Nose Rib Spacing

[Scott]

Hi all
Looking for a little advice on nose rib installation.

I don't think it's critical but there seems to be little consistency in the location of the nose ribs. The most repeated dimension is approximately half way between the full rib flange centrelines, so I'm going with that. But at the strut fittings the ribs need to be offset to accommodate the strut fitting.

From my old leading edges and spars I get a location that is further inboard than the drawing shows and that it needs to be.

I don’t see the reason for moving so far inboard but if that's where the factory put it (second pic) I'll go with that. Just looking for confirmation.

[Robert Lees]

Re: Nose Rib Spacing

Scott

I see you still got the old leading edges. That will give you a good indication. I think you're right: it's not critical. I bet in the factory they threw them together (I understand/believe at peak build they were churning them out at 30 aircraft a day for a short time). Have you got the factory drawing?

I see from those photos you have incorporated the Gilberti/Harer/Bown STC, well done.

Rob

[Scott]

Re: Nose Rib Spacing

I have a drawing with Taylorcraft Aviation Corp. printed at the bottom right corner but there is no proper title block. Experience with this drawing suggests it is a partially updated version of an earlier wing. It shows detail of stamped ribs and BC12D specifics but several things, like trailing edge false ribs shown, don't exist in the stamped rib wing.

The drawing shows the subject rib outboard of the strut attach bolt location, which is only really possible if the rib lower flange is trimmed.

I was a little suspicious as there was a repair in this area, but then I remembered my old spars are original stamped factory parts, and there are no other nail holes.

So I think I've now talked myself into using the old locations (give or take)!

Thanks!

[Hank Jarrett]

Re: Nose Rib Spacing

The wing drawings for the pre and post war wings specify the spacing of the nose ribs. They ARE NOT random! On a few you can see a reason for moving them slightly away from centered, but some others I still don't know why. Just do it to the drawings to be sure. An anal retentive inspector could hit you with building your wings with deviations from the factory specs. It isn't likely you will get caught, but he risk isn't worth it.

Hank

[Scott]

Re: Nose Rib Spacing

Where on the drawing do you see those specs Hank?
Thanks

[Hank Jarrett]

Re: Nose Rib Spacing

The wing drawings I have show spacing to the middle of each rib (nose full and TE).

Hank

[Scott]

Re: Nose Rib Spacing

Yes my drawing appears to show that, though there are no specific notes or dimensions. I suspect we have the same drawing ie a large version of the one that's in the various manuals.

Check the strut attach location. It shows the nose rib in the centre of that Bay. That's what caused me pause as the actual location (as taken from my factory spars) is about 5.25" outboard of the full rib to its inboard (shown in the second photo).
S

[Mark Bowden]

Re: Nose Rib Spacing

Hi Scott,

Great to see such a beautiful new Tcraft wing!

I have one of those “manual” drawings that is in pretty decent shape but missing some parts.

Attached is a photo of the section. From your old spar it looks like the old location is too far inboard per the drawing. Also you typically do not want to put loads into the end of a doubler, you are trying to get the load lower and transferred into the spar by the end of the doubler, thus tapered shapes, reduced thickness, smaller rivets, etc…

The drawing shows you have it mocked up about right but maybe too far inboard yet. That old line on the old spar doubler looks about right, not where the rib nails were.

From the top view on the drawing is shows the rib centered in that bay and just outboard of the inboard edge of the bottom of the strut attach fitting.

If you want me to send you a scan of what I have shoot me a PM with an email address.

Mark

[Scott]

Re: Nose Rib Spacing

Sshhh....! we're not allowed to used the term "new" (at least in Canada).

Thanks Mark, I appreciate your research. That is the same drawing I have, and lead me to consider the good points you've raised. (Any idea what the hidden detail is in the leading edge area in the same location?)

In order to put the rib in that location however, it is necessary to trim off the lower flange and remove the tab that wraps around the spar. I did ensure the rib ended up on the full span of the doubler and in the end choose to believe the locations indicated on my old spars, which came from Alliance. It seems unlikely that the spars on both wings were replaced with factory spars and both left and right wings were assembled incorrectly. More probable is the drawing was never updated to reflect all the changes associated with the implementation of stamped ribs (or the updated drawings are long gone). Perhaps the plan was to allow for installation of a landing light or maybe, as Rob suggested, in the production environment it was hastily relocated just to make for easier assembly. I also found photos of other stamped rib wings that seem to confirm the offset.

Anyway it's going back as it was and with 020" leading edges I'm sure it will be fine.

thanks again for your help
S

[Mark Bowden]

Re: Nose Rib Spacing

I don't have an idea what the phantom part might be. It is drawn at two angles as well, not parallel to the spar in any plane. If you were going to box a rib bay structurally you would do it one more out at the spar/strut attach bay.

Most lights are at the ~75% span, outboard. It is a puzzle as the draftsmen of the ink/bluelines era didn't make many, if any mistakes. I have seen (once) a photo of a Tcraft with what looked like a LE slot in that bay but it is too fuzzy to tell what it is.

Can't wait to see the next progress update on the blog.

[Robert Lees]

Re: Nose Rib Spacing

The hidden item is a brace, possibly where the two section of leading edge meet. I found the same on my 1946 Taylorcraft. It is an "L" section, and I don't recall that it was riveted or otherwise tethered at either end or indeed attached other than by pressure between the leading edge and ribs. See attached photo.

I don't quite understand its purpose, but it may be to reinforce the leading edge joint during expansion/contraction due to temperature changes? Or the rib spacing was a little too wide to not require a small reinforcement against airflow pressure?

Rob

[Hank Jarrett]

Re: Nose Rib Spacing

My wings all had that little angle too. I assumed it was probably needed because of the strut attach tube behind it. It would be an easy fix if they got a little "oil canning" in the LE skin. Just guessing here.

Hank

[Scott]

Re: Nose Rib Spacing

Ah haa!
Excellent thank you.

The reason it's not parallel to the spars is because the nose ribs have 5 tabs and the full ribs have 4