Wing Fold Problem

[ksatter26]

Not TOO bad a problem, but I hope Chris has a fix ...

With the port wing supported at the tip I ONCE AGAIN checked the sweep, dihedral, and washout measurements. All good. I then drilled out the AN5 wing spar root mounting hoes at the fuselage. I secured the aft fitting with the AN5 bolt, washers, and nut. I assured that the fwd mounting AN5 pin easily slipped into position. (I did note that the lower end of the pin just clears the bottom of the spar fitting with just enough space to insert the cotter clip)

I initially voiced some concerns that it might be difficult to pivot the wing backwards on the aft mount possibly due to the spar root clearing the fwd mount. This proved to be a non issue. the spar slipped easily and smoothly off. All good to this point. HOWEVER, when the wing nears the folded position in relation to the tail-feathers, the upright flaperon bumps into my 3/16" rod h-stab flying wires BEFORE achieving the fully folded position (as in Chris' pictures.

I should note that the wing "settled" a fair amount when I removed the tip supports AFTER pinning the spars. Hopefully Chris will point me in the right direction with a fix/work-around. I'm thinking it might just be extending the rod-end bearing shaft a few turns at the lower (fuselage) lift strut mount.

Folding the wing does free up a lot of shop space.

[LA F2 Flyer]

Hi Kurt. If the wing DID actually settle a fair amount after removing the supports, it sounds like you will need to readjust the rod end bearings and remeasure until you are where you want (or need) to be. The wings folds straight back, and there shouldn't be any interference of the flying wires at the tail.

Honestly, it sounds like an easy enough fix, but my two most pertinent questions would be WHY did the wing settle, and how MUCH did it settle?

What were you using to support the wing when you set the rod end bearings for the strut? And is there any play in the bearing mounting points? Perhaps an over-diameter mounting hole, or ???

On the up side, it sounds like the root mounts are working fine and not binding, so you are halfway there. As I recall, I also had to do a little bit of adjusting on one wing because I supported it with a tie down, which is rather elastic by design. On the mounting of the other wing I rested it on a ladder, which gave me a more "locked in" position when the hardware was added.

Let us know what you find. It also might help to see some close-up pictures of the spar root mounting points (to the fuselage) as well as the upper strut mounting points on the wing.

[ksatter26]

My supports are pretty solid. I use 2 roller shop stands, one at the fwd spar and one at the rear. The shop stands are rather short so I place them on a 29" tall worktable (old IKEA). I use the laser rule to measure from the bottom of each spar to the floor (with the tail supported in the level position. At the root, the fwd height from the floor is 65.25" . At the tip I place a 5/8" shim between the spar and the roller stand and get a measurement of 38.75" to the table top ... adding in the 29" from the table top to the floor, I get the required 67.75" ... giving the 2.5" dihedral. At the rear spar I clamp the spar down to the rear shop stand 5/8" lower than the front spar to account for the washout. The spar lift strut mounts are secured at the proper distance with epoxy and 34 rivets each.

I adjust the rod end bearings in the strut mounts to a tight fit and secure the location with the jam-nut. The wing still "settles" (as Chris describes it in the manual). I just don't see where the movement might come from. BTW, the jury struts are in place.

[LA F2 Flyer]

Your wing stands look plenty robust, so there doesn't seem to be an issue there that I can see. And I don't think the jury struts would make much of a difference in the static wing support; their function becomes more apparent when in flight, correct? (I'm curious, do they tend to be more for flutter than for flex?) A moot point, since you mentioned that they are mounted.

Do you adjust the rod end bearings in the strut mounts with washers, or has the design there changed? (As I recall, I had to add five washers to take up the gap in between the plates of the rod end bracket.)

Can you post pictures of the through-bolts for the front and rear spar roots, as well as both ends of the struts?

Also, "At the rear spar I clamp the spar down to the rear shop stand 5/8" lower than the front spar to account for the washout." Did you mis-speak here? Unless I am misunderstanding something, I believe the front spar should be LOWER than the rear spar...the wing tip should have less angle of attack than the root, correct?

[ksatter26]

You are correct: the rear spar is 5/8" HIGHER than the fwd spar at the tip. If the leading edge is higher it is WASHIN.

[LA F2 Flyer]

I did not know that there was a term for the other way around - washin. A little more knowledge gained!

[Badland-F5 Pilot]

Kurt, can you give us a picture of the wing folded as far as it'll go from the cabin facing towards the rudder? Something might be there but I can't compare with the current picture.

Todd