ORIGINAL: cervelott
I am assuming that the aircraft C of G testing done at completion of a build is done without fuel. Both my latest ARF builds (LT40 and Pulse XT 60) don't mention fueling the tank prior to testing the
C of G. I am assuming that this is because the fuel tank is positioned in a C of G neutral position...correct???
You are mostly correct but wrong on one assumption.
Most fuel tanks are not mounted in a nuetral position. An airplane can be easily controlled if it is a little nose heavy but difficult to impossible if tail heavy.
with the tank in the front, as most airplanes are, as you run low on fuel the CG shifts toward the rear. We balance with no fuel so we know our planes are OK to fly when the tank gets low and even though with the tank full and the aircraft a bit nose heavy it is still controllable.