Drift (of an aeroplane as distinct from the propeller)—The horizontal component of the reaction produced by the action of driving through the air a surface inclined upwards and towards its direction of motion plus the horizontal component of the reaction produced by the "detrimental" surface plus resistance due to "skin-friction." Sometimes termed "head-resistance."
Drift, Active—Drift produced by the lifting surface.
Drift, Passive—Drift produced by the detrimental surface.
Drift (of a propeller)—Analogous to the drift of an aeroplane. It is convenient to include "eddies" and "cavitation" within this term.
Drift, to—To be carried by a current of air; to make leeway.
Dive, to—To descend so steeply as to produce a speed greater than the normal flying speed.
Dope, to—To paint a fabric with a special fluid for the purpose of tightening and protecting it.
Density—Mass of unit volume; for instance, pounds per cubic foot.
Efficiency—
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