COG help

[pc_pilot]

Can someone tell me where the COG is based on these dimensions of a swept wing.

inches.
root chord = 9
tip chord =5
span=27

thanks

[CloudyIFR]

pc_pilot,

If you have a spreadsheet program this will help.

http://www.charlesriverrc.org/articles_modeldesign.htm

Download the file "Sailplane Calc" under Software.

I can run the data but is there any sweepback in the leading edge of the wing? Is the 27 inches full or half span? To get more accurate what type of plane is it? Canard, Sailplane, Power Plane? A safe starting point is 25% of the Mean Aerodynamic Chord. The spreadsheet will calculate all that with some very basic measurements.

Any more help please ask.

Curtis

[vintage1]

Can someone tell me where the COG is based on these dimensions of a swept wing.

inches.
root chord = 9
tip chord =5
span=27

thanks

Not without knowing where the stabilizer is and how large it is, no.

Or is this a tailless design?

[feihu]

The CG of an airplane sets the stability margin of the airplane, and may vary according to the pilots desired handling/flying qualities. For a conventional configurated airplane, a good starting point is about 30% mean aerodynamic chord (MAC). You may want the CG at 25% MAC or 35% MAC to suit your model and your flying style.
For a swept wing airplane with a conventional tail, you must first find the MAC and establish your desired CG on the MAC and then balance at that point on the wing, or project that point to the fuselage for a balance point adjacent to the fuselage.
Here is a graphical solution to finding the MAC of a conventional or swept wing.