商照Ground Lesson No 5 - Weight and Balance

商照飞行员地面理论课程

Ground lesson .5

商照飞行员地面理论课程

商照飞行员地面理论课程

Weight and Flight Performance A heavier gross weight will result in: Longer T/O/LDG roll, shallower climb, faster touchdown speed, slow acceleration/deceleration Increased retarding force (drag and ground friction)

Climb and cruise performance is reduced which can lead to: Overheating in climbs, added wear on engine, increased fuel, slower cruise, reduced range

商照飞行员地面理论课程

Weight and Structure Structural failures which result from overloading may be catastrophic but they often affect structure progressively making it difficult to detect/repair An airplane is certified to withstand certain loads on its structure based on the category

The results of routine overloading are cumulative and may result in failure later during normal ops

As long as gross weight and load factors limits are observed, the total load will remain in limits If the max gross weight is exceeded, load factors within the load factor limits can cause damage A structure under 3 G’s must withstand an added load of 300lbs for every 100lb weight increase

商照飞行员地面理论课程

CG Limits the specified forward and aft points within which the CG must be located during flight. These limits are indicated on pertinent aircraft specifications.

商照飞行员地面理论课程

An airplane with forward loading “Heavier” and consequently slower than the same airplane with a further aft CG;

Requires a higher AOA, which results in more drag and, in turn, produces a higher stalling speed. The airplane is more controllable (Longer arm making the elevator more effective).

Nose up trim is required which requires the tail surfaces to produce a greater download adding to the wing loading and total lift required from the wing to maintain altitude.

商照飞行员地面理论课程

With aft loading, the airplane requires less download allowing for a faster cruise speed. Faster cruise because of reduced drag (smaller AOA and less down deflection of stabilizer). The tail surface is producing less down load, relieving the wing of loading and lift results in a lower stall speed. Recovery from a stall becomes progressively more difficult as it moves aft.

商照飞行员地面理论课程

Load Factor - Force applied to an airplane to deflect its flight from a straight line produces a stress on its structure. Load factor is the ratio of the total air load acting on the airplane to the gross weight of the airplane.

N=L/W

N = Load Factor L = lift W = Weight

商照飞行员地面理论课程

Load factor are important to the pilot for 2 distinct reasons Because of the obviously dangerous overload that is possible for a pilot to impose on the structure Because an increased load factor increases the stall speed and makes stalls possible at seemingly safe speeds

商照飞行员地面理论课程

In a constant altitude, coordinated turn in any aircraft, the load factor is the result of two forces: centrifugal force and gravity. For any given bank angle, the rate of turn varies with the airspeed—the higher the speed, the slower the rate

of turn. This compensates for added centrifugal force, allowing the load factor to remain the same.

商照飞行员地面理论课程

This chart reveals an important fact about turns—the load factor increases at a terrific rate after a bank has reached 45°or 50° . The load factor for any aircraft in a 60°bank is 2 Gs. The load factor in an 80°bank is 5.76 Gs. The wing must produce lift equal to these load factors if altitude is to be maintained.

商照飞行员地面理论课程

Standard empty weight (GAMA)—aircraft weight that consists of the airframe, engines, and all items of operating equipment that have fixed locations and are permanently installed in the aircraft, including fixed ballast, hydraulic fluid, unusable fuel, and full engine oil.

Basic empty weight (GAMA)—the standard empty weight plus the weight of optional and special equipment that have been installed.Licensed empty weight—the empty weight that consists of the airframe, engine(s), unusable fuel, and undrainable oil plus standard and optional equipment as specified in the equipment list. Some manufacturers used this term prior to GAMA standardization.

商照飞行员地面理论课程

Standard weights—established weights for numerous items involved in weight and balance computations. These weights should not be used if actual weights are available. Some of the standard weights are:Gasoline ............................................... 6 lb/US gal Jet A, Jet A-1 .................................... 6.8 lb/US gal Jet B ...................................................6.5 lb/US gal Oil ......................................................7.5 lb/US gal Water .....................................................8.35 lb/US gal

商照飞行员地面理论课程

Payload (GAMA)—the weight of occupants, cargo, and baggage. Useful load—the weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation (GA) aircraft only.

商照飞行员地面理论课程

Maximum zero fuel weight (GAMA)—the maximum weight, exclusive of usable fuel. Maximum ramp weight—the total weight of a loaded aircraft, and includes all fuel. It is greater than the takeoff weight due to the fuel that will be burned during the taxi and run-up operations. Ramp weight may also be referred to as taxi weight. Maximum takeoff weight—the maximum allowable weight for takeoff. Maximum landing weight—the greatest weight that an aircraft normally is allowed to have at landing.

商照飞行员地面理论课程

Weight Shift

商照飞行员地面理论课程

Weight Shift

商照飞行员地面理论课程

Adding Weight

商照飞行员地面理论课程

Subtracting Weight

商照飞行员地面理论课程

Pilots must ensure that the CG is and remains within approved limits for all phases of a flight.

Additional information on weight, balance, CG, and aircraft stability can be found in FAA-H-8083-1 Aircraft Weight and Balance Handbook

商照飞行员地面理论课程

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