Vertical fin rib stitch

[asq]

What is the norm for the vertical stabilizer rib stitches? I have very little of the fabric that came off this BC12D ,but I do have this portion and I find 15 stitches in the VS. Both the horizontal ribs and the diagonals are stitched. Any advice appreciated. Larry Huntley

[Mark Julicher]

Re: Vertical fin rib stitch

If memory serves me correctly, the original rib stitch pattern is three equally spaced stitches in the top horizontal rib and NO other rib stitches in the fin.

[asq]

Re: Vertical fin rib stitch

If memory serves me correctly, the original rib stitch pattern is three equally spaced stitches in the top horizontal rib and NO other rib stitches in the fin.

Thanx Mark,
That makes a lot more sense. That is pretty much how Piper did it and I don't have another Tcraft near here to check. Much appreciated.
Larry Huntley

[mulwyk]

Re: Vertical fin rib stitch

My stabilizer has 5 stitches, all on that first rib. The stitches are about 4" apart.

[crispy critter]

Re: Vertical fin rib stitch

I believe if you read your fabric manual you will discover the stitches are supposed to be 2 1/2 to 3 inches apart. If on the prop wash side they are supposed to be 2 1/2" and the rest can be 3" between. Now,because this is on the tail assembly it leaves a lot of debating about this and also you can't stitch the virtical 2 1/2 on one side and 3" on the other,lol. Also,I have seen t-crafts with both of the horizonal ribs stitched on the vertical stab but I prefer to just stitch the top horizonal rib which I think is what was done by the factory. If you try to stitch the bottom one too then you really have to pull the fabric in tight and in my opinion this could cause problems later. My advise is to stitch the top horizonal rib only and space your stitches at 2 1/2 inches. Nobody will ever ground you for having to many stitches but they might if they feel you don't have enough.

[Mark Julicher]

Re: Vertical fin rib stitch

Crispy,

Yes, 43-13 and the fabric manual are both acceptable data - works good lasts a long time.
However,
Original T-craft stitches were not as numerous as the current manuals, so I suppose it all depends on how original you want to be.

[Ron Greene]

Re: Vertical fin rib stitch

Don't know if this applies, I have attached a page out of the L-2 repair manual that shows the rib stitching for the vertical fin, rudder, elevator, horizontal stabilizer and ailerons. The tail feathers on the L-2 (D model) are the same as the BC-12D so may be the same for stitching. The aileron is also the same size with a few minor differences.

[Robert Lees]

Re: Vertical fin rib stitch

Well I put eight stitches on the top horizontal rib only (46 BC12D) because that's what was there before:

[asq]

Re: Vertical fin rib stitch

Thanx to all. I think I will stitch the top rib and then put a couple of stitches on the bottom rib sort of like Piper did. The stitches are not pulled down tight ,but just enough to take a bit of tension on the fabric and keep it from "fluffing" or vibrating. I appreciate all the input. The L2 manual probably answers a lot of questions on our birds. Are these manuals available? I have a Univair Service manual and it isn't worth much. Larry Huntley

[Robert Lees]

Re: Vertical fin rib stitch

I would suggest that you just stitch the top rib...and certainly not the lower horizontal rib (it pulls the fabric in too tight, and looks awful when painted). This despite Ron's definitive source, so it's just my opinion.

I now have ~500 flying hours on my project, and there is no suggestion of the fin fabric wafting around.

[mulwyk]

Re: Vertical fin rib stitch

I think there's something in 43.13 about using double the stitch spacing on the tail feathers. In other words, if 2 1/2" is ok on the wings, then 5" is good on the tail. Or something like that. Check it out, I could be wrong, the old memory isn't exactly running on all cylinders these days.

And maybe not a good idea to stitch the second rib. The fabric makes a nice smooth curve down to the fuselage in that area.

[Robert Lees]

Re: Vertical fin rib stitch

I think there's something in 43.13 about using double the stitch spacing on the tail feathers. In other words, if 2 1/2" is ok on the wings, then 5" is good on the tail. Or something like that. Check it out, I could be wrong, the old memory isn't exactly running on all cylinders these days.

And maybe not a good idea to stitch the second rib. The fabric makes a nice smooth curve down to the fuselage in that area.

It's the other way around (AC43.13.1b refers to spacing in the propwash area being smaller than that away from the propwash area).

However, the original design data supercedes AC43.13.1b. For example, my Taylorcraft wing wire spacing (in the wings) is the same both in and out of the propwash area, so this supercedes anything that AC43.13.1b states.

However, apart from Ron's L2 data (referred to above), I don't know what the design data is for the B models. What we want is someone with access to the B model tailfeather stitching drawings.

[asq]

Re: Vertical fin rib stitch

Thanx Robert,
The lower stitches would just make contact with the fabric, maybe 1/4" more. But I think I will skip that anyway and just go with the stitched top rib as your suggestion.
It would be wonderful to have drawings available for these birds. This is the first time I worked on a Tcraft and I have had a tough time with some parts of it. If not for this group I would have really been in trouble. Russ Hardy lives 100 or so mi west and he has been a great help also.
I have covered Pipers, Aeroncas and a Funk and all of these birds had info and drawings available for most everything I needed. This one has been a lot of surprises. Thanx again to everyone for being so helpful. Good group. Larry Huntley

I would suggest that you just stitch the top rib...and certainly not the lower horizontal rib (it pulls the fabric in too tight, and looks awful when painted). This despite Ron's definitive source, so it's just my opinion.

I now have ~500 flying hours on my project, and there is no suggestion of the fin fabric wafting around.

[crispy critter]

Re: Vertical fin rib stitch

I agree with robert on this one. I would not stitch the bottom rib,just the top. With the dacron fabric shrunk to specs you will never be able to get it fast enough to ever have any fabric flop or flutter problems in this area,in fact you would probably have to get fast enough that the wings would come off before the fabric on the lower part of the vertical would ever wiggle,lol. I spaced the stitches on my top rib at 2 1/2 inches. I measured one inch forward of the tail brace wire attach hole then spaced them at 2 1/2 inches from there forward. Once I had the spacing marked I then stitched from front to back using the hiden knot. I'll try to post pics at another time.

[3Dreaming]

Re: Vertical fin rib stitch

straight from AC43.13 1B

b. When the original lace spacing on the
empennage surfaces and fuselage, is not
known, a maximum spacing of two times the
spacing shown in figure 2-12 for the slipstream
area (prop wash) on the wings may be used.

Spacing is 2 1/2" in the slip stream, so 5" on the tail if the manufacture data is not available.