This paper presents the philosophy for the function and responsibility of the preliminary design weight engineering in aircraft conversion and modification design.

With the increasing demand for new airborne systems brought about by advancing avionics technology, a need for special manned aircraft types has been created. The inflationary cost of new aircraft developed has made it cost-effective to modify existing or obsolescent aircraft into new roles. Since weight establishes, to a large extent, the range; endurance and performance of aircraft, it is necessary to develop quick reaction pre-design weight estimation techniques for modification and conversion programs. In addition, methods for estimating moment of inertia and mass distributions must be available to support the structural performance analysis groups.