The DC-10 has two slat positions; one setting from flaps 0 (slats only) to anything less than 35-degrees to my knowledge which yields optimum Lift/Drag ratio, and the second setting from Flaps 35 to Flaps 50 (full-down) which while not yielding the best Lift/Drag ratio, gives the most lift of the two.
The L-1011 has a single slat position which from the minimum flap setting (Flaps 4 IIRC) all the way to Flaps 42 (Full-Down)
-Why doesn't the L-1011 use a similar set-up to the DC-10?
-Is the L-1011's slat set-up optimised for the highest Lift/Drag ratio, or a best-fit across the whole range of speeds which the flaps are down?
(BTW: This thread even though being about the L-1011 and DC-10 is not in anyway connected with the previous thread about the L-1011 and DC-10's wing positions)