The weight of an aircraft and its balance are extremely important for operating an aircraft in a safe and efficient manner. When a manufacturer designs an aircraft and the Federal Aviation Administration (FAA) certifies it, the specifications identify the aircraft’s maximum weight and the limits within which it must balance.
The maximum allowable weight is based on the surface area of the wing, and how much lift it will generate at a safe and appropriate airspeed. If a small general aviation airplane, for example, required a takeoff speed of 200 miles per hour (mph) to generate enough lift to support its weight, that would not be safe. Taking off and landing at lower airspeeds is certainly safer than doing so at higher speeds.
Where an aircraft balances is also a significant factor in determining if the aircraft is safe to operate. An aircraft that does not have good balance can exhibit poor maneuverability and controllability, making it difficult or impossible to fly. This could result in an accident, causing damage to the aircraft and injury to the people on board. Safety is the primary reason for concern about an aircraft’s weight and balance.
A secondary reason for concern about weight and balance, but also a very important one, is the efficiency of the aircraft. Improper loading reduces the efficiency of an aircraft from the standpoint of ceiling, maneuverability, rate of climb, speed, and fuel consumption. If an airplane is loaded in such a way that it is extremely nose heavy, higher than normal forces will need to be exerted at the tail to keep the airplane in level flight. The higher than normal forces at the tail will create additional drag, which will require additional engine power and therefore additional fuel flow in order to maintain airspeed.
The most efficient condition for an aircraft is to have the point where it balances fall very close to, or perhaps exactly at, the aircraft’s center of lift. If this were the case, little or no flight control force would be needed to keep the aircraft flying straight and level. In terms of stability and safety, however, this perfectly balanced condition might not be desirable. All of the factors that affect aircraft safety and efficiency, in terms of its weight and balance, are discussed in detail in this chapter.