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Wings

June 2018

Painting 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!

 Additional inspection rings added in the tank area and on the root rib.
 I used .025" aluminium to reinforce the filler neck.
 I cut the the hole in the doilie about 1/4" smaller than the neck and forced it on.

This causes the fabric to form tightly around the neck.

Some additional tapes are also added where the tank straps and flanges are close to the fabric.



 Only other trick bits are the outboard rib tape leading edge, and of course forming the 4" leading edge tape around the wing tip.
 Made the tape from prestretched light fabric.
 Forming the 4" tape

 Once everything hardened up  I opened the holes for the jury struts, sump drain and fuel line.  I also cut out one of the inspection rings in the root rib... the plan is to connect the fuel line from above while installing the wing.


And I think that's it for this section :)
March 2018
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 learned long ago there's no point in masking shortcuts so everything gets masked off and sealed closed.

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.
 I wet sanded the leading edge primarily for paint adhesion and finish but also to de-emphasize the leading edge lap joint.
 I used vinyl transfers for the registration.

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.
Done








December 2017

Ideally 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.



As mentioned there are two rib flange stitches for each rib forward of the spar,
 at the lower leading edge.
 "....just cut them from pre-srunk light fabric...." the Polyfiber manual says.  Sounds like a 5 minute job... it isn't!  Anyway I cut enough doilies to do both wings.
 The aileron belcrank access panel frame goes on,
 and a doily cut,
 and secured in place.
 A couple of locations need custom doilies.
Way back at my last OSH Polyfiber workshop, I learned that instead of pre-coating by brush before applying each tape, might as well just spray a coat of Poly Spay over the whole thing. So that's what I did and not only is this a great time saver, but it ensures the pre-coat has ample time to dry (which I think reduces the tendency for tiny bubbles to form later).





 So the question of what to do about the strut fittings has been on my mind long enough that I've looked at a lot of strut fittings in the field.  The solutions are wide ranging and, to be frank, not that great in many cases!
 Anyway, after debating (with myself) about what to do I decided that aluminium was the best way to keep the air, water and vermin out and add some stability to the fabric.

020" 2024 T3 to be precise.  I made two craft card patterns and then cut out 4 reinforcing plates (two left and two right).
 After epoxy primer,
 a doily is attahed to the plate.
 The whole thing is placed in position, with abundant Poly Tac on the doubler to secure it to the wing fabric,
and then the doily is Poly Brushed in place.



























 A couple of other details to take care of...





 I installed a standard inspection ring in the wing root in case access is ever needed to replace the pitot tubing.
 Using my plexiglass straightedge to draw lines for the rib tapes.  Turned out to be a very useful tool.
 The Rib tapes are straightforward except for the outboard rib at the wing tip.  I traced a section to go around the leading edge as it's not possible (at least for me) to heat form a 2" tape without reducing its width.


 Butt joints are made at the top and bottom span-wise tapes.
 For the false ribs, the span-wise tape is all that's needed on the lower surface.  I used these strips to reinforce the upper rivet locations.
 Trailiing edge tapes.
 Chalk lines for the span-wise tapes.
 Finally a four inch tape goes on the leading edge,
 and continues around the tip to the nav light location.
 The 4" tape is heat formed and
 trimmed to end up at 3" at the nav light.
 A 3" tape is installed from the nav light back to the trailing edge and medium fabric is used to bridge the gap.
 Heat formed around the nav light mount and butt joints with the forward and aft sections.
 The butt joints eventually get poly spray and some wet sanding
 Thanks to the clan on the Taylorcraft Forum, the preferred drain grommet locations are confirmed.

I made a bunch from .020" 2024 T3
 Although I had been smoothing out the seams, tapes, gussets etc. as I went, I spent at least a whole day with the iron going over everything.

Despite this there were still a couple of things that didn't show up until the silver went on.

The Polyfiber manual suggests using teflon sheet or oven bag material to iron down pinks etc once the Poly Spray is on.  I have not been able to use these or any other tricks successfully.  Bottom line is I fixed issues with the iron, trying to be as smooth as possible, but in the end surface blemishes have to be fixed by wet sanding and additional local coats of Poly Spray.


