Originally Posted by colj00
oh ive read a fair amount of times that 35% is a good place to start.
I think you may be confusing the actual CG measurement with something I see often on RCG (it makes me cringe) and that is some people provide the CG measurement from the wing root without explaining that the calculation is done on the Mean Aerodynamic Chord (MAC) and not the root chord. Quite often you'll see this on Delta planforms where the OP say "the CG is at 50% from the leading edge" when the CG is actually 20% of the MAC (even though the physical point on the aircraft is the same)
I've actually seen someone try to balance a conventional plane at 50% from the leading edge "because my delta flew fine that way" The results, of course, were disastrous.
Read the article
that scirocco linked to and take a look at a CG calculator
. None will recommend an actual CG starting point back as far as 35%. (realize that there are exceptions for everything and some 3D pilots will run a rearward CG because they think it makes hovering easier, but may adversely affect all other aspects of flight)