I am in late so I hope some are still watching. As a 24000 hr instructor pilot, I am amazed at the misinformation given out. Vmc is not affected by weight as much as one might think.. As weight increases, the CofG moves aft. Vmc is a function of the amount of lift that the fin and rudder can produce to offset the assymetric thrust of the engines. When the CofG moves aft, the moment arm is less, therefore the rudder has a shorter moment arm to work with, erga, a higher Vmc. In a Lear, as weight is increased, the CofG moves forward because the weight is added forward of the wing, and the Vmc decreases. Drag from the windmilling prop will increase, erga, a higher Vmc. Beech B200 has a Vmc of 87Kts but with a 4 blade prop, if the prop does not feather, Vmc can be as high as 108 kts. Landing gear will create some drag and have either little or no no effect. The amount of power the operating engine is producing will have a profound effect. Get below Vmc and cannot maintain directional control, reduce power on the operating engine, lower the nose to gain airspeed and increase power as required. The Navajo with BLC vortex generators has a lower Vmc because the generators increase the effectivness of the fin and rudder, therefore a lower Vmc. Counter rotating props reduce the P factor on the right engine to match the left so there is no critical engine. All "traditional" American engines rotate clockwise when viewed from behind. "traditional' British engines rotate the opposite. All American airplanes, the left engine is critical, British the right is critical. Not so much for Vmc as performance. Vmc is always the worst case. Do anything to improve and Vmc will be less. All airplanes with a max take-off weight less than 6000 lbs and a stall speed in landing configuration, when measured at 5000ft ISA(+5C) configured for single engine cruise do not have to demonstrate the ability to climb or maintain altitude on one engine, so be careful. Do not attempt to do something the airplane is not capable of doing.