Rib Count

[1938BF50]

Hmm....

I stripped the LH wing last night and stepped back to look at the two stripped wings stacked against each other. What the H_ _ _ ! The RH wing has 13 ribs and the LH 15. I noticed the 15-rib wing also has laminated spars. Is this a wing off a later craft? It still has the built-up aluminum ribs as does the RH. Excepting the issue descrbed below, and short of the dissapointment of not having originality or symmetry, are there any otherissues with proceeding to recover this wing?

Perhaps something even more disconcerting was the fact that this wing has the plywood spar doublers at the wing root attach fitting "inlayed" into the front spar. Inlayed may not be the proper term here. Picture the spar thickness narrowed via a planer on both front and back surfaces for about a half inch past the doubler length...then blending into it's full thickness on a nice radius. Makes me wonder if this has any relevance on Bill Berle's issues on the overall width variations that prompted the lengthy Harer STC post (spar/doubler) a while back.

What do I have in this wing?

[VictorBravo]

Re: Rib Count

Seems like you have one early pre-war wing and one late pre-war wing???

The doublers at the root are normal per what you mentioned. The spars are milled down so that after the root doublers are put on the ribs can slide over the spar.

I don't know if, or which, wing spars were laminated. My GUESS is that they're both fine, mix and match, as long as the laminated one is done correctly.

You should be far more concerned with the condition, cracks, loose glue joints, oblonged holes, etc.

While you have it apart, my advice is to put in the larger root bushings and larger spar fittings. If you ever want to put in a larger engine the hard work will already be done.

[Ragwing nut]

Re: Rib Count

If the 15 rib wing has the same type leading edge as your 13 rib wing, it is from a 41 Deluxe. The Deluxe has a higher gross weight than theother prewar models at 1200# which is the same as postwar models. If it has the later style leading edge which the top side goes all the way back to the spar, the it is a '45 model wing.

Mike

[Ray36048]

Re: Rib Count

I recently bought a pair of NOS main spars, still in the 1946 box with dated shipping papers from Taylorcraft in Ohio. Both of these spars are laminated, one was made from more pieces than the other.

[VictorBravo]

Re: Rib Count

Could you take a quick look at the spars, in the area of the strut attach point, and tell me what the exact thickness is at that point (main spar plus any/all plywood doublers)? Mine measures one inch exactly, a 3/4 inch spar plus two 1/8 inch doublers. Some airplanes reportedly had a slightly greater thickness due to the addition of two very thin plywood doublers on top of the 1/8" doublers.

[Forrest Barber]

Re: Rib Count

Laminated are later 1946, Tolerton Lumber Co. in Alliance did wood work for Taylorcraft & other companies. The ahd a special glueing & drying process, Bob Tolerton is still around and may be at the fly-in this year. Your mix & match wings are okay if you have a gross wt below 1200....did you check for a ser# palte nailed to the rear of rear spars by the aileron bellcrank.?

[1938BF50]

Re: Rib Count

Forrest,

Yes, there is a small SN# plate where you say. Should this # correlate to the planes SN#? (In my case it will not). I will check the # and report later.

Look forward to meeting you at the fly-in!

[1938BF50]

Re: Rib Count

Did you check for a ser# palte nailed to the rear of rear spars by the aileron bellcrank.?

Forrest,

The plate is on the newer wing only. It reads #6599 followed by a circle including the letters TAC over the number 7.

[1938BF50]

Re: Rib Count

Could you take a quick look at the spars, in the area of the strut attach point, and tell me what the exact thickness is at that point (main spar plus any/all plywood doublers)? Mine measures one inch exactly, a 3/4 inch spar plus two 1/8 inch doublers. Some airplanes reportedly had a slightly greater thickness due to the addition of two very thin plywood doublers on top of the 1/8" doublers.

Bill,

Here goes.....I rounded up or down a few thousandths to get even numbers. No "double doublers" or x-tra plys anywhere. I will call the laminated wing spars the "newer wing" and the non-lam the old wing. Starting to think the "newer wing" is just the old wing with newer spars inserted.

In the area of the strut attach point the old wing rear spar measures .750" over a .650" spar(.050 ply doublers), the front spar measures .930 over a .760" spar which yields .085 ply doublers. The "newer laminated wing measures .800" over a .650" spar(.075 ply doublers) and 1.054" over a .770" spar(.142 ply doublers) for the front strut attach area.

