WINGS, WEIGHTS, PARTS

[Larry H]

I've been enjoying building the Legal Eagle XL. I started with the wings so I thought I'd share some of my information.
I like most started with the ribs. While waiting for my LEXL kit to arrive from John Bolding I, as mentioned before, purchased a couple sticks of fur 1X 2s at my local Lumber yard. I made one rib from some of the 1/4 X 1/4s I cut from them. I also decided to use 4130 3/32 thick 4130 for my wing fittings. I may not but now have plans to trailer my LEXL. I thought the steel might take more abuse in multiple tightening and banging around.

All of my plywood is Birch
The nose ribs weigh 1 oz each
The fur rib weighed 4.6 ounces
My spruce ribs weigh 4.2 ounces
Ribs with Kblock & aileron nose ply weigh 4.8 ounces
The just inboard aileron pivot rib #6 on the plans rib with 1/4 in plywood attached for aileron pivot which has a K block and a 1 1/4' wide 1/4' filler for the aileron pivot pin weighs 7.2 ounces
The 3/4 X 3/4 " diagonals weigh 6.6 ounces
The 1/4 X 3/4" compression sticks that are glued front to rear spar on the side of four ribs weigh 1.4 ounces each
Aileron Ends/plywood with holes weigh 2.4 ounces
The front spar weighs 8 lbs 8 oz with four 3/32nd 4130 steel wing attach fittings
The rear  spar weighs 6 lbs 3 oz with four  3/32nd 4130 steel wing attach fittings
The 1/8 aluminum wing fittings weigh about 1.5 ounces.   These fittings have a 4,875 lb tensile strength
The 3/32nd 4130 steel fittings I made for mine weigh 2.1 ounces.  These steel fittings have a 5,922 lb tensile strength

The 2 7/16 " extruded aluminum airfoil shape wing strut material comes in 106 " pieces from Mrs Carlson, they weigh 4.7 lbs ea are $63.00 ea. A front strut about 79" weighs 3.5 lbs. a 78" rear strut weighs about 3.4 lbs


The first photo has rib #6 in the plans with the 1/4" plywood downward showing the 1 1/4" wide  plywood inset for the hinge pin pivot point to pass through. The aileron hinge pin will go through the aileron hinge block, 1/4" side of rib structural gusset, 1/4" interior 1 1/4" wide filler block, the 8mm plywood shown bottom right corner of page 37 on the LEXL Plans. My photo shows the side up which is the side towards the aileron and still needs fully covered with 8mm plywood towards or on the aileron side matching the 1/4" plywood already glued on the other side. The #6 ribs side towards the fuselage has the 1/4" plywood and will get the hinge pin block glued to it. The hinge pin blocks will also be glued to the aileron end ribs on the aileron interior sides/insides

One photo shows one nose rib and one aileron end rib both made from 1/4" plywood as detailed in the plans.

[scottiniowa]

Larry H, that is as extensive and well done weight list as I have seen.  By having all the weights included (metal parts) it means so much more. 

Great Job!

[Larry H]

Thank You Scott

Larry

[ArcticDave]

Looks really good! I am suprised at the weight of the streamlined struts. Those suckers are heavy! 
I too am using 4130 for the attach fittings. Seems like a good strength upgrade.

[Larry H]

Thanks Dave, it looks like pretty close to 14 pounds for a full set of 4 streamlined wing struts cut to proper length for the LEXL.
I'm a little behind my planned schedule for finishing the wings. I'm taking several days off and plan to be back at it by the end of the week.

Larry

[ArcticDave]

Your woodwork looks great. I hope mine turns out half as well. I'm putting off any woodwork on mine until the weather warms up to good gluing temps. Still a little chilly here in AZ.

[JTMaze]

I'm back building my LEXL and have a  weight question. I will be making the 1/4" wing rib gussets and the aileron end ribs and nose pieces within the next couple of days. I was given a sheet of 1/4" mahogany (aircraft quality) but this stuff sure seems to be heavy. Should I be using birch?

[Tom XL-7]

I am confused by" 1/4" wing rib gussets".  I am thinking 0.8mm ply for rib gussets.
Yes on the aileron nose and ends. 
 For what it is worth birch ply should weigh a little more than mahogany ply.  About 5 pounds per 4x8 sheet.
mahogany can be harder to glue, sand lightly. A good idea regardless of species. 
Tom XL-7

[Larry H]

Hi JTMaze,
Make one of the aileron end ribs out of the mahogany, weigh it and see how much it weighs compared to my birch aileron end rib, mine weighs 2.4 oz

You need only one per wing of the 1/4" full rear end of rib #6 on the plans rib gusset for the aileron pivot pin structure, This is the rib on the inboard side of the aileron.

Mahogany plywood is a very common type used for making aircraft fuselage side walls and bottoms, Usually 1/8" or less though. The thinner sheets of Mahogany plywood are usually lighter weight than birch, I'll assume the 1/4" is Lighter than 1/4" birch but I don't know.
My 1/4" birch aileron end ribs weigh 2.4 oz.
My 1/4" nose ribs weigh 1 oz

[JTMaze]

Thanks for the information. Should have said hinge brace and not gusset.

