Airplane Center of Gravity

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There are several methods used to compute the center of gravity, or weight and balance as it is sometimes referred to. The operations manual for the plane you are flying will have a weight and balance section, which should detail computational methods and C.G. (Center of Gravity) limits for that aircraft. Loading the airplane such that its balance point is outside of its proscribed limits invites serious control difficulties that may render the airplane uncontrollable in some flight regimes. Individual planes are different in their specific weight and balance, so information specific to that plane (not type) must be available to the pilot.

V-speeds, or the various critical velocities needed for the airplane you fly, are an important part of flight maneuvers. Stall speeds should be uppermost in your mind as you take off and land. Maneuvering and climb speeds play a crucial part in extracting maximum performance and safety from the airplane. V-speed abbreviations provide a notation standard common to the aviation industry. Here are a few to be concerned with.

Stall speeds
Depending on the plane, there may be a number of different V-speeds associated with different aircraft configurations, from flaps up, to partial flap extension, to full flap extension, gear extended, gear retracted, and anything else that might be useful to the pilot. Here are two modifiers to stall speed that should be of interest.

Vso (Stall speed landing configuration)
Vso is minimum flight speed in the landing configuration. This configuration can vary from plane to plane, but generally is gear down, flaps down, and power off at maximum landing weight. Pilots will often refer to this configuration as “dirty” because of the additional drag caused by having the gear and flaps extended into the airstream. Some pilots use a memory aid here; Vso stall speed with all the “stuff out.”

Vs (Stall speed clean configuration)
Vs is the stall speed for the clean configuration. This means the plane has the flaps (and landing gear, if the plane is a retractable) retracted. Planes normally stall at a higher airspeed in the clean configuration due to the loss of lift resulting from the flaps being retracted. Keep in mind that Vso and Vs stall speeds are for when the plane is in level flight.

Vfe (Flap extension speed)
Vfe refers to the maximum airspeed at which flaps should be in the extended position. If you fly the airplane at speeds that are greater than Vfe with the flaps extended, it is possible to cause physical damage to aircraft structures. The flap connecting rods, rollers, tracks, or the flaps themselves could be bent or ripped from the plane if you exceed Vfe with the flaps extended. The same damage could take place if you extend the flaps above Vfe. The airspeed indicator commonly depicts safe operating airspeeds for the flaps with a white arc.

Vne (Velocity never exceed)
Vne, or the airspeed above which the airplane should never be flown, is a very important number to keep in mind. Indicated by the red line on the airspeed indicator, Vne is the maximum speed an airplane can safely be flown at in smooth air. Vne is determined by the aircraft manufacturer based on engineering design and aircraft testing. Faster speeds than Vne are not recommended as they will eventually result in premature structural failure.

Va (Maneuvering speed)
Maneuvering speed, known as Va, is the airspeed at or below which rapid movements of the controls or turbulence will not cause damage to the aircraft at gross weight. Va is not normally marked on the airspeed indicator because it may change dramatically with lighter weights—typically slower; but may be placarded on the instrument panel. If it is not placarded, you should look it up in the operations manual for the plane you fly. If you should encounter turbulence, you should reduce the airspeed you are flying at to at or below Va. If you fly at these airspeeds, the plane will theoretically stall before it generates loads that are sufficient to damage the aircraft. At speeds above Va, turbulence or rapid control movements may generate g-loads that exceed the structural design of the plane and may damage the plane to the point of structural failure.

Vx (Best angle of climb speed)
The best angle of climb speed for an airplane allows you to gain the greatest amount of altitude within a given distance. Best angle of climb is the airspeed intended by aircraft manufacturers for climbs after a short-field takeoff or when there are obstacles you must clear at the end of the runway. Due to the relatively high angle of attack that is achieved during a climb at Vx, the engine may have a tendency to overheat; for this reason you should avoid prolonged climbs at best angle of climb.

Vy (Best rate of climb)
The best rate of climb will allow the plane to gain the largest amount of altitude over a given period of time. Vy is often recommended by aircraft manufacturers for extended climbs to cruise altitudes. The angle of attack used during a climb at Vy airspeeds is lower than Vx, allowing better airflow through the engine compartment and lower engine operating temperatures. You will notice substantial differences in engine oil temperatures during the summer between flying at Vx or Vy.

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