The dims at the butt fittings are .740 (no doublers) on front spar of the old wing and .640"(no doublers) at the butt of the rear spar. The newer laminated spar is .786" over .093 ply (milled in) for the front and .650" over .093 ply(milled in) for the rear spar. Hope this all helps. Let me know if you need any dims clarified.

[VictorBravo]

Re: Rib Count

Bill,
In the area of the strut attach point the old wing rear spar measures .750" over a .650" spar(.050 ply doublers), the front spar measures .930 over a
.760" spar which yields .085 ply doublers.

Thanks for taking the measurements. they raise some interesting but completely esoteric points:

So the original 1938 B model front wing spars are 3/4" nominal thickness (plus 10 thousandths variation), but only have doublers that are less thaan 3/32" thick? And the entire front spar assembly at the strut attach is 15/16"?

It appears that you will have a little bit extra spar thickness on your new replacements, which is probably just fine. The information I collected indicates that all B model airplanes were supposed to have 3/4" spars with 1/8" doublers at the strut fitting, yielding a total thickness of one inch.

Perhaps your original spars, and your new spars, are both within the acceptable variation, but I wonder of the same ribs and wing parts are supposed to fit either spar!

IF you decide to do the spar fitting portions of the Harer upgrade on the strut fitting and the root fitting at this time, please consider my humble additional advice.

Bolt together the strut fittings, new spar, and the upper end of the wing strut all together on the bench, all properly aligned and snugged up. Then TACK weld a new steel reinforcement plate to the strut fitting assembly, taking care to use heat sinks and wet rags to prevent damage to the spar wood.

Then, disassemble the newly joined fitting and make sure it slides on and off the spar... not loose but not tight enough to cause hard interference. Make up a block of wood EXACTLY the same thickness as your new spar (1.054 or whatever), and very lightly clamp it in place. Leave the strut bolted in to the fitting too.

Then, finally, you can finish-weld the edges of the fitting. This extra bit of effort will give you a perfect fit when it all goes back together. Trust me, it's worth the extra little tiny bit of effort... I wish I'd have known this when I did it.

You will likely have to trim one or two of the ribs to allow the new fitting to slide into place, or slide the fitting in before certain ribs are installed.

When you get your STC paperwork from Harer, and you see the part where it says to weld the strut fittings together at a specific distance apart, a distance that does not match your spars or the majority of other Taylorcraft spars ever built, take a look at the fittings you already have welded, smile, and say "yeah, that looks just about right". Raise your glass and say it once again for me

Ironically, the dimension you measured on your new laminated spar is closer to the dimension on Harer's drawing than most, but if your laminated spars had the extra thin plywood doublers installed, your spars would be too big to fit the strut fitting Harer proposes.

It would be an interesting bit of information to ask the Taylorcraft factory if they have the wing strut fitting for the 85/100 horse airplane available for sale... and most importantly to ask them the exact distance between the flanges (spar thickness).

[1938BF50]

Re: Rib Count

Bill,

Glad to be of help!

I have no intentions of doing any mods other than taking it back to as stock original as possible in a future restoration. Interesting that all my paperwork shows a 1300# gross. Never any mention of the spar/wing change, although I am missing the original log thru 1943. Log #2 picks up at somewhere around 1000 hrs.

[Larry Lyons]

Re: Rib Count

Bill,

Glad to be of help!

Never any mention of the spar/wing change, although I am missing the original log thru 1943. Log #2 picks up at somewhere around 1000 hrs.

As an aside my "41" logs show she was ground looped hard enough to require wing repair or replacement 3 times by 1946. If I remember right the first two were in the first 2 or 3 years! LOL.
Larry

[M Jones]

Re: Rib Count

Hmm....

I stripped the LH wing last night and stepped back to look at the two stripped wings stacked against each other. What the H_ _ _ ! The RH wing has 13 ribs and the LH 15.

Mike,

Just noticed your post here. maybe we should put our two birds together. I have a RH 15 rib, and a LH 13 rib wing... (1150 gross wt.)

[Forrest Barber]

Re: Rib Count

lots of folks have traded wings around before.... do it!