Ken, I don't know the answer to this myself but I think that your 1/4C reply might be just a bit off-hand.

1/4C of what? Root chord? MAC Chord?

What about area proportions? Like 33% or 10% of area in front of pivot?

Just think for a bit laddie, and remember that the t/p of a SU27 has a fair old sweep to it, it is not a simple plank sticking out there.