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ryanbatcund

ASI's that change

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What is the difference between planes that have a moving ASI and fixed?

 

For example I'm looking at the barber pole on the Carenado BE20. It's around 290 at sea level (guessing from their pics). At around 15,000 it's down to about 240 kias.

 

In the Turbine Duke that one always sticks at 198 (I believe 198 is VNE - or is it VMO?)

 

How does this work since their both Turboprops? Does it depend on powerplant?


|Ryan Butterworth|

| i7 4790K@4.4GHz | 32GB RAM | EVGA GTX 1080Ti | ASUS Z97-Pro | 1TB 860 Evo | 500GB 840 Evo Win10 Pro | 1TB Samsung 7200rpm | Seasonic X750W |

 

 

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From Wikipedia:

 

The term on the barber pole is pilot jargon that refers to flying an aircraft at the maximum safe velocity. The airspeed Indicator on aircraft capable of flying at altitude features a red/white striped needle resembling a barber pole. This needle displays the VMO (Maximum Operating Velocity) or—at altitude—the MMO (Mach Limit Maximum Operating Speed) of the aircraft.[21] This needle also indicates the maximum operating Mach number above the VMO/MMO changeover level. As the aircraft increases in altitude and the air decreases in density and temperature, the speed of sound also decreases. Close to the speed of sound, an aircraft becomes susceptible to buffeting caused by shock waves produced by flying at transonic speeds. Thus, as the speed of sound decreases, so the maximum safe operating speed of the aircraft is reduced. The "barber pole" needle moves to indicate this speed. Flying "on the barber pole" therefore means to be flying the aircraft as fast as is safe to do so in the current conditions.[22]

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Yeah but why is it fixed on the duke and dynamic on the king air?


|Ryan Butterworth|

| i7 4790K@4.4GHz | 32GB RAM | EVGA GTX 1080Ti | ASUS Z97-Pro | 1TB 860 Evo | 500GB 840 Evo Win10 Pro | 1TB Samsung 7200rpm | Seasonic X750W |

 

 

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