Spars!! Everyone jump in on this one!

[Don Eide]

Re: Spars!! Everyone jump in on this one!

Bill,

The 1/32 birch plywood (Front Spar Reinforcing) is shown twice on the plans. On Dwg. No. G-108 "Spar Front" it is shown on the front face of the spar as 3 lines outlining the 5 holes.
Second, it is shown on the top view of the spar (just above the front view). It shows the 3/4 inch spar, the two 1/8 inch plywood doublers and the two 1/32 inch birch plywood doublers.

Here is something else to fret about.
There are some mistakes in the plans.

1. Dwg. No. G-133 "Fuel System Installation" The large top view shows a nipple between each wing tank and the elbow. It's not shown or listed in the "Schematic Layout-Fuel System" or in the "Bill of Material-Fuel System"
But it is required in my Taylorcraft. It's about 2 1/2 inches long.

2. The fuel valve is shown as a Imperial #108-HD-3/8. A 108 is a 3 port valve.
What you need is a 103HD 04x04

Here's another mistake.
Dwg. No. G-155 "Headliner-Baggage Compartment Installation".
The plans show Fabric (Doped) around the steel tube that is the back of the seat. Can't be done. The seat sling attaches to this tube.

I have found others but they are very very minor.

Just my observation.

Don

[VictorBravo]

Re: Spars!! Everyone jump in on this one!

I agree that there are several mistakes or mis-measurements on the plans.

My STC spar drawing G-108 shows the box around the holes. Plainly visible, but there are no call-outs or nomenclature associated with those lines... why?

The top view in the same drawing does not exactly match either my airplane or your description. There appears to be a main spar, then only one 1/8" thick doubler at the lower (forward) part of the spar, but no 1/8" thick doubler on the rear of the spar. Then there are indeed two sets of narrow lines that certainly could be your 1/32" doubler. I'll gladly give you that.

So if I take this G-108 drawing as the gospel, there's only one 1/8" plywood doubler on the front of the 3/4" spruce spar, then the two 1/32" doublers, which would yield a total spar thickness of 15/16".

When you put the 1 and 1/16" wide strut fitting in place over this 15/16" spar, it will be even more loose than the 1/16" gap we have been discussing. Worse yet it would be structurally weak... missing a thick birch plywood doubler.

So now we have two or three possible spar configurations. And yet the only clear wording on the STC instructs me to make no changes to what I already have. How come?

It's been weeks since I first raised this issue. In this discussion group, I suspect there are trained engineers, IA's, people who have done this conversion both "by the book" and "whatever fit correctly", and people who have had to figure out the answers to this exact question. I HAVE to believe that there are people who know the proper spar dimensions for the different Taylorcrafts, and I HAVE to believe that there are people who know whether there was an unofficial variation in the thicknesses of the spars actually put into the production airplanes.

But none of those people have been willing to come up with a definitive answer and share it with other Taylorcraft owners.

That fact is more disturbing to me than the mystery itself. I would have bet my life that three or four qualified people would have jumped right in the next day and resolved this to everyone's understanding. I'm really disappointed, and I've even asked for more input from additional members of this group with no success.

I think I am gonna put my airplane back together now, and just make everything fit, tell my IA that the STC says "no changes", and go fly. If the spar breaks because it can't handle the load, then so be it. Perhaps then the club members will take it more seriously and make an effort to figure out this mystery. Perhaps they will not address it even then.

But I think I'm done looking for answers in this forum. Anyone I pissed off by having the nerve to ask for assistance here has my apologies. Anyone who wants to communicate with me about this can do so privately.

Blue skies to you all,

Bill Berle

[stormman]

Re: Spars!! Everyone jump in on this one!

So sorry Bill but my stc is still packed in the moving van after my move to Arkansas and im still rebuilding the house. 15 hours days are hell , but one has to make hat when the sun shines. Sleep comes later.Hell i havn't even seen my T since i bent the rudder taking it off the trailer, should have flown it to Arkansas.
As for the other guys , its play and work time right now and everyones busy. Im sure this thread would get more response in the dead of winter.
Soooo don't get pissed off, do the Foxworthy thing and "get er gone" or hang in there. Rome wsn't built in a day

[Rich. Anderson]

Re: Spars!! Everyone jump in on this one!

I will look at my spars and see what the doublers are. I beleive both sides have 1/8 birch only. Thought you would receive info from others. Will get back to you this weekend.

I am in need of a schematic for the hinge bolt through the aileron casting for the cables and push pull tube. What washers go where?

Rich Anderson

[Rich. Anderson]

Re: Spars!! Everyone jump in on this one!

I looked at the spars on my 46 - BC12 D. There are two 1/8 inch doublers of three ply birch. Thats it. The rear spar also has two doublers that are 1/16 birch plywood but due to curvature of the doubler edge it was hard to measure. Maybe adding a 1/16 inch to the doubler would help with increasing the allowable loading but would also take the ship out of the Sport Aircraft category if that is a concern. Rich Anderson

Anyone have a schematic for the aileron horn hinge pin and washers??

[VictorBravo]

Re: Spars!! Everyone jump in on this one!

Thanks Rich

I'm glad to find info on the spar thickness and number of plywood doublers from anyone and everyone.

Bill

[Don Eide]

Re: Spars!! Everyone jump in on this one!

