How do I determine the CG. of a swept wing

[jsowell]

My name is Jim and I am a mechanical engineer student at NMSU. I am the lead engineer on my senior project, which is to design, manufacture, and fly a UAV. I need help determing the lacatoin of where the CG should be. Anything would help. Thank you!

Jim
NMSU ME

[phat23]

Try this site
http://www.geistware.com/rcmodeling/cg_super_calc.htm

[Abomination]

you can find the center of gravity (CG) using the statics you learned - find the resultant gravitational force of all the aircraft components.

what is most important is the center of lift (CL) - thats the resultant pressure (lift) force on the aircraft. You want to make sure the CL is on or behind the CG to insure a naturally stable system. Finding the CL isnt too difficult, I tried to a way to approximate it here:

http://www.rcgroups.com/forums/showthread.php?s=&threadid=205268&highlight=center+of+lift

but it would be best for you to hit up the library and find an aero book and make yourself comfy.

Here is another link you might want to read - this is a pretty good looking site:

http://142.26.194.131/aerodynamics1/Stability/Page7.html

BTW - I am a UTEP grad so you might want to dismiss all the above...

[Sparky Paul]

Ab, "center of lift" is outmoded, and has been replaced by the static margin and neutral point considerations.
Although the center of lift can be applied, it's a mathematical construct which fails at the end points.
It's easier to find modern design principles for the static margin etc.. Martin Simons and Andy Lennon cover it thoroughly in their books.

[Abomination]

Good point. I like the CL explanation because it's more intuitive to me than:

make sure dCM/dCL < 0, etc...

Here is another good link:

http://adg.stanford.edu/aa208/amsc.html