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Difference between revisions of "Velocity - Minimum Control (air) (Vmca)"

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<BIG>'''V<sub>minimum control air</sub>'''</BIG>
 
<BIG>'''V<sub>minimum control air</sub>'''</BIG>
 
==Definition==
 
==Definition==
{{Definition|Notion=Vmca|Definition=the minimum control speed in the air, with one engine inoperative (critical engine on two engine airplanes), operating engine(s) takeoff power, maximum of 5 degrees bank into the good engine(s).}}
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{{Definition|Notion=Vmca|Definition=the minimum control speed in the air, with one engine inoperative (critical engine on two engine aerolanes), operating engine(s) takeoff power, maximum of 5 degrees bank into the good engine(s).}}
 +
 
 
==V<sub>mca</sub> / Derated Thrust Relationship==
 
==V<sub>mca</sub> / Derated Thrust Relationship==
 
To maintain directional control with an inoperative engine, the rudder must be deflected to counteract the adverse yaw. The force that can generated by the rudder is dependent upon the size of the rudder, the amount that the rudder can be deflected and the speed of the airflow across the rudder surface.  
 
To maintain directional control with an inoperative engine, the rudder must be deflected to counteract the adverse yaw. The force that can generated by the rudder is dependent upon the size of the rudder, the amount that the rudder can be deflected and the speed of the airflow across the rudder surface.  

Revision as of 00:34, 19 November 2014

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Vminimum control air

Definition

Vmca is defined as the minimum control speed in the air, with one engine inoperative (critical engine on two engine aerolanes), operating engine(s) takeoff power, maximum of 5 degrees bank into the good engine(s).


Vmca / Derated Thrust Relationship

To maintain directional control with an inoperative engine, the rudder must be deflected to counteract the adverse yaw. The force that can generated by the rudder is dependent upon the size of the rudder, the amount that the rudder can be deflected and the speed of the airflow across the rudder surface.

In the case of an aircraft fitted with engines that can be derated for takeoff, the reduction in thrust will result in a corresponding reduction in the amount of yaw induced should an engine fail. As the rudder size and deflection capability remain constant, the amount of force required to counter that yaw can be generated at a lower airspeed than would be case during a full thrust takeoff. This results in a reduction in Vmca.

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