Eagler's Nest
General Category => Builders logs => Ken's XL-F-34 Builders log => Topic started by: dz1sfb on March 17, 2016, 03:47:50 PM
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Well I received my plans on March 14, 2016.
My background as a Metal Model Maker, and a Model Airplane Designer and Kit Manufacturer, has taught me to study the drawings carefully and read everything, more than once. Don't miss any notes.
That also can give me grief! Listening to Sam Buchanan's EAA Webinar on the Legal Eagle confirmed my condition. The simplicity of the plans means there are not too many hard fast dimensions. Just be consistent! That can be a problem as Sam mentioned for the guy who is used to working to thousandths of an inch (hundredths of a millimeter). I am used to and more comfortable working in more concrete numbers and detailed drawings. However, this makes the project more interesting for me and I will make up some CAD sheets to complement the originals for my use.
A big thank you to scottiniowa for his CAD work. I am utilizing his services in this project as well.
This next month of April will find me somewhat sidelined from starting any physical building, but I will be studying the drawings and seeking answers to the questions inherent to the plans.
I will try to find answers initially by combing through the site, and have already revived one thread on tail surfaces that seemed incorrectly answered to me.
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Everything you need is in those drawings. Just enjoy the journey. You really don't want measurements like 5 and 63/64ths inches.
I will not weld or drill anything on my fuselage regarding tailfeathers until same feathers are built. Then I will make it work. Yes I will do my best but I would rather mount them than change them. Everypart we make is pretty much handbuilt without jigs except the ones we one off jig. My ribs will be different than your ribs and on and on. It's OK. It is just the way it will be.
PS hint from old site I believe John Bolding. Only put one wing mount on the fuselage(front) until your wings are done.
Tom XL-7
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Thanks for the encouragement Tom!
The process for construction of this project allows for variation. Just keep the steps in order to not build yourself into a box. This holds true even for more precision work. You always have to allow for variation. It is all about controlling what is important and making allowances for everything in between.
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I continue to study the plans until it all seems clear. I taped up the sections of full size wing ribs and found that they don't match very well. Some overlap, others are not able to touch. Notably on the nose rib sheet there is a scale shown on there and there is .050" growth per inch on the sheet, plus the distance measurements are illegible. I would love to put together a good set of tiled sheets that Leonard could have in his plans sets. This is really important to start with correct at the beginning.
Does anyone have some distance numbers for the full size airfoil?
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I continue to study the plans until it all seems clear. I taped up the sections of full size wing ribs and found that they don't match very well. Some overlap, others are not able to touch. Notably on the nose rib sheet there is a scale shown on there and there is .050" growth per inch on the sheet, plus the distance measurements are illegible. I would love to put together a good set of tiled sheets that Leonard could have in his plans sets. This is really important to start with correct at the beginning.
Does anyone have some distance numbers for the full size airfoil?
I would suggest you get a full size sheet from Leonard or do what I did was buy the plan sheet set from Scott "Iron Design L.L.C." he has some good sheets/supplemental's from the high school project.
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You're right, the pages for the ribs don't fit perfectly end to end. But if you take the time to make sure the drawings line up again over the gaps and overlaps, you will create a template that is the correct size. Mine was less than 1/8 in under 55 inches when finished.
If you photo copy the drawing received from Leonard, make sure the copies are correct. This forum has suggested drawing a scale in pencil on the originals and then measuring that scale on the copies to verify size.
A teacher once told me that when making a table, it doesn't matter if the length of the legs are correct, just make sure they are all the same.
It's kind of the same thing with the ribs.
Good luck.
Vince
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The sheets will go together. Many here have done so. Run your drawings through a copier. Save the originals-always.
The pages don't go edge to edge. not even ink to ink. Try an overlapping layout matching the given lengths The bottom will be a flat line. There is a lot of white paper that needs to be cut off. Still you will overlap. Go for a fair curve on top, keep the bottom as a line. Ignore the diagonals. they go between the vertical sticks.
No head scratching required.
I got it to work, made a jig and then drew one from scratch. I was amazed at how well the two matched. Good enough that I will not remake the jig.
The airfoil data is on the old site but I believe Dan posted it here at one time.
It doesn't take long to draw one . You will need a piece of paper 54 " long plus. I used the back side of two 24 x 36 architectural drawings taped together.
You make a straight line 54" long. (chord line), Mark the stations along same, then with a square mark the upper and lower values. The bottom is easy. the top will require you to generate a fair curve.
I will see if I can find this data in a form I can copy and send . Mine are in excell and are not cooperating.
Tom XL-7
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Notice my chord is 54 inches and others is 55. Makes for a good question. Leonard calls out 55 on the first page of the plans in the specs.
My jig is 54 with a blunt trailing edge. I guess it will be 55 when I add the tapered trailing edge piece. 3/8 x 1' taper.
But that might explain the slight misfit of the hand drawn from coordinates paper to my jig. The values use 54 inch chord round nose to pointy trailing edge.
Tom XL-7
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I would suggest you get a full size sheet from Leonard or do what I did was buy the plan sheet set from Scott "Iron Design L.L.C." he has some good sheets/supplemental's from the high school project.
I am planning on getting the sheet from Scott. His work is more than worth the money. No gripes here.
I know I can interpolate the sheets together and get fairly close. The part that bothers me most is the oversize to what appears to be the scale on the nose rib sheet. This is giving me no confidence in it, and the non readable dimension line below the rib that calls out the space between spars and distance to the trailing edge. I really like those reference dimensions when it comes to taping a tiled drawing.
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The sheets will go together. ... The airfoil data is on the old site but I believe Dan posted it here at one time. It doesn't take long to draw one . You will need a piece of paper 54 " long plus. I used the back side of two 24 x 36 architectural drawings taped together. You make a straight line 54" long. (chord line), Mark the stations along same, then with a square mark the upper and lower values. The bottom is easy. the top will require you to generate a fair curve. I will see if I can find this data in a form I can copy and send . Mine are in excell and are not cooperating. Tom XL-7
[size=undefined]That would be awesome Tom!
Thank you. I will do some digging for it also.
[/size]
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The missing values are 27.5 between spars and from front of rear spar 18.75 to end (blunt end not point)
the nose rib is another one of those things that are best made after the ribs and front spar. nothing else matters more than that they fit.
aileron rib ends-ply, I made my pattern then spliced an extension on it
try to not get too far ahead as you build.
use the actual airplane as your jig-as in landing gear- wouldn't be hard to be off on that -just a hair is too much.
don't know if attachment works
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The attachment appears to work
I hand drew the 2nd chart , It is 54 overall and I think you should draw the first chart. The 55" NACA 4412
In the spread sheet the charts are the same if you change the value of chord length to match.
I did not say the legal eagle rib is NACA 4412 but this information from the old site suggests it. I also have a clark Y airfoil that has been put up as well.
Next go round for me will be to draw the NACA 4412 and snip the point off the trailing edge and see how that sits in my jig.
Tom XL-7
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Tom,
Excellent information!
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The attachment appears to work
I hand drew the 2nd chart , It is 54 overall and I think you should draw the first chart. The 55" NACA 4412
In the spread sheet the charts are the same if you change the value of chord length to match.
I did not say the legal eagle rib is NACA 4412 but this information from the old site suggests it. I also have a clark Y airfoil that has been put up as well.
Next go round for me will be to draw the NACA 4412 and snip the point off the trailing edge and see how that sits in my jig.
Tom XL-7
Attached...
I'm gonna say the solid line is the Clark-Y...
Not much difference, except where max thickness occurs and camber. It does not take much in the way of these kind of details to make big differences over an area the size of a wing. For example center of lift, pitching moment, etc.
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So
Does either represent the eagle rib.
Both have quite a history.
Appears both are close
we know the max height location on the eagle rib is where that tallest vertical lays.
tom xl-7
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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...
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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.
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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?
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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.
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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!
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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.
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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.
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Attached is your scan with naca 4414 superimposed... I am beginning to wonder if it is a clark Y at 15 % thick...
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Here is the Clark YH. Does not look to be the one with the reflexed trailing edge.
Nice online airffoil plotter here (http://airfoiltools.com/plotter/index)
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Here is your scan with clarkYM15 superimposed... This may be the one.
Attached.
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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
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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.
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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...
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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?
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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.
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Ken,
Here is your last one superimposed... How about plotting the Clarck YM 15 in that sofware and let me put it on top of your mini-max rib drawing..?
Attached.
It appears to me that if you put the blocks into your rib jig for a Clark Y between the front and rear spars, and bent a rib stick around them, you would have it...
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Don,
Here's the plot of the Clark YM-15. The nose rib area looks closer, but with more variation in the upper surface and of course quite a bit taken off the bottom.
I am thinking that the Minimax rib profile is a great choice. Looks like it will tolerate a higher AOA before stalling.
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The nose rib doesn't count of course, because it is built separate. The lower rib stick doesn't count, because we know it is modified to be flat.
That only leaves bending the rear portion of a rib stick over the rear spar, and you would have it.
W2P evidently means, "I know what I did, but I am going to my grave without telling what it was...
So if you want to compare airfoils, you will just have to accept that the nearest published performance you are going to get is the Clark YM-15, and go from there.
Attached.
