475. Design and Development of a Balance Computer for the C141A (Starlifter)
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Paper
Abstract
This paper presents the various designs considered in the development of a new type balance computer for the Lockheed Starlifter. The development program was initiated after Military Air Transport System personnel had expressed dissatisfaction with the accuracy and utility of the standard balance computer.
During the development phase of the C-141A balance computer, 4 different designs were considered. All designs departed from the compartment centroid concept for cargo loading in an attempt to improve overall computer accuracy.
Design $#$1 consists of a plotting board which indicates gross weight on a vertical scale, and index units on a horizontal scale. These scales provide information through the zero fuel gross weight condition of the loading or load planning. The information thus obtained is transferred to the back side of the rule which displays a gross weight vs. % MAC graph. Over this graph is a movable cursor displaying fuel loading curves. By using this cursor in conjunction with the gross weight vs. % MAC graph, instant graphic portrayal of airplane center of gravity travel (caused by fuel burn off and fuel shift) for the complete flight is provided.
The second design consists of a mechanical nomograph which computes both gross weight and center of gravity. This computer uses 2 cursors. One indicates gross weight; the other indicates index units. The two cursors are connected by a spring which carries a pointer. The pointer travels in a slot graduated in % MAC, and gives C.G. readings for any gross weight and index setting.
Design $#$3 offers innovations in that it is a circular computer employing ‘windows’ for center of gravity readings as used in the MB-9 navigational computer. The fourth design attempts to combine the most desirable features of the first and third designs. This computer is circular and incorporates fuel loading information and graphic center of gravity display as carried on the plotting board design.
The fourth design attempts to combine the most desirable features of the first and third designs. This computer is circular and incorporates fuel loading information and graphic center of gravity display as carried on the plotting board design.
Design $#$3 has been tentatively selected by the Air Force. The small size and low procurement cost were deciding factors in the selection.