For example, the pilot may load the aircraft within the allowable takeoff weight limit, then find a CG limit has been exceeded. In extreme cases, a CG location that is forward of the forward limit may result in nose heaviness to the extent that it may be difficult or impossible to flare for landing. Step 4 - To determine the CG, divide the total moment by the total weight. The datum is an arbitrary point, established by airplane designers, which may vary in location between different airplanes. A restricted forward center-of-gravity limit is also specified to assure that sufficient elevator deflection is available at minimum airspeed. If the weight of any object or component is multiplied by the distance from the datum (arm), the product is the moment. During flight, fuel burn is normally the only weight change that takes place. Another undesirable characteristic produced from tail-heavy loading is that it produces very light control forces. Figure 9: Sample weight and balance using an airplane with a published zero fuel weight. US Department of Defense 2005. As the CG moves aft, a less stable condition occurs, which decreases the ability of the airplane to right itself after maneuvering or turbulence. The force of gravity continually attempts to pull the airplane down toward earth. Simple and orderly procedures, based on sound principles, have been devised by airplane manufacturers for the determination of loading conditions. The location of the object or part is often referred to as the station. Dictionary of Military and Associated Terms. Preflight planning should include a check of performance charts to determine if the airplane's weight may contribute to hazardous flight operations. In this example, the total weight of the airplane less fuel is 4,240 pounds, which is under the zero fuel weight of 4,400 pounds. The weight of the airplane can be changed by altering the fuel load. The force of lift is the only force that counteracts weight and sustains the airplane in flight. This can be done because the CG will shift a distance that is proportional to the distance the weight is shifted. CFI Notebook, All rights reserved. The same steps should be followed as in the computational method except the graphs provided will calculate the moments and allow the pilot to determine if the airplane is loaded within limits. The pilot of an airplane should always be aware of the consequences of overloading. NOTE: The weight and balance records for a particular airplane will provide the empty weight and moment as well as the information on the arm distance. All other moments were determined in the same way.) There are various methods for determining the loaded weight and center of gravity of an aircraft. To determine the loaded weight and CG, follow these steps. Location of the CG with reference to the lateral axis is also important. The equipment list must be updated, if appropriate. Determine the location of the CG if 100 pounds is removed from station 150. The advanced tools of the editor will direct you through the editable PDF template. Balance, stability, and center of gravity. In this sample loading problem, the airplane is loaded within limits. The aft center-of-gravity limit is the most rearward position at which the CG can be located for the most critical maneuver or operation. The pilot must also consider the consequences of an overweight airplane if an emergency condition arises. If the weight is greater than the lift generated, the airplane may be incapable of flight. These are usually small airplanes with the seats, fuel, and baggage areas located near the CG limit. Loading in a tail-heavy condition has a most serious effect upon longitudinal stability, and can reduce the airplane's capability to recover from stalls and spins. Dictionary, Encyclopedia and Thesaurus - The Free Dictionary, the webmaster's page for free fun content, weight (something) against (someone or something). Remember that fuel weighs 6 pounds per gallon. The information and limitations are contained in tables provided by the manufacturer. The downward force of the weight can be determined by multiplying 50 pounds by 100 inches, which produces a moment of 5,000 lb-in. For the B1900D, we have a weight and balance form that we fill in manually before each leg. ///////////////////////////////// { // must always be within limits, however, depending where in the allowable range the C.G. The airplane owner or operator should make certain that up-to-date information is available in the airplane for the pilot's use, and should ensure that appropriate entries are made in the airplane records when repairs or modifications have been accomplished. Adverse balance conditions affect airplane flight characteristics in much the same manner as those mentioned for an excess weight condition. Operating an airplane above the maximum weight limitation compromises the structural integrity of the airplane and adversely affects its performance. Determining loaded weight and center of gravity. Contributing to the accident was the external load and the downwind takeoff, The pilot's inadequate preflight planning, which resulted in a takeoff with the airplane's center of gravity aft of its limit and led the