Studying the Plan

[Dan_]

So
Does either represent the eagle rib.

tom xl-7

The consensus at one point according to John Bolding was that the NACA airfoil that is closest is the 4414.  However the airfoil has been modified to be a straight line on the bottom.

Also the fact is that the airfoil is a direct duplicate of the Airbike/Minimax airfoil, which is claimed to go by the name of "WP-2" if I am not mistaken.  The story goes that Wayne Ison sat down with a #2 wide pencil and drew the airfoil in a stroke of genius...

You may have more results going down the WP2 or mini-max google search rabbit hole trying to run down the actual coordinates...

Edit:
Wayne Ison apparently co-founded Fisher Flying Products, so that may be where the airfoil originally came from...

If I find anything on it, I will edit again...

[dz1sfb]

I found plotting the airfoil was similar but not really the same as the LEXL. I do have the plans for the Minimax and have created a CAD file of the wing rib.

This may all be academic at this point as I have Scott's drawings on the way. Any discovery is sure to help future LEXL builders.

[dz1sfb]

I've got the Minimax rib traced out to scale and tiled for 6 sheets of letter size paper, for what it's worth. Cleanly dimensioned. Sorry for the 4 place decimals.

See if this is comparable?

[joecnc2006]

I've got the Minimax rib traced out to scale and tiled for 6 sheets of letter size paper, for what it's worth. Cleanly dimensioned. Sorry for the 4 place decimals.

See if this is comparable?

Do you have a cadd file i can overlay it.

[scottiniowa]

Hello XL Builders
   About once per year, sometimes every other year, I get a bit into why I created the sheets I did. Have not done for awhile so thought this would be a good time to cover it again.  So take this as a explanation of only what I did. Absolutely not saying this is the only way- (we all know it has been done many ways) nor that anyone else's way is wrong.  Simply a way to quickly move fwd with the project. So the details.

• We have all heard that the full length rib drawing and the rib drawings in the plans 8.5" x 11" pages are not exactly the same, but certainly let it be known at the speed of the aircraft, both will work fine. I simply took the closest coordinates (computer generated) that I could find, and created the full scale wing rib drawing. I clearly mark the estimated   cg line on this drawing, and the estimated one for the drawing in the plans. I guess to be fair, I should have three lines on it.  But clearly they are all so close that if you have big feet vs little feet,  lean fwd or back in the seat... at these speed,  none to worry.
• With these drawings, I created full scale templates, (included in the drawings) to match the wing rib that I have drawn. This should cut down your time to make parts by 70-80% And certainly one of the main reasons I did this.
• The just mentioned parts are for EVERYTHING on the wing rib.  NOSE-AILERON- what I call a K BLOCK for the cove-any any other PART required. All for time savings, NOT a correction to your plans. But these are for what I drew, not to make parts for the plans drawings. (they won't match exactly)  But mine will match my drawing.  NO mix and match intended.
• With the full scale drawing, of the rib, you should be able to have your rib jig built in 2 hours or less, with parts on hand.  Just a huge time saver as intended
• I drew all the gussets, simply to make best use of the .8mm ply.  Remember, this was all intended to let high school kids-learn the basics of building project and gently  guide into the art of waste reduction and planning.
• I drew for those that like building but don't really care to calculate every last part of the wing, or study in depth of "how to build-and in what order" 
• I did not change how the wing attaches - the strut attach locations -nor how the wing is built.
• I did simplify how to view during the build process.
• I did price this at my  printing/shipping cost to help keep folks going fwd in their project.
• I do not- supply CAD files on what I drew... as I find those without associative CAD file systems- soon make changes to one area, without it then changing the next affected area- thus soon becoming Scott's fault that something did not work out... I'm sorry, but presently don't have time, to delve into "what was done wrong, to find what to make right"  This can quickly develop, and if I was retired, maybe...but presently simply can't do this detective work.  Just presenting a " do this and it will all fit " set of drawings.
• I never intended, nor intend to do plans for the whole aircraft. They are supplemental only- and 90% for the wings. There are things here and there that are perhaps improvements to various areas of the aircraft, but NONE are intended to dramatically change the bird. My background is in far larger aircraft, with gross weights of 1700 to 2500, so this is a treat to me.

