Thorp Air Command - T18.net

Can I ask a dumb question? On the "C," do the aileron interconnects in the wing gaps separate "automatically" or does one actually have to disconnect some linkages?

It kinda looked to me like the bellranks magically come apart when you pull the wings outboard, but I couldn't tell for sure. I pulled the pins and bolts today to fold the wings and I was unable to actually separate the outer panels. Mind you, I also didn't put all of my back into it for fear of breaking something. Plus I was by myself, so I didn't want to get into trouble.

So.. I'm looking for guidance from those who have been down this road before me.

When I get it right, I'll try to remember to post a sequence of pictures.

dw

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In theory, theory and practice are the same. In practice, they are not.

The inner wing and outer wing each have an aileron control bell crank and when outer wing is pressed into position to insert the 2 primary retaining pins, the bell cranks (or rocker arms) mate. If you have removed the pins and the connecting bolt or pin at the trailing edge of the mated sections, then the outer wing should be easily separated by a slight pull and maybe a little wiggle necessary. I can only imagine that either the mating aileron rocker arms were not correctly made and got locked in a tangle or the assembly with primary retaining pins has corroded or for some reason is sticking improperly. I would assume that if the latter happened, it would be released by rocking the wing tip. I had problems getting the aileron bell cranks to mate correctly. Correct mating requires that the center holes are vertically aligned. A single long bolt through both holes assures the alignment, then if the two wing sections do not seat correctly to the bell cranks then spacers may need to be riveted in the proper place to form a solid fitting mating. Then, of course, with the wings separated, each bell crank is secured by its bolt. I am adding a pic of the inner wing showing the bellcrank hanging loose before positioning and attachment with the center bolt.

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hal

Dick,
After you pull the pins you have to lift up to get the outer wing off it's cam. I recommend you have something about the height of the main spar to set outer wing on (IE 0 deg. dihedral). Once you have it off the cam pull out a bit (maybe 6 inches) and set the wing down on whatever you have come up with to support it and disconnect anything you may have in there (nav light VOR antenna etc.). I doubt it's somehow "tangled". It's just two bellcranks that mate up to each other, a pin (or bolt), 2 pins at the main spar and the rear spar tube/universal.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

Yes they do separate "automatically" when you fold the wing. If you have all the pins out (3 of them), are you able to lift up on the wing at the wing tip ? Does the wing move at the main attach fittings when you lift it up ? Does it move at all when you lift it up ? You should be able to lift up at the tip and pull out the wing from the main attach fittings. It may be possible that the rear "tube" that fits into the inner wing (tube that is attached to the universal joint) was fitted to a very close tolerance. I helped a gent at CNO remove his folding wings for inspection and they were very tight ! The problem was the rear tube and it being fitted to a very close tolerance. It took wiggling, shaking, pulling, spray lube, cussing and finally they came out. I don't believe the tubes need to be fitted to that close a tolerance (in fact according to the S-18 catalog the A/C can be flown with the rear spar pip pin missing), so the tube is more of a support item when the wings are folded. My tubes are a bit snug, but not tight.

The wings may also be hung up on the "catch" at the main fittings. If it was an early build, it may have it. Later S-18's did not have it on the plans. Mine does not. When was the last time the wings were removed or folded ? I'am guessing it has been a while.

First thing I would see is if the wing moves at the joint when you lift it up. Second area would be the rear "tube." Not an operation you can really do yourself. One person to move the wing, another to observe all the monkey motion at the wing joint.

RB

Yep...they mate like two mad dogs ! [:p] Apply a little lube to the steel wing fittings and let it soak in between the fittings. If they haven't been apart in years could be a little rust, grud, corrosion lurking in there. You can actually rock the wing left a right a little ( I said a little ) bit to help move/loosen the "tube" and apply the lube...if that's part of the problem. Good luck and may the Force be with you ! [}:)]

I just noticed you said you could see the aileron bellcranks ? If it was built to plans you can not see them with the wings mated (skin overlap). Sounds like you have a full length gap cover rather than the partial leading edge gap cover.

RB

The tubes fit into the inner wing and there are aluminum fittings inside to accept them. They may have a bit of corrosion between the two causing them to seize ? Some moly lube upon reassembly may cure the problem. I forgot about the Kiss system and just remove the bolt at the U-joint since you have the full length gap cover.

RB

Just curious...was there a "pip pin" (quick release type pin) at the rear spar (where the two wings mate) or was a bolt used ?

RB

Probably another reason for the full length gap cover (and using a bolt) as the plans called for "pip pins", I could not find. I found some surplus pins very, very close (length wise) to what was called for. The quick release pins are not considered to be a component to make the wing structural, according to the parts catalog and the A/C can be flown if one falls out.

What are other S-18 folks using ? Quick release pins or bolts ?

RB

Bolts, which, if not removed (I could not find the wing folding instructions), make it extremely difficult to fold the wings!!!!!
Cheers
Graham
N444DD
PS I finally found a set of instructions and they are now incorporated in what we T-18 guys call our Ops Manual, my former Navy and Marine colleagues call NATOPS (Naval Air Training and Operating Procedures Standardization) and the Air Force guys call the "How do I Work This?" manual. I recognize that having unsuccessfully tried to fold a wing with that rear pin still installed, that there is a possibility that some misguided USAF guy may question my credibility.

** admin posted for Grahm Kerr ***

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Forum Administrator

There is no such thing as a misguided USAF guy, we do however use a tad bit more runway, at times,

Lance38dt

"A tad bit more runway." [:o)] I don't think I ever landing on an Air Force runway that was less than 10,000ft long ! Wait a minute...I take that back, I did land on one of the shuttle runways at EDW that was about 30,000 ft long and yes I did make the first turn off ! [;)]

RB

It always gave me a warm and fuzzy felling inside while lining up on final and seeing all that runway.

I guess bashing long runways is now in vogue. Last Saturday i got a comment from. SWA frequent flyer. She said the discussion in the back always centers around AF pilots greasing them on and Navy guys trying to dent the concrete. I'll take the long runways and a reuseable aircraft.

** admin posted for Cubes ***

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Forum Administrator

My folding wing uses a 1/4" bolt at the rear spar, no quick "pip" pins for me, it also has the full length gap covers. Note: this was the first folding wing to fly on a Thorp and it has the original airfoil.

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Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Dick - those wings have not been off since early turn of the century - I kept wanting to do what you are doing, but my mangina kept protesting - so goodonya - once you finished doing everything, you should apply for and get the plane certified.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)