Going just a bit further with the discussion, and looking at the Lockheed TriStar in particular, some might ask just why did Lockheed design the horizontal stab the way they did?
My understanding is that the particular design was selected so that in conjunction with the other quite unique TriStar design feature, direct lift control (DLC
), is that this particular feature allowed for very stable approach paths to be flown, for automatic approach/land (autoland) operations.
The TriStar was the FIRST widebody civil jet transport to achieve CATIIIB certification, and it did so directly from the factory.
A superb design, quite unique in many respects....and liked a LOT by the folks who still fly them, myself included.
It is quite apparent that a huge amount of design effort was put into the flying qualities of the TriStar, and it paid off very well.
An absolute delight to fly.