"D" Windows

[Curly]

JohnW,

Don't take any notice of those who tell you to "keep it brief" - I like the way you write and while I might be a bit of an old dog, I do like to learn new tricks!, I soak up any and all information, tips, advice etc. like a sponge. You obviously have the knowledge and experience so if you wan't to fill a page with information and advice when answering a query, I for one will enjoy reading it.

Curly

[Gilbert Pierce]

John W
I for one appreciate your knowledge and the fact you share it with us. I have copied many of your posts to a notes file labled John W I keep for future reference.
If folks don't like wordy posts there is no rule they have to read them. Some folks today just have too short an attention span.

[Steve Pierce]

John, I figured you could describe it better than me and I seem to remember you having a Short Wing with the original fabric.

[JohnW]

Gilbert: Whatterya gonna do with THAT uh...scrapbook? dossier???? Beat me to "writing my own book"? (joke, Son)

Tell ya what, Fellas...I'll give you a teaser for now (if this works the way I THINK it will!) and then I will Post a painfully long text on the "wing root former" issue next day or two. Here's the INSIDE view of the area in question, from behind the [removed] rear baggage compartment wall inside my 1963 Colt project; last flown 1967; 799.9 on the clock and guaranteed Factory original (except for the obvious fungi infection!). You can bet your Bippy that "one look down in there" and it was "break out the air-in respirator", for me! No way I was going in THERE bareback! Does that stuff lay dormant for a thousand years until something it can LIVE ON walks by? Cripes, the back side of that headliner was pretty freaky!

[JohnW]

Okay, here's what Piper did. First, they used 54" Grade A bolts of fabric when they covered their airplanes. You can see quite nicely (in my slightly dark pic) that 54" didn't make it all the way up and over the wing butt. So they scabbed on a triangular "extension" (using a French Fell seam) big enough to finish the gap. You can see that the side wall fabric was installed so as to be "perfectly straight" up and behind the wing butt, and the "extension" follows along the "line" of the side fabric. There it is then cemented in a "Z" around the wing butt all the way to the top of the birdcage structure where the top fabric was cemented "around the corner" . They finished (as you can see in the pic) by taking the "pocket area" formed by the added fabric and the larger -but too short- side piece and gluing down the "flap" wherever it would lay against "back side" of the "extension piece" between the "Piper channel" that covers the butt after the extension was cemented shut. I have other pics showing that Piper used TWO SEPARATE sections of fabric to cover the TOP in "halves", not "one". The Piper drawings show where these join at the stringer as a cemented seam along the top stringer, but "the Jewel" (again, a 1963 Colt) had a straight double-stitched sew-job at the stringer, and a "flap" was left hanging inside that was cemented full length to the right-side edge of the top stringer and around the bottom of it. Gluing this "flap" is pretty handy, because it "locks in" the seam right there while you finagle the outboard edges onto the "reverse curve" made by the top longerons. That's a BUNCH easier with dacron than it was with cotton, lemme tellya! Piper also dressed that seam with 1 1/2" pinked tape. I use 3", to comply with 43.13 and to get the pinked edges further out from the stringer to simplify sanding so I can make the tape "disappear". The "two halves" for the top panel allowed Piper to get each side of that top panel to turn and cover the sides of the fin, and placing the final cemented seam over and slightly below the top longeron, where it hides nicely UNDER the horizontal stabs, once they are installed.

So, what I do "differently" (mostly because dacron is more prone to "showing" a French Fell out in the open than Grade A was) is I take the 70" dacron straight up from the bottom longeron all the way to the top longeron. This is "entertaining" (okay, it's downright "tedious") where you have to slot the fabric to pass the channel that makes the wing butt and glue to the longeron, but "extra care" is not required since the top fabric will "later" come all the way down around the wing butt and "hide" the slots. The headliner hides the slots cut from the interior side. Now...Although Piper effectively left their "hidden area" on the upper part of the side wall fabric UNDOPED (well, their fabric was "pre-doped" by their manufacturer/supplier and they clearly used Randolph tinted nitrate to glue the cotton -in "the Jewel" anyway- but one coat of clear butyrate is basically "undoped", IMO) Since I am a dyed-in-the-wool nitrate/butyrate kinda guy, I go an "extra step" at this time and apply nitrate base coats and four or five brush coats of clear (tinted) butyrate to the area that will be "closed up" (were I to use another system, I would basically do the same regarding "base coats" for that system), since the finished exterior fabric does not allow access "under there" during the dope cycle. I don't use silver or color in that area, since it is never exposed to "the elements" once the doping is done. Hey, it HAS TO be as good or better than what Piper did! I paint the nitrate about 1/2" below the bottom of the butt so the area will have a continuous base coat for the exterior , but stop the butyrate where it will not affect the cemented seam that attaches the part of the top fabric that "turns the corner" and fully covers the side of the wing butt. This gives me THREE sides of the bottom channel to cement it to, and I even turn it down into the channel, as well as "working it around the back side" by pushing away the side wall cover. I finish it all off, when the time comes, with pinked tape. This "method" gives me a positive attach for the side wall fabric (the top longeron) and 9/8th of an inch of glued seam where the top fabric finishes. I like it.

