V speeds

Encyclopedia : V : VS : VSP : V speeds

V speeds are speeds that define certain performance and limiting characteristics of an aircraft. They are established by the manufacturer during design and testing, and are specific to the aircraft model. In many cases, they are defined by reference to the standard atmosphere or other specific conditions, and/or at the aircraft's maximum gross weight, and the pilot is responsible for calculating the effective value based on the actual weight and air density..

In the U.S., V speeds are stated in knots or, for older aircraft models, miles per hour. For faster aircraft, some speeds are also defined by Mach number. Typically, V speeds are given for an aircraft at maximum gross weight, and should be adjusted downward if the aircraft is flying lighter.

Contents

1 Speeds frequently used in
2 Speeds used in high performance aircraft and other reference speeds
3 Non-regulatory speeds
4 Speeds indicated on Airspeed Indicator

Speeds frequently used in

V_A

design maneuvering speed (stalling speed at the maximum legal G-force, and hence the maximum speed at which abrupt control movements will not cause the aircraft to exceed its G-force limit).

V_FE

maximum flap extended speed (a different maximum speed may be specified for partial flap extension).

V_LE

maximum landing gear extended speed.

V_LO

maximum landing gear operating speed.

V_MC

minimum control speed with the critical engine inoperative.

V_NE

never-exceed speed.

V_R

rotation speed. The speed of an aircraft at which the pilot initiates rotation to obtain the scheduled takeoff performance. It must be greater or equal to the V₁ speed.

V_NO

maximum structural cruising speed (the maximum speed to be used in turbulent conditions) or can refer to the velocity of normal operation. V_NO is specified as the high end of a green arc on many airspeed indicators. This speed is specific to the aircraft model. The range above V_NO is marked on the airspeed indicator as a yellow arc from V_NO to the V_NE.

V_REF

reference landing approach speed; speed (in calm air) at the landing screen height of 50 ft. Often used by pilots as a base from which to calculate speeds to be used during landing, and calculated as 1.3×V_S0 ( JAR regulations changed : Class B 1,3 Vso and Class A 1,23Vsro ).

V_S

the stalling speed or the minimum steady flight speed at which the airplane is controllable. Usually synonymous with V_S1.

V_S0

the stalling speed or the minimum steady flight speed in the landing configuration.

V_S1

the stalling speed or the minimum steady flight speed obtained in a specific configuration (usually a "clean" configuration of flaps, landing gear and other sources of drag).

V_X

speed for best angle of climb. This provides the best altitude gain per unit of horizontal distance, and is usually used for clearing obstacles during takeoff.

V_Y

speed for best rate of climb. This provides the best altitude gain per unit of time, and is used for normal climbout, and for en-route climb under instrument flight rules (IFR), or to climb above icing.

Speeds used in high performance aircraft and other reference speeds

V_B: design speed for maximum gust intensity.

V_C: design cruising speed.

V_D: design diving speed. Usually 1.4×V_NO.

V_DF/M_DF: demonstrated flight diving speed.

V_EF: the speed at which the critical engine is assumed to fail during takeoff.

V_F: design flap speed.

V_FC/M_FC: maximum speed for stability characteristics.

V_FTO: final takeoff speed.

V_H: maximum speed in level flight with maximum continuous power.

V_LOF: lift-off speed.

V_MO/M_MO: maximum operating limit speed.

V_MU: minimum unstick speed.

V_SR: reference stall speed.

V_SR0: reference stall speed in the landing configuration.

V_SR1: reference stall speed in a specific configuration.

V_SW: speed at which onset of natural or artificial stall warning occurs.

V_TOSS: takeoff safety speed for Category A rotorcraft.

V₁: critical engine failure recognition speed. V₁ is the minimum speed in the takeoff, following a failure of the critical engine at V_EF, at which the pilot can continue the takeoff with only the remaining engines. Any problems after V₁ are treated as inflight emergencies. In the case of a balanced field takeoff, V₁ is the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance and the minimum speed at which the takeoff can be continued and achieve the required height above the takeoff surface within the takeoff distance. In this context, V₁ is the takeoff decision speed.

V₂: takeoff safety speed. Also called takeoff screen speed, the minimum speed in the second segment of a climb following an engine failure.

V_2min: minimum takeoff safety speed.

Non-regulatory speeds

These values are not defined by FAA regulations.

V_BE: best endurance speed; the speed that gives the greatest airborne time for fuel consumed. This may be used when there is reason to remain aloft for an extended period, such as waiting for a forecast improvement in weather on the ground.

V_BG: best power-off glide speed; the speed that provides maximum lift-to-drag ratio and thus the greatest gliding distance available.

V_XSE: speed for best angle climb with the critical engine inoperative.

V_YSE: speed for best rate of climb with the critical engine inoperative.

V₂: t/o safety speed

V₃: steady initial climb speed with all engines operating

V₄: steady climb speed with all engines operating to be achieved by 400 ft gross height

V_a: design maneuvering speed

V_c: design cruising speed.

V_clmax: max coefficient of lift speed.

V_d: design diving speed

V_dmin: minimum drag

V_df: demonstrated flight diving speed

V_ef: the CAS at which the critical engine is assumed to fail

V_f: design flap speed

V_fe: max flap extended speed

V_fto: final t/o speed

V_imd: minimum drag

V_imp: minimum power

V_h: max speed in level flight with max continuous power.

V_le: max landing gear extended speed

V_lo: max landing gear operating speed

V_lof: lift-off speed

V_mbe: max brake energy speed

V_md: minimum drag

V_mc: minimum control speed with critical engine inoperative

V_mca: minimum control speed, air

V_mcg: minimum control speed, ground

V_mcl: minimum control speed, approach and landing

V_me: max endurance

V_mo: max operating limit speed

V_mp: minimum power

V_mr: max range

V_mu: minimum unstick speed

V_nd: max structural cruising speed

V_p: aquaplaning speed.

V_ra: rough air speed

V_ref: reference landing speed

V_s: V-stall

V_so: stall speed in landing configuration

V_s1: stall speed in a specified configuration

V_s1g: one g stall speed

V_sr: reference stall speed

V_sse: safe single engine speed

V_t: threshold speed

V_tmax: max threshold speed

V_x: best angle of climb

V_xe: best angle of climb, single engine

V_y: best rate of climb

V_yse: best rate of climb single engine

Speeds indicated on Airspeed Indicator

Airspeed Indicator

V speeds are nearly always given as Indicated Airspeed (IAS), so that pilots can read them directly off the airspeed indicator (ASI). ASIs carry color-coded markings that give the pilot an immediate reference, as follows:

V_S0

bottom of white arc.

bottom of green arc.

V_FE

top of white arc.

V_NO

top of green and bottom of yellow arcs. The yellow arc is a caution, as speeds in this region may add dangerous stress to the aircraft, and are only to be used in smooth air when no turbulence or abrupt control inputs are expected.

V_NE

red line and top of yellow arc.

In addition, on a light multi-engine aircraft, V_YSE is indicated by a blue line, and V_MC is indicated by a red line near the bottom of the green arc.

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