(%mac)

[quailbird]

I am a little stumped! On the calculator for center of gravity you need to know the % of MAC. It won't calculate unless you have that number. Same way on the CG. How do you get the %MAC in order to finish the calculations?

[Sparky Paul]

Where do you want the c.g. to be. is the question posed by those programs.
That depends on the aircraft configuration.
Determine where the c.g. is normally placed for that shape, and use that number.

[omega blood]

You can start at 25% on a conventional plane and work from there. On a flying wing 15-20% is a good starting point.

[Ollie]

On a tandem wing configuration the CG is well aft of the trailing edge of the forewing.

Given a trainer and an aerobat of the same configuration, the trainer should have a somewhat more forward CG than the aerobat. The better the eyesight, reflexes and experience of the pilot the more aft the allowable CG.

Two planes of similar configuration but one having lots of parasitic drag in the form of uncowled engine, fat fuselage and unstreamlined apendages, the aerodynamically "dirty" plane will require a slightly more forward CG.

[Dick Huang]

quailbird,
See the enclosed spread sheet. You might want to set one up to keep up with the CG,MAC and static margin.
Dick Huang