More questions about wing numbers....

[Dan_]

Might as well throw this attachment on the pile...

[Tom XL-7]

Gee Dan, I don't know. That looks pretty hard. Wouldn't it be easier to use the drawings? You know.
the ones we paid for. 
 Or might you be suggesting my attachment is of similar practical use?
There are some interesting things to see and the math has been worked out. 
For instance, the load at the strut is 540kG while the load at the fuselage is only 41kG (R1, R2)
That's only 7%. not only that but the fuselage wing mounts are not being "lifted" up but are being pushed down into the cabanes.
That is not how most people would assume.
 hey you English majors is this a metaphor:
consider the wing as a teeter-totter. It pivots at the strut attach. The outer section of the wings lift pushes the inner section down.
  
Tom XL7
We haven't even talked about the compression loads. 
But I feel we have had enough for now

[Dave Stroud]

Geeze....I find this stuff very interesting and do appreciate your taking the time to do it in almost layman's terms. Do the numbers 540 kg and 41 kg represent any legal Eagle design  or are those numbers just an example for illustration purposes ? What happens at the bottom of the lift strut ? My LEXL plans say gross weight of 575 lbs or 261 kg. Any chance you could translate that gross figure to each end of the lift strut and wing root to fuselage point in say a 3 or 5 g scenatio?  

I seem to remember my Christavia being rated for 5 g positive and 3.5 g negative with a safety factor of 1.5 at gross weight. I don't think I've seen numbers like that in print regarding the Legal Eagle designs but I may have missed it. Are they out there? 

Thanks, Tom

[Dan_]

Or might you be suggesting my attachment is of similar practical use?

Absolutely not.  I just sent that to show what a can of worms it is to account for all the considerations necessary to become a "designer".

The XL wing was load tested with 1000 lbs.  The load was evenly distributed instead of a load schedule calculated to represent the lift distribution. 

The deflection was 5 inches and no damage.

The 560 lb gross weight mini max is rated 4.4 positive and 1.8 negative.  Which is squarely in the utility rating.

My guess would be the XL wing is at least this good or better.

[John Reinking]

re Reply's #27 & 29:    Thanks, Scott

[Dave Stroud]

Thanks for that info, Dan. I've got a copy of the book Stress Without Tears and have dug into it a couple of times but the deeper I get, the tears start to flow from me getting stressed. :-)  I'm new at the Legal Eagle thing and just trying to become more informed.

[Dan_]

Thanks for that info, Dan. I've got a copy of the book Stress Without Tears and have dug into it a couple of times but the deeper I get, the tears start to flow from me getting stressed. :-)  I'm new at the Legal Eagle thing and just trying to become more informed.

I don't have that particular book, but I have some others I get the same sensation as you from...

[Tom XL-7]

Dave that was just an illustration that I thought could answer the question of what part of the spar is most stressed. Remember that question?
My interest in this is mostly curiosity. I want to know what's going on with my aircraft just as I am interested in the details of automobiles.
You might know what that noise is if you have a clue about what's under there and what it does.
 Since we are building our aircraft there won't be any mysteries about the what and how it is put together. The why is what I am trying to learn.
I believe the illustration is a work up of a wing for the High-Max. It is very similar. Much of it is the same. Most actually.  
 Tom XL-7