[Graham Boak]

Can you clarify this point, please? Improvements to the Vmc will normally come from changes to the directional stability (yaw) - i.e. larger fin/rudder. Extending the wingtips would improve the lateral stability (roll).

Indeed, increasing the wing area will have reduced the take-off speed, thus increasing any interval between Vunstick and Vmc, thus placing the aircraft more at risk?

Admittedly the two stabilities tend to be linked - in this case yaw leading to roll as one wing "digs in". I can see how a reduction in the rate of roll due to yaw would be beneficial during this stage, but increasing the span wouldn't have been the change of choice to improve Vmc, surely?