Definition
The downward bending of helicopter rotor blades when the rotor is stopped or turning at low RPM, caused by the weight of the blades acting against insufficient centrifugal force to hold them out straight.
Plain English
When a helicopter's rotor blades are not spinning fast, they sag downward under their own weight. Once the rotor spins up to normal speed, the spinning force pulls them straight out again.
Context Anchor
Seen in helicopter preflight, rotor start, shutdown, and discussions of rotor blade clearance.
Derivation
‘Droop’ comes from the Old Norse ‘drupa,’ meaning to sag or hang down. It describes exactly what the blades do at rest — they hang lower than their flying position.
Why Pilots Care
Confirms safe clearance between the blades and the fuselage or ground before rotor startup.
Grounding Statement
A stopped rotor blade is being held up mostly by its structure, not by the spinning force that helps straighten it in operation.
Intuition Check
Blade droop does not mean the blade is failing or loose by itself. It means the blade is sagging downward, especially when the rotor is stopped or slow.
Example Sentence 1
During shutdown, the pilot waited for the rotor to slow before exiting, knowing blade droop would lower the tip path.
Example Sentence 2
During shutdown the pilot watched the blades settle into their normal droop position.