droop

droop

The deviation from a preset value of a controlled liquid level, temperature, variable pressure, or differential pressure (at minimum controllable flow) when the flow through a regulator is gradually increased from its minimum controllable flow to its rated capacity.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

droop

i. A downward curvature of the leading edge of an airfoil to provide increased camber.
ii. A progressive decrease in RPM that occurs when a fuel control flyweight governor spring is extended and made weaker. It takes less flyweight force to come to an equilibrium with the weaker spring force and consequently a lower RPM will result.
iii. The inability of the engine power to increase as the rotor pitch is increased, causing the rotor to slow down.

An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved