v speeds Flashcards
V A
● Design safety speed or maximum manoeuvring speed.
○ Full deflection of the controls above this speed will cause structural damage.
○ Remember that V A increases as aircraft weight increases.
○ For this reason it is not indicated on the airspeed indicator.
V B
● Design speed for maximum gust intensity.
○ This is the maximum speed at which a ‘standard’ gust will not overstress the airframe.
○ A standard gust is defined as one of 66 ft/s.
○ This is a certification standard meant to protect transport category aircraft.
○ Vb will be higher than Va
V C
● It is the design cruise speed Vc.
○ A maximum vertical gust for Vc is 50 f/s.
○ Vc will be higher than Vb
V D
● It is the design dive speed Vd.
● Vd is based on the principle of an upset when the aircraft is experiencing a speed increase in a shallow dive after flying at Vc, until the complete recovery is made.
● The aircraft must also be strong enough to withstand a vertical gust of 25 ft/sec at Vd
V 1
● Critical engine failure recognition speed or decision speed.
- in general, highest speed at which a take off may be aborted.
- assuming a balanced field, aborting take off above this speed will result in going off the end of the runway
Accelerate-Go Distance
● The distance that is required:
- to accelerate to V 1
- critical engine failure at V 1
- continue accelerating, lift off and reach 35 feet AGL by the end of the runway
Accelerate-Stop Distance
● The distance to accelerate to V 1 and then to stop.
● Balanced Field Length: Accelerate-stop distance = Accelerate-go distance
V 2
● Take-off safety speed.
○ This is also sometimes called the best climb gradient speed.
○ It is the speed at which the airplane will achieve the minimum obstacle climb gradient requirements in the event of an engine failure.
○ This speed will be (must be) attained by 35 feet above the runway
V FS
● Velocity of the Final Segment.
○ This is the speed that jets will use during the final segment of their climb.
V MBE
● Velocity of Maximum Brake Energy.
○ This is the maximum speed at which we could stop the plane with brakes only.
V REF
● Threshold Crossing Speed:
o This is the desired speed that the aircraft will have at a 50 foot height if the landing distances calculated are going to be obtained.
● Calculating the Vref speed will also take into account the following items:
o Weight
o Temperature
o Field Elevation
o Flap settings
V MC
● The minimum indicated airspeed (minimum control) at which it is possible to retain control of the aeroplane and maintain straight and level flight through the use of maximum rudder and not more than 5 degrees of bank, following the sudden failure of the critical engine.
○ Lower red line on ASI
The critical engine is the engine whose failure will result in the most adverse handling characteristics. Typically the left hand engine is the critical engine due to clockwise rotation of its propeller
VS
● Stalling speed or minimum steady controllable flight speed.
○ For this determination, the wings are considered level.
○ Bottom of green arc on ASI.
○ It is considered and calculated to be with no engine power.
Vs0: landing configuration.
V FE
● Maximum speed with flaps extended.
○ Generally this is the top of the white arc
● This speed will likely vary with the amount of flap deployed:
V S1
● Stalling speed or minimum steady flight speed obtained in a specific configuration.
○ This speed is often the same speed as the “clean” stall.
