II.F - Airplane Weight And Balance Flashcards
What is Arm (moment arm)?
The horizontal distance in inches from the reference datum line to the CG of an item.
What is basic empty weight (GAMA)
The standard empty weight plus the weight of optional and special equipment that have been installed
Center of gravity (CG)?
The point about which an aircraft would balance if it were possible to suspend it at that point.
It is the mass center of the aircraft, or the theoretical point at which the entire weight of the aircraft is assumed to be concentrated.
It may be expressed in inches from the reference datum, or in percent of MAC.
It is a 3-dimensional point with longitudinal, lateral, and vertical positioning in the aircraft
Datum (reference datum)?
An imaginary vertical plane or line from which all measurements of arm are taken.
It is established by the manufacturer
Licensed empty weight
Consists of the airframe, engines, unusable fuel, and un-drainable oil plus standard and optional equipment as specified in the equipment list.
Mean aerodynamic chord (MAC)?
The average distance from leading edge to the trailing edge of the wing.
Moment?
A force that causes or tries to cause an object to rotate.
The of weight of an item multiplied by its arm.
Expressed in pond-inches (lb-in)
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.
Station?
A location in the aircraft that is identified by a number designating its distance in inches from the datum, the datum is therefore, identified as station zero
Useful load?
The weight of the pilot(s), passengers, baggage, usable fuel, and drainable oil.
It is the basic empty weight subtracted from the maximum allowable gross weight.
Applies to GA aircraft only
Why does fwd loading make the plane slower?
It is heavier and Nose up trim is required which requires the tail surfaces to produce a greater down force which adds to the wing loading, increasing the total lift required from the wings.
It also requires a higher AOA, which results in more drag and, in turn, produces a higher stalling speed.
Why does aft loading make the plane faster?
With aft loading, the airplane requires less down force allowing for a faster cruise speed because of reduced drag (smaller AOA and less down deflection of stabilizer)
The tail surface is producing less down force, relieving the wing of loading and lift resulting in a lower stall speed
What is the difference between station and arm?
Arm is the distance in inches from the reference datum line to the CG OF AN ITEM
Station is a specific LOCATION on the aircraft that is measured by inches to the datum
