Definition
A large, ducted fan mounted vertically in the fuselage or wing of a VTOL or STOL aircraft that produces direct upward thrust to lift the aircraft during takeoff, hover, and landing. The fan is typically driven by a connected turbine engine through a shaft and clutch, and is used only during low-speed vertical operations; once the aircraft transitions to forward flight, the fan is disengaged and its inlet and outlet are closed by doors so the wings carry the load.
Plain English
A built-in vertical fan that pushes air downward to lift the aircraft straight up off the ground. It is only used for taking off, hovering, and landing, and is shut off and covered up once the aircraft is flying forward on its wings.
Context Anchor
Seen in discussions of vertical-lift aircraft, short-takeoff aircraft, and propulsion systems that help an aircraft hover or lift off in a small area.
Why Pilots Care
Lift fans change how the aircraft handles in the vertical phase of flight. The transition between fan-supported lift and wing-supported lift is a critical, high-workload moment, and understanding the system is essential for managing power, balance, and timing during takeoff and landing.
Grounding Statement
When the lift fan spins, it sends air downward, and the aircraft is pushed upward in response.
Intuition Check
A lift fan is not just a cooling fan or cabin fan. In this context, it is part of the aircraft’s lifting system and is used to help raise the aircraft.
Example Sentence 1
The pilot engaged the lift fan and the aircraft rose vertically off the deck.
Example Sentence 2
During preflight inspection the mechanic checked the lift fan intake screen for any obstructions that could reduce airflow.