TAS and IAS

[Aaron]

Can someone please explane TAS and IAS to me?

Thanks


Aaron

[wells]

IAS = 'indicated airspeed'
TAS = 'true airspeed'

IAS is what the pilot reads on the gauge in the cockpit.
TAS is the speed, corrected for density.  Because the density is low at high altitudes, the TAS is higher than the IAS.  At sea level, TAS = IAS

If you apply wind components to the TAS, you get groundspeed, otherwise TAS = groundspeed.

[Minotaur]

IAS is the speed that is important for manuvering.  This is the speed of the air passing over the wings and control surfaces.  In essence, how much lift or control force the airframe can provide.

The difference between TAS and IAS increases as the plane increases in altitude.  Considering level flight, at sea level they are almost equal.  At 30,000ft TAS can be almost double IAS.

Example:{/b]
If TAS is 360mph and IAS is 220mph.  Any manuver the plane is capable of, especially verticle manuvers, is based on IAS or 220mph.  Not the higher TAS of 360mph.

Good Luck!

Mino