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need,wing cg ronnies

Old 01-24-2004, 05:05 PM
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Ronnies
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Default need,wing cg ronnies

wing cg
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Old 01-24-2004, 05:15 PM
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CafeenMan
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Default RE: need,wing cg ronnies

*Edited to remove answer to a question that wasn't asked*
Old 01-24-2004, 05:39 PM
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Default RE: need,wing cg ronnies

It depends on the size of the stab and the moment arm but if they are fairly normal I'd start with the balance back at the 3 inch point back from the leading edge at the root. It'll probably be too far forward still at that point but you can fine tune it from there. Certainly better than too far back.
Old 01-24-2004, 05:42 PM
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Default RE: need,wing cg ronnies

thanks BMATH ....RONNIES
Old 01-24-2004, 09:46 PM
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Default RE: need,wing cg ronnies

Note... the CG does depend on the rest of the aircraft configuration somewhat.

If its a conventional type.. Engine in front, then main wing then the tail surfaces back a bit behind the main wing... the above is correct. (unless the Stab is very small or very close to the main wing... then act like its a flying wing.)

If its a flying wing, you need to move the CG forward at least 1.25 inch.

If its a Canard... we need to know the Canard (the little wing in front) size and how far between the wings. (CG could be forward of the main wing with a Canard.)
Old 01-24-2004, 10:01 PM
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TLH101
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Default RE: need,wing cg ronnies

Her's a caculator. Use 25-30% for MAC : http://www.palosrc.com/instructors/cg.htm
Old 01-24-2004, 11:30 PM
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Default RE: need,wing cg ronnies

Old 01-25-2004, 01:23 AM
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Default RE: need,wing cg ronnies

Oh great. You drew it backwards. In drawing wings like your sketch it's generally accepted that the upper side is the leading edge.


This changes everything. The balance point in this case should be about 2.25 inches back from the leading edge.
Old 01-25-2004, 05:05 AM
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Ronnies
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Default RE: need,wing cg ronnies

Thanks again BMatthews RE: need,wing cg ronnies (in reply to CafeenMan) .sorry about the inverted picture as you can see the only hint is that I drew in the ailerons, Its a good thing I didnt mount the wing yet.so Ill make the CG at 2.25 inches from the front edge going back.
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Old 01-25-2004, 05:22 AM
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CafeenMan
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Default RE: need,wing cg ronnies

Ronnies - I thought you had asked how to find the area. My response was to divide the wing into triangles and then do the math. I don't know why I thought you asked that. I must be getting old.
Old 01-25-2004, 05:40 AM
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Ronnies
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Default RE: need,wing cg ronnies

Ill bet Im older than you at age 56, I wouldnt know the triangle math just basic, but Im glad you helped me anyway.Thanks Ronnie
Old 01-25-2004, 05:45 AM
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CafeenMan
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Default RE: need,wing cg ronnies

ORIGINAL: Ronnies

Ill bet Im older than you at age 56, I wouldnt know the triangle math just basic, but Im glad you helped me anyway.Thanks Ronnie
When you have a funny shape that is mostly straight lines, there aren't any useful formulas for finding the area in one shot. So you draw lines to cut part into simpler shapes - triangles, rectangles, etc. Then you find the area for each part and add them together.

Area of a triangle is 1/2 x base x height. So if the triangle is 6" on one side and 18" on the other, then 1/2 x 6 x 18 = 54 square inches.

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