 4 coats of Poly Brush and 4 coats (2 cross coats) of Poly Spray, and then  wet sanding being careful not to sand high spots associated with structure, lacing, rivet/screw heads etc..  Then localized Poly Spay where any significant sanding was needed, followed by two more full coats Poly Spray.

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.




October 2017
With the basic wing structure complete, the next step was to ensure they fit. So I test installed the wings and lift struts.

 While the wings were in place I also checked for symmetry simply by measuring from the rudder post to various points on the wings and comparing right to left.

 The symmetry check provided further confirmation that the wing trammeling was good (and the fuselage was basically straight).
   I also checked the alignment of the aux fuel tank outlet and took measurements to fabricate the connecting tube.
With the wings back on the stands, next job was the leading edges starting at the tip.

The tip leading edges are made of very soft aluminum and originally supported by a couple of small wood blocks nailed to the spar.  I suspect the fabric would sag between the blocks so I made up some strips of the correct dimension and glued them to the spar top and bottom edge.  This should provide support for the soft material.

 I'd previously spent several hours removing dents, and spent a few more.  There were also some repairs needed.
 The tip spot welds had popped and the metal was torn from the Pk screws so I made a couple of flush patches.
 The material is soft enough that I formed the joggle after riveting the patch in place.
 Should be good
 The holes that previously had rather large Pk screws are repaired.
 Fitting, trimming, tap tap tapping.  Eventually achieving a satisfactory result.

 Etched, alodined and primed.  I used a little vinyl ester filler to fair in the rivets and joints.
 Riveted and nailed in place.
 Instead of driving screws into the tip bows, I used proseal so the soft material won't be as susceptible to cracking again.  Will also look better under the fabric and is likely stronger, not that any real strength is needed here.
The stiffner at the forward strut attach is riveted in.



The original leading edges were .020."  I had used 025" 2024-T3 and when I tried the initial fit, I wasn't happy with the amount of force needed to pull the skin tight against the rib leading edges.

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.
 Anyway,  all four skins were "squeezed" a little and the result was much better.
 Important to end up with the correct airfoil shape.



 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,
 and I made a small hole-finder to pick up the lower holes.

Inboard skin fitted in the same way.
 I used my nylon bar again to form a small flange at the tip and centre lap joints.
 The result is a nice tight transition.
Skins get etched, allodined and epoxy primer.

 Riveting the skins was straightforward for the most part.

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.
 I randomly riveted the middle row next, followed by the top aft edge.

Rivet gun and bucking bar for the top rivets.
 The tip is a little trickier because my hand only just fit through the lightning hole in the lower part of the tip.
 Repeat for the left wing.

 Except I had to install the pitot tubing.
Temporarily installed the jury strut to get the proper alignment.
 Lower edge riveted


















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.


 A few more details to take care of before covering begins.

I installed the aileron pushrods and secured them so they don't flop around.
 The ends of the trailing edges were not very fabric-friendly so I made some plugs to finish them off a bit.
 When rigged square, the root rib and trailing edge didn't line up well.  So a spruce plug improves that too.

There are several edges on each rib that need chafe tape.  Each rib has two joints and there's the joints to the leading and trailing edges.

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)

 I don't know if the slots were created by wear over time, or if the damage was done as the clip wires were installed.  I suspect the latter, but eitherway, if I'd wanted to use clips, I would have had to either repair all the damaged holes, or drill new holes.

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....

 Per the Polyfiber manual, the leading edges and aileron bay skins get two coats of Poly Brush.

Chalk lines are pulled and I use fine line tape to reference (to pencil a line) the centreline around the wing tip.
 Cutting a straight line is not easy, especially when one's hands are kinda shaky.  Good sharp scissors are of course a must. (I raided my wife's sewing box... but I ended up having to sharpen them so I think she got a good deal).
Leading edge attached.  Some additional heat forming needs to be done at the tip.


