When is V2 limited by Vmca
Join Date: Aug 2001
Location: Dorset
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The minimum acceptable value for V2 is V2Min. This must be at least a fixed multiple of the stall speed (the multiple depends on number of engines for turboprops and whether one-engine-out stall speed can be reduced for jets), But V2MIn must also be at least 1.1 Vmca.
So anything that reduces stall speed will reduce V2Min until it reaches 1.1 Vmca. Such factors include low weight and high flap angle. Once V2 has reached 1.1 Vmca this becomes the limiting factor. So further reductions in stall speed have no further effect on V2.
But Vmca increases with any factor that increases thrust. And any increase in Vmca will increase V2Min.
Thrust is proportional to air density, so anything that increases air density will increase Vmca. Such factors include low temperature, low pressure altitude and low humidity.
So in conditions of low weight, high flap angle, low temperature, low pressure altitude and low humidity, V2Min is likely to be limited by Vmca.
So anything that reduces stall speed will reduce V2Min until it reaches 1.1 Vmca. Such factors include low weight and high flap angle. Once V2 has reached 1.1 Vmca this becomes the limiting factor. So further reductions in stall speed have no further effect on V2.
But Vmca increases with any factor that increases thrust. And any increase in Vmca will increase V2Min.
Thrust is proportional to air density, so anything that increases air density will increase Vmca. Such factors include low temperature, low pressure altitude and low humidity.
So in conditions of low weight, high flap angle, low temperature, low pressure altitude and low humidity, V2Min is likely to be limited by Vmca.