[Dave Stroud]

Just me again....looking for clarification as usual, please. The sketch on the right bottom area of my plans page 51 seems to show the 1/4" rib aileron hinge reinforcement piece to go full length from the trailing edge right up to the rear spar but there is that word gusset with a small triangle there to contradict what I seem to see. Page 37 on my plans seems to show that 1/4" reinforcement piece to go from the rear of the rear spar back to just aft of the hinge block.

Larry's nice work shows the reinforcement plate only from the trailing edge up to the K block area as does at least one of Scott's drawings. Page 37 of my plans has a note of correct 9-12-12. Any ideas appreciated. Thanks...

[Larry H]

Hi Dave,
I saw what you are talking about on the plans on page 37. Look at the bottom right corner of page 51 and you will see the side view of rib #6 with plywood all the way to the trailing edge. It doesn't stop just aft of the aileron hinge point. I decided to do what Scott's drawings show. I made my large 1/4" gusset like Scotts starting forward of the aileron hinge point and going all the way to the trailing edge with the lightening holes. I assumed the truss like structure of the rib between the aft side of the rear spar and where I started the 1/4" plywood would support that. I glued the identical shape 8mm plywood with lightening holes on the opposite side of that same rib.
Page 34 shows an end view of the front spar tapering the wrong way in the bottom left corner, don't do that. Leonard told me to use pages 36 and 37 for the placement of the 3/4" x 3/4" diagonals.
page 51 shows the diagonals ending at the wrong ribs. I bet he just quickly drew those diagonals to give the impression which way they would be angling for quick reference but not as a detail of where they are to be glued in. There are several places where more detail would have saved a lot of research time and speculation as to how he intended it to be done. That 1/4" gusset all the way to the rear spar would add additional weight probably not needed. The 1/4 x 1/2" angle braces will stiffen the 1/4" rib on one side and the metal cuff forming the pocket for the leading edge of the aileron nose will stiffen it on the other side of that rib.

Dave, I'm sure that 1/4" plywood gusset from the rear of the spar stopping aft of the pivot pen would work and might be the strongest way to do it, I don't know. Plus it may become heavier this way.


Larry H

[scottiniowa]

Hi Dave,
I saw what you are talking about on the plans on page 37. Look at the bottom right corner of page 51 and you will see the side view of rib #6 with plywood all the way to the trailing edge. It doesn't stop just aft of the aileron hinge point. I decided to do what Scott's drawings show. I made my large 1/4" gusset like Scotts starting forward of the aileron hinge point and going all the way to the trailing edge with the lightening holes. I assumed the truss like structure of the rib between the aft side of the rear spar and where I started the 1/4" plywood would support that. I glued the identical shape 8mm plywood with lightening holes on the opposite side of that same rib.
Page 34 shows an end view of the front spar tapering the wrong way in the bottom left corner, don't do that. Leonard told me to use pages 36 and 37 for the placement of the 3/4" x 3/4" diagonals.
page 51 shows the diagonals ending at the wrong ribs. I bet he just quickly drew those diagonals to give the impression which way they would be angling for quick reference but not as a detail of where they are to be glued in. There are several places where more detail would have saved a lot of research time and speculation as to how he intended it to be done. That 1/4" gusset all the way to the rear spar would add additional weight probably not needed. The 1/4 x 1/2" angle braces will stiffen the 1/4" rib on one side and the metal cuff forming the pocket for the leading edge of the aileron nose will stiffen it on the other side of that rib.

Dave, I'm sure that 1/4" plywood gusset from the rear of the spar stopping aft of the pivot pen would work and might be the strongest way to do it, I don't know. Plus it may become heavier this way.


Larry H

  Scottiniowa  here,   have been following this with interest, and when this is logically decided upon (I think this is close)  I will make sure the supplemental drawings show the "final" thoughts on this.

Being that "the boss" looked them over and did not tell me to change anything, I have assumed they were as intended.  But I never mind to be corrected, if the correction is worthy of being shown or changed.

I am guessing that if the for end of the 1/4" piece I have shown needs just a bit more,  it might well be just adding a large gusset of .8mm, 1/8" or even the 1/4" extended.  Let me know or this subject line and I will read accordingly. 

[Larry H]

I called one of my several nephews who are structural engineers. The one I called is also a pilot and understands these structures. He has a set of double eagle plans he purchased a few years ago, so he is familiar with Leonard's drawings. He is the one that calculated the tensile strength of the steel and aluminum wing and strut attach fittings for me. I sent him photos of my #6 rib with the 1/4" plywood glued on like Scott's drawings. He agreed with my thoughts that the rib truss structure is good enough to support everything. The rib truss diagonal coming from the bottom of the rear spar up to the top of the leading edge of the 1/4" plywood and K block is the key piece. If that stick wasn't there then the plywood would probably need to go all the way to the back of the rear spar and be glued to the shearwebb. I also increased the size of the gussets on this rib on the stick immediately against the back side of the rear shearweb/spar to extend that load pattern a little further out. Look at my photo and you will see the two different size gussets on either side of where the rear spar goes through the rib.
After consulting with my nephew I'm satisfied with the way Scott Weinberg drew them up and the way I've built mine.
Thank You Scott for your effort in making these clarification drawings.

Larry H