 The fabric needs to be well attached to the concave portion of the aileron bay.  So a generous layer of Poly Tak is applied over the dry two coats of Poly Brush and the fabric is immediately set into the adhesive.
 Need to work fast and chase out wrinkles and bubbles.
 Once dry I smooth it out more with the iron set under 250 degrees (we don't want any shrink here.

Later I shrink each lightening hole with the small iron.
 Fabric is heat formed around the root rib and attached with Poly Tak.
Finally the fabric is attached to the tip bow and an initial shrink, just enough to remove the big wrinkles.

I cut to expose the strut attach points so I can attach the wing stand.







 With the wing flipped topside up, excess fabric is trimmed and....
 remainder attached.
 Ready for top fabric, but before getting started,
and while I can clearly see all the structure, cables, drag wires etc., I took some time to establish the rib lacing locations, and marked them on my Plexiglas straightedge.











 New chalk line for the leading edge lap joint.
 Fabric needs to be trimmed straight.
 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.

 Heat forming and shrinking required at the tip leading edge.
 This was troublesome but eventually went down with "removable" wrinkles.
 Trailing edges trimmed and lap joints made.
 Joint at the root rib.  I left a tab of fabric attached so I'd have something to pull on while heat forming the aft corner.
 The third and final nav light mount....
and I finally figure out how to get a reasonable result!




 Shrinking is a satisfying experience.

The wrinkles show which areas to shrink first, ie which areas need to move in which direction (you need to be there!)
 After shrinking the whole wing at 250 degrees, the remaining protrusions are opened.
 Leave as much fabric as possible cuz the final shrinking stage at 350 will pull the openings larger.
 Before further shrinking, I made gussets for the aileron bay inboard corners.

Using copper house wire to get the profile of the false spar.
 Plywood form cut.
  Medium fabric formed to conform to the 'S' shape.
 The pre forming allows the gusset to lay flat so

it's easy to Poly Tak in place.










Finally the whole wing is shrunk again, this time at 350 degrees, and both wings get the brushed coat of Poly Brush.











 I mark the rib stitch locations on the top of the root rib, and then use a lazer to mark the bottom locations.

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 stretched construction string spanwize between the marks,

and punched all the holes.















  a lodda holes!
 Reinforcing tape applied.
 It became evident that it would be difficult to ensure the lacing would end up clear of the control cables, so...
 I made some reinforcing rings,
 Referenced the cable locations off the fuselage and attached the rings and doilies, and
 fished out the cables.
 There are two locations on each lower forward rib where the leading edge skins prevent lacing all the way over the top of the rib.

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.

 We usually had two needles on the go.

Masking tape helps in locating the holes from the opposite side.
My daughter and I both gained a respect for people who once did this for a living.

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!




July 2017
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.


 I measured each compression strut.  The ones for the lift strut attach locations are of course considerably shorter to allow for the thickness of the spar doublers and strut brackets, but the remainder vary in size by up to .040" in my case which impacts the shim thickness requirements and, critically, the distance between the wing root attach brackets.
 Accurately measuring and shimming will (hopefully) result in an easy fit of wings to fuselage.

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).
 Don't forget to install the drag wire nipples!
 After some back and forth, all the rib approximate locations were established.  Final positioning comes only after the spars are trammeled.

 I had left the inboard aileron bay ribs un-assembled as I thought they may need to be nailed in place first.  In the end I choose to rivet them together first.  Installing the nails between the rib halves was tricky but not a huge problem.
 Measuring from the centreline of the wing attache bolts, a reference is marked on the front and rear spars.
 With the drag (and anti-drag) wires installed but not tensioned, the objective is to snug the wires up while keeping the spars square and straight.
Working from the root toward the tip, the wires are gradually "tensioned," which is to say the slack is removed.

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!




 Spirit level attached to a drywall square makes an oversize square to help square up the spars.
 Once I got things straight and square, the lock nuts are tightened and witness-marked.  This way I know which ones I've secured so I don't go round and around.
 Repeat on the right wing, and of course, the fuel tank needs to go in.


The tank straps are not a nice way to hold the tank in place because as they are tightened, they pull the spars together.  If you tighten the straps enough to actually hold the tank, the spars can be damaged.

