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Powered Aluminum Dragon (Part 1) 11 Oct 2014 10:26 #836

so sorry not to check site, try sending contact, or contact me through my web site www.proppastie.com
there is an e-mail link there.

I have been doing calculations not much drawings, I can send you profiles of tip and root rib with flaperon, I plan on making my own drawings. be glad to help you though.
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Powered Aluminum Dragon (Part 1) 15 Oct 2014 12:08 #837

Hi Don and Roger and Phil. From my drawings ( see the topics " Wing dimensions and coordinates " ) i otain coordinates for wing rib 1 and tip, perhaps it can help you :

File Attachment:

File Name: CDrootribc...nate.txt
File Size:1 KB

File Attachment:

File Name: CDtipribco...nate.txt
File Size:1 KB

These are SELIG files ( .dat ) but you can open with Notepad. You can also view profiles with a free software ( Compufoil for exemple ).( to see with Compufoil, you must change the files extension to .dat )

I saw that DON obtain the dihedral... 1.43°. With the same data ( the plan n°9, the main spar fitting ), i get 1.3° !!! ( inv tan 0.25"/11" = 1.3° )( 11" is distance between upper and lower fittings )
Last edit: by Bertrand Botrel. Reason: bad extension for files
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Powered Aluminum Dragon (Part 1) 15 Oct 2014 20:10 #839

Hi Bertrand,

I got a dihedral angle of 1.3° also, which raises the mid-point of the wing tip 6" above the mid-point of the root rib. You can see my analysis here:


Steve Adkins also arrived at a very similar result by measuring the drawings:

www.ihpa.ie/carbon-dragon/index.php/home-top/plans#steve-adkins - scroll down to his notes on dihedral: "Dwg 1: Dihedral - Note the dihedral in the wing on the frontal view, Dwg 1 by laying a clear straight edge on the front view. Dihedral is moste notable when evaluating Dwg 9D1 thru 5 wherein the lower spar assembly pins are 1/4 inch further from the #1 rib than the upper pins. You do the math ... 1/4 is to 11-1/16 inches as X is to 264 inches; thus, the center of the wing tip will be 5.96 inches higher than if no dihedral. Careful measurement on Dwg 1 confirms this calculation. Don't decide to use a different dihedral ... it can effect the stability and handling of the glider."

I came across another set of rib coordinates a while back - I don't know if they're of any use to you or how they compare:


I'll check out Compufoil when I get a moment to myself!

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Powered Aluminum Dragon (Part 1) 27 Oct 2014 20:48 #842

Hi Phil, i spent time to manually enter the coordinates from " Aerodynamic analysis " in Compufoil. Unfortunatly, the results shows some bumps on the profiles, some coordinates have to be wrong.
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Powered Aluminum Dragon (Part 1) 27 Oct 2014 21:45 #843

I think I used drawing 9 and did my layout using the fitting drawings. Some how my rise at the tip ended up 6.6 in. and that is the difference. I did not want to use the 1/4 scale 3 view drawing. I am not sure .1 degree or 1/2" over 22 ft. is a problem but those are the types of decisions we make doing this. My initial layouts are not cast in stone either.
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Powered Aluminum Dragon (Part 1) 29 Oct 2014 18:53 #844

When I put in those numbers 8.25 and 8.5 over the height of the fittings, I come up with 1.3 degree.

sorry for the confusion. I can tell you what I did wrong but that is not important. I mostly am doing calculations to make the conversion to Aluminum, and the learning curve is steep.

I will be re-drawing all the details, as aluminum is so much different than wood. My plan is to preserve the aerodynamics, geometry, CG, weight if possible.

Thank you for pointing out my mistake.
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