SAWE RP-6, 1999: Standard Coordinate Systems for Reporting the Mass Properties of Flight Vehicles

Anyone who has worked in the mass properties field for any length of time knows the problem: one person’s X is another person’s Y. Since the numerical values of the mass properties of an object are entirely dependent on the coordinate system chosen, it is essential that engineers include a precise definition of their coordinate system along with the mass properties data. To minimize confusion and to make the job of defining your coordinate system easier, the SAWE has adopted two standard coordinate systems:

Standard “A” is used for aircraft or any other vehicle which “flies”

Standard “S” is used for objects which orbit the earth

The intent of this Standard is to reduce errors and costs associated with improperly defined coordinate axis systems. Although mass properties engineers will often be forced to use coordinate systems dictated by other parties, the SAWE strongly encourages you to use one of these standards whenever you have the freedom to choose your own coordinate system. The success of a standard of this type depends on its widespread use. You are encouraged to make copies of this standard and to attempt to influence flight dynamics engineers and others at an early stage of the design of a flight vehicle. It is very difficult to change coordinate definitions once a project in underway.