setting the wings

[LSaupe 123]

Installed the wings yesterday.  Now the question is, how to set orientation.  My manual (which I think is a partial manual) is silent with regard to verifying correct orientation (such as dihedral, verifying washout  and other cross check points).  Things went together suprisingly well, however, I do see that when folded that one wing tip is slighty higher than the other so know I have (or assume) some fiddling to do.

 

 

Is there a measurent or rigging sheet/instructions to ensure I have everything dialed in correctly?

 

Kitfox Model III.

 

Many thanks,

 

Larry

 

 

 

 

[TJay 1041]

Here is what I did, drill the top hole on the rear spar, set dihedral at 1 degree and washout, Make sure your wings are square with the tail then drill the rest of the holes in the spar for your pins. I wouldn't mess with it after its rigged I would have a fear of putting pressure on your spar bolts and pins. I have heard alot of people having different height wing tips when folded. For some reason mine came out perfect in all directions, good luck.

[Av8r_Sed 82]

Larry, PM sent.

 

You may not be able to get it perfect with the flaperons even when folded.  Mine are off just a bit.  It's more important to have it rigged right for flying.  It takes a little fiddling, but you should be able to arrive at a good compromise.

[EDMO 1078]

I don't care how mine look when folded - It's the flying that counts.

     Tip:  One degree = .017" per inch, so multiply that times the length of your level to set the dihedral, and tape a spacer block on the end of your level to make it simple.  A 48" level would take a spacer block about 13/16 high, or .816", but not that critical, as long as both wings are the same.  I may use 7/8" spacer, and 1" would still be OK.  

The level should be placed between the fuselage and the strut on the front spar.

This has to be done before you drill the bottom holes in your spars - after that, you can't move them much.

I have forgotten the difference in height from front spar to rear spar, I think it only says to measure the one that is not adjustable, and match the other to it. 

The Cessna Birddog L-19 I used to fly had about 3 times that much dihedral, and low wings have much more.

EdMO

Edited 27 Jul 2015 by Ed In Missouri

[LSaupe 123]

Thanks.  So... is 1 degree the correct dihedral setting?  Washout seeting I assume to be that specified during the build process? 

[EDMO 1078]

One degree is the correct dihedral.

     I posted a lot of info earlier about the washout:  Dean Wilson designed the wings for a light, slow airplane and gave it a large 1 1/2" to 1 3/4" washout for novice flyers to maintain control at slow speeds and to make it hard to stall.  This wing hits a "wall" at about 90 mph because of the undercamber ribs.  Kitfox copied his design.

     As the engines got more powerful, and gross weight went up, the pilots wanted more cruise speed, the washout was reduced to only 1/2".  The bottom of the rib was flattened some for the Speedster but did not perform much better.

     Harry Riblett did some tests on the original modified Eppler undercambered wing ribs, and discovered that a bubble formed under them causing drag.  He designed a new rib and Kitfox put it on the Model 4, Classic, and later models to increase cruise speed while still having almost the same stall speed, and keeping the 1/2" washout.

     I have modified my undercamber ribs to be similar to the Riblett ribs, but mine already had 1 1/2" washout, and I can't change that without completely rebuilding the wings, so the washout will slow me down a little.

     Yes, the washout is established when the wings are built.

Hope this helps.

EdMo 

Edited 27 Jul 2015 by Ed In Missouri

[LSaupe 123]

Thanks all.  The snag here is that the holes were drilled prior to me aquiring the project.  Not known whether the wings were ever set up on the fuselage (I assume it must have been).  The  rod ends however were loose and not set.  Did my best to get the wings up in a no-stress mode for the root pins then put on the lift struts.  Think I am "close" but understand small deviations can have sometimes large effects.

 

So... from that stand point, looking to do external checks to make sure are where they need to be. 

 

Edited 27 Jul 2015 by LSaupe

[EDMO 1078]

If you cant get both wings set exactly the same, or reset after flying, your plane may want to fly with one wing low - you may have to  adjust your flaperons to make up for that, until you fly with stick centered.  Most builders don't have a problem with that.

EdMO

Edited 27 Jul 2015 by Ed In Missouri