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drop tank[′dräp ‚taŋk]
A fuel tank on an airplane that may be jettisoned.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The auxiliary fuel tank(s) carried externally either under the wing (normally referred to as wing drop tank) or fuselage (called belly drop tank and which can be jettisoned, if so desired. Fuel is consumed from drop tanks first and from the aircraft internal tanks later, so that the drop tanks can be jettisoned, if so required.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved