One of the shorter term instrumentation "engineers" at Lockheed on the L-1011 saw the fuselage sans wing for the first article.
The cutout for the wing carrythru is definitely not what one would expect.. It resembles an NACA 23012 airfoil, inverted!
The fat part is on the bottom!
This weenie wrote an official letter to the company president, saying Lockheed's aero guys had put the wing on upside down!
He knew this because he had a pilot's license and flew a Cessna 152.
He wasn't there much longer..
Was sent off to Lockheed Missiles, working on a submarine.. we always wondered if he'd ever tried to open a hatch underwater to see what would happen.
Anyway, the changes in wing profile from root to tip on the L-1011 are quite extreme, going from "upside down" at the root to lifting at the pylon to symmetrical at the tip.. all figured to contribute to the full flight regime of the airplane, doing specific jobs at some speeds, and not interfering at others.
The DC-10/MD-11 has an extreme example of the changes in profile and incidences root to tip. for the same reasons.
Any full-scale plane with its large operating envelope is a flying compromise of parts, all intended to work well, but not interfere when they're not needed..
Interference costs money to the customer, and he don't like that!
We spent many many hours fine tuning the aerodynamics of the plane, for 1 or 2 drag counts, which translate into millions of dollars of fuel -not bought- by the customer over the life span of the plane.
SWAG when used with experience, as Lou mentions, is what anyone at the upper end of the performance envelope uses when looking for that last itty-bitty bit of performance, in full-scale and toy airplanes.
For the bank-and-yank crowd, just add more motor!