RE: Let's talk P-13
Typical P11: 3000-3500 mAh and no more than 06:30, usually 06:00.
If the square loops four corners should have the half the radius of the half loop preceding it plus a straight line before and after the half roll, it will be twice as big as the half loop. Then the plane is below ground level :-)
It's a choice between a gigantic 9 or a very tight square.