Alpha rate

[ramshorn]

Hi guys/girls
Can someone please let me know the difference between pitch rate and alpha rate?:)

[Cabotage Kid]

I assume it is basically it is the difference in the rate of change of the Angle of Attack (alpha) and Pitch. Although I have not heard anybody asking for the alpha or pitch "rate" before.

The definition of AoA is the angle between the mean chord line of the wing and the relative airflow. Pitch is the angle between the longitudunal axis of the a/c and the 'horizon.'

[Dick Whittingham]

Think of a steady loop. Pitch is increasing as the nose comes up, but alpha is more or less constant. Pitch rate high and positive, alpha rate zero.

Stall warning and avoidance systems essentially interrogate alpha, for alpha defines the stall. However, if alpha is rising rapidly toward the stall value it would be prudent to start the warning or recovery before the whole thing overshoots and turns to worms. Therefore modern stall warners interrogate alpha rate as well as alpha.

Dick W

[Cabotage Kid]

Thanks Dick. I've certainly benefitted from your explanation.

[ramshorn]

I'll second that.thanks for the explanation Dick.
Ramshorn