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The FAA’s Pilot’s Handbook of Aero–nau- tical Knowledge, page 5-43, tells us:
The rearward CG limit of an aircraft is determined largely by considerations of stability. The original airworthiness require- ments for a type certificate specify that an aircraft in flight at a certain speed dampens out the vertical displacement of the nose within a certain number of oscillations. An aircraft loaded too far rearward may not do this. Instead, when the nose is momentarily pulled up, it may alternately climb and dive becoming steeper with each oscillation. This instability is not only uncomfortable to oc- cupants, but it could even become dangerous by making the aircraft unmanageable under certain conditions.
A heavily loaded airplane is usually loaded further toward the aft end of the envelope than many pilots are used to. Passengers and baggage that make up the extra weight that drives the gross weight upward are usually added to the aft part of the cabin, moving the center of grav- ity toward the aft end of the weight and balance envelope. In some airplanes, the CG moves rearward as fuel is burned; in some types, the CG change is negligible, while in others the CG may actually move forward under some conditions. This is the sort of type-specific knowledge you should have learned when you transi- tioned into the airplane. If you don’t know the characteristics of the airplane you fly, now’s the time to figure it out.
Taking Off
Center of gravity distribution can have a significant impact on takeoff handling and performance. If the CG is forward, it will take more control force to establish the liftoff and initial climb attitudes. Give the controls the input you’d do at farther aft loads, and the airplane won’t climb as it should. The increase in control deflec- tion necessary to overcome the breakout forces, and the higher angle of attack for a given pitch attitude that results, increase drag, increase the ground roll distance and reduce the initial climb rate.
If the CG is toward the rear of the envelope, the controls will be lighter. The airplane will tend to over-rotate and pitch up excessively, increasing angle of attack and making a takeoff stall more likely. The airplane will lift off sooner and climb faster, but only if the pilot puts more subtle effort into flying the proper pitch attitudes.
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TWIN & TURBINE • 19