Definition
The rearward and downward movement of a helicopter rotor disc that occurs as the helicopter gains forward airspeed. As airspeed increases, the advancing blade produces more lift than the retreating blade, causing the rotor disc to flap up at the front and down at the rear, tilting it back relative to the direction of flight.
Plain English
When a helicopter speeds up going forward, the spinning rotor disc naturally tips backward a little. The pilot has to push the cyclic forward to correct for it.
Context Anchor
Seen in propeller-system discussions, especially when describing the forces that act on propeller blades during flight.
Derivation
From 'blow' (to push by air movement) and 'back' (rearward). The name describes what the pilot sees and feels: the rotor disc appearing to be blown backward by the oncoming air as forward speed builds.
Why Pilots Care
Uncontrolled blowback can increase propeller pitch, raise engine load, and reduce efficiency unless countered by weights or hydraulic mechanisms.
Intuition Check
Blowback does not mean exhaust, smoke, or flame coming back toward the airplane here. It means airflow twisting a propeller blade toward a lower blade angle.
Example Sentence 1
As the helicopter accelerated through translational lift, the instructor reminded the student to apply forward cyclic to counter blowback.
Example Sentence 2
During high-power climb the pilot monitored engine RPM to detect any signs of blade blowback.