TOPIC: CD wing dimension and coordinates.

CD wing dimension and coordinates. 29 Aug 2014 20:20 #829

Hello, i am studying the wing of the Carbon Dragon. It's very difficult to get true dimensions of the wing. The builder's manual give 61.2" at the root and 22.5" at the tip, but that does'nt match with plans. By reading forum, i obtain 60" at the root and 22" at the tip. Finally, by measuring plans, i have 59.88" at rib 1 ( not exactly root ) and 21.75" at the tip.
I have a CNC to cut foam and i need good set of coordinates. I found two sets in the forum, unfortunetly they are not accurate enough. I have used QCAD to draw ribs to get coordinates.
Here are my drawings for the set of ribs ( you can compare with the plans ). If it is suitable, you can print on A2 or A3 size printer for scale 1 ribs templates.
Are the dimensions good ?
Austin.

Edit : see below for revision of the drawing.

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Last edit: by Bertrand Botrel.

CD wing dimension and coordinates. 30 Aug 2014 10:24 #830

Hi Bertrand,

Welcome to the group! Careful study of the plans will reveal a number of minor discrepancies, most of which are documented somewhere in the documents on this site. The one that fools most people is where the plans specify 8mm plywood in various places... which is in fact supposed to read 0.8mm (1/32") ply!

As for the wing dimensions, Stick to 60" at the root and 22" at the tip. You can find an analysis of the wing dimensions, loads and stresses in my spreadsheet here: www.ihpa.ie/carbon-dragon/index.php/cd-b...wing-stress-analysis .

Roger Hardie in South Africa is also starting work on analyzing the drawings and has produced a set of CAD drawings which might be of use. If he doesn't respond to this post, you can contact him through the list of registered users (Main Menu - Login - Registered Users).

I'm very envious of you and Roger with your CNC set-up - it would have saved me *many* hours of work cutting out the rib molds and foam cores!

By the way, if you are going to use a CNC machine to cut out your molds then you should investigate making them out of a material that will not sitck to epoxy (like HDPE or similar). The MDF molds I used worked well but are delicate and have their limitations! Again, Roger has been working on a set of CAD drawings for the rib molds.

Good luck with the project, and don't hesitate to ask questions!

All the best,

Phil.

PS - I'll print out and compare your rib drawings over the weekend and see how they compare to the originals...

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CD wing dimension and coordinates. 04 Sep 2014 19:53 #831

Hi Phil, thanks you for your complete answer. As you said in an other post, we can suspect a difference between vertical and horizontal scale of the scan. I have noted a difference up to 5/1000 in many plans. To match 60" chord and 11.75" spar depth, i reduce 2.5/1000 vertical scale.
But for 60" rib 1 chord, i can't reach 22" at the tip chord ( 21.78" )...

Edit : I slightly modify my drawing. And now i have 60" at the root chord and 22" at the tip chord... BUT, there is a real problem with the drawing of the flaperon rib 28 on plan n°11.( corresponding to wing rib 13 )
When we copy the shape of the flapperon rib 1 ( plan N°11 ) and copy it on plan N°8, the dimensions and angles match correctly with the wing rib. It's impossible to do the same with Flaperon rib 28 and wing rib 13.

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Last edit: by Bertrand Botrel.

CD wing dimension and coordinates. 06 Oct 2014 07:01 #835

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CD wing dimension and coordinates. 15 Oct 2014 12:22 #838

Hi, here is a summary of the wing dimensions... Do you agree with this ? ( especially with dihedral )

Edit : see below for revision of the drawing.

Thanks you.

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Last edit: by Bertrand Botrel.

CD wing dimension and coordinates. 27 Oct 2014 20:26 #841

CD wing dimension and coordinates. - Jim Maupin's Gliders
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File Name: Hi, according to my wing rib contours drawing, the flapperon rib contours slightly change. I also add the wing dimension on the same drawing...

( I have noted an error on plan n°10 : the measure 148,92" seems to be wrong. By the way, i have modified all the set of measure )


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