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Old 4th June 2011 | 15:18
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OK465
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From: BOQ
And the cosine of 61 degrees is 0.4848, so the longitudinal component of 151 kt is 73 knots?
HN 39:

I may not see exactly what you’re getting at. If I look at the triangle I think you’re referring to, i.e. aircraft longitudinal axis and FPA and I close it vertically, I get a near equilateral triangle, not a right triangle, so the cosine function of 61 degrees is N/A? If you close it either of two ways to make a right triangle, I’m not sure what that other side represents?

For a constant given inertial FPA (in this case -45), with vertical speed along the vertical axis & groundspeed along the horizontal axis, as you increase any postulated headwind component, for a given constant pitch attitude (in this case +16), it has the effect of lowering the existing aero AOA (higher KTAS & consequently higher KCAS for the conditions) while the inertial AOA (in this case 61 degrees, 16+45) remains the same. I think…
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