Wright's 1936 paper reports four distinct learning curves, not one flat 80% — the whole-airplane composite rises from 83% to 90% as quantity scales

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The single "80% learning curve" popularly attributed to T. P. Wright's 1936 paper is, by the paper's own numbers, one of four separate figures Wright reports — the labor-only curve. Raw material has its own, slower-improving curve: "the curve for material reduction applying to raw material is given as a ninety-five percent curve (exponent of .0732)." Purchased material sits between the two: "purchased material this factor is shown at eighty-eight percent (exponent of .184)." Higher percentages mean slower cost reduction per doubling, so both material curves improve more slowly than the 80% labor curve.

Combining labor, material, and overhead for the whole airplane produces a fourth curve that is not even a constant percentage: "it is indicated that the curve will start out at eighty-three percent, then change to eighty-five percent, then change to eighty-seven percent, and finally reach ninety percent" as cumulative quantity increases. The composite drifts upward — cost reduction per doubling slows — as material's comparatively slower-improving share of total cost comes to dominate labor's faster-improving share.

The popular flat-80%-for-everything shorthand is therefore not what the 1936 paper itself presents: the whole-airplane curve is neither flat nor 80% at scale. (A further popular claim, that a flat 80% curve "became the gold standard for defense contracting," was not checked against a primary this session and is not asserted here.)