![]() ![]() Maximum speed in level flight with maximum continuous power. This speed decreases as weight decreases. Final segment speed (jet takeoff) with critical engine inop. The minimum speed required for flap retraction after takeoff. The purpose of flaps during landing is to enable steeper approaches without increasing the airspeed. Positive load for Normal category airplanes is usually reduced from 3.8 Gs to 2 Gs with the flaps down, and negative load is reduced from minus 1.52 Gs to zero. Many aircraft allow the use of approach flaps at speeds higher than VFE. The highest speed permissible with wing flaps in a prescribed extended position. VFC is expressed in knots MFC is expressed in percentage of Mach. Instability could develop beyond the pilot’s ability to recover. It must be regarded with the same respect as VNE: redline. Maximum speed for undesirable flight characteristics. If the engineers did a good job, the actual flap speed, or VFE, will be the same. The flaps are designed to be operated at this maximum speed. Jets accelerate to VENR above 1,500 feet agl. En route climb speed with critical engine inop. Speed at which the critical engine is assumed to fail during takeoff (used in certification tests). When this is the case, the test pilot dives to the maximum speed possible - the demonstrated flight diving speed. Some aircraft are incapable of reaching VD because of a lack of power or excess drag. Accelerate/stop decision speed for multiengine piston and light multiengine turboprops. It can worsen until the aircraft is destroyed, even if airspeed is reduced as soon as flutter begins. ![]() If flutter begins, it can become catastrophic in a matter of seconds. Control surfaces have a natural vibration frequency where they begin to “flutter” like a flag in a stiff breeze. The aircraft is designed to be capable of diving to this speed (in very smooth air) and be free of flutter, control reversal or buffeting. It is the highest speed at which the structure must withstand the FAA’s hypothetical “standard 50 fps gust.” VD The completed aircraft may actually cruise slower or faster than VC. Speed at which the aircraft was designed to cruise. ![]() Turbulent-air penetration speed that protects the structure in 66 fps gusts. Design speed for maximum gust intensity for transport-category aircraft or other aircraft certified under Part 25. Typically add (to VREF) half the headwind component plus all the gust factor (to a max of 20 knots). VREF plus configuration (flaps/slats setting) and wind factor. Missed-approach climb speed for flap configuration with critical engine inop (2.1 percent climb gradient). This speed decreases as weight decreases.įormula for determining VA at less than max landing weight: VA2 equals VA multiplied by current weight divided by max landing weight. If only one speed is published it is usually determined at max landing weight. It does not allow for multiple large control inputs. The highest safe airspeed for abrupt control deflection or for operation in turbulence or severe gusts. ![]()
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