Why Are Flaps Used in Some Soft-field Takeoffs?

Who said flaps don't increase lift? Flaps do increase lift. Reference Chapter 6 of the Pilot’s Handbook of Aeronautical Knowledge, which states, "Flaps are the most common high-lift devices used on aircraft. These surfaces, which are attached to the trailing edge of the wing, increase both lift and induced drag for any given angle of attack (AOA)."

Meg Godlewski

Tuesday, September 20, 2022 at 08:49 AM ET

Verified

A Cessna 170B with flaps extended. [Credit: Adobe Stock]

Key Takeaways:

Flaps are high-lift devices that increase both lift and induced drag, contrary to the premise that they do not increase lift.
A minimal flap setting is used in soft-field takeoffs for some aircraft because it lowers the stall speed, allowing the aircraft to lift off at a lower airspeed.
The correct flap setting for takeoff is crucial and specified in the Pilot's Operating Handbook (POH); using too much flap can excessively increase drag, diminishing lift's usefulness and hindering takeoff.

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Question: If flaps don’t increase lift, then why is a small amount of flaps used in soft-field takeoffs for some aircraft?

Answer: Who said flaps don’t increase lift? Flaps do increase lift. Reference Chapter 6 of the Pilot’s Handbook of Aeronautical Knowledge, which states, “Flaps are the most common high-lift devices used on aircraft. These surfaces, which are attached to the trailing edge of the wing, increase both lift and induced drag for any given angle of attack (AOA).”