The Tank Drain Simulation program was developed using current computer technology to generate vehicle
flight center of gravity versus fuel consumption data. This program was written in the early 1970s by
the General Dynamics Convair Division Cruise Missile Mass Properties group and has been modified
through the years for improved accuracy, simplification, and applications to unique vehicles. The
current version uses the resources of the Convair Division computer system to generate a vehicle flight
graph.

The program simulates internal fuel tank geometries to compute longitudinal center of gravity for the
fuel volume of each cruise missile tank. Using FORTRAN IV computer language, the internal tank geometries
are defined by the basic equations from the Society of Allied Weight Engineers handbook. Individual tanks
are represented by individual subroutines, which are prompted by tank identifiers. Output data issued as
input for the Center of Gravity History program. This program is a plotting routine that plots weight
versus center of gravity as a function of fuel consumption.

The cruise missile has a complex geometric arrangement of fuel tanks. A combination of vehicle size and
performance requirements necessitates any available missile space to be used as fuel volume. This results
in a mass properties requirement to provide 1ongitudinal center of gravity accountability as a function
of vehicle weight, flight time, and varying attitudes. The Tank Drain Simulation/Center of Gravity
History program package verifies that stability control limits are not exceeded.