Hope this helps explain- Great fun helping.  As always, I have said, that if you don't like, I will return your funds less shipping, when I get the plans back. To date, none have been returned. Enough said.

Best of success all!

[dz1sfb]

Thank you Scott! I have the highest confidence in what you are doing here, fully intending to use your drawings as the master since spar and rib details are all coordinated. I just get a little itchy and doing what I do helps me understand what I need to do to "work smart, not hard". Trying to comprehend the entire project. I build in my head first.

Here are a couple of screen shots of that work.

[Dan_]

I've got the Minimax rib traced out to scale and tiled for 6 sheets of letter size paper, for what it's worth. Cleanly dimensioned. Sorry for the 4 place decimals.

See if this is comparable?

Attached is your scan scaled to 54 inch chord with A Clark Y I downloaded from the internet scaled the same...  

There are more than one Clark Y profiles.  I.E. Clark YH...  There is enough similarity, I guess I need to find the YH.  

[Dan_]

Attached is your scan with naca 4414 superimposed...  I am beginning to wonder if it is a clark Y at 15 % thick...

[dz1sfb]

Here is the Clark YH. Does not look to be the one with the reflexed trailing edge.

Nice online airffoil plotter here

[Dan_]

Here is your scan with clarkYM15 superimposed...  This may be the one.  
Attached.

[Dan_]

I am fairly certain you would plot these coordinates starting with the upper surface points leading edge to trailing edge and then lower surface leading edge to trailing edge.  Left column being the X coordinate and the right column being the Y.

Best I remember to do it by hand, you would multiply each number by the chord you want...

Some of the airfoils listed do not close at the trailing edge, i.e. the trailing edge has a finite thickness as designed.

CLARK YM-15 AIRFOIL
       17.       17.

 0.0000000 0.0000000
 0.0116400 0.0249000
 0.0237000 0.0379200
 0.0480900 0.0554500
 0.0726700 0.0676000
 0.0973400 0.0772500
 0.1468400 0.0917500
 0.1965100 0.1013600
 0.2962600 0.1086900
 0.3962600 0.1087300
 0.4964900 0.1020800
 0.5969100 0.0899300
 0.6974900 0.0728900
 0.7982100 0.0519600
 0.8990400 0.0279300
 0.9495000 0.0146600
 1.0000000 0.0008000

 0.0000000 0.0000000
 0.0132000 -.0202500
 0.0259100 -.0265100
 0.0511600 -.0337400
 0.0763000 -.0376800
 0.1013800 -.0402100
 0.1514900 -.0431900
 0.2015000 -.0436700
 0.3014200 -.0411300
 0.4012800 -.0373000
 0.5011200 -.0325600
 0.6009400 -.0272300
 0.7007300 -.0212900
 0.8005100 -.0148600
 0.9002800 -.0080300
 0.9501500 -.0044100
 1.0000000 -.0008000

[dz1sfb]

Dan,
The site I referenced for generating airfoils allows you to save as a .svg file. This is a native vector file for Inkscape (which is free). Then you can save as a .dxf or many other vector formats.

I raised the height on the Clark Y to 121.56% and got somewhat closer.

[Dan_]

Yep,
I'm convinced that what we have here is a clark Y @ 15-18% thickness.  The modifications include a flat bottom, and accommodation for a pre-determined rear spar height...

Simple as that.  W2P my ass...

[scottiniowa]

Yep,
I'm convinced that what we have here is a clark Y @ 15-18% thickness.  The modifications include a flat bottom, and accommodation for a pre-determined rear spar height...

Simple as that.  W2P my ass...

Love it,
   The "same" but "different"   

   Dan, how do you "accommodate" a X-Y plot point profile for a pre-determined rear spar height?

[Dan_]

Love it,
   The "same" but "different"  

   Dan, how do you "accommodate" a X-Y plot point profile for a pre-determined rear spar height?

Increase the max thickness percentage until it clears, connect the ends if necessary.  

I think my conclusion is more plausible than "humidity" and printer paper distortions...

What airfoil coordinates did you use..?  Inquiring minds want to know.