At 03:36 18 April 2012, Bob Gibbons wrote:
-- Max gross with or without the engine is 500kg. The issue with the
engine in place is the 255kg non-lifting limit. With the engine in
place, the pilot weight determines whether the max gross of 500kg or
the non-lifting limit of 255kg kicks in first.

You've lost me somewhere.

Why does pilot weight stop you getting to max gross as long as the wing
tanks are big enough?

Assuming tanks *are* big enough to get to max gross without the engine then
it should be a piece of cake to get there *with* the engine.

PF