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Air Speed Indicator Markings & V speed definitions

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rc2017's version from 2017-09-03 19:58

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Question Answer
What is V speed?V speeds are standard terms used to define various airspeeds useful to all aircraft operations, ensure safety and best performance. V speeds are also a requisite for airworthiness of an aircraft's certification
Importance of ASI color codingColour coding is important since in every aircraft you can see Vso, Vs1, Vx, Vy, VFE, VNO, Vne & Va etc immediately on the colour
White Arc range in ASIThe Flaps Operating Range is denoted by the White Arc. Flaps may only be used within this range of speeds. It ranges from Vso (stall speed in dirty configuration-flap down-ready to land) to VS1 (stall speed in clean configuration -flaps up) and also covers till the top part of the white arc: the VFE (Flaps extended at 10 degrees or at 10-30 degrees)
VSOThe lower scale end of the white arc is the stalling speed with wing flaps fully down. It is the minimum flight speed with a dirty configuration for landing. (i.e. Gear Down and Flaps Down)
VSO in C172r33 Knots
VFEThe upper end of the scale of the white arc. Full Flaps Extended speed. Maximum speed at which flaps may be fully extended upto 30 degrees
VFE in C172r85 Kts
VS1The beginning scale of the Green Arc is the Stalling Speed or minimum steady flight speed in the clean configuration (flaps fully retracted)
VS1 in C172r44 Kts
VxVx is the best angle of climb - with reference to distance on runway during Takeoff
VyVy is the best rate of climb - with reference to time spent on runway during Takeoff
Green Arc range in ASIThe Green Arc on the Airspeed Indicator depicts the normal operating airspeed range. VS1 to VNO (stall speed in clean config to normal operating speed)
VnoVno is the safe structural cruising speed for normal operations. Upper end scale of the green arc
Vno in C172r129 kts
Yellow Arc range in ASIBeyond the Green Arc, we see the Yellow Arc. The speed range marked by the Yellow Arc is the Caution Speed Range. VNO to VNE (normal operating limit spped to never exceed speed)
VneThe Red Line at the top of the Yellow Arc is the Velocity (V) that you Never (n) Exceed (e). Exceeding the Vne Airspeed can cause flutter, and failure of structural components on the aircraft.
Vne in C172r163 Kts
VaVa is maneuvering speed. This is the speed above which it is unwise to make full application of any single flight control
Va in C172r99 Kts
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