When is V2 limited by Vmca

[airmiles]

Can someone please help me answer this question?

Which conditions might cause V2 to be limited by Vmca?

Cheers,
Airmiles :ok:

[Rivet gun]

Probably conditions of light weight and high thrust

[Keith.Williams.]

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.

[hedges81]

It would appear that Mr airmiles is revising for his performance exam on June 5th, as are many others including myself. What a bastard eh.

Get off the computer and do some work, or you'll fail!

[RYR-738-JOCKEY]

I would imagine rudder effectiveness has a large impact on Vmca. Small rudder, high Vmca, large rudder, low Vmca. Anyway, that's what I remember being important...