). This was followed by paint striper where necessary,and then a trip to the media-blaster.
I tried soda-blasting but it really was not enough, especially where there was surface corrosion. I did a couple of test pieces using aluminium oxide and this worked great. Still it was several days work to get all the ribs and trailing edge parts cleaned up.
Before I get into the nitty gritty of wing part repairs, the issue of what to do about the lift strut AD has been in the background since I started the project. I'm happy to say I believe a good solution has been found.
The purpose? a preliminary evaluation to determine if it was worthwhile shipping the struts to Wag Aero to be sealed as a terminating action for the AD.
If you're prone to vertigo don't watch the video, because for $20 all you get is a camera attached to a cable. I controlled the camera inside the strut, through a .280" hole, with a straightend clothes hanger and a length of fishing line.
Anyway the good news is all four struts looked really good and have been shipped out for sealing. Hopefully this means CF-CLR will have original struts with no repetitive inspection requirements :)
Some parts turned out to be not practically repairable so I set about fabricating new duplicates. First up, for no particular reason, were the outboard aileron bay trailing edges.
This was the better of the two so I used it as the pattern and sacrificed the other to make the blanks.
Dimensions to make the plywood form:
From the flattened out left wing part I made two blanks:
The upper "structure" is bent on the brake, but the finished angle is over 135 degrees so not possible on the brake.
I found that a steel 90 from the local hardware store was close to the right size. Several minutes with a surface grinder to get the right bend radius and dimensions, then clamped to the work bench yields an acceptable result.
Next the lower flange is formed over the plywood form made from the old part:
Forming the lower edge causes most of the "S" profile, the rest is formed by hand.
The last step is dimpling for the flush rivits, which will be installed after primer is applied.
Meanwhile, other parts are cleaned, inspected and assembled. Here the right side aileron bellcrank and hinge bracket is assembled. Later I made 4 new aileron cables and both sides are now ready for installation.
Several nose ribs were damaged and two were barnyard fabrications that were obviously adequate (were in the wings for many years and flying hours) but not really up to acceptable standards. Fabricating a wing rib is typically part of an AME/A&P training program, but I had actually never done one before. Anyway the Tcraft ribs are kind of goofy in that there is a relatively complex form in the web and around the lightning hole but the flanges are a series of tabs rather than shrunk or fluted.
I began by cutting the shape and "casting" the web forms from couple of good ribs. I used Vinyl-ester resin (West System Epoxy).
The male forms were easy. For the females I first layed out the centres, then routed the blanks:
Females after rough routing:
Then I poured resin into the roughed out forms and clamped the males, ribs and females together (with some plastic film and silicone lub as mold release).
The results seemed good. One hitch is that to obtain the right finished size, the form needs to bend the aluminium beyond the finished dimension. To achieve this I "milled" the males' mating surfaces and sanded the female forming surfaces by hand. Also filled and sanded any voids/imperfections formed during the epoxy curing.
Again I sacrificed one rib to use as a template for the blanks:
The first rib actually looked pretty good:
On closer inspection however I spotted a crack. At first I thought this was a few hours of work down the drain, but I actually ended up salvaging this rib to replace one of the intermediate ribs (material where the crack was is not needed), and of course learned from the experience:
For the second attempt, I decided to cut the lightening hole, and form the top and bottom straight flanges first, before pressing:
A shop casualty clearly indicated I needed a better way of pressing out the ribs!
As it turns out, my apple tree yielded a bumper crop this Fall and rather than let so many of the drops rot on the ground, I made an apple press.
After pressing 6 gallons of soon-to-be scrumpy, the press was employed to make ribs!
This shot represent several weeks of work. perhaps I should have bit the bullet and tried to buy the parts :)
Next up was the wing tip ribs. Both had been repaired but one had a "repair" on its repair:
Perhaps it was a field repair that was ment to be temporary! Anyway obviously had to go.
Repair on a repair... I bet the pop rivets were top quality ;)
So I used the same basic procedure as for the nose ribs to fabricate a repair piece:
Using the rib from the other wing to mold a plug from plywood and vinylester resin.
The male form:
Using my drill press as a milling machine to undercut the form to get the correct finished dimensions.
Routing the female
The first attempt looked good:
But once again closer inspection revealed a crack
The second time I took a good deal more care in cutting the holes in the blank, and success:
A section of the cracked atempt was used to repair the left rib:
The wing root ribs are always a problem due to dope shrinkage and an inadequate design. I fabricated a repair doubler from .032" 2024T3. The additional thickness will provide the rigidity needed to a) overcome the oil-canning that I was unable to work out of the rib web and b) provide the strength necessary to prevent deformation in the future (though this should be less of a problem with the current generation covering system). I started by bending the doubler blank flanges:
Repair "kits" were fabricated for both left and right with roots. To be riveted after primer.