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I am going to build the wing using the supplemental drawings supplied by scottiniowa. I am really not up to experimenting at this level. Someone once wisely said, "don't fix what isn't broken". We have a stable working platform here and this is my first full scale project.
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:( - NACA 4412 up to 4418 have convex tops and bottoms, even if ever so slightly. Thus, the wing section used in our Eagles are NOT true NACA.
Section thickness, per full rib drawing is (204/1397)*100= 15% and this % depends on your trust on the drawing! Copies may not be scaled equally on the horizontal and vertical axis. Case in point, using the stated dimensions from full rib drawing and working out a scale, they are different for Y-axis and X-axis!
If the scaled vertical dimension is used, thickness the section comes up at ~18%! These facts have pushed me out of my comfort zone.
Therefore, my DE wing will use a Harry Riblett's GA30A418.
azevedoflyer
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:( - NACA 4412 up to 4418 have convex tops and bottoms, even if ever so slightly. Thus, the wing section used in our Eagles are NOT true NACA.
These facts have pushed me out of my comfort zone.
Therefore, my DE wing will use a Harry Riblett's GA30A418.
azevedoflyer
I shouldn't even go into this can of worms and most of you know there are entire books and many of them all about airfoils...That being said, there a few but important things to remember.
- At the speeds of this/these aircraft will attain, if the airfoils are close, the c.g. very close, and known plots for building are done in a easy to follow format (i.e. smooth and repeatable) Then the likely hood of being able to discern between two of them will be tough to judge on performance.
- Harry Riblett's book on GA airfoils is very interesting and he "talks about" other airfoils at great length.
- The angle of the cord line to datum line and the H stab have perhaps a greater effect on performance than anything else, but you hear very little of folks changing these figures (I am not saying you should) but some airfoils allow the tail to be drug through the air 1-3% different than other airfoils. But again, at 60 mph, vs 61 mph, it gets hard to know what did what as often the case that the builder changed more than one thing at a time. (creates an impossible task of knowing what results changed, and what actually did the changing)
- Drastically changing an airfoil on a 180 mph plane vs a 60 mph plane, can have huge effects on one, and little effects on the other, depending what changes were made. But....... as we have seen over the years, some airfoils really work, and some have scared the heck out of a few test pilots. (maybe alarmed would be better stated)
- Having the ability to know exactly how your wing is going to be built, before you build it, and a pretty good idea on how it will fly is a pretty big battle already won!
Best of success to you all!
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ScottinIowa,
Agree with your arguments, specially about "...a major battle already won".
In defense of my choice, the GA30A418 is not much different from the well behaved NACA 4418, as stated by Harry Riblett himself. However it incorporates a few corrections worth the + effort in my opinion. We shall check it out when I get my DE done. Besides, this is what EAA is all about, is it not? :)
Cheers,
azevedoflyer
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ScottinIowa,
Agree with your arguments, specially about "...a major battle already won".
In defense of my choice, the GA30A418 is not much different from the well behaved NACA 4418, as stated by Harry Riblett himself. However it incorporates a few corrections worth the + effort in my opinion. We shall check it out when I get my DE done. Besides, this is what EAA is all about, is it not? :)
Cheers,
azevedoflyer
Oh yes, I would never say a bad thing about any of Ribbletts airfoils. Harry really worked the numbers. And certainly is what homebuilding is all about.
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ScottinIowa,
Agree with your arguments, specially about "...a major battle already won".
In defense of my choice, the GA30A418 is not much different from the well behaved NACA 4418, as stated by Harry Riblett himself. However it incorporates a few corrections worth the + effort in my opinion. We shall check it out when I get my DE done. Besides, this is what EAA is all about, is it not? :)
Cheers,
azevedoflyer
How are you going to figure out where to put the spars and diagonal / vertical brace strips..?
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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!
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H, Can anyone help me, Rear wing strut notch cutting, is this really need ? Or can I use same as the front wing strut ? I am building XLC95...
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H, Can anyone help me, Rear wing strut notch cutting, is this really need ? Or can I use same as the front wing strut ? I am building XLC95...
I'll bite, what is a " rear wing strut notch" I must be losing something in translation?
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I'll bite, what is a " rear wing strut notch" I must be losing something in translation?
Scott, I'm pretty sure he's talking about the 5 degree angle on the rear strut fittings, and the notch that needs to be cut out to do that.
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Scott, I'm pretty sure he's talking about the 5 degree angle on the rear strut fittings, and the notch that needs to be cut out to do that.
I see, well, without going into to many finite details there are some things that just have to be. Not many years ago, a fellow designed from scratch what he thought would be the perfect ultralight engine. Gets down to the valve push rods, and decides the only way it will work is with bent push rods... :o
I didn't know what to say to him...But as the saying goes, two wrong things don't ever make a right thing. :grin: