Heavy wing

I took all four struts off for sandblasting and paint. I carefully marked each strut, so they went back in the same place. I took the rod end out to put some Par-al-ketone in the struts. When I took the rod ends out I counted the threads, broke loose the jam nut 1/4 turn then put tape around the nut and the shank so I would know how far to screw them back in. I know they are all adjusted to withen 1/2 turn, but the left wing is heavy. It's not bad but it's not like it was before. I need advice before I make it worse.

Tim
2+2

Well, I posted this once before, but apparently you didn't read it...

Mounted mine high on the stick... I constructed a rotatable mount so that I can use it for trim... Left wing heavy, rotate extinguisher to the right side of the stick... A little nose heavy, rotate the extinguisher to the back of the stick... Only problem I've had is getting my hand around the stick and extinguisher, although I can get my finger through the extinguisher little ring thingy and hold on the stick that way......




Just kiddin'...

Cuby, I have a cup holder on my stick that rotates 360deg.. It works with a full can of beer, but when the can is 1/2 empty, heavy left wing. Somebody must know what strut to lenghten or shorten!

Tim said:

Cuby, I have a cup holder on my stick that rotates 360deg.. It works with a full can of beer, but when the can is 1/2 empty, heavy left wing. Somebody must know what strut to lenghten or shorten!

Click to expand...

Keg in the back seat. Tap it prior to reaching 1/2 can. Sorry can't help you on the strut part, my mechanic makes all those adjustments.

Bill

Turn the fork on the rear strut on the left wing in half a turn and see what happens. This will give you a tad of lift on the left side. Believe it or not if I have to remove the struts and remove the forks I use a micrometer to measure the length of the fork along with marking where each strut goes.

Sounds like a legitimate problem to me. Somebody help this guy!
My solution involves one of these new carpenter's levels - possible brand name "Smart Level". They read out in degrees, and are quite accurate. Check carefully the rib closest to the fuselage, then the rib at the outer edge of the aileron. The Cub is adjusted for equal wash-in on each wing. I have found anything from .6 deg to 1.8 deg, and I personally prefer the lesser wash-in which yields an imaginary increase in speed, at the expense of stall characteristics.
I had your problem, but it was due to unmatched ailerons. One of my ailerons had a defect in the trailing edge, causing a trim-tab effect, and leading me to much fooling around with wash-in prior to discovering the aileron problem.
To detect an aileron problem, level flight, hands off, and watch your ailerons. they should be faired even with the wing trailing edge. Both of them!
Also, be aware that fuel imbalance can affect the heavy wing syndrome. That's what the fire extinguisher is for - you can burn one tank dry, trimming with the extinguisher, and then use the extinguisher to put out the fire after you crash with the other tank full.
By the way, the Smart Level eliminates the need to level the aircraft prior to re-rigging. It gets a more accurate aircraft alignment. And it is not supported by the Piper manual, so be careful about the glowing reports in the log book. As I recall, the Piper procedure is to place a 1/8" block at the end of a 30" spirit level, and that works out to around 1.7 degrees.
bob

bob turner said:

Sounds like a legitimate problem to me. Somebody help this guy!

bob

Click to expand...

Tims been on this site long enough to know the guys have to have their fun before they give him the real answer, which I think steve did. Thats what I do too. Although I usually take it off at the wing if I'm alone and then I have to turn it a whole turn. Am I right in remembering that piper actually recommends increasing washout in the light wing though? One of them safety things with washout we argued about way back when.

Heavy Wing

I personally don't like to start the rigging process in the middle. I'd start at the beginning and make sure the dihedral is right. I do this with a length of "Spider Wire" fishing line strung between the wing tip lights and centered on top of the spars. Measure down from the "very tight" line to the fuselage attach fittings and adjust the front lift strut forks in and out until it is exactly 3". Then put the twist in the wings. As I recal it is -.7 degrees when the plane is leveled off of the bottom tube in the door opening or bottom of the sliding window frame. Get this right and then go fly it in calm air. Adjust the rear fork a 1/2 turn at a time until it flys flat at cruise RPM when you let go of the stick. Crash

Crash, I usually do the same but if you think you got one off by half a turn when putting them back together like it seems Tim did, that is a lot of work to go through and it won't show up if it is half a turn off. I've done it.

Rigging

I tried to fight a problem like this with just wing twist thinking the dehidral was right, but the plane never would fly right. I was sure the dihedral was right. Finally got tired of pulling my hair out and checked. It was off, way off. Got it right and everything fell right into place. If I have not personally rigged the plane before and am not sure of the dihedral, I check it first and get it right on the money before going to washout. Just my opinion. Crash

I agree. Picked one up at a salvage yard after an off airport landing. Had to replace an aileron hinge bracket cause the insurance hauler bent it. I never changed the struts and it wouldn't fly wings level. tried adjusting the struts a little and finally got frustrated and did as you said and started from scratch. Sometimes you get lucky. I kept looking at my Dad's Clipper and noticed he had a lot more diehedral than me and I knew mine was right. Finally convinced him to let me rig it. It was way off. He still comments on how much better it flies.

Thanks Steve, Crash, S2D, etc. I'm going to try Steve's way this morning and see what happens. I know it can't be off much. If it's still dosn't fly the way I like, I will get the plane level and start over. I guess I should off sand blasted and painted them on the plane.

Success, I think.
I couldn't afford a smart level so I used the old method, a level and a 1/8 block. I had about 3/4 inch washout in both wings. I took my time and got both sides as close as I could useing the level and 1/8 block. The wind down here today was 10 to 15 on the ground 25 to 30 and gusty in the air so I can't tell for sure, but it's very close. I'll try again tonight if the wind dies down. I did some stalls and slow flight and couldn't see much difference in slow flight. It might have stalled at a slower speed but it was so gusty I'm not sure. Anyway it's much better than it was before.
Thanks again for everybodys input.

Tim
2+2

Tim,

I figure that you have put in a bit more angle of attack on the light wing or a bit less on the heavy one. If so the light one should stall first and you will drop off that way.

Make the front strut on the light wing just a little bit shorter and the one on the heavy wing just a little bit longer. It does not take much.

Gary

Tim,

I figure that you have put in a bit more angle of attack on the light wing or a bit less on the heavy one. If so the light one should stall first and you will drop off that way.

Make the front strut on the light wing just a little bit shorter and the one on the heavy wing just a little bit longer. It does not take much.

Gary

Gary, I flew it again tonight when the wind died down. There was no wind on the ground and only a slight steady breese at 1500ft. Both tanks had about 8 gallons and I was in the left seat. Very slight and I mean VERY slight heavy left wing. If I moved over into the right seat very slight heavy right wing. If I sat in the center it was perfect. It seamed to stall 2 or 3 miles an hour slower also. At 22inches and about 2200rpm It was 2 or 3 miles an hour faster ( about 107mph indicated). It's hard to believe that 1/2 inch of washout could make that much difference. I'm happy! Thanks all

Tim

Tim,

So, the wnd died! I came up Wednesday evening hauling a trailor for the brush cutter. I would not have been wanting to be up.

Some of the weeds are gone and I am back in South Florida. We will be back again about the first week of January. Like too see you then and your lower stalling newly painted 2plus.

by-the-way, I have played with a turn here and there and been glad to get it back to somewhat near what I am used too. Air does not forget.

GR

Can anybody tell me where to find the factory numbers for dihedral and washout? I'm rebuilding my 12, and my IA tells me to build in 2.5 deg of wash in jigging the wings during assembly. I'm seeing somewhat smaller numbers cited in this thread.

In setting up dihedral, it seems necessary to level the fuselage then set each wing to the correct angle rather than just measure the included angle of the wings with string as mentioned above.

I'd really appreciate any pointers to sources for factory rigging specifications and/or instructions.

Gordon

Send me a PM with your e-mail address and I will send you a scan of Piper SM 8 which is the factory rigging procedure for a PA-12