A320/321 holding speeds
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A320/321 holding speeds
Is there, out there, an ETPS graduate or a CFS A1 or someone with a proper degree in aerodynamics who can explain why the A321 holds at green dot and the A320 holds at green dot plus about 20kts?
The brochure says that green dot is max lift/drag ratio. At 1g, presumably that is equal to Vimd since lift is constant = weight.
The problem occurs on the corners. If you speed select green dot on the A320, then, when you go round the corners the Vls comes up to meet the selected speed and the engines have to wind up to loads of fuel flow in order to maintain the speed - plainly not sensible.
So it seems that the A321, when it gets to the corners, stays on the right side of the drag curve and the A320 doesn't. I can't make a mental model of how the tiny increment in load factor required for the corners, at an angle of bank of about 25 degrees, can make so much difference to the A320 when it's the same wing.
Can anyone help?
The brochure says that green dot is max lift/drag ratio. At 1g, presumably that is equal to Vimd since lift is constant = weight.
The problem occurs on the corners. If you speed select green dot on the A320, then, when you go round the corners the Vls comes up to meet the selected speed and the engines have to wind up to loads of fuel flow in order to maintain the speed - plainly not sensible.
So it seems that the A321, when it gets to the corners, stays on the right side of the drag curve and the A320 doesn't. I can't make a mental model of how the tiny increment in load factor required for the corners, at an angle of bank of about 25 degrees, can make so much difference to the A320 when it's the same wing.
Can anyone help?
