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When Boeing launched the 757 and 767 aircraft, they widely touted it's improved fuel efficiency relative to previous airliners. Notably:

  • Delta stated that the 767 was "quieter and 30 percent more fuel-efficient than Delta's older jets it replaced." Source
  • Guy Norris stated, "aerodynamic improvements contributed to the 30% fuel burn savings that were claimed for the 767 over previous types" Source

In what ways did Boeing engineer's improve the design of the aircraft to lower the fuel burn of the aircraft? Of course, propulsion advances (e.g. GE's CF6 engine) played a huge role. However, my interest is in other aspects of the design, most specifically the design of the wing and other aerostructures.

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  • $\begingroup$ The primary driver of reduced fuel burn through the history of gas turbine-powered flight is increased efficiency of the engines, which comes from two things: 1) new blade materials that permit operation at higher temperatures and 2) bypassing the core and generating thrust with a fan. $\endgroup$
    – niels nielsen
    Feb 1, 2022 at 19:35
  • $\begingroup$ Definitely understand that! And I picked up a couple of great books on the evolution of engines. For example: amazon.com/Starting-Something-Big-Commercial-Emergence/dp/…. That's why I asked about wings & aerodynamics specifically, since that's what I know the least about :) $\endgroup$
    – interested22
    Feb 1, 2022 at 20:47

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Your Norris source states most of the aero improvements came from the wing.

enter image description here

The airfoil mentioned has a supercritical section. Below is a typical supercritical section compared with one from the 707. The actual 767 section is Boeing proprietary and its profile is not likely to be easily found. Shown is the comparatively greater thickness and aft camber of the supercritical airfoil.

enter image description here

Important for fuel burn reduction is the drag characteristic these sections give to the wing. Comparing the drag polars for the two sections you see that the minimum drag is similar, but that the 'drag bucket' for the supercritical section is four or five times wider than that of the 707.

This matters because aircraft have to operate at different weights due to payload, flight length and fuel burning off during a flight. An aircraft with the drag characteristic of the supercritical section can stay in the low drag region longer, while the 707 section equipped aircraft has to move up the curve into higher drag and thus higher fuel burn. The angle (alpha) at which minimum occurs doesn't matter as aircraft are designed to take this into account.

enter image description here

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  • $\begingroup$ Thanks for the answer! That raises another question in my mind, which is whether the supercritical aerofoil was improved over time for future aircraft, like the 777. That is, the goal of a supercritical aerofoil, as I understand it, is to delay the onset of the shock and flatten the pressure distribution over the top wing. Did post-767 aircraft do that "better" than the 767 did in some way? $\endgroup$
    – interested22
    Feb 17, 2022 at 2:10

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