All of this winds up giving you one really sexy curve in the fabric at the base of the stab, NO seams where the stab was "grafted on", and allows the final cemented closing seam to "hide" right at the most desirable location on the fuselage...right below where the horizontal stab mounts. It also gives you an overlapped cemented seam along each side of the top longeron in just about the WORST place you could want it. Extreme care in making a nice trimming cut to these edges and not bringing them any further down the side that you absolutely HAVE TO to get the required overlap results in a darn nice looking job with no worries about attachment integrity in later life. Man, is this stuff FUN, or what?

As far as using an envelope??? Well, this is a real problem at this location because there isn't a whole lot of "extra material" supplied here when the "sock" is sewn up. All you have is what you can "steal" from the rear door opening on the left or the D-window on the right. Now, the D-window needs enough "stuff" to cement down into both sides of the window channel (no rear door on the Colts, but all "mine" get D-windows on both sides), so you are pretty limited as to "what you have to work with" there. Just one more reason why I really don't LIKE envelopes! Most airplanes I have "checked out" after someone used an envelope on the fuselage not only has seams running back and forth across the longerons, but most also have a simple "z" glued around at the wing butt and no cuts in the fabric. I have to say that I have seen this "method" let go in service on several airplanes, and I don't "like it". Winds up being held in place with the #4 fairing attachment screws. What's with THAT? As I guess you can figure out for yourself, the extra piece of steel added to this area helps out a lot in this regard, if that is the method you want to use. It gives you someplace to glue the fabric to. I used that method on several airplanes myself, but adopted the version of doing it [above] several airplanes before I got "the Jewel" with it's Factory fabric (boy, it is genuinely RARE to find an airplane that old still in Factory Cotton nowadays! Oooweedoggies). I HATE sewing (but I do it when I have to) and doing a nice French Fell with dacron really taxes about all my available patience, and with Dacron you WILL see it in the finished product. On the other hand, two straight shots for a simple flat seam for the top panel doesn't bother me much. All in all, this method of fabric attachment seems best to me, despite the little bit "more piddly work" attaching the side fabric to the top longeron around all that channel (which "welding on a strip of steel" approximates). I actually feel that this methodt will provide more integrity to the fabric attachment, too. (There's a "my opinion" if you ever saw one). So... FIVE pieces of fabric, not FOUR. And even then, dammit...keep that top longeron STRAIGHT!!!

I guess this brings me back to one of my favorite sayings: "There's as many ways to do it as there are people doing it." This is just "one way". Well, I guess it's "two ways", since mine is SLIGHTLY modified from how Piper did it with Grade A Cotton.

[Homer Landreth]

Relative to Hillbilly reply that use of a fuselage sock might eliminate the need for the reinforcement that Steve described, I am in my second use of a fuselage sock, and i would suggest that the reinforcement structure is necessary even with the fuselage sock. When I went to the higher temperature for shrinking the fabric, it really pained me to see that the entire stress of the shrink process was on the glue points, and it actually popped some of the fabric off the glue because the horizontal points were actually a fulcrum point relative to the pressures on the vertical section of the fabric glued to that angled section at the wing root. I built the reinforcement pretty much the same as Steve's shape, however after all the glueing and shrinking was done, I used a small piece of 90 degree angle steel and steel screws and fastened it over the fabric. Now the stress on the fabric that is glued onto the vertical section at that point is being mitigated by the support from the angled steel portion that is secured to the horizontal portion of the angle steel piece.

[Hillbilly]

OK gentlemen, thank you so much for your input. Now that we have that cat skinned, might I trouble this crowd for a bit more advice? As most of you know I'm prepping my frame with stripper and naval jelly and I'm almost done with the segment just aft of the area in question. I have discovered one more small area of welding and I'm approximately an eon away from unfurling the covering so could you be so kind as to being a bit more specific as to the size of the reinforcement strips and your methods of locating them? I am hoping to be dragging out the TIG equipment for the last time, at least in this phase of this restoration.
I really appreciate being able to take advantage of your collective experience and defeat a potential problem before it ever arises. Thank you all again, - Hillbilly

[Hillbilly]

Alright, just came in from the shop took some measurements and did some staring, (after making more chemical messes)
And what I come up with is 22.5" long strip by 1" (1.25?? 1.5??) that butts against the bottom of the root rib channel on the starboard, and a somewhat shorter 16.5" length above the door. Sound about right to anyone? and what about preference for width? I plan to use .035 4130....Somebody stop me if I'm not in the right neck of the woods!

[Steve Pierce]

I think I used .025 or .032. I will look tomorrow and let you know the width and thickness. Got another modification involving the front door hinge I will post tomorrow now that my internet is back up.

[Hillbilly]

I think I used .025 or .032. I will look tomorrow and let you know the width and thickness. Got another modification involving the front door hinge I will post tomorrow now that my internet is back up.

Anything on width Steve?