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Old 07-01-2009, 01:24 PM
  #26  
ryan1234
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Joined APC: Jun 2008
Position: USAF
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Originally Posted by shdw View Post
Joe,

I am talking to those that have been talking about CAS/TAS/EAS and going into airflow separation differences, pressure changes, and decreased resistance in the boundary area merely to describe a simple stall speed increase with altitude (actual speed). If I am not mistaken the question was answered on the first reply and since the topic has veered off.

KIAS doesn't change period, the designers figured that would make sense. Landing at an airport at 10,000 feet would still be approach at 60 in 172, the actual aircrafts speed is however faster. Who cares whether you call that actual speed CAS/EAS/TAS? Sure EAS is the most realistic or "accurate" aircraft speed. In actuality that argument was merely a search for the most accurate aircraft speed and a distraction from the point, actual speed goes up with altitude and indicated does not. This applies across the board for all, with few exceptions as always, other V-speeds.

For us piston guys, EAS is worthless and accounts for at most a knot difference.

~Brian

Edit: PS that whole bit wasn't to you Joe, only the explaining that I was replying to other posts not the original topic. After that is just my opinion on the original topic.
Indicated stall speed does change because CLmax decreases (i.e. critical AoA) with an increase in altitude, thus a higher stall "speed".
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