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jetman · February 22nd, 2005, 03:20

USMCmech

The way i understand it:the airspeed indicator measures the dynamic pressure in the pitot
as the plane moves forward through the air [.really it measures the difference between dynamic and static systems pressures]
The value of the dynamic pressure is not only dependent on the airplane speed [ it increases with an increase in speed]but also on the air density[ atmospheric prss and temp.] If we flew at sea level .29.92 '' and 15C IAS and TAS would be the same,as we climb, the air is less dense and exert less dynamic press even if we mantain the same FORWARD SPEED THROUGH THE AIR [TAS] so you would see a decrease in the IAS .Rough correction : for every 1000' of pressure alt. add 2% to the IAS to calculate TAS

Dont know if this may help,regards
Jetman

February 22nd, 2005, 03:20	#2
jetman Junior Member Join Date: Jul 2003 Posts: 188	Re: TAS/CAS/IAS USMCmech The way i understand it:the airspeed indicator measures the dynamic pressure in the pitot as the plane moves forward through the air [.really it measures the difference between dynamic and static systems pressures] The value of the dynamic pressure is not only dependent on the airplane speed [ it increases with an increase in speed]but also on the air density[ atmospheric prss and temp.] If we flew at sea level .29.92 '' and 15C IAS and TAS would be the same,as we climb, the air is less dense and exert less dynamic press even if we mantain the same FORWARD SPEED THROUGH THE AIR [TAS] so you would see a decrease in the IAS .Rough correction : for every 1000' of pressure alt. add 2% to the IAS to calculate TAS Dont know if this may help,regards Jetman