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66 Aircraft
furnishings weights. Thus the fixed useful load weight is calculated for the flight state; and from it the
useful load weight and operating weight are calculated. The gross weight, payload weight, and usable
fuel weight (in standard and auxiliary tanks) complete the weight information for the flight state.
For each weight group, fixed (input) weights can be specified; or weight increments added to the
results of the parametric weight model. The parametric weight model includes technology factors.
Weights of individual elements in a group can be fixed by setting the corresponding technology factor
to zero.
For scaled weights of all components, the AFDD weight models are implemented.
7–12 Weight Statement
Aircraft weight information is stored in a data structure that follows SAWE RP8A Group Weight
Statement format (ref. 3), as outlined in figure 7-2. The asterisks designate extensions of RP8A, for
the purposes of this analysis. Typically only the lowest elements of the hierarchy are specified; higher
elements are obtained by summation. Fixed (input) weight elements are identified in the data structure.
A weight statement data structure exists for each component. The aircraft weight statement is the sum
of the structures from all components.
7–13 References
1) McCormick, B.W.: Aerodynamics, Aeronautics, and Flight Mechanics. New York: John Wiley &
Sons, Second Edition, 1995.
2) Kuethe, A.M.; and Chow, C.-Y.: Foundations of Aerodynamics. New York: John Wiley & Sons,
Fifth Edition, 1998.
3) Weight and Balance Data Reporting Forms for Aircraft (including Rotorcraft), Revision A. Society
of Allied Weight Engineers, Recommended Practice Number 8, June 1997.