The Vmc Table

The V_MC Table shows us how V_MC can substantially increase or decrease under certain regimes, and furthermore how climb performance is affected.

The "published" V_MC depicted on your airspeed indicator as a red radial line is determined under specific conditions during aircraft certification. It is basically the worst case scenario (highest V_MC). Below is an explanation of those conditions as reprinted from FAASafety.gov.

14 CFR 23 Criteria for Establishing V_MC Under 14 CFR Part 23 small airplane certification rules, the specific set of circumstances required to determine V_MC are as follows:

Maximum available takeoff power
Propeller windmilling in takeoff pitch (or feathered, if equipped with autofeather)
Most unfavorable (aft-most) center of gravity and maximum takeoff weight (or any lesser weight necessary to show Vmc)
Landing gear retracted
Wing and cowl flaps in the takeoff position
Trimmed for takeoff
Airborne, out of ground effect.

Under these conditions, the flight test pilot must be able to:

Stop the turn that results when the critical engine_{(see note)} is suddenly made inoperative within 20 degrees of the original heading, using maximum rudder deflection and a maximum of five degrees angle of bank into the operative engine; and
Thereafter, maintain straight flight with not more than a five degree angle of bank

_{Note on critical engine: If you fly an Aerostar 700P, you have contra-rotating propellers and neither engine is considered critical.}

The V_MC Table

By Doug Moskowitz

The V_MC Table
Factors Affecting V_MC and Climb Performance
YouTube Credit: PrettyFlyForACFI

Factor	Lower V_MC		Increase Rate of Climb
Center of Gravity	FORWARD	Forward CG results in longer moment arm from CG to rudder which produces additional rudder effectiveness to oppose asymmetric turning tendency	AFT	Aft CG requires less elevator downward force and therefore less overall downward force on the aircraft
Angle of Bank Into Operative Engine	STEEPER	Steeper bank produces additional horizontal component of lift to assist rudder in opposing asymmetric turning tendency	SHALLOWER 3˚- 5˚	Although there is a loss of vertical component of lift, the bank angle allows the aircraft to be aligned with direction of flight (zero slideslip) and less drag
Weight	HEAVIER (if banking)	Heavier weight in level flight requires additional lift which in turn produces more horizontal component of lift to oppose asymmetric turning tendency	LIGHTER (if banking)	Less weight results in additional excess lift
Power	LESS	Less power from operative engine’s offset center of thrust produces less asymmetric turning tendency	MORE	More power results in additional excess thrust
Density Altitude	LESS	Lower density altitude results in less engine power resulting in less asymmetric turning tendency while rudder remains nearly equally effective	MORE	Improved performance of all aerodynamic surfaces
Drag Devices	EXTENDED	Drag devices interrupt airflow of operative engine and also produce opposite asymmetric drag against asymmetric turning tendency	RETRACTED	Less drag improves performance
Windmilling Propeller	FEATHERED	Reduces asymmetric drag and therefore increases rudder effectiveness	FEATHERED	Less drag improves performance
Critical Engine	OPERATING	Lowers adverse effects of P-factor, accelerated slipstream, torque	OPERATING	Lowers adverse effects of P-factor, accelerated slipstream, torque

The V_MC Table