Clean configuration is the

flight configuration Clean configuration is the flight configuration of a fixed-wing aircraft when its external equipment is retracted to minimize drag (physics), drag, and thus maximize airspeed for a given power setting. For most airplanes, clean configuration mean ...

of a

fixed-wing aircraft A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinc ...

when its external equipment is retracted to minimize drag, and thus maximize

airspeed In aviation, airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: * Indicated airspeed ("IAS"), what is read on an airspeed gauge connected to a Pitot-static system; * Calibrated a ...

for a given power setting. For most

airplane An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spe ...

s, clean configuration means simply that the

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...

flaps and

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

are retracted, as these are the cause of drag due to the lack of streamlined shape. On more complex

s, it also means that other devices on the wings (such as

slats Super Low Altitude Test Satellite (SLATS) or Tsubame was a JAXA satellite intended to demonstrate operations in very low Earth orbit (VLEO, below 200 km), using ion engines to counteract aerodynamic drag from the Earth's atmosphere which i ...

, spoilers, and leading edge flaps) are retracted. Clean configuration is used for normal cruising at altitude during which lift, or rise in altitude, is not needed. In military aviation, a clean configuration is generally without external stores which reduce maximum performance both due to increased weight and even more so due to increased drag.https://books.google.com/books?id=kaqvC4e_EKcC&pg=PA246&dq=%22clean+configuration%22+stores&hl=en&sa=X&ved=2ahUKEwjg8sCyydbrAhUKlFkKHfEmDiMQ6AEwAXoECAIQAQ#v=onepage&q=%22clean%20configuration%22%20stores&f=false page 246

References

Aerospace engineering {{Aviation-stub