Vmca vs Flap again
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Vmca vs Flap again
Hi
It seems that increase in flap can on some aircraft increase the Vmca. I see this as being for the following reason.
1) Increase Flap = increase lift on live engine due to slipstream and subsequent roll and yaw to dead side.
2) Aileron on dead side defected down to compensate which leads to higher angle of attack and higher drag which requires more rudder to compensate which is now no longer available.
However certification requires the Vmca speed to be no more than 1.2Vs. This would mean a lower Vmca speed with associated lower stall speed with flap increase.
So, is there a more definitive answer or a case of individual aircraft having different chararcteristics.
Cheers
It seems that increase in flap can on some aircraft increase the Vmca. I see this as being for the following reason.
1) Increase Flap = increase lift on live engine due to slipstream and subsequent roll and yaw to dead side.
2) Aileron on dead side defected down to compensate which leads to higher angle of attack and higher drag which requires more rudder to compensate which is now no longer available.
However certification requires the Vmca speed to be no more than 1.2Vs. This would mean a lower Vmca speed with associated lower stall speed with flap increase.
So, is there a more definitive answer or a case of individual aircraft having different chararcteristics.
Cheers
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It seems that increase in flap can on some aircraft increase the Vmca. I see this as being for the following reason.
Increase Flap = increase lift on live engine due to slipstream and subsequent roll and yaw to dead side.
If it's a aileron-limited Vmc, rather than rudder-limited, the increased rolling moment could well increase Vmc.
Aileron on dead side defected down to compensate which leads to higher angle of attack and higher drag which requires more rudder to compensate which is now no longer available.
However certification requires the Vmca speed to be no more than 1.2Vs. This would mean a lower Vmca speed with associated lower stall speed with flap increase.