When you water ballast the four wing tanks of an LS8a you fill the
inner tanks first, and when you dump the water there’s provision for
the inner tanks to drain last. With a RS LS8-18 (and the newer DG LS8-
s) this procedure is reversed - the outer tanks are filled first and
there’s provision for the outer tanks to drain last. This was a
deliberate decision, because mechanical changes were made to the two-
handled dump system levers.

Why would aircraft designers want to keep weight towards the wing
tips? Does it have something to do with going from a 15m to an 18m
span? Wouldn’t the increased moment of inertia and wing spar bending
negatively affect performance?

-John