I know that setting up the CG is critical, so I hope someone help me out with this question.

When I measure back from the leading edge, do I measure along the curve like in picture one or just straight back like in the second picture? I know the difference is very little, but I’m trying to get things setup as close as possible.

Just like you have it in the bottom picture. Good Luck, Dave

The greater mass of the the plane must hang down

High wing right side up

Low wing upside down

like the bottom picture is correct....

I remember a few years back when I learned that low wing models should be balanced upsidedown. Is there a big difference in balancing a low wing model upside down vs "upside up?"

Imagine trying to find the "CG" of a pendulum with it sticking up, and you'll have your answer.

"Upside up" balancing on a low will never work. The plane will be so sensitive to balance that it will fall off nose or tail at the slightest movement. You will never know where the balance is.

That is an excellent first post, congrats it seems you will have what it takes to make it in this hobby.

Thanks Learned something new even today, not bad

Thanks to everyone’s help and advice! Glad to find forums like this available for what might be the simple but yet sometimes puzzling questions.

good question , I would like to ask another while on the subject. should i measure back from where the leading edge straightens out or right close to the fuselage ?

Allways measure from the wing root, where the wing meets the fuselage, unless the manual tells you otherwise.
Dont ask me how I found out that

Read this:

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=601]Balancing Up-Side Down?[/link]

hey guys.. is there any "standard" for the CG for all planes? I noted that almost all the guys from my club will try to balance a "new" plane on the field like they already know where it suppose to be.

i try for the main spar and if it's a smooth wing I go for the thickest part

A lot of times it's right at the spar, but that's only a good guess. It's always best to check with the manufacturers suggested CG location. Really try to start at the suggested location, it really can make a difference. I know when I flew CL, out at the field we would check with our fingertips right at the spar, it's at least a good starting point for checking.

Usually it should balance at about 25- 30% of chord measured from leading edge at fuse side. Once you have it in the air you may find you wish to move it further back or foreward. If you're an experienced good flyer you will probably like it back somewhat. It becomes more maneuverable especially for 3D, snaps, and spins.