The root ribs, in addition to the cracks and deformations at the rear spar location, were basically bananna-shaped in plan view, again the result of the continued shrinkage of the dope/ fabric over the years. To sort this situation it was necessary to shrink the rib flanges. I don't have a shrinker so I used fluting pliers to first pull the metal up, then, with a nylon hammer and bucking bar, bash the flutes flat while holding the rib straight. Then re-formed the flange back to it's original shape. After a few flutes and bashes in the right locations the ribs sat flat on the workbench (with no additional cracks!).
Many many repairs like this:
Both aileron bay training edges were in tough shape at the bellcrank/push-rod location.
Again I used angle iron from the local hardware store to form channels. I used .032" material extended 3-4" beyond the push rod opening to make up for the fact that this really is a week point in terms of the needed rigidity of the top edges.
The end of the repair channel is just visible through the lightning hole.
|Shown here is a piece of leftover channel|
Many other small repairs:
Pressure testing the aux fuel tank revealed many small leaks.
When I bought this aircraft I noticed signs of a fuel leak from the aux tank. I repaired the fuel shutoff valve and put fuel in the tank once... it was obvious there was another leak somewhere so I did not use the aux tank at all. Take a look at this shot. The red lines indicate various fuel levels OUTSIDE the tank, in this case between the tank and the root rib, clearly indicating the aircraft was fueled repeatedly with what must have been seen and smelled as a significant problem. wow!
The fuel pickup fitting is a big iron pipe which had had several visegrip marks and was full of rust. I cleaned it up and epoxy primed it inside and out as I'm assuming this is the factory part. (Eventually I decided to go with a replacement screen from Aircraft Spruce.
Predictably the most significant leak was at the outlet fitting:
After sealing, cleaning, and a thorough inspection the glove stays inflated :)
Finally the "specialty" ribs are etched and primed with epoxy primer. Many more parts left to be etched and primed will be the next job.
I spent several hours bashing, rubbing and rolling the wing tip leading edges and not done yet.
Work on the spars began in earnst at the end of June. I picked the best of each of the front and rear original spars to use as templates (taking into consideration that none of the 4 old spars is straight, although 3 out of the four could be used again if the laminates were replaced and spars refinished).
First job was planing the root ends to accept the 1/16 ply doublers. I also did the tips as these eventually get crushed by the wing tip bow installation. (actually I did the tips first as a screw-up wouldn't have been terminal :).
The original Taylorcraft doublers extended only to the beginning of the radius left by the planer. I sanded the new ones such that the surface is continuous.
Clamped in place while the epoxy cures overnight.
A good result obtained after a light sanding
Next the strut attach point doublers out of 1/8"
and strut fittings checked for a snug fit.
Tips are cut to shape,
Four spars ready for drilling
Using the old spar as a drill template, drill and bolt the new to the old in a few places before drilling all the other holes (except one wing tip hole which I'll drill when installing the tip bow)
Attach brackets checked for fit.
Note that I also turned the new attach bushings per the Increased gross wt STC.
Three coats of urethane and the spars are done. As always, a lot more work/time than expected
A few other parts worked on while waiting for epoxy to dry etc;
new bushings installed for the Ailerons (to be line-drilled after installation on the wing.
I made the part by flattening a round tube. Not sure if this is how Taylorcraft did it.
I used the wing attache tube to ensure the correct spacing and welded in place
lots of other parts to strip clean and paint: (this shot also shows that you can't have too many readers of different magnifications around the shop!)
Magnesium parts receive a chromic acid wipe down just prior to receiving (non-chromate) primer. I found a plating shop in NY that sells the wipes for a few $ each, a much better solution compared to trying to by chromic acid (nearly impossible these days it seems)
Another couple of hours behind the paint gun....
small parts have many nooks and crannies and it takes time to ensure full coverage
Next up.... ribs. I've been slowly soaking and cleaning wing ribs. It will take a while to get them all repaired prepped and primed.
So I've done a lot of work but can't say I feel I've made a big dent in the project.
I've been evaluating key components. The wing spars are obviously very important consideration. The originals are, as far as I can tell, the ones installed at the factory and have been repaired in a couple of areas including one full splice (which is adequate but not how I would have done it). Anyway I decided to go for four new spars and blanks were ordered.
So I started evaluating the steel parts
Wing tips were corroded through so the rot was cut off and new 4130 spliced in
Similar repair completed on the other tip along with straightening and repainting.
I purchased the gross weight increase STC as this is a good time to incorporate the upgrades:
More etch-cleaning and epoxy primer and the inventory of parts ready for assembly slowly grows