airplane to exceed its critical angle of attack and experience an aerodynamic stall during the initial climb. These factors may require a reduction in weight prior to flight. Balance refers to the location of the center of gravity (CG) of an airplane, and is important to airplane stability and safety in flight. // COPYRIGHT DATE FUNCTION // The addition or removal of cargo presents a CG change problem that must be calculated before flight. For each item of weight existing to the left of the fuselage centerline, there is an equal weight existing at a corresponding location on the right. To learn more on how to complete the weight and balance sheet below go to The pilot should be able to determine the minimum load shift needed to make the aircraft safe for flight. Although an airplane is certified for a specified maximum gross takeoff weight, it will not safely take off with this load under all conditions. The pilot must use these procedures and exercise good judgment. copyrightDate(); // Excessive weight in itself reduces the safety margins available to the pilot, and becomes even more hazardous when other performance-reducing factors are combined with overweight. When the object or component is located aft of the datum, it is measured in positive inches; if located forward of the datum, it is measured as negative inches, or minus inches. Calculating weight and balance is a skill that will pay dividends when you graduate from the training environment and start planning trips in the real world: friends, suitcases, and all. falls will effect performance [, Longer takeoff distance (more airflow required to provide more force to lift heavy nose), High stall speeds (more airflow deflection of the elevator required to maintain altitude at slower airspeeds resulting in high AOAs), As the CG moves rearward (towards the tail), the aircraft becomes more and more dynamically unstable, The tail will feel heavy to compensate which requires additional nose down force, Should the aircraft stall or spin, it will be much more difficult to recover without the nose drop to increase airspeed, The center of gravity for tailwheel aircraft are typically located behind the pilot, As discussed, the aircraft rotates about the center of gravity meaning if directional control is lost due to erratic inputs or simply poor technique as airspeed decreases control surface effectiveness, the tail will want to come off to the side, This can result in a ground loop where the pilot is unable to stop the center of gravity taking over directional control for the pilot/control surfaces, It is important to understand that an aircraft's weight is concentrated at the CG and the aerodynamic forces of lift occur at the CP, When the CG is forward of the CP, there is a natural tendency for the aircraft to want to pitch nose down, If the CP is forward of the CG, a nose up pitching moment is created, Therefore, designers fix the aft limit of the CG forward of the CP for the corresponding flight speed in order to retain flight equilibrium, Aircraft weight must be distributed in accordance with the design described in the aircraft's flight manual. If starting with a known aircraft weight, CG, and total moments, calculate the new CG (after the weight shift) by dividing the new total moments by the total aircraft weight. Therefore, to assure that the lift generated is sufficient to counteract weight, loading the airplane beyond the manufacturer's recommended weight must be avoided. In many modern airplanes, it is not possible to fill all seats, baggage compartments, and fuel tanks, and still remain within the approved weight and balance limits. Remember "weight x arm = moment.". Placement of baggage and cargo items determines the CG location. Another method for determining the loaded weight and CG is the use of graphs provided by the manufacturers. The total moments, however, do change in relation and proportion to the direction and distance the weight is moved. The center of gravity is a point at which an airplane would balance if it were suspended at that point. Weight and Balance Basics Aircraft performance and handling characteristics can be significantly affected by weight and center of gravity limits. var year = today.getFullYear() // It might be advantageous at this point to review and discuss some of the basic principles of how weight and balance can be determined. Didn't find something you're looking for? If the lines intersect within the envelope, the airplane is loaded within limits. Figure 9 is a sample of weight and balance computation using an airplane with a zero fuel weight. Conversely, if the CG is displaced too far aft on the longitudinal axis, a tail-heavy condition will result. Then draw a line straight down to determine the moment. For the B200 our COM says to use the weight and balance from Jeppesen Flitestar, but being in Africa flying in remote areas, we sometimes can't print those W&B Reports. ΔCG (change of CG)/Distance weight is shifted. For some airplanes the CG limits, both fore and aft, may be specified to vary as gross weight changes. The pilot should realize that if the CG of an airplane is displaced too far forward on the longitudinal axis, a nose-heavy condition will result.