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.
 So I made 8 small angles and formed the straps to fit the spars and the tank.

 The Aileron hinges need to be aligned by shimming. Also note that the wing tip bow wires can affect the alignment of the outboard hinges.

 Measuring and marking all the shims helps.
 Clearance and the root and tip need to be adjusted too, and the position of the tip ribs, and
 the location of the aileron bay inboard wing rib is established.

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.
Construction string helps line up the trailing edges of the inboard wing and ailerons.



 The trailing edge inner-wing braces provide the final rigging/positioning/clearance.

 Need to leave enough space for at least two layers of fabric, tapes, adhesive, polybrush/spray, and topcoat, plus adequate clearance.
 Tip rib in position and square.
 Aileron bay panels are installed,
 Including the outboard panels I fabricated way back in 2014.
 There is a small stiffener that attaches between outboard panel and the rear spar.  The original part is an aluminium angle, nailed to the bottom of the spar and PK screwed to the outboard panel lower flange.

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....
 Craft card to make a pattern, then 2024 T3 025" is used.
 Fitting and trimming.

 Primed and installed.
 Nailed to the front and read face of the spar.

















All the little steel angles are installed being careful not to alter the location of the hinges.
 There are a couple of somewhat tedious jobs.  One is riveting all the ribs back together.
 I have this little rivet squeezer that made the job much quicker (and easier on my ears!)
 Finally the rib position vertically on the spars is set.  I used a laser because I have it but string works too.
 Those tricky aileron bay ribs... nailed em!
 Standing the wing up makes it a little less awkward to do the front spar aft nails.
 Straight edge is your friend for sure.  Checking and double checking.  Once the nails are in, they're not easily removed.
 Couple of loose ends like securing the drag wires.

Back to back figure eights,
 and a square knot.
 I used my Plexiglas straightedge to align the ribs mid-span before securing with inter-rib tape.

I also used tape aft of the rear spar to help straighten the inboard trailing edge ribs.
 False ribs are located in the centre of each bay and aligned with a straightedge and square.

 One point of confusion for me was at the lift strut attach locations.  The nose ribs are offset in this location and not as depicted in the available Taylorcraft drawing.

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.

 Making the "hoop" was a fun distraction.
 Two 2x4s plywood sides from an old shipping crate and 12V winch.  (mild steel bends much easier than chromoly!)


  Cut and splice
 Add the mounts to pick up on the lift strut attach points, and some nylon rollers, stand and casters.

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.....






March 2015



  
 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
 I'd read of using a plexiglass knife to cut thin alluminium sheet.  I experimented but in the end I just drew a line and cut it in half with my snips


Small flange is made on the upper and lower edges

 little tool works pretty well once you get the hang of it
Four panels ready for bending











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!

 I measured as best I could, the centreline of the leading edge from the ribs and the old leading edges.  Then 1/4 the circumference of the tube is subtracted, then the radius of the tube is subtracted.  The result is the dimension  to the inside edge of the pipe.

The square is used to line up the marks and the tube bolts are tightened to clamp all.





Can't see it in the photos but the rope runs to a pulley attached to the wall and down to the winch secured to the floor.

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 :)
 Next the sides are duct taped to the bench and shop vac attached.  Then two hands push the skin to the surface of the table and air pressure does the rest, forming the skin tightly round the tube.









Magic!


 More time spent working out the dents in the wing tips.  Beginning to wonder if I'll ever get them smooth.








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.



December 2014

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:
 Typical cracks

 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.
This is a video of inside the lower 18-24" of one of the rear wing struts.  I recorded the video with a USB camera I bought for $20.

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 :)

The fabrications:
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!




Once the pressure is on, the flanges are formed with a soft mallet.  I did use my fluting pliers as well to get a better result.  Taylorcraft did not do this and I think this is why the ribs are prone to cracks.
One of the finished ribs next to the barnyard fabrications being replaced:

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:
Cutting and forming around the lightning holes was time consuming.  I couldn't come up with any other way to do it except fit-form-trim, fit-form-trim at little at a time until a good result was achieved


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
A rather irritating Taylorcraft manufacturing practice was to use steel pop rivets.  Here I've replaced a collection of non-critical but no less irritating ones:

Many other small repairs:


Aux Tank:
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.