Last weekend I seen a T-craft on floats with an C-85 in the nose.
I measured his wing spar fittings.
They were exactly the same as mine and the Harer STC.
Main spar = 1 1/16
Rear spar = 3/4

Just more info.

Don

[VictorBravo]

Re: Spars!! Everyone jump in on this one!

Don, did this airplane have the 1/32" doublers in it, or were his spruce spars 13/16" thick?

Bill

[Don Eide]

Re: Spars!! Everyone jump in on this one!

Bill,

I've never seen spars that are 13/16 except those with about ten coats of varnish put on in the last 59 or 60 years. I assume this T-craft had the 1/32 Birch ply doublers since Drawing 2569 has been out since 1947. I couldn't see the spar because there was fabric tucked between the fittings and I wasn't about to remove an inspection cover off of someone elses airplane.

Don

[VictorBravo]

Re: Spars!! Everyone jump in on this one!

I'd be interested to find out whether this airplane has the 1/32" pieces. If you get a chance to look inside that wing, let me know.

So far, more than half of the people who have measured their spars for me do not have these extra pieces. Rob's plane in England does not have them, but his spars measure 1 and 1/16 WITHOUT the extra plywood... so I'll have to ASSUME that his spruce spars are 13/16".

Even though that 2569 drawing may have existed since 1947, there are factory Model 19's built AFTER 1947 that seem to have been certified up to 1500 pounds gross weight without them. Nobody has addressed that issue... why?

I posed a couple of fairly straightforward questions for your IA (and the source of this drawing) to answer, for ALL of our benefit. Still waiting.

Also, you're the only one who seems to know about this drawing:

I've never seen it,
Harer knows nothing about it,
Forrest knows nothing about it,
Rob knows nothing about it,
My IA and fellow T-craft owner has never seen it,
Nobody on this group except you has ever seen it,
Drawing 2569 is not included any STC that I know of,
Nobody with an upgraded airplane under Gilberti / Harer has come forward and mentioned anything about these pieces (other than you and I),

etc. etc. etc.

And yet I will agree that the outline of this piece is probably the three lines around the spar fitting bolts on the drawing.

I looked through a set of T-craft blueprints, and saw several mentions of thin plywood shims and spacers, to be used when necessary to make other parts fit. In the absence of any other credible explanation ... I'll say that they're shims. I challenge anyone to prove me wrong using anything official from the factory, the FAA, or any proper structural engineering calculation.

[Don Eide]

Re: Spars!! Everyone jump in on this one!

Bill,

You stated the following about Drawing 2569.

1. I've never seen it.
2. Harer knows nothing about it.
3. Forrest knows nothing about it.
4. Rob knows nothing about it.
5. My IA and fellow T-craft owner has never seen it.
6. Nobody on this group exept you (me) has ever seen it.
7. Drawing 2569 is not included any STC that I know of.
8. Nobody with an upgraded airplane under Gilberti/Harer has come forward.

1. When it comes to computers, I'm Fred Flintstone. I don't have the
equipment or knowhow to put pictures on the computer, but if you
would send me your snail mail address or fax number I can make a copy of
Drawing 2569 and send it to you, any of you.
2. I'm not surprized. He bought the STC from Giberti. Giberti did all the work.
3. I am surprized that Forrest doesn't know about this.
4., 5. & 6. As I have found out, nobody knows everything.
7. That's possible. It's a T-craft drawing.
8. Can't answer that one because I don't know why.

I'll try to get ahold of my IA this week and ask him where he got this drawing.
He probably got it with some of the Taylorcraft drawings he bought a few years ago and ended up selling it all to Wag Aero. Wag Aero should have it, but don't hold your breath.

Don

[VictorBravo]

Re: Spars!! Everyone jump in on this one!

OK, Don, you can send it to me if you like. From your previous descriptions I think I know what it looks like, but I am glad to have it. My address is:

Bill Berle 10125 DeSoto #7 Chatsworth, CA 91311

Although I'm a little better than Fred Flintstone on the computer, I'm not quite as good as Barney Rubble. I can scan this drawing and e-mail it to the list administrator, and he can make it available to everyone who wants it.

Based on your posts, I fully believe that drawing 2569 exists. Based on the strange lines on Gilberti drawing G-108, I also fully believe that those lines are the outline of the 2569 doubler. What I have trouble with is the notion that nobody ever wrote down what it accomplished, or what functions it does or doesn't do.

When you speak to your IA, try to get him to explain the precise function of the thin plywood pieces. I don't care where they originally came from or who designed them. I care about knowing what the function of those pieces is... the consensus is that they are shims to allow the use of a later, wider, factory strut fitting.

As far as who knows what and why they are not saying anything, I've already addressed this in another post. I'm heartbroken about that, as is probably obvious when reading all the previous posts I made.

How's your wing rebuild coming? I hope you got the doublers and compression struts and such all went together properly. It may take some extra time to do the trammeling because of the compression strut length, as we previously discussed. But once it is done I'm sure it will be fine. I'm almost done with mine. I found that the previous restorer forgot to put in the fuel tank straps around the spars. Anyone who is working inside the wing, please make sure that the fuel tank hold down straps are there. My wing tank was held in place with only the tension of the internal brace wires!

Bill