June - July:
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.






One jury strut has a splice.  Not sure why as it was surely more work to fabricate the splice than make a new member.  anyway

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!)
 Couldn't stand the sharp corners on these little steal brackets any longer so radiused them all (probably saved a few grams too)



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)
 My trip to OSH last week and a prearranged purchase yielded two control wheels which although pitted under the layers of paint, cleaned up ok.


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.


 April-May:
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.

 When they finally arrived 3 out of the 4 blanks had been damaged in shipping.  Replacements are on the way and I hope they're ok, because the packaging leaves much to be desired.

 So I started evaluating the steel parts














 Wing tips were corroded through so the rot was cut off and new 4130 spliced in
 Ready for welding.  I haven't done a lot of welding in the last couple of decades and good eyesight and a steady hand are great assets.... two things age apparently takes away from us!
Anyway after a good deal of practice and a couple of on-line refresher courses, an acceptable result.  It was a good idea to start with something non-critical!



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:




I used the old spars to get the correct spacing








More etch-cleaning and epoxy primer and the inventory of parts ready for assembly slowly grows




7 comments:

  1. just started watching this thread.. are you in the taylorcraft forum

    I am swoeric on there

    ReplyDelete
    Replies
    1. Yes, the folks on the forum have been a big help and I try to contribute when I can. (username Scott)

      Delete
  2. Just love your workmanship! You've given me several great ideas. I just made some new tank straps and the two braces that go between the spar and aileron bay trailing edge. Great idea, easy to make and so much better. Thanks!!!

    ReplyDelete
    Replies
    1. Thanks!
      Glad the information has been useful for you. Good luck with your project

      Delete
    2. I can't tell you how helpful your work was to me. I have a great deal more areas to look for when inspecting the three Taylorcraft projects I am going to look at before I buy one, or two. THANKS ALOT.

      Delete
  3. Great blog and job with the restoration. I am working on a 1946 BC12D 65hp. I am trying to track down the source of a stiff alieron. Are there any cable guides for the cables. I can see on mine that the cable is rubbing the double at the trailing edge.

    ReplyDelete
    Replies
    1. Thanks, and thanks for looking.
      There are a couple of phenolic guides in the ribs for the aft cables, and one for the front cable at the inboard aileron hinge bracket. Unless someone has incorrectly routed the cables this is probably not your problem. You should be able to sight along the tensioned cables to confirm the cables are routed correctly.

      check the cables behind the instrument panel, around the 'H' yoke and up the side post to ensure no interference.

      There is a tendency for mechanics to over tension the cables and this can cause stiff/poor operation. The bridal cable (runs down to the control yokes) changes tension as the elevator is operated. If you adjust the cable for about 5lbs with the elevator neutral, you'll see around 20 in the full up or down position. The wing cables will end up with different tensions because the ailerons have no mass balance. So with the cable tension released, ailerons installed, the forward cable will have tension. Adjust that cable so the ailerons are fared with the wing, then adjust the aft cable for minimum tension (<5lbs) which should result in the ailerons "drooping" 3/16-1/4" ( which will result in them being good in flight).

      The pushrods end up very close to the upper false spar cap and sometimes it's difficult to see a rub there. Use a piece of card or feeler gauge to confirm clearance through full motion.

      Someone may have also tried to tighten up the ball joints on the push rods which can result in tight spots.

      If the aircraft is covered using dope, shrinkage can cause problems with the ailerons and the wings that can cause tightness. Check the top forward part of each aileron for signs of rubbing on the false spars. The aileron ribs get crushed forward pushing the screw heads up and rub on the aileron cove.

      Remove the outboard hinge pin and see if the aileron naturally lines up with the hinge.

      That's about all I can think of for now. Do a search on the Taylorcraft forum and you'll probably get a